La Metallurgia Italiana, n. 11-12 novembre/dicembre 2020 by aimnet3

Metallurgia Italiana

International Journal of the Italian Association for Metallurgy

n. 11-12 novembre/dicembre 2020 Organo ufficiale dellâ&#x20AC;&#x2122;Associazione Italiana di Metallurgia. Rivista fondata nel 1909

La Metallurgia Italiana International Journal of the Italian Association for Metallurgy Organo ufficiale dell’Associazione Italiana di Metallurgia. House organ of AIM Italian Association for Metallurgy. Rivista fondata nel 1909

Direttore responsabile/Chief editor: Mario Cusolito Direttore vicario/Deputy director: Gianangelo Camona Comitato scientifico/Editorial panel: Livio Battezzati, Christian Bernhard, Massimiliano Bestetti, Wolfgang Bleck, Franco Bonollo, Bruno Buchmayr, Enrique Mariano Castrodeza, Emanuela Cerri, Lorella Ceschini, Mario Conserva, Vladislav Deev, Augusto Di Gianfrancesco, Bernd Kleimt, Carlo Mapelli, Jean Denis Mithieux, Marco Ormellese, Massimo Pellizzari, Giorgio Poli, Pedro Dolabella Portella, Barbara Previtali, Evgeny S. Prusov, Emilio Ramous, Roberto Roberti, Dieter Senk, Du Sichen, Karl-Hermann Tacke, Stefano Trasatti Segreteria di redazione/Editorial secretary: Valeria Scarano Comitato di redazione/Editorial committee: Federica Bassani, Gianangelo Camona, Mario Cusolito, Carlo Mapelli, Federico Mazzolari, Valeria Scarano Direzione e redazione/Editorial and executive office: AIM - Via F. Turati 8 - 20121 Milano tel. 02 76 02 11 32 - fax 02 76 02 05 51 met@aimnet.it - www.aimnet.it

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Editoriale / Editorial La pandemia

a cura di: Ing. Federico Mazzolari - Presidente AIM............................................................................ pag.04

Memorie scientifiche / Scientific papers Relevant properties of a (liquid) powder for continuous casting of steel

R. Carli, M. Alloni, S. Casagrande....................................................................................................... pag.06

Alleviation of internal cracks in continuous casting bloom of steel 100Cr6 induced by soft reduction process

N. Zong, S. Ma, W. Sun, T. Jing, Z. Lu.................................................................................................. pag.14

n. 11-12 novembre/dicembre 2020 Anno 112 - ISSN 0026-0843

The Effect of Minor Element Addition on Thin Walled Brass Casting

N. Tamsü Selli, C. Imer Ozgu.............................................................................................................. pag.23

Study on duplex process with a single converter

A. Zhao, L. Zhang, Y. Fu, H. Long, N. Ali, Z. Zhou, Z.n Nie, C. Zhang................................................... pag.36

Attualità industriale / Industry news

La corrosione microbiologica negli acciai inossidabili: una mini-review

a cura di: D. Lega , M. Romitelli........................................................................................................... pag.45

indice

Scenari / Experts' Corner

High strength fasteners. Requirements, material selection, heat treatments and properties

edited by: Seppo Härkönen, Finland.................................................................................................. pag.57

Pubbliredazionale............................................................................................... pag.64 Atti e notizie / AIM news

Eventi AIM / AIM events ....................................................................................... pag.71 Comitati tecnici / Study groups........................................................................... pag.72 Normativa / Standards ........................................................................................... pag.75 Indice analitico / Analytic Index.......................................................................... pag.78 Indice autori / Author Index.................................................................................. pag.88

editoriale - editorial

LA PANDEMIA

Metallurgia non fa rima con pandemia. AIM, pur nel suo piccolo, si è attivata tempestivamente per contrastare quella che in febbraio sembrava essere una epidemia: dal 23 febbraio anche sulla scorta della imminente chiusura delle scuole abbiamo messo in pratica lo smart working, e devo

Ing. Federico Mazzolari Presidente AIM

dire con successo, grazie alla disponibilità di tutti. Rapidamente abbiamo capito che il nostro ricco programma per il 2020 sarebbe stato rivoluzionato, francamente all’inizio non si pensava a tal punto da non riuscire a realizzare nessun evento in presenza se non quello ante Covid di gennaio della Winter School of Metallurgy organizzato tramite Comet e relativo alla Metal additive manufacturing. Un programma che oggi in pre-chiusura vedrà realizzati 18 eventi, 17 dei quali via Web.

“

Per noi di AIM, e non solo, una speranza, che dalla primavera del 2021 si torni ad una quasi-normale attività gestibile in sicurezza. Forse siamo ancora in tempo per salvare il mondo. Ing. Federico Mazzolari

AIM dopo il primo shock di marzo ha reagito inventandosi un proprio modo di interagire con gli utenti chiamato FaReTra - Fair remote training – che Carlo Mapelli ha avuto la felice intuizione di battezzare e lanciare operativamente già da aprile per il CS Acciai ad alto tenore di carbonio. Posso dire che AIM è stata reattiva e grazie ad un impegno molto focalizzato del proprio personale ha salvato l’attività di un’annata imprevedibilmente difficile. Allargando la visuale oltre la nostra attività la situazione si presenta molto critica e forse stiamo perdendo un ultimo autobus relativo alla sostenibilità ambientale. L’anno scorso accennavo al problema della competitività ambientale quale necessità per il settore e più in generale per il nostro pianeta. Ogni programma di miglioramento ambientale transita attraverso sviluppo, ricerca e messa in atto di investimenti colossali che non possono essere che sostenuti dalla Comunità, ora guidata da una Presidente, Ursula von der Leyen, che si dimostra molto attenta ai problemi di prospettiva ambientale

La Metallurgia Italiana - novembre/dicembre 2020

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editoriale - editorial

che possono essere risolti solo dando sostenibilità allo sviluppo. L’Europa ha il ruolo di apripista al resto del mondo. Il dilemma ovvero il problema che si presenta è il seguente: quei mille miliardi di euro che sarebbero serviti a salvare l’ambiente – la vita delle generazioni future – oggi sono stati destinati a salvarci dalla pandemia che potrebbe condurci ad una crisi economica devastante e a milioni di vittime nel giro di un anno. Sì, ma non possiamo procrastinare il programma ambientale altrettanto importante anche se in una prospettiva a 20 anni. La mia aspettativa è che si riesca con uno sforzo finanziario all’apparenza non sostenibile di dare prospettive alle generazioni a partire da qui a trent’anni anche se a costo di sacrifici sul piano della qualità materiale della vita. In altre parole i genitori e i nonni devono fare qualcosa di importante anche a costo di privazioni per il futuro dei propri nipoti. Per noi di AIM, e non solo, una speranza, che dalla primavera del 2021 si torni ad una quasi-normale attività gestibile in sicurezza. Forse siamo ancora in tempo per salvare il mondo.

La Metallurgia Italiana - November/December 2020

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Memorie scientifiche - Colata continua

Relevant properties of a (liquid) powder for continuous casting of steel R. Carli, M. Alloni, S. Casagrande Present paper concerns noteworthy effort which has been conveyed in defining characteristics of conceptual liquid

powder, more precisely a liquid casting powder. Expanding the idea of mixing properties of liquids and casting powders, a new material composed by a solid-liquid dispersion of conveniently formulated continuous casting powder in

synthetic oil has been conceived. Aiming to prove that a material with higher load of solid component behaves like a

liquid, few lab samples with different proportions between solid and liquid phases have been formulated and extensively characterized.

Rheological properties of this liquid casting powder samples proved those have to be considered as liquid with well-defined real-world technological properties. In particular, it has been pointed out that this material shows a specific viscosity which is connected to its solid component load through Robinson equation and its rheological behavior is described by Bingham constitutive equation.

Eventually a liquid casting powder is working as a liquid slag of a casting powder pumped at room temperature into the mold and, in comparison with natural/mineral or synthetic oil used in open steel stream, it is adding effective lubrica-

tion and control capability of heat transfer between strand and mold wall, resulting in mild homogenous cooling and

in a significant increase of effective length of the mold. Indeed a tremendous improvement of general casting process quality has been observed.

KEYWORDS: MOLD FLUX, CASTING POWDER, LUBRICANT, NON-NEWTONIAN FLUID, BINGHAM, STEEL CASTING, SOLID-LIQUID DISPERSION. INTRODUCTION

The expression liquid powder referred to lubrication of ste-

el forming shell in a continuous casting machine has been used for the very first time by Prof. Alan Cramb during his plenary lecture at the 5th European Continuous Casting Conference held in Nice (F) in June 2005, when trying to

stress the importance of a very innovative attitude in field

of steel casting he said “we do not know what in the future… maybe a liquid powder for continuous casting…”.

The idea of using a liquid slag to lubricate a strand in a slab

caster has been studied and realized by some researchers

Riccardo Carli, Marco Alloni, Simone Casagrande Prosimet Spa, Filago, Italy, 24040

from POSCO 1) . However, a more viable and radical so-

lution has not yet been identified, none of existing materials correspond to the set of characteristics of a conceptual liquid powder or better liquid casting powder. In first approximation, such an object should be a liquid bearing

some feature of a powder, more precisely in the present

case an oil used for continuous casting bearing some cha-

La Metallurgia Italiana - novembre/dicembre 2020

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Scientific papers - Continuous casting racteristics of a mold flux. A rapid survey of the attributes of

a typical mold flux points to few performance carrying traits

which cannot be transferred to a standard oil for continuous

any extant standard products used in continuous casting of steel.

casting, mainly inflammability, apparent bulk density, CO2

TECHNOLOGICAL

aningless talking about melting of a liquid casting powder.

Attempting to figure out what a liquid powder looks like in

and total Carbon contents. Moreover, it sounds really me-

POWDER

CHARACTERISTICS

LIQUID

It seems that a substantial preliminary approach to possible

the context of steel continuous casting, one can analyse

conceivable characteristics. Starting from this task, present

nological field as it follows from a Value Innovation metho-

design of a liquid powder compels a broader definition of its

paper deals with description of main characteristics of a the-

properties of existing liquids and powders used in this tech-

dological approach 2). Thus, the exercise consists in ranking

oretical liquid casting powder, consequently trying to pro-

common elements of perceived quality of those products,

ned set of properties is actually possible, resulting in a new

In Figure 1, results of such analysis for three different mate-

ve that realization of an object complaining with a well-defi-

technological-intensive material. It will be shown that such

a wonder product performs in a way not comparable with

to evidence their relative strength and weakness. rials, are depicted.

Fig.1 - Elements of perceived quality for loose powder mold flux (black dots), granular mold flux (grey dots) and oil for continuous casting (white dots). These results are based on data collected with a simple que-

stionnaire distributed among technical personnel of steel casting department of some steel plants, where at least two

of products under scrutiny are used. It is possible to infer that a casting powder in granular form is by far showing better perceived quality than the same product in fine powder

only for undemanding commercial steel grades.

It seems natural to conclude that a substantial value-inno-

vated material should exhibit whole set of perceived quality elements laying on dashed bold line in Figure 1, concep-

tually drawn simply mixing quality of casting powder and oil.

form. This is very a well-known fact in the field, somehow

Expanding this idea of mixing, a new product, composed by

gree of dependability it can be deduced that perceived qua-

nuous casting powder in synthetic oil based on fatty acids

of a casting powder for all considered elements but cast se-

the realization of a product featuring characteristics of both

validating this approach. Therefore, with a reasonable de-

a solid-liquid dispersion of conveniently formulated conti-

lity of oil used in continuous casting is higher than the one

glyceric esters, has been conceived. Aim of this attempt is

mis quality. Generally casting with oil is considered suitable

oil and continuous casting powder, to be used as lubricant

La Metallurgia Italiana - November/December 2020

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Memorie scientifiche - Colata continua in steel casting process.

have been ball-milled for 30 min in twin agate mortars with

a bench mechanical orbiting device (Philips, MINIMILL) or

EXPERIMENTAL

Following the method described elsewhere

3,4

), some sam-

ples based on specific raw materials have been prepared. Namely, Al2O3 (Nabalox® 104RA, alpha- Al2O3 98%, Al2O3

99.8%), CaF2 (Fluospar, Acid Grade, CaF2 > 95, ISO5439, structure controlled by XRD, Brüker D2 PHASER), CaSiO3

(Wollastonite, Industrial Grade, CaO 44÷45 %, structu-

re controlled by XRD, Brüker D2 PHASER), Na2CO3 (Sig-

ma-Aldrich, anhydrous, free-flowing, Redi-Dri™, ACS reagent, Na2CO3 ≥99.5%), have been selected. These materials

for 15 min in a Titanium Carbide eccentric mechanical mill (Hertzog HSM100H), then sieved with mechanical vibrating

sieving system (Retsch AS200), collecting fraction below 60µm.

Few hundred grams of Powder Component, PC, has been

prepared with these milled and sieved raw materials simply by mixing for two hours in a rotatory drum bench mixer. Final composition of the mix has been determined by XRF analysis (performed with Brüker S8 TIGER) and it’s reported in Table 1.

Tab.1 - Chemical analyses of Powder Component. Ni

Weight %

CaO

38.0

SiO2

44.0

Na2O+K2O

6.5

Al2O3

1.2

5.5

Basicity

0.9

Bulk Density‡

1.94 ±0.06 (kg/l)

Bulk Density, BD, is marked with “‡” symbol to indicate that parameter poses quite an issue in evaluation for a mixture

of different solids. Value reported is the measured density

ther number crunching has been performed by in-house-developed Python routines.

of a high pressure casted pill of PC. This value has been then

PHYSICAL-CHEMICAL CHARACTERISTICS OF LIQUID

mineral components N as BD‡=

Viscosity

validated by calculating molar fraction weighted sum of all .

Different amounts of PC have been dispersed in a poly-α-olefin oil, PAO, (Mobil SHC 500) with lab scale high peripheral

speed colloidal mill (IKA, MK2000/05) for 5 min. 5 different

samples have been prepared with different PC load, A: 60%

wt./wt., B: 50% wt./wt., C: 40% wt./wt., D: 30% wt./wt., E: 20% wt./wt..

POWDER

As stated above, it has been essential to study parameters

affecting viscosity of dispersions trying to obtain a liquid with suitable properties, in particular fluidity. Investigation

on complexity of solid-liquid dispersion systems requires in depth theoretical interpretation of all relevant interaction forces affecting status of dispersed particles 6). It has been

Bearing in mind that hypothetical limit to consider a liquid

pointed out that most essential elements in describing the

load preserving suitable fluidity for effective and stable pu-

me concentration of dispersed particles or solid volume

zed by research rheometer Anton-Paar MCR302. Measure-

and ρp is bulk density of dispersed particles (BD‡) and void

as a liquid powder can be a mix with at least 50% wt./wt. PC

mping, rheology of these samples has been fully characteriments were performed @ 298 K, consistently with standard

procedure ASTM D2196-15 ). Raw data processing was 5

executed with Anton-Paar RHEOCompass software. Fur-

La Metallurgia Italiana - novembre/dicembre 2020

system are: kinematic viscosity of liquid medium η0, volu-

fraction φ=CM/ρp , where CM is mass concentration of solid fraction 1−φ/φm, where φm is maximum volumetric fraction

of solid. See Figure 2.

pagina 8

Scientific papers - Continuous casting

Fig.2 - Elements describing solid-liquid dispersion system. Based on these quantities semi-empirical correlations for

ger-Dougherty equation has shown some deviation for

been developed in the past. Krieger-Dougherty equation

siders only trend of void fraction 1−φ/φm. Indeed, better re-

suspensions reasonably described by a model of non-in-

ratio between volume concentration of dispersed particles

relative viscosity, ηr=η/η0, of hard-spheres suspensions have

has shown considerable applicability in wide range of real teracting hard-sphere solid-liquid dispersion ). However, 7

in case of liquid casting powder here described, the Krie-

higher φ, probably because implemented correlation consults were obtained with Robinson equation 7), Eq.1, where

φ and void fraction 1−φ/φm is taken into account.

In Eq.1, term [η] is the intrinsic viscosity or the crowding factor as described by M.Mooney ). This quantity is a constant 8

for a specific system and is generally derived along with φm

as a curve fitting parameter. Experimental data fitting for measured relative viscosities of A-E samples is reported in Figure 3, where best fitting is also represented.

Fig.3 - Fitting of experimental data (grey dots) by Robinson equation (line).

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Memorie scientifiche - Colata continua It’s interesting to note that fitted parameters for data depi-

knowing viscosity for a specific range of working conditions

which are similar to same parameters reported for different

liquid casting powder. Indeed, a more accurate rheologi-

cted in Figure 3 shown values of [η] = 1.059 and φm = 0.549

suspensions of poly-dispersed minerals ). Further, value of 9

φm = 0.585 is very close to theoretical random close packing

fraction of uniform hard spheres φ*m = 0.63 proving effecti-

veness of packing of poly-dispersed solid particles in liquid powder.

will not be enough to define technological properties of a cal methodology needs to be taken up in evaluating factors

which actually affect behaviour of a liquid casting powder.

Particularly, an equation relating stress, strain, time and sometimes other variables such as temperature (constitutive

equation), is needed to describe the rheological behaviour of non-Newtonian fluids 9).

Rheological model

In studying rheological properties of liquid casting powder,

very first observation was the shear-thinning nature of this suspension which is indeed quite common characteristic of real non-Newtonian fluids. This characteristic has been

clearly observed for all samples A through E. Therefore,

Then, aiming to define a suitable constitutive equation for the liquid casting powder, first approach was to interpolate experimental data of shear stress measured in a relatively wide range of shear rates where Bingham model generally applies, see Eq.2.

2) Where τ0 is the stress yield (Pa), the limiting stress below which the fluid is stagnant or gives an elastic response ), 10

ηP is the plastic viscosity (Pa*s) accounting for the excess

of the shear stress over the stress yield divided by the shear rate 11) and γ is the shear rate (s-1).

Fig.4 - Bingham fitting of liquid casting powder sample. Although results of measurement are reasonably fitted in

between relative viscosity, η (relative to kinematic viscosity

and pipeline flowing (10 -10 s ) ) (see Figure 4), parame-

present case 298 K), stress yield τ0 and plastic viscosity ηP

dependent on interpolating range, indeed it seems that,

It has been stated above that an eligible liquid casting pow-

the shear rate range reported as typical for stirring, mixing 0

-1 6

ters of stress yield τ0 and plastic viscosity ηP are strongly for a specific values interval, a different constitutive equation better fits experimental data

). In spite of that, final

criterion to establish appropriate behaviour of a sample of

liquid casting powder has to be defined as suitable balance

La Metallurgia Italiana - novembre/dicembre 2020

of liquid medium η0 measured @ reference temperature in

from Bingham model.

der has to be composed by at least 50% or more of PC, then deeming very first acceptable composition among samples A-E, namely sample B, it has to be clarified in which sense this is a liquid. Considering possible application of a liquid

pagina 10

Scientific papers - Continuous casting casting powder, liquid means a product bearing main fea-

Flow through cylindrical pipes

previous paragraph. Therefore, attention has to be focused

tely sized matching characteristics of pipes required in

tures of an oil used in continuous casting, as illustrated in a

on what has been accounted as feeding, in other words the

possibility to feed the product to a continuous casting machine during normal operations as oil is pumped through pipes to the casting mold.

Sample B has characteristic values as follows: η=2.619 @ 298

K and γ = 4.6 s-1), stress yield τ0 = 4.922 Pa and plastic viscosity ηP = 0.5637 Pa.s from Bingham model, then question is

how these factors are affecting fundamental technological

characteristics of this liquid casting powder such as flow

Generally, selected pumping system has to be appropria-

transferring the liquid powder from a reservoir vessel to a

casting mold. Therefore, piping and pumping systems have to be designed based on knowledge of head pressure re-

quirement for a given transfer duty. Clearly, the scope is to maintain stable flow of the liquid powder to a mold.

Limiting present discussion to laminar flow regime, it can be shown that for Newtonian fluids Hagen-Poiseuille equation holds:

through pipes.

3) Where η is fluid kinematic viscosity, D and L are respectively

τW =

Equation, Eq.3, in case of a non-Newtonian fluid assumes a

gham fluid as discussed above, Eq.3 becomes 13):

diameter and length of pipe and ΔP is pressure requirement.

specific form which is corrected by a function of parameters

, defined as shear stress at pipe wall. In the case of

liquid casting powder which is in first approximation a Bin-

of relative constitutive equation or rheological model and

4) Where �=

40÷70 g/min and a linear pressure drop of 3000÷5000 Pa*m-1,

Equation, Eq.4, effectively establishes pressure required for a

it is possible to define a given working space which is fairly

casting powder sample, explicitly sample B.

ters of 12 and 13 mm (approximately ½ inch). See synopsis

given transfer duty in case of a Bingham fluid, thus for a liquid

In a functional example, for a specific feeding interval of

crossed by only two equations, EQ.3, plotted for pipe diamein Figure 5.

Fig.5 - Definition of actual working space for real application of a liquid casting powder.

La Metallurgia Italiana - November/December 2020

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Memorie scientifiche - Colata continua At this point of present discussion, it can be concluded that

component, PC, of this solid-liquid dispersion is melting

der, namely sample B, has to be considered a liquid in all

of liquid medium. This feature is perfectly matching normal

first eligible sample to be classified as liquid casting powpondered aspects, in particular it has been pointed out that

this material shows a specific viscosity which is connected to its PC load through a Robinson equation (Eq.1) and its

rheological behavior is described by a Bingham constitutive equation (Eq.2). Remaining subject concerns the performance of this material when used in a continuous casting process. Is it actually a liquid casting powder?

LIQUID CASTING POWDER HOW IT WORKS

Based on plant results presented elsewhere

14-16

very rapidly at the expenses of heat produced by burning-off operations of continuous casting of long products in open steel stream, where thermal insulation of liquid steel bath is not an issue. The advantage resides in the fact that a liquid

powder is not a compromise like oil, which is burning in contact with liquid steel. Liquid powder actually provides a

liquid slag with all known properties of commercial casting

powder for continuous casting in close steel stream. Chan-

ge introduced by such a product in present technology is by ), it is pos-

sible to depict the behaviour of a liquid casting powder in a real working environment. It has been observed that solid

any perspective a radical one. As depicted in simple scheme

of Figure 6, the liquid powder is fed through a tip especially designed to fit specific mold size and shape.

Fig.6 - scheme of liquid powder functioning in mold. Liquid casting powder in contact with liquid steel is sprea-

used for continuous casting in close steel stream.

scus area. This effect is a result of pressure produce by first

open steel stream, liquid powder is surely adding effective

ding across the entire surface laying entirely close to meniimpact wave of steel stream which push slag toward mold

wall and some specific characteristics of slag. In particular, slag surface tension and viscosity have to be carefully ba-

lanced to endow proper wettability and spreadability, avoi-

ding potential slag entrapment. It has been observed as a general consequence that feeding rate set below a critical limit does not give any interference with liquid steel stream, dumping possible slag entrapment.

In spite of all important operational advantages, nothing is

comparable with tremendous improvement of general casting process quality due to infiltration of liquid slag into

gap between strand shell and mold wall, when the liquid casting powder starts working as a standard casting powder

La Metallurgia Italiana - novembre/dicembre 2020

In comparison with common natural or synthetic oil used in lubrication and, more important, control capability of heat transfer between strand and mold wall, resulting in mild ho-

mogenous cooling and in a significant increase of effective length of the mold.

Consequence of this situation is a large tide of benefits pointed out in operations and semis quality during exten-

sive plant trials, such as strong rombohedricity reduction, considerable drop in scale formation and major increase of casting speed 17). CONCLUSIONS

Significant effort has been conveyed in defining characte-

ristics of conceptual liquid powder, more precisely a liquid

pagina 12

Scientific papers - Continuous casting casting powder. Based on expanding idea of mixing, bor-

considered as liquid with well-defined real-world techno-

elements of perceived quality by end-user of this concep-

as a liquid slag of a casting powder pumped at room tem-

rowed from Value Innovation methodological approach to

tual product, a new material composed by a solid-liquid dispersion of conveniently formulated continuous casting powder in synthetic oil based on fatty acids glyceric esters,

has been formulated, in samples with different proportion between solid and liquid phases.

Extensive characterization of rheological properties of this liquid casting powder samples proved those have to be

logical practical properties. Indeed, this product is working perature into the mold and in comparison with standard na-

tural/mineral or synthetic oil used in open steel stream, it

is adding effective lubrication and control capability of heat transfer between strand e mold wall, resulting in mild homogenous cooling and in a significant increase of effective length of the mold.

REFERENCES 1]

J. W. Cho, H. S. Jeong, J. M. Park, G. H. Kim, O. D. Kwon, J. K. Park, S. K. Lee, S. H. Lee, K. H. Moon: Continuous casting machine and method using molten mold flux, Patent WO 2007148941 A1, (2007).

W. Chan Kim and R. Maubornie: Blue ocean leadership, Harvard Business Review Classics, Boston, Massachusetts, (2017), 1.

R. Carli: Lubricating composition for continuous casting processes, Patent EP 2 626 407 B1, (2017).

R. Carli: Lubricating compositions for continuous casting processes and methods for making and using same, Patent US 9 109 183 B2, (2015).

ASTM D2196: 2015, Standard test method for rheological properties of non-Newtonian materials by rotational viscometer.

T. F. Tadros: Rheology of Dispersions: Principles and Applications, 1st ed., Wiley-VCH, Singapore, (2010), 7, 53.

S. M. Peker and S. Helvaci: Solid-Liquid Two Phase Flow, 1st ed., Elsevier, Amsterdam, The Netherlands, (2008), 177.

M. Mooney: J. Coll. Sci., 6(1957), 162.

H. A. Barnes, J. F. Hutton and K. Walters: An Introduction to Rheology, 1st ed., Elsevier, Amsterdam, The Netherlands, (1989), 125 and 160.

10]

R. Turian, T-F. Yuan: AlChE J., 23(1977), 232.

11]

H. A. Barnes, J. F. Hutton and K. Walters: An Introduction to Rheology, 1st ed., Elsevier, Amsterdam, The Netherlands, (1989), 20.

12]

S. Casagrande, M. Alloni, R. Carli, manuscript in preparation.

13]

R. P. Chhabra, J. F. Richardson: Non-Newtonian Flow and Applied Rheology, 2nd ed., Butterworth-Heinemann, Oxford, UK, (2008), 115.

14]

M. Alloni, R. Carli: Proc. of 36th Convegno Nazionale AIM, Milan, (2016), no page (electronic support).

15]

A. Giacobbe, R. Comanecky, R. Carli, M. Alloni: Proc. of AISTech 2017, AIST, Warrendale, (2017), 2001.

16]

S. Barella, A. Gruttadauria, C. Mapelli, D. Mombelli, A. Soleo, R. Carli, M. Alloni: Proc. of 7th International Congress on Science and Technology of Steelmaking, AIM, Milan, (2018), no page (electronic support).

17]

M. Alloni, R. Carli, S. Casagrande, manuscript in preparation.

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Memorie scientifiche - Cricche interne

Alleviation of internal cracks in continuous casting bloom of steel 100Cr6 induced by soft reduction process N. Zong, S. Ma, W. Sun, T. Jing, Z. Lu

To comprehensively investigate the formation mechanism and alleviation technology of internal cracks in steel 100Cr6 during the soft reduction process, a three-dimensional mechanical model has been developed to obtain equivalent strain of as-cast bloom under different reduction amount and reduction position. The specific relationship between area of cracking zone, centre solid fraction and maximum equivalent strain of cracking zone has been researched under a number of withdrawal units. In the present work, a novel soft reduction technology for eliminating internal cracks, center shrinkage cavities and center segregation of as-cast bloom has been designed, which aims to provide theoretical basis for improving the internal quality of steel 100Cr6. According to the results of optimum designed experiments, the internal cracks were effectively alleviated and center shrinkage cavities were nearly eliminated. In addition, the center segregation generated by the optimum designed experiments of steel 100Cr6 was remarkably improved in comparison with that induced by the conventional soft reduction process.

PAROLE CHIAVE: INTERNAL CRACKS, CENTER SEGREGATION, CENTER SHRINKAGE CAVITIES, SOFT REDUCTION TECHNOLOGY. INTRODUCTION

High carbon chromium bearing steel 100Cr6 according to

EN ISO 683-17, has been widely used for severe working conditions of bearings in engineering system[1]. A lot of

effort has been devoted to research the cleanliness in the composition, size, and distribution of inclusions in ste-

els[2-3], and shrinkage cavities and center segregation are

also main defects forming at the center position of blooms during continuous casting process[4-5]. To satisfy these ne-

eds of engineering application, the internal crack, center se-

gregation and shrinkage cavities of as-cast blooms should

be simultaneously eliminated during the soft reduction process. Soft reduction technology has the capacity to al-

leviate center segregation and shrinkage cavities in many

Nanfu Zong, Sida Ma, Weizhao Sun, Tao Jing Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

Zhifang Lu

Xingtai Iron and Steel Corp., Ltd., Hebei 054027, P.R. China

industrial applications, however, internal cracks are always formed in the internal region of as-cast bloom induced by many reduction technologies[6-9].

The compression deformation induced by soft reduction

process is inevitably located in the brittleness temperature

range of as-cast bloom[4], especially for the large-section size bloom. Seol et al.[10] have reported that the brittleness

La Metallurgia Italiana - novembre/dicembre 2020

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Scientific papers - Internal cracks temperature range of steels can be characterized by the

steel 100Cr6.

rature (ZDT), the boundaries of ZST and ZDT corresponded

MODEL DESCRIPTION AND ANALYSIS OF AS-CAST

et al.[11] have analyzed the internal cracks of as-cast bloom

A three-dimensional mechanical model

that the internal cracks mainly originated from the inter-

nical soft reduction (MSR) has been developed to calculate

zero strength temperature (ZST) and zero ductility tempe-

to the solid fractions of 0.75 and 0.99, respectively. Wang induced by soft reduction process, the results have shown nal area of the brittleness temperature range. The maximal stress and strain have been calculated to investigate the formation of internal cracks of as-cast blooms.

[12]

However, the

former researchers have done the research on formation and alleviation of center segregation and shrinkage cavities of as-cast bloom respectively, and seldom learned it from

the control perspective of internal cracks. Given the high quality demand of steel 100Cr6 has attracted some industries and researchers’ attention, many investigations have

been urgently needed to simultaneously alleviate center

segregation and shrinkage cavities without internal cracks in as-cast blooms with soft reduction technologies. In the

present work, a novel soft reduction technology designed for eliminating internal cracks, center shrinkage cavities and center segregation of as-cast blooms, which aims to pro-

vide theoretical basis for improving the internal quality of

BLOOM INDUCED BY SOFT REDUCTION PROCESS

A finite element model of as-cast bloom induced by mechathe strain distribution using the software ABAQUS®. Figure

1 shows the three-dimensional mechanical model, which is a 3-strand straight-arc rectangular bloom continuous casting machine with a section size of 280 mmx325 mm, and

its casting speed of as-cast bloom is 0.70 m/min. The MSR

is carried out by seven pair of withdrawal units, which are

located between 16.19 and 24.49 m of the distance from the meniscus. All withdrawal and straightening units with a pair

of 450 mm diameter rolls, were located in the air-cooling zone, and reduction roll gap and rotation speed of each unit

could be adjusted by the corresponding hydraulic cylinder

and driving motors respectively during the implementa-

tion of MSR. Temperature distribution of as-cast bloom has been calculated firstly[6-7,9], which was transferred to as-cast

bloom as the initial temperature field in this finite element model.

Fig.1 - Deformation finite element model. In addition, a kind of high carbon chromium bearing steel,

strain curves under different strain rates, has been taken in

search steel grade. Related thermal material properties of

induced by MSR[15].

100Cr6 according to EN ISO 683-17, was taken as the re-

material, such as the density, conductivity and enthalpy, can be found in the authors’ previous work[6-7,13], and more

detailed parameters about steel 100Cr6 can be found in the other previous work

[9,14]

. Furthermore, Arrhenius-type

constitutive equation, which was derived from true stress-

La Metallurgia Italiana - November/December 2020

this research to describe the flow behavior of steel 100Cr6

TEMPERATURE DISTRIBUTION AND CRACKING ZONE

OF AS-CAST BLOOM INDUCED BY SOFT REDUCTION PROCESS

All internal cracks of as-cast bloom are generated in the

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Memorie scientifiche - Cricche interne cracking zone, and propagate along the following soft re-

point temperature of bloom narrow surface center was me-

tion and cracking zone under different reduction position,

tions. Figure 3 shows the comparison between the measu-

duction process. Figure 2 shows the temperature distributhe cracking zone of as-cast bloom is defined as the tem-

perature range between ZST and ZDT[10]. The characteristic

asured by a thermal infrared camera at different strand posired temperature and the corresponding calculated results.

Fig.2 - Temperature distribution and cracking zone under different reduction position. a) Centre solid fraction 0.55 - b) Centre solid fraction 0.66 -c) Centre solid fraction 0.79

Fig.3 - Comparison between the calculated and the measured temperature of the bloom narrow surface center.

The temperature distribution of as-cast bloom has been calculated to determine the cracking zone as the centre solid fraction increases from 0.55 to 0.79.

shrinkage cavities and center segregation of as-cast blooms, which aims to provide theoretical basis for improving the internal quality of steel 100Cr6.

RESULTS AND DISCUSSION

EQUIVALENT STRAIN OF AS-CAST BLOOM UNDER

formation finite element model to obtain equivalent strain

Figures 4, 5 and 6 have shown the equivalent strain of as-

Internal cracks of steel 100Cr6 have been developed by deof as-cast bloom under different reduction amount and reduction position. According to the relationship between area of cracking zone, centre solid fraction and maximum

equivalent strain of cracking zone, a novel soft reduction

technology designed for eliminating internal cracks, center

La Metallurgia Italiana - novembre/dicembre 2020

DIFFERENT REDUCTION AMOUNT

cast bloom under the centre solid fraction of 0.55, 0.66 and

0.79 respectively. Temperature data of bloom center slowly decreased in the reduction zone of as-cast bloom because

of the released latent heat from the mushy region during the continuous casting process.

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Scientific papers - Internal cracks

Fig.4 - Equivalent strain of as-cast bloom under different reduction amount (centre solid fraction 0.55): (a) 4mm; (b) 6mm; (c) 8mm; (d) 10mm.

To clarify the deformation difference between as-cast blo-

strain along the bloom thickness direction was a uniform di-

om surface corner and its center, equivalent strain of as-cast

stribution, the variation of the equivalent strain at the bloom

bloom implemented at different bloom positions was si-

inner region was obviously larger than that at location of the

mulated under different reduction amount. The equivalent

bloom outer region.

Fig.5 - Equivalent strain of as-cast bloom under different reduction amount (centre solid fraction 0.66): (a) 4mm; (b) 6mm; (c) 8mm; (d) 10mm.

La Metallurgia Italiana - November/December 2020

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Memorie scientifiche - Cricche interne

Fig. 6 - Equivalent strain of as-cast bloom under different reduction amount (centre solid fraction 0.79): (a) 4mm; (b) 6mm; (c) 8mm; (d) 10mm.

Fig. 7 - Equivalent strain distribution for cracking zone in the inner transverse section of the bloom: (a) centre solid fraction 0.55; (b) centre solid fraction 0.66; (c)centre solid fraction 0.79.

La Metallurgia Italiana - novembre/dicembre 2020

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Scientific papers - Internal cracks The bloom temperature difference along the bloom cross

CENTRE SOLID FRACTION AND MAXIMUM EQUIVA-

section can effectively promote the transfer of reduction

LENT STRAIN OF CRACKING ZONE

deformation from the bloom surface into its internal region.

The internal cracks is hardly to prejudge and control in the

Equivalent strain distribution for cracking zone in the inner

actual production process of as-cast bloom induced by soft

transverse section of the bloom for different centre solid

reduction process. Therefore, most scholars have taken

fraction of as-cast bloom has been shown in Figure 7, the

the equivalent strain to analyze and estimate the internal

equivalent strain difference between the bloom inner sur-

cracks of as-cast bloom. When the equivalent strain is lar-

face and its center gradually increased with the increase of

ger than the critical strain, internal cracks will be generated,

reduction amount under the same centre solid fraction of

the critical strain of steel 100Cr6 was taken as 0.015[16], and

as-cast bloom. However, the equivalent strain between the

its deformation strain rate is from 10−2 to 10−4s−1. Influence

bloom inner surface and its center gradually decreased with

of reduction amount and reduction zone on the maximum

the increase of centre solid fraction of as-cast bloom under

equivalent strain of cracking zone has been shown in in Fi-

the same reduction amount, and the equivalent strain in the

gure 8. When the total strain exceeds the critical strain, the

bloom internal region also had a similar declining trend.

internal cracks are formed between the columnar crystals

RELATIONSHIP BETWEEN AREA OF CRACKING ZONE,

and located midway between the surface and centre of ascast bloom.

Fig. 8 - Influence of reduction amount and reduction zone on the maximum equivalent strain of cracking zone.

Fig. 9 - Area of cracking zone, centre solid fraction and maximum equivalent strain in cracking zone under a number of withdrawal units.

La Metallurgia Italiana - November/December 2020

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Memorie scientifiche - Cricche interne When the centre solid fraction of as-cast bloom reaches 0.79,

trol stage of center segregation, the reduction amount was

equivalent strain is smaller than the critical strain when the

(withdrawal units 2#, 3# and 4#) without forming of internal

internal brittleness temperature range is disappeared and the reduction amount is less then 5mm. The relationship betwe-

en cracking zone area, centre solid fraction and maximum

equivalent strain in cracking zone has been established under a number of withdrawal units, as shown in Figure 9. Al-

enhanced to improve the homogeneity of as-cast bloom crack. In the control stage of center shrinkage cavities, the

as-cast bloom was compressed to improve the compactness of as-cast bloom (withdrawal unit 5#).

though the internal cracks can been effectively alleviated as

OPTIMUM DESIGNED EXPERIMENTS OF STEEL 100CR6

mented in the mushy region for simultaneously improving

According to the above simulated results and theoretical

present work, withdrawal unit was mainly implemented for

shown in Table 1. Shrinkage cavities and center segregation

the increase of centre solid fraction, a deformation implethe center segregation and center shrinkage cavities. In the

improving the center shrinkage cavities when center solid fraction of as-cast bloom reached 0.9. Therefore, a novel soft

reduction technology for eliminating internal cracks, center shrinkage cavities and center segregation of as-cast bloom

has been designed, which aims to provide theoretical basis for improving the internal quality of steel 100Cr6. In the con-

INDUCED BY SOFT REDUCTION PROCESS

analysis, optimum designed experiments of steel 100Cr6 are are mainly forming at the center position of blooms. Due to

the symmetry of the as-cast bloom along its width direction,

the longitudinal morphologies of as-cast bloom are taken to validate the designed experiment cases, as shown in Figure 10.

Tab.1 - Optimum designed experiment case. No. withdrawal machines M1

No.Cases

0.92

1.00

Centre solid fraction 0.55

0.66

0.79

0.85

Reduction of MSR (mm) Case 1

4.0

3.5

3.0

2.0

0.0

Case 2

1.5

2.0

3.0

2.0

0.0

Case 3

0.0

2.5

5.0

4.0

2.0

0.0

Fig.10 - Longitudinal morphologies of as-cast bloom under designed experiment cases: (a) case 1; (b) case 2; (c) case 3. A great quantity of internal cracks and large centre shrinkage

dway between the surface and centreline of the as-cast blo-

as-cast bloom for case 1, these internal cracks are located mi-

serious and intensive than that in the outer transverse section

cavity are obviously observed in the longitudinal section of

La Metallurgia Italiana - novembre/dicembre 2020

om, and the internal cracks in the inner transverse section are

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Scientific papers - Internal cracks of as-cast bloom. In order to weaken the internal crack, the

also clearly observed under the application of case 2, and the

withdrawal unit 1# and 2#. However, the internal cracks are

as-cast bloom.

reduction amount of reduction roll is both decreased for

center shrinkage cavities are also located in the centerline of

Fig.11 - Effect of designed experiment cases on centerline segregation grade. The maximum equivalent strain in the cracking zone for withdrawal unit 1# is more larger than the critical strain, there-

fore withdrawal unit 1# should be avoid to make reduction

operation. Case 3 is a novel soft reduction technology, wi-

thdrawal units 2#, 3# and 4# are taken to control center segregation without internal crack, and withdrawal unit 5# is added to control center shrinkage cavities. The longitudinal

morphologies of as-cast bloom indicated the internal crack

and center shrinkage cavities can both be eliminated under case 3 as compared with case 1 and case 2. Figure 8 shows the effect of designed experiment cases on centerline segregation grade. The prepared drill samples were analyzed

using the carbon-sulphur analyser, and the solute segregation ratio was calculated by taking the solute content at each

location divided by the ladle composition. Although the total

reduction amount of case 1 is 4mm larger than that of case 2, the centerline segregation grade difference is small. In addition, the center segregation generated by the optimum designed experiments of case 3 was remarkably improved in

comparison with that induced by the conventional soft re-

duction process. According to the results of optimum designed experiments, the internal cracks were effectively alleviated and center shrinkage cavities were nearly eliminated. CONCLUSIONS

Comparative analysis of theoretical model and industrial

La Metallurgia Italiana - November/December 2020

experimental results, the formation mechanism and allevia-

tion technology of internal cracks in steel 100Cr6 have been

researched during the soft reduction process, the major conclusions are listed as follows:

(1) To comprehensively investigate the internal cracks in as-

cast bloom during the soft reductions, the specific relation-

ship between area of cracking zone, centre solid fraction and maximum equivalent strain of cracking zone has been researched under a number of withdrawal units.

(2) A novel soft reduction technology for eliminating internal cracks, center shrinkage cavities and center segregation

of as-cast bloom has been designed, which aims to provide theoretical basis for improving the internal quality of steel

100Cr6. In the control stage of center segregation, the reduction amount was enhanced to improve the homogenei-

ty of as-cast bloom without forming of internal crack. In the control stage of center shrinkage cavities, the as-cast bloom was compressed to improve the compactness of as-cast bloom.

(3) According to the results of optimum designed experi-

ments, the internal cracks were effectively alleviated and center shrinkage cavities were nearly eliminated. In addition, the center segregation generated by the optimum designed experiments of steel 100Cr6 was remarkably improved in

comparison with that induced by the conventional soft reduction process.

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Memorie scientifiche - Cricche interne Acknowledgments

The present work is financially supported by The National Key Research and Development Program of China No.

2017YFB1103700. The authors are also grateful to Dr. Zhifang Lu in Xingtai Iron and Steel Corp., Ltd for discussing on the accuracy of strain analysis in as-cast bloom during soft reduction operation.

REFERENCES [1]

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Komolova O A, Grigorovich K V. Mathematical models, algorithms and software for dynamic simulation of ladle treatment technology. La Metallurgia Italiana. 2019;3:20-24.

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Tanaka S, Onoda H, Kimura S, Semura K. Nitrogen adjustment in molten steel using rh vacuum degasser. La Metallurgia Italiana. 2019;3:5-12.

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Flemings M C. Our Understanding of Macrosegregation: Past and Present. ISIJ International. 2000;40(9):833-841.

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Choudhary S K, Ganguly S. Morphology and Segregation in Continuously Cast High Carbon Steel Billets. ISIJ International. 2007;47(12):1759-1766.

[6]

Zong N, Zhang H, Liu Y, et al. Analysis of the off-corner subsurface cracks of continuous casting blooms under the influence of soft reduction and controllable approaches by a chamfer technology. Metall. Res. Technol. 2019;116:310-322.

[7]

Zong N, Zhang H, Wang L, et al. Application of a chamfer slab technology to reduce internal cracks of continuous casting bloom during soft reduction process. Metall. Res. Technol. 2019;116:608-617.

[8]

Kim K, Han HN, Yeo T, et al. Analysis of surface and internal cracks in continuously cast beam blank. Ironmak Steelmak. 1997;24 (3):249-256.

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Luo S, Zhu MY, Ji C. Theoretical model for determining optimum soft reduction zone of continuous casting steel. Ironmak Steelmak.2014;41(3):233-240.

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Seol D J, Won Y M, Oh K H, Shin Y C, Yim C H. Mechanical Behavior of Carbon Steels in the Temperature Range of Mushy Zone. ISIJ International. 2000;40(4):356-363.

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Wang W, Ning L, Biilte R, et al. Formation of internal cracks in steel billets during soft reduction. J Univ Sci Technol Beijing. 2008;15 (2):114-119.

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Li XB, Ding H, Tang ZY, et al. Formation of internal cracks during soft reduction in rectangular bloom continuous casting. Int J Miner Metall Mater. 2012;19(1):21-29.

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Zong N, Zhang H, Liu Y, et al. Analysis on morphology and stress concentration in continuous casting bloom to learn the formation and propagation of internal cracks induced by soft reduction technology. Ironmak Steelmak. 2019;46 (9):872-885.

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Ji C, Luo S, Zhu MY. Analysis and application of soft reduction amount for bloom continuous casting process. ISIJ Int. 2014;54 (3):504510.

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Ji, C., Wang, Z.L., Wu, C.H., Zhu, M.Y., 2018. Constitutive modeling of the flow stress of GCr15 continuous casting bloom in the heavy reduction process. Metall. Mater. Trans. B 49, 767-782.

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Hiebler H, Zirngast J, Bernhard C, et al. Inner crack formation in continuous casting: Stress or strain criterion?. Steelmaking Conf. Proc.1994;77:405-416.

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Costanza G, Donnini R, Kaciulis S, Maddaluno G, Montanari R. HT-XRD analysis of W thick coatings for nuclear fusion technology. Key Engineering Materials 2014; 605: 31-34.

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La Metallurgia Italiana - novembre/dicembre 2020

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Scientific papers - Foundry of copper alloys

The Effect of Minor Element Addition on Thin Walled Brass Casting N. Tamsü Selli, C. Imer Ozgü

Thin walled brass faucet casting is an important requirement of the industry in terms of both transportation and cost. Fluidity of molten metals is one of the important issues for thin walled castings. In this study, various metallic powders were added to the brass alloy in order to increase the fluidity of brass alloy and to provide casting at low pressures. Aluminum and nickel metallic powders were chosen as special additives. It is aimed to increase the fluidity of the brass composition by adding minor elements to the composition. In this work, the microstructure and melt fluidity of a (CuZn39Pb1Al-C) brass alloyed by small additions of aluminum and nickel were studied. These two metallic elements were added to the main melting furnace at amount of 0.0055 wt.%, 0.03 wt.% and 0.05 wt.%. The microstructures were investigated with the help of scanning electron microscopy equipped with energy dispersive X-Ray analysis (SEM/ EDX) for determining significant changes of the properties. In particular, the addition of 0.03 % by weight of nickel facilitated the casting and reduced the casting pressure by 80 mbar. This reduction in the casting pressure resulted to thickness value decreased by 55% compared to the standard.

KEYWORDS: BRASS CASTING, FAUCET, THIN WALLED CASTING.

INTRODUCTION

Non-ferrous metals and their alloys are used in industry to produce ornaments, utensils, cables, machine component etc., because they are easy to form by casting, rolling, for-

ging and machining [1]. One of the most important example is the use of brass alloys. The most important places for the use of brass alloys is also brass faucets. Brass faucets

has high corrosion and high mechanical strength proper-

ties. Thin walled faucet production is one of the most challenging study in the foundry industry. The demand of thin walled section in this industry is continuously increasing due to their light weight related to economical reasons and

transportation of the products. The most critical parameter

for thin section brass casting is to control the fludity of the

N. Tamsü Selli

Department of Materials Science and Engineering, Gebze Technical

University, 41400 Gebze, Kocaeli, Turkey - Corresponding author email: ntamsu@gtu.edu.tr

C. Imer Ozgü

VitrA Innovation Center, Eczacıbaşı Building Products Co., 11300 Bozüyük, Bilecik, Turkey

melt. Fluidity strongly depends on two variables : the metal related variables and mould related variables. Metal related

variables are: viscosity, surface tension, superheat, mechanism of solidification, oxide film and non metallic inclusion

formation, specific weight, melting point; mould related variables are: thermal physical properties, temperature, gas

permeability, metallostatic pressure, surface characteristics

La Metallurgia Italiana - November/December 2020

pagina 23

Memorie scientifiche - Fonderia leghe di rame [2- 6]. One of the most important parameters affecting the fluidity is the melt viscosity (Eq.1).

In the viscous force F:

1) Where η is the kinematic viscosity coefficent of the melt, S is the contact area between two flow layers, and dѵ/dx is the velocity gradient. η is closely associated with the tem-

perature [7]. The viscous forces in the fluid tend to cause slow-moving regions in the fluid to move faster and the fa-

ster-moving regions to move slowly. Thus on a microscopic scale, the viscosity of a fluid determines a measure of the frictional forces acting on an atom in the moving fluid.

Viscosity is crucial for a fluid system since it helps to cate-

gorize the fluids based on the change of viscosity with ex-

ternal parameters such as temperature, pressure and shear rate. Since all fluids exhibit a decrease of viscosity with in-

crease in temperature and pressure to categorize fluids [8].

During the casting of these thin walled parts, the tendency of the bulk component, is to solidify before filling the entire mould [9]. Ziolkowski et al. [10] noted that some defects due to the misrun of the casting in thin walled sections

may be seen. The fast solidification rate of the thin walled

sections cause insufficent feeding of the body. Voigt et al. [6] showed that when the surface tension increases in the

mould wall which reduces the fillability of thin sections are reduced. They used various mould coatings (such as graphite, an alcohol-based zircon wash, chromite and commercial

coatings like Ceramcoat, Velvaplast etc.) and they determined that coatings reduce the surface tension and casting

fillability increases. Li et al. [7] investigated the effect of the casting temperature of the melt. They stated that increasing

casting temperature promotes the completion of the filling process. Therefore, achieving this condition is difficult due

to the production circumtances. Besides of these factors, also metal composition has a crucial effect on fluidity of the

melts and fillability of the moulds. However, increasing the

casting temperature has a limitation in that, for production

of premium quality casting with increased mechanical properties casting temperature should be as low as possible

[2]. Campbell et al. [11] stated that the oxide contents of

melts of the common Al-7%-0.4 Mg alloy will reduce the

ported that Fe content decreases the fluidity of the A380 die

casting alloy. And also the addition of Zn to A380 alloy decreased the fluidity of the molten metal. On the contrary addition of Cu to the A380 alloy resulted increasing fluidity of the alloy. In the literature, there are many composition stu-

dies for aluminum and iron alloys, while there are few studies on brass alloys fluidity. S. Lassmann [14] reported that

if iron content in the brass exceeds 0.03 wt.% and silicon

0.002 wt. %, hard inclusions formation promoted. Romankiewicz et al. [15] also investigated the influence of the chemical composition of selected armature brasses on the for-

mation of hard inclusions. However, these studies focused on hard inclusions in brass faucet, and did not give enough information about composition effect on fluidity. Apart from the major alloying element zinc, small additions (less

than 5 %) of other alloying elements affect the structure and

mechanical properties of brasses such as strength, machinability, corrosion resistance etc. [16-18]. Nickel, manganese, aluminum, tin, and silicon, listed in approximate order

of increasing effectiveness which improve the mechanical

properties by solid solution strengthening and also improve the corrosion resistance. Hardening in these systems is

great enough to make useful objects without encountering brittleness associated with second phases or compounds [18, 20, 21]. Aluminum is one of the most common element

present in the composition of brasses (0.2-0.7 wt.%). Aluminum improves castability, reduces the zinc evaporation

and protects the melt from the oxidation at high temperature. In addition, aluminum increases the volume faction of beta phase in microstructures [18-21]. When dissolved

in the α solid solution and the β phase, aluminum increases

the ultimate tensile strength, the strength, and the hardness and affects the phase transformation temperatures. More-

over, aluminum inhibits dezincification, and also it increa-

ses toughness and the corrosion resistance of brasses by forming a protective Al2O3 oxide film on their surfaces [17,

22, 23]. Garcia et al. confirmed that the Al has a significant

fluidity of the material. In addition, this study showed that

effect on grain size, when 0.25% Al was added to Cu-Zn-Sn

pure Al. Wang et al. [12] studied the effect of Fe addition in

[24]. Reducing the grain size improves hot tearing resistan-

ses the fluidity of the alloy. Also Gowri and Samuel [13] re-

alloy systems [25]. Alloying elements modify the structure

a few mass per cent addition of Sn reduces the fluidity on

brass alloy, and the grain size rating increased from 2 to 4.5

the molten aluminum alloy. Increasing Fe amount decrea-

ce, casting fluidity and enhances surface finish of various

La Metallurgia Italiana - novembre/dicembre 2020

pagina 24

Scientific papers - Foundry of copper alloys in both constituents and sizes [26]. These modifications can

effect the metal related casting properties of the alloys such as fluidity. The addition of nickel can modify the properties

of brass alloy due to changing microstructure and chemical composition of phases [16]. Nickel improves the strength,

density, corrosion resistance of the alloy and decreases the

tendency of the brasses to corrosion cracking, reduces the amount of dezincification [17, 23]. Under the light of these

literature surveys, thin walled section parts of the brass can

be casted by adding minor elements in the composition. In this study, aluminum and nickel metallic powders are used

for obtaining thin walled castings by changing the fluidity of the alloy. Decreasing viscosity and increasing fluidity of the

alloy can be evaluated by comparing the casting pressures and flow length of the brass samples. EXPERIMENTAL PROCEDURE Materials and Methods

The present work involves studying the effect of some special metallic powders on the thin walled section castings

of copper-zinc-lead-aluminum (CuZn39Pb1Al-C) alloy as cast. Leaded brass alloy (CuZn39Pb1Al-C) which consists

of copper, zinc and other minor additions is selected accor-

ding to European Standards (EN 12165) and 4MS Initiative, as shown in Table 1.

Tab.1 - Standard Copper-zinc-lead-aluminum (CuZn39Pb1Al-C) alloy chemical composition (wt.%) Element (%)

wt. (%)

58-63

Remainder

0,3-0,9

0,2-1,4

≤0,05

≤0,3

≤0,2

For obtaining the thin walled brass casting parts, metallic aluminum (>98% purity) and nickel (>99% purity) powders were selected (Ege Nanotek Chemical Industry/Turkey

and Ortam Metal Chemical Industry/Turkey) and added as

minor metallic additions in the leaded brass alloy (CuZn39Pb1Al-C) melt. Chemical composition of alloy is deter-

mined using SpectrolabTM M9 optical emission spectro-

Preparation of the Composition & Production Process

The melting and casting process of copper-zinc-lead-aluminum (CuZn39Pb1Al-C) alloy is carried out in low pressure die casting in Artema Eczacibasi Company industrial

line. The production process of taps is given in Fig. 1 as a flowchart.

meter.

Fig.1 - Process flow chart of faucet production.

La Metallurgia Italiana - November/December 2020

pagina 25

Memorie scientifiche - Fonderia leghe di rame During the casting process mold is covered by with a spe-

cess are given in Table 2. A1, A2, A3 represents aluminum

cial powder mixture. It is used as a protective cover to pre-

addition and N1, N2, N3 represents nickel addition in the

vent oxidation and also prevent contaminations [27]. Du-

standart brass composition (Table 1). The maximum wei-

ring standard low pressure die casting process, different

ght percent was determined considering the standard fau-

amout of the pure metallic powders were added to com-

cet chemical composition interval. The production pro-

position seperately. Each experiment was carried out by

cess of the composition was performed by producing the

adding different amount of metallic aluminum and nickel

100 faucet products of each of the composition. For thin

powder (Table 2) in a casting ladle. Then, the ladle was im-

walled sytem, fluidity of the melt was determined by the

mersed into the standard leaded brass composition melt

pressure reduction during the casting. Faucet weight with

in electric furnace. Addition amount of metallic nickel and

standard leaded brass composition was measured and was

metallic aluminum powder in the standard brass compo-

found approximately 1000 g.

sition (CuZn39Pb1Al-C) during low pressure casting proTab.2 - Preparation procedure of the casting compositions. Compositions

Type of metallic powder additive

wt.%

Production Pieces (faucets)

Aluminum

0,0055

100

Aluminum

0,03

100

Aluminum

0,05

100

Nickel

0,0055

100

Nickel

0,03

100

Nickel

0,05

100

Testing and Examination Process

Strip Fluidity Measurement

The testing and examination processes are used to deter-

This test provides a true and wider representation of actual

mine the effect of the composition on the faucets quality

casting conditions and is therefore, also popularly called

performance. “TS EN 817: Sanitary tapware: Mechanical

as ‘Casting fluidity test’ since it measures the ability of the

mixing valves (PN 10)-General technical specifications”

metal to fill a mould of different cross section. In this test,

standard is used to control the leak tightness of the pro-

the drag portion of the mould has four strip of equal len-

duct. This standard specifies characteristics with which

gth, equal width and of different thickness. These strips

mechanical mixing valves need to comply. Specifically, it

are fed by a perpendicular sprue on the down runner whi-

specifies dimensional, leak tightness, pressure resistan-

ch is also molded in the drag half. The length of the metal

ce, hydraulic performance, mechanical strength, endu-

flow in all strip mould summed together or individual strip

rance and acoustic characteristics. Samples are subjected

mould is taken as a measure of casting fluidity [2].

to compressed water in a period of time to observe the pressure tightness and pressure resistance of the product.

Standard leaded brass composition, aluminum and nickel

“TS EN 248: Sanitary tapware: General specifications for

added brass compositions strip fluidity test were carried

electrodeposited coatings of Ni-Cr” is used to control the

out to investigate the change of the casting fluidity. In or-

corrosion resistance of the product. In this test method

der to examine the fluidity of these alloy compositions

sanitary tapware is subjected to neutral saline-spray for

strip fluidity test mould was used (Fig. 2).

minimum 200 hours. After completing the salt-sprey test, samples are controlled for corrosion defects.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 26

Scientific papers - Foundry of copper alloys

Fig.2 - Strip fluidity test mould. Before casting the mould was preheated and after that spe-

ples are shown in Fig. 3. In case of the strip fluidity mould,

cial powder mixture was applied over the inner surface of

both the individual strip lengths as well as the sum of all

the mould. These trials were carried out ten times for one

the four strip lengths were determined as the function of

composition. Photographic view of strip fluidity test sam-

different compositions used.

Fig.3 - Photographic view of strip fluidity test.

La Metallurgia Italiana - November/December 2020

pagina 27

Memorie scientifiche - Fonderia leghe di rame Microstructural Analysis

washed again to remove the remaining etching solution.

using a ZeissTM Supra 50 VP and HitachiTM Regulus 8230

RESULTS & DISCUSSIONS

gy dispersive X-Ray analysis (EDX). To reveal the phase

change

Microstructure analyses of cast products were performed

scanning electron microscope (SEM) equipped with ener-

structure, cast product surfaces were etched using two different solutions. 100 ml distilled water and 10 g Fe-

Cl3H2O powder were mixed together and 6 ml of HCl was added in the mixture (solution 1). Etching was performed for about 10 seconds using solution 1. After etching with ferric chloride solution, surface of the product was wa-

shed with distilled water to remove the etching solution residues. Solution 2 was prepared by using 100 ml distilled

water and 10 g K2Cr2O7 powder. These components were mixed together and 5 ml H2SO4 was added in the mixture

(solution 2). Second etching was performed for about 20 seconds using solution 2. Surface of the cast product was

Variation of the filling pressure versus compositional In order to produce thin walled brass casting faucets,

composition studies were carried out and metallic ni-

ckel and metallic aluminum powders were added to the CuZn39Pb1Al-C composition. Reduction of the casting

pressure during the casting process and also fillability of the die were determined the performance of the com-

positions with metallic additions. Fig. 4 shows the pressure reduction during casting versus the compositions.

All pressure reduction values were taken from the brass

casting machine and all measurements were carried out

for 100 trials for each composition, and mean values were calculated.

Fig.4 - Filling pressure change during casting of the composition. Usually, copper alloys intended for permanent mold ca-

sting process contain various amounts of aluminum which

is added to improve casting fluidity in permanent mold casting [25]. Casting pressures of the faucets during process is constant at all times. Addition of 0.0055 wt.% metallic

aluminum powder to the CuZn39Pb1Al-C composition,

A1 composition, caused 10 mbar drop in filling pressure.

The casting pressure decreased 20 mbar by means of 0.03 wt.% metallic aluminum powder addition as seen in Fig. 2

(A2 composition). When aluminum powder amount increased to 0.05 wt.%, the casting pressure decreased by 50 mbar. Unlike aluminum addition, nickel addition in the sy-

stem caused significant decrease in casting pressure. The pressure reduction is 20 mbar with the addition of nickel to

La Metallurgia Italiana - novembre/dicembre 2020

the composition at a rate of 0.0055 wt.%. The pressure re-

duction was 80 mbar by increasing nickel addition to 0.05 wt.%. The optimum amount of nickel addition was found to be 0.05 wt.%.

The viscosity change according to the additions in the composition have been calculated according to Eq. 1.

Results are represented in Fig. 5. Calculations have been

carried out by taking the casting parameters during ca-

sting. Viscous force (F) and velocity gradient values were taken the brass casting machine database. Contact area

of the samples (S) were constant for all samples because one type of product mould was used, and this value was

150 cm2. All measurents were carried out for 100 trials for each composition, and mean values were calculated. The

pagina 28

Scientific papers - Foundry of copper alloys viscosity dropped significantly with increasing nickel level in the composition especially up to 0.05 wt.%. This effect

could be explained the pressure drop of casting.

Fig.5 - Calculated viscosity of the composition according to the casting variables. Microstructural evaluation

high sensitivity to the atomic mass of the individual ele-

6) contains Îą-phase precpitated into the Î˛-phases with

with brighter regions being generated from areas of higher

The microstructure of standard leaded brass faucet (Fig. lead (Pb) particles (white particles) distributed through the structure [28]. The alpha/beta interphase boundaries

are high interfacial energy sites and hence, potential lead distribution centres [29]. SEM micrographs were produced using back-scattered electrons (BSE), which exhibits

ments. BSE images display atomic number (Z) contrast average atomic number. In the case of standard leaded brass faucet the basic components are Cu, Zn, Pb, thus it

is expected that the brighter BSE intensity might be origi-

nated from Pb particles. Fig. 6 shows the standard leaded brass faucets microstructure.

Fig.6 - SEM image of the standard leaded brass faucet after casting process. Standart leaded brass faucet microstructure with elemen-

lead particles [29]. Lead is not soluble in copper alloys. It

is given Fig. 7. SEM studies revealed an alpha-beta dual

particles along the interdendritic regions and grain boun-

tal and phase distribution structure after casting process phase structure with a fine distribution of non-dissolved

La Metallurgia Italiana - November/December 2020

segregates to the eutectic liquid and solidifies as pure lead daries [25, 30].

pagina 29

Memorie scientifiche - Fonderia leghe di rame

Fig.7 - SEM micrograph of standard leaded brass faucet microstructure with phase distribution and Pb after casting process. In Fig. 8 the microstructures of increasing amount of alu-

minum in the leaded brass composition are presented. Phase structure consisted of α phase crystals precipitated

in a β phase matrix as shown in Fig. 8. While A1 and A2 mi-

crostructures are similar to the standard one, some particles have been observed to settle in grain boundaries in A3

microstructure. Sadayapan et al. [21] investigated effects of grain refiners at different alloys. By contrast with our experiments, after addition of 0.35 wt.% Al in Cu-36 wt.%

Zn alloy, aluminum reduces the grain size marginally. The microstructure is modified from a interlocking dendritic

structure to a fine feathery structure. García et al. [24] and

Sadayappan et al. [25] confirmed that Al has a significant effect on grain size, when 0.25% Al was added to Cu-Zn-

Sn brass alloy. It is known that different alloy compositions show distinct microstructural effects. Aluminum is known

as a promoter of beta phase in Cu-Zn alloys and considered at least 6 times effective than Zn. In other words, 1 wt.% Al addition is as effective as 6 wt.% Zn addition. Ca-

sting faucet microstructure (Fig. 8c) contains much more beta phase than cast standard faucet microstructure (Fig. 8a).

Fig.8 - Comparison of the microstructure images of the standard leaded brass composition with (a) standard (b) 0.0055 wt% (c) 0.03 wt.% (d) 0.05 wt.% aluminum added compositions

La Metallurgia Italiana - novembre/dicembre 2020

pagina 30

Scientific papers - Foundry of copper alloys The microstructure of cast faucet samples was studied by

served from EDX measurements. Elemental analysis re-

tions in microstructure was determined. In the standard

at α-phase and β-phase had wt.% 45 Cu, wt.% 55 zinc ap-

micro-area quantitative analyses and elemental composibrass faucets, EDX analysis after casting showed copper, zinc and lead in the microstructure (Fig. 9). Alpha (copper

rich) and beta (zinc rich) phases and Pb particles were ob-

sults showed that wt.% 56 Cu, wt.% 44 zinc was present proximately. At scanned area wt.% 77 Pb, wt.% 15 Cu and wt.% 8 Zn was determined.

Fig.9 - SEM micrograph of the faucet with standard leaded brass composition. The result of the EDX study of A3 composition, which

Spectrum 1 area [29]. Elemental analysis results showed

lower pressure with aluminum addition, is given in Fig.

of α-phase (Spectrum 2) and β-phase had wt.%48 Cu, wt.%

enables the thin section casting to be performed with 10. The white particles in the microstructure (Fig. 10) are

lead-rich particles revealed by EDX measurements at

that wt.% 51.2 Cu, wt.% 48.8 zinc present at scanned area 50,6 zinc and wt.% 1.4 Al, approximately (Spectrum 4).

Fig.10 - SEM micrograph of the brass faucet with A3 composition.

La Metallurgia Italiana - November/December 2020

pagina 31

Memorie scientifiche - Fonderia leghe di rame Some alloying additions have a large effect on the structu-

re of brass, by altering the proportion of alpha, betta, or

gamma phase present. Alloying elements like Al lead to the increase of the area fraction of hard intermetallic pha-

ses in the brass matrix [30]. The addition of aluminum was

increased up to 0.05 wt.% in this study (A3). The alloy matrix has a duplex phase microstructure both alpha and beta phases. Microstructure of the standard leaded brass

faucet consists of copper, zinc and small amounts of aluminum as pointed with different areas in Fig. 9. Discrete

lead particles are primarily founded in grain boundaries

and inter-dendritic regions [24]. When alloying elements

are added with large amounts, the coarser and brittle inter-

metallic compounds form in the grain boundaries and that causes cracks and sealing problems [30].

Since the thickness of the castings could not be reduced to the desired level with the addition of aluminum for thin

section trials, the addition of nickel metallic powder was

continued. Different amounts of metallic nickel powder

was added to the melting furnace according to the Table

2. The microstructures of the compositions with increasing nickel addition (0.0055 wt.%, 0.03 wt.%, 0.05 wt.%)

are presented in Fig. 11a-d, respectively. According to the

standard brass faucet composition (Fig. 11a), nickel content was increased to 0.0055 wt. % (Fig. 11b) and casting pressure was decreased approximately 40 mbar. It is believed that nickel addition increases the fluidity of the al-

loy. After this trial, nickel content of the brass composition was increased to 0.03 wt.% (Fig. 11c) and increasing nickel content (N2) caused coarse microstructure and it made ca-

sting process difficult [7]. However, increasing the nickel

content to 0.05 wt. % (Fig. 11d), it was observed that the microstructure was re-fined and a homogeneous micro-

structure was obtained. In N3 microstructure clear needles was observed. Microstructural re-finement of copper

based alloys is aimed at improving the pressure tightness of plumbing components [19, 21].

Fig.11 - Comparison of microstructural images of (a) standard (b) 0.0055 wt.% (c) 0.03 wt.% (d) 0.05 wt% nickel-added cast compositions. The maximum reduction in the filling pressure was achieved with the addition of nickel at the maximum level (0.05

wt.%), and thin section samples were able to be cast at

this low pressure. Fig. 12 shows the microstructure of the brass faucets obtained after casting with the maximum nickel addition (0.05 wt.%), defined as N3 composition. Ac-

cording to the analysis taken from the Spectrum 2 point (white area) is characterized as lead-rich particle. Elemental analysis results showed that wt.%53 Cu, wt.%47 Zn

La Metallurgia Italiana - novembre/dicembre 2020

present at Spectrum 2 point (the Îą-phase brass). Spectrum

4 elemental analysis result showed that this area might be

referred as Î˛-phase with wt.% 43 Cu and wt.% 56 Zn. Scan result of bigger area (red area) showed nickel peaks in the

EDX analysis but the amount of nickel is quite minor than copper and zinc. Nickel rich areas could not observed in the microstructure as clear as aluminum containing areas in the grain boundaries like A3 composition (Fig. 10).

pagina 32

Scientific papers - Foundry of copper alloys

Fig.12 - SEM micrograph of N3 composition with EDX analysis points. Strip Fluidity Test Results

according to the standard leaded brass composition. It’s

the viscosity, the lower will be fluidity of the liquid me-

effect the strip. Our experiments also showed that when

Strip fluidity test results are given in Table 3. The higher tal. This information is supperted by fluidity length measurements. It is observed that the lengths of the strips of

aluminum and nickel added compositions were longer

believed that increasing fluidity of the alloy compositions fluidity lengths are increased, the casting pressures of the alloys are decreased.

Tab.3 - Strip fluidity test results of the samples depend on the compositions. Compositions

Flow Length (mm) Mean±S.D.*

226±6

240±8

320±6

293±7

270±5

365±5 S.D.*: Standard Deviation

Standard Quality Test Results & Wall Thickness

sion and leakage tests of at least 100 faucets of all com-

positions (A1, A2, A3 and N1, N2, N3) was prepared and

248 and TS EN 817, respectively. Test results were presen-

For the thin walled brass casting process, 6 different comlow pressure die casting process was carried out. Corro-

positions (A1, A2, A3) were performed according to TS EN ted in Table 4.

Tab.4 - Standard test results of brass faucets after casting. Compositions

Corrosion Test Result (200 hours)

Reduction of the thickness according to standard composition

Leakage Test results

Crack ratio (%)

Passed

%40

Passed

%40

Passed

%45

Passed

3-5

Passed

%40

Passed

%30

Passed

3-5

Passed

%55

Passed

La Metallurgia Italiana - November/December 2020

pagina 33

Memorie scientifiche - Fonderia leghe di rame According to these results, the addition of aluminum to

compositions (N1, N2, N3) were tested for corrosion and

ckness by 40 %, however, when addition amount of the

vely. However, the number of cracks in N2 composition

the leaded brass composition resulted a reduction in thialuminum was increased, the cracks formed due to the

high amount of aluminum deposition around the grain boundaries. Therefore, the aluminum amount that can be

worked in production of cast brass faucets was held 0.03 % by weight. For nickel addition, at least 100 pieces for all the

leakage according to TS EN 248 and TS EN 817, respecti-

increased. Fluidity of the N2 composition was less than N1

and N3 and this behavior made casting difficult. During casting with N2 composition crack ratio increased up to 5 %. Crack sample of the faucet surface is seen in Fig 13.

Fig.13 - Crack sample of the faucet surface. According to the standard brass composition, N3 compo-

brass faucet are seen in Fig. 14a and Fig. 14b, respectively.

nal images of standard brass faucet and thin walled (N3)

thickness with respect to standard composition (Table 4).

sition is provided the reduction of thickness. Cross-sectio-

N3 composition caused approximately 55 % reduction of

Fig.14 - Cross-sectional area of a) standard, b) N3 brass samples after casting. CONCLUSIONS

nickel metallic powder addition, there has been a signifi-

cet can be successfully produced with controlled CuZn-

reduced as 80 mbar by increasing nickel addition to 0.05

In this study, it has been showed that thin walled brass fau-

39Pb1Al-C melt composition. In addition, it has been

found that aluminum and nickel metallic powder addition

to the melt due to the reduction of the casting pressure. The addition of aluminum provided high fluidity in the

melting composition during casting. Therefore, in higher increments of the aluminum up to 0.05 wt.% (A3 compo-

sition), it was found that aluminum deposited in the grain boundaries that caused cracks and sealing problems. For

La Metallurgia Italiana - novembre/dicembre 2020

cant decrease in casting pressure. The casting pressure

wt.% (N3 composition). And also it is observed that the microstructure was refined and homogeneous. This composition was provided the reduction of the wall thickness

by 55 % ratio, when compared to standard faucet. Accordingly, for studied N3 composition, thin wall brass faucets

can be successfully produced according to brass faucet corrosion and leakage standards (TS EN 248 and TS EN 817).

pagina 34

Scientific papers - Foundry of copper alloys ACKNOWLEDGEMENTS

Authors would like to thank Mr. Burak Erçetin, Mr. Hüseyin Akyel, and Mr. Mehmet Ayan for their help and fruitful discussions throughout this study and all pilot trials in Eczacibasi Factory.

REFERENCES [1]

Khurmi R S, Gupta J K, A textbook of workshop technology: Manufacturing processes, S. Chand Publishing, New Delhi (1981).

[2]

Saxena S, Sharma P K, IJIRSET 6(2) (2017) 3018.

[3]

Flemings M C, MT 5 (1974) 2121.

[4]

Mollard F R, Fleming M C, and Nyama E F, AFS Trans 95 (1987) 647.

[5]

Meier J W, Research in Premium quality casting in light alloys, Mines Branch Research Report R149, Department of Mines and Technology Surveys, Ottawa (1965).

[6]

Voigt R C, Fillability of thin-wall steel castings, Office of Scientific & Technical Information Technical Reports , United States Department of Energy, Pennsylvania (2002).

[7]

Li F, Zhang J, Bian F, Fu Y, Xue Y, Yin F, Xie Y, Xu Y, and Sun B, Materials 8(6) (2015) 3701.

[8]

Macosko C W, Rheology: principles, measurements, and applications, VCH (1994).

[9]

Mugeri H, Matizamhuka W, Adebiyi D I, and Deppinar J H, Procedia Manuf 7 (2017) 402.

[10]

Ziolkowski J, Apelian D, Modeling of an aerospace sand casting processes, M Sc Thesis, Worcester Polytechnic Institute, USA (2002).

[11]

Campbell J, Castings, Oxford (2003).

[12]

Wang L, Makhlouf M, and Apelian D, Int Mater Rev 40 (1995) 225.

[13]

Govri S, Samuel F H, Metall Trans A 25 (1994) 437.

[14]

Lassmann S, Z Metallkd 91(10) (2000) 868.

[15]

Romankiewicz R, Romankiewicz F, J Cast Mater Eng 3(3) (2019) 51.

[16]

Alirezaei M, Doostmohammadi H, Int J Cast Met Res 29(4) (2016) 222.

[17]

Pugacheva N B, Pankratov A A, Frolova N Yu, and Kotlyarov I V, Russ Metall 2006 (2006) 239.

[18]

Suksongkarm D, Rojananan S. Rojananan S., Adv Mater Res 802 (2014) 179.

[19]

Strubel G C, Mach Des 42(4) (1970) 59.

[20]

Brooks C R, Heat treatment, structure and properties of non-ferrous alloys, ASM, Ohio (1982) p 20.

[21]

Sadayappan M, Cousineau D, Zavadil R, Sahoo M, and Michels H, AFS Trans 02-108 (2002) 1.

[22]

Choucri J, Zanotto F, Grassi V, Balbo A, Ebn Touhami M, Mansouri I, and Monticelli C, Metals 9(6) (2019) 649.

[23]

Jha S, Balakumar D, and Paluchamy R, Int J Automot Mech Eng 11 (2015) 2317.

[24]

García P, Rivera S, Palacios M, and Belzunce J, Eng Fail Anal 17(4) (2010) 771.

[25]

Sadayappan M, Thomson J P, Elboujdaini M, Gu G Ping, and Sahoo M, Grain refinement of permanent mold cast copper base alloys, MTL Report, Copper development Association, New York (2004).

[26]

Hussein R M and Abd O I, IJMS 909506 (2014) 1.

[27]

Silva E C Q, Defect sources in brasses and new low lead compositions, M Sc Thesis, University of Aveiro, Portugal (2016).

[28]

Mnif R, Elleuch R, Elleuch K, Haddar N, and Elhalouani F, Strength Mater 43(2) 2011 217.

[29]

Pantazopoulos G, Vazdirvanidis A, Microscopy and Analysis 2008, 13.

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Fadhil A A, Ghattas M S, Iskander B A, Ajeel S, and Enab T A, Alex Eng J 57(3) (2018) 1301.

La Metallurgia Italiana - November/December 2020

pagina 35

Memorie scientifiche - Convertitore ad ossigeno

Study on duplex process with a single converter A. Zhao, L. Zhang, Y. Fu, H. Long, N. Ali, Z. Zhou, Z. Nie, C. Zhang

This paper introduces the production practice of duplex process with a single converter of 120t BOF in steelworks. This work considers the smelting process, oxygen supply, slag-forming practices, and final control of dephosphorization, etc. as the technical characteristics of duplex process with a single converter. The results show that the endpoint [P] content is reduced to 0.018%, and the dephosphorization rate reaches 87.20% by duplex process with a single converter, while compared with the previous smelting process it was increased by 2.01%. At the same time, it also reduced oxygen supply time by 62s and the average amount of lime by 510kg per BOF heat. The consumption of lime and metallic charge materials was also reduced significantly. A correlation analysis is used to investigate the relationship between the consumption of lime and the dephosphorization rate, which is consistent with the industrial production results and proves that the consumption of lime is an important factor for the dephosphorization rate in duplex process with a single converter. It allows the stable production of the steelworks to achieve obvious economic benefits.

KEYWORDS: BOF, THE DEPHOSPHORIZATION RATE, DUPLEX PROCESS WITH A SINGLE CONVERTER. INTRODUCTION

In order to adapt to the change of the steel market, the domestic and foreign steelworkers[1-4] have been exploring

BOF smelting process, looking for ways to improve the

quality of molten steel and reduce the smelting cost. Domestic and foreign metallurgical workers[5-8] studied the

smelting process of BOF at the early stage of industrial

production. They believe that the high-quality smelting process not only improves the quality of molten steel pro-

duced from the BOF but also accelerates the smelting efficiency in order to reduce the cost. Therefore, the selection of the smelting process is of great importance to the BOF

production. Xue et. al[9] determined (P2) as one of the main

dephosphorization products, while (P2O5) and (FeO) in the

slag were found to be reduced at high temperature. Wang Minglin

[10]

Aonan Zhao, Liqiang Zhang, Naqash Ali, Chaojie Zhang

SSchool of Metallurgical Engineering, Anhui University of Technology, Maâ&#x20AC;&#x2122;anshan 243002, P.R.China

Corresponding author Liqiang Zhang ,e-mail: zhangsir508@163.com

Yudong Fu, Haishan Long, Zhiyong Zhou, Zhibin Nie Yangchun New Iron&Steel Co. Ltd of Xiang Steel Group, Yangchun, 529600, P.R.China

studied the dephosphorization behavior in the

early stage of converter steelmaking process and concluded that the double slag-retaining method can reduce the consumption of raw materials by lowering the phosphorus

content of steel. K. Yoshida[11] developed a simple refining

process (SRP) by using two 250t capacity top and bottom

La Metallurgia Italiana - novembre/dicembre 2020

pagina 36

Scientific papers - BOF blown converters, namely dephosphorization and decarbu-

rization furnaces, in order to recover the mass production process of both low-phosphorus and conventional steel

grades. Low (P2O5) lumpy slag obtained from the decarburization furnace was used as a dephosphorization agent in the dephosphorization furnace, which reduced the total lime consumption to achieve stable and quick refining. Fu

Qiang[12] investigated on a less-slag smelting technology in

120t converter although the dephosphorization rate at the

endpoint was increased. The BOF cycle was prolonged and

amount after the first blowing in the new process, while the remaining slag is dumped after tapping in the new process, as compared to the original smelting process in which the

slag is dumped after the smelting. The duplex process with

a single converter reduced the consumption of lime and increased the dephosphorization rate, while the (TFe) and the metallic charge material consumption decreased. Finally, the new process reduces the risk of spatter accident and thus ensures the safety.

the smelting time was also enhanced in Beiying Iron&Steel

ANALYSIS OF DUPLEX PROCESS WITH A SINGLE CON-

not perfect which can stabilize the steelmaking process to

Analysis of phosphorus content [P]

Co. Ltd of ben steel group. However, the process route was reduce the consumption of lime.

In this paper, the smelting process of 120t BOF in steelworks is studied experimentally. The duplex process with a single

converter is more scientific and advanced than the original

smelting process (Fig. 1a). Slag is dumped after smelting in

VERTER

From many years of production practice it was found that the dephosphorization effect will be efficient if the product of (CaO) and dephosphorization (P2O5) in the slag is

stable[13]. The equations describing the dephosphorization process are:

the original smelting process. The slag is dumped in a small 1) 2) The stability of (3CaO∙P2O5) is weak during the production

slag, which are (PO3-4) in the ionic constitution of slags[14-15].

stable at high temperatures. In terms of thermodynamics,

Therefore, the equilibrium constant Kp can be defined as,

process in the BOF converter, while the (4CaO∙P2O5) is

two compounds have the same conclusion in an alkaline

4) Dephosphorization reaction is the slag steel interface re-

action, and the catalytic effect of the early slag making process on the dephosphorization reaction is to increase the

distribution coefficient of phosphorus [P] between the slag and steel[14-15].

5) (LP,KP are the distribution coefficient and equilibrium con-

in the molten steel. Eq. (4) shows that the equilibrium con-

stant respectively, a is the activity, ∆G is the Gibbs energy

stant of dephosphorization reaction increases sharply when

in the standard state, R is a constant, while W1 and W2 are the

temperature drops, as a result the prominently enhanced

weight of metal and slag respectively.

dephosphorization was observed. The dephosphorization

With the progress of the smelting process, the (CaO) de-

reaction was exothermic, and the dephosphorization rate

creases gradually, while the continuously increasing level

decreased with the increase of temperature. The increa-

of slag (CaO∙P2O5) also declines the content of phosphorus

se of (FeO) content and basicity of slag is beneficial to the

La Metallurgia Italiana - November/December 2020

pagina 37

Memorie scientifiche - Convertitore ad ossigeno dephosphorization process. It is necessary to control the

perature, which ensures that the lime, dolomite and other

appropriate temperature of the molten pool to avoid the

slag-making materials melt completely. Meanwhile, the ba-

increase of [P] content in the middle and later stages of the

sicity of slag increases with the higher (MgO) content. Then

BOF smelting process, and the high oxidation and basicity

the decarburization reaction takes place, resulting in a sub-

environment can produce high-quality slag.

stantial reduction in oxides such as (FeO). With the increase in BOF temperature and the continuous lime melting, the

Analysis of BOF slag - making practices

basicity of slag increases again. How to achieve rapid slag

At the beginning of BOF smelting process, the silicon [Si],

formation is the key to improve the dephosphorization ef-

manganese [Mn], phosphorus [P], iron [Fe] and other ele-

fect. In the later stage of smelting, the [P] content in molten

ments in the molten iron produce oxidizing material in the

iron decreases, and the slag basicity becomes the key to the

slag, at the same time the addition of slag-making materials

dephosphorization process.

such as lime or dolomite also melt gradually. The slag is low alkaline acidic slag with a relatively high composition of

DUPLEX PROCESS WITH A SINGLE CONVERTER

(FeO), (SiO2), (MnO), while the composition of (CaO) is low.

Manufacturing process and experimental conditions

The [P] content in the molten iron is also relatively high. By

In this paper, the 120t BOF industrial production line of a

increasing the content of (FeO) in molten slag, the oxida-

plant is taken as the research object. The manufacturing

tion of [P] in molten iron can be accelerated, as a result the

process is: 1280 m3 blast furnace (BF), 120t basic oxygen

stirring of molten iron can be increased and the kinetic con-

furnace (BOF), and 155mm*155mm Continuously Cast bil-

ditions can be improved to facilitate the mass transfer of [P].

let. The duplex process with a single converter is shown in

It completes the early dephosphorization process, while

Figure 1, while the initial molten iron condition is shown in

the oxidation heat of [Si] and [Mn] increases the melt tem-

Table 1.

Fig.1 - Duplex process with a single converter (a) the original process flow chart of a factory (b) the process flow chart of a factory using a single converter double method.

Tab.1 - Initial molten iron condition. w(C)%

w(Si)%

w(Mn)%

w(P)%

w(S)%

The initial molten iron

3.90-4.62

0.14-1.07

0.22-0.42

0.08-0.24

≤0.07

Smelting target

0.20-0.25

0.30-0.55

1.20-1.55

≤0.02

La Metallurgia Italiana - novembre/dicembre 2020

pagina 38

Scientific papers - BOF The experimental plan for the oxygen supply

in the middle of smelting to prevent the slag drying and

The plant uses a Laval oxygen lance nozzle with 5 holes

large accumulation of (FeO), as the temperature of the

and the oxygen outlet pressure was set at 0.88Mpa with

furnace increases. Because the more material is added for

the oxygen flow rate of 25000 Nm3/h -27000Nm3/h. The [C]

the first time, the lance position is increased in order to

content of the final steel was controlled to 0.06%-0.12%.

prevent the rapid increase of temperature, which causes

For the initial slag formation, the position of the oxygen

the slag splashing. In the later stage of smelting, the metal

lance was adjusted at 1.2m away from the liquid level in

and slag were mixed uniformly with the low pressure of

the early stage of the BOF smelting process. After 90s, the

oxygen lance. In the first slag pouring, the amount of slag

oxygen lance position was changed to 2.3m from the li-

in the furnace will be reduced with thinner slag layer, and

quid level. In the middle of the smelting process, the oxy-

oxygen can penetrate the slag layer with an improved uti-

gen lance operation was started after 9 min to prevent the

lization rate, resulting in decreased oxygen blowing time.

slag drying, while its position was adjusted to 0.9m in or-

The constant oxygen pressure, the closed location of the

der to ensure a uniform stirring of the molten pool.

nozzle to liquid surface, the smaller and deeper impact

In the duplex process with a single converter, the slag

area and the great impact of velocity on the liquid surface

making materials (mainly lime and dolomite) are added in

are the more favourable factors to enhance the mixing of

batches. The first batch of the materials (lime =1t and all

the molten pool. The mixing intensity also affects the de-

amount of dolomite) was added after the start of the smel-

phosphorization by producing favourable external factors.

ting process, while the remaining lime and other slag ma-

The comparison of the oxygen blowing time and amount

terials were added after blowing for 8 min.

in different manufacturing processes is shown in Figure 2. The blowing time by the duplex process with a single

RESULT AND DISCUSSION

converter is compared with the original process, which

Oxygen supply

reduces from 863s to 801s with the average reduction in

The "low-high-low" is the operation specification of oxy-

oxygen blowing time of 62s. The oxygen blowing amount

gen lance in steelworks. The quick slag formation is the

is also compared with the original process which increases

main purpose of low lance position in the early stage of

from 5627m3 to 6516m3 with an average increase of 889m3.

smelting process. The lance position is increased to 2.3m

Fig.2 - Comparison of the oxygen blowing time and amount in different manufacturing processes.

La Metallurgia Italiana - November/December 2020

pagina 39

Memorie scientifiche - Convertitore ad ossigeno Slag-forming

the increase of basicity, (MnO) will promote the dissolution

that the slag fluidity in the duplex process with a single con-

slag formation is fast which cannot dry up easily in the mid-

After 100 smelting experiments in steelworks, it was found verter is perfect. The speed of converter slag formation de-

pends upon the dissolution rate of lime, especially under

the condition of high phosphorus hot metal smelting. The rapid formation of liquid dephosphorization slag with high oxidation property and appropriate slag basicity (R=CaO/

SiO2) is the fundamental guarantee to ensure the timely dephosphorization and no return of phosphorus to the steel.

In the initial stage of smelting, the converter goes through

the desiliconization and dephosphorization, and when the

slag pouring operation starts the superheat degree of the slag increases with the rise of converter temperature. This

phenomenon is beneficial for the lime and slag penetration, as a result the melting point of lime decreases, With

of lime when the (FeO) content in slag is sufficient, so the dle of oxygen blowing. Therefore, the high lance position increases the (FeO) in the slag and the slag has good capa-

bility of quick dephosphorization. The composition of slag

is controlled and the slag system with low melting point is obtained. The new manufacturing process is suitable for the

actual conditions of steelworks. In the actual production conditions of molten iron, the average amount of dolomite

added in slag making materials per BOF does not change

much and it reduces the lime by an average of 510kg per BOF. The consumption of lime is also reduced by 4.36kg/t,

which achieves the obvious economic benefits. The comparison of slag making materials is shown in Table 2.

Tab.2 - Comparison of slag making materials (the average of 100 industrial experiments). Lime(t)

Dolomite (t)

Consumption of lime (kg/t)

Metallic charge material consumption (kg/t)

The original manufacturing process

3.26

1.64

26.99

1062.95

Duplex process with a single converter

2.75

1.62

22.63

1060.13

The consumption of metallic charge materials is reduced

from 1062.95kg/t to 1060.13kg/t, which implies that the duplex process with a single converter improves the metallic yield.

During the smelting process, a part of the slag remained in the furnace for smelting, which means that the slag with

high (FeO) content will indirectly participate in the carbon-oxygen reaction. In the slag pouring process, the con-

tent of FeO decreases gradually. The (FeO) participates in the reaction to obtain [Fe] in the decarburization stage (pha-

se decarburization), then [Fe] element returns to the furnace, and oxygen is blown again for the complete oxidation of silicon and other elements in the early stage. The lime

and other slag making agents have been put into the furnace

and the slag amount becomes relatively less than that of the original process. The smaller (TFe) content in the slag leads

to a minimum loss of molten iron, which increases the yield

of steel, while the iron and steel materials consumption

was reduced by 2.82kg/t. The new manufacturing process decreased the basicity of the final slag and (CaO), and also

reduced the basicity of the final (TFe) by 1.45%. The (CaO) content decreases with the minor decline of slag basicity in

the double method. When the basicity of slag is too high, there will be more (CaO) and (MgO) suspended particles in the liquid slag, which will reduce the fluidity of slag and

is not favorable for the dephosphorization. Therefore, it is

necessary to understand the influence of slag basicity on the slag dephosphorization ability in a dialectical manner. Overall, this method is suitable for the stable production of a certain plant, its smelting effect is obvious, and the service life of the converter can be improved. The comparison of the slag for different processes is shown in Table 3.

Tab.3 - Comparison of slag (the average of 100 industrial experiments). CaO/%

SiO2/%

MgO/%

MnO/%

TFe/%

R(CaO/SiO2)

The original manufacturing process

48.48

14.55

8.98

4.05

14.82

3.33

Duplex process with a single converter (the early stage of the slag)

38.75

19.77

7.16

3.11

14.21

1.96

Duplex process with a single converter (the endpoint stage of the slag)

46.45

16.17

7.83

3.48

13.37

2.87

La Metallurgia Italiana - novembre/dicembre 2020

pagina 40

Scientific papers - BOF Dephosphorization

endpoint [P] to 0.018%, and the dephosphorization rate

is found that the lime consumption, endpoint temperature

smelting process increased by 2.01%. The quick slag pou-

Through the correlation statistical test of 100 furnaces, it

and dephosphorization rate of the converter are significantly correlated. The dephosphorization rate has a significant downward trend with the increase of endpoint tem-

perature. The double method fully utilizes the influence of temperature change on the dephosphorization reaction

and reduces the endpoint temperature of the original process by 1.95C. The temperature, phosphorus content, and dephosphorization rate at the smelting end in the original manufacturing process and the duplex process with

a single converter are shown in Table 4. It completes the

reaches 87.20%, which when compared with the original ring and retaining after the end of the blowing process can

carry out the dephosphorization reaction more thoroughly. By using slag retention operation in the early stage, the residual slag will have a certain temperature and the

appropriate composition as shown in Table 3. The process of first slag formation produces a low temperature in the early stage of the molten pool with better dephosphori-

zation ability. The scatter plots for different factors are shown in Figures 3 and 4, while the Pearson correlation test results are shown in Table 5.

Tab.4 - Comparison of dephosphorization (the average of 100 industrial experiments). Endpoint temperature/Â°C

Endpoint [P]/%

Dephosphorization rate

The original manufacturing process

1652.59

0.019

85.19%

Duplex process with a single converter

1650.64

0.018

87.20%

Fig.3 - Scatter plot of melting endpoint temperature and dephosphorization rate.

Fig.4 - Scatter plot of lime consumption and dephosphorization rate.

La Metallurgia Italiana - November/December 2020

pagina 41

Memorie scientifiche - Convertitore ad ossigeno The red scatter region in the figure indicates that there is

the dephosphorization rate of converter significantly. The

a linear relationship between the melting endpoint tem-

correlation coefficient for the added lime and the endpoint

perature, lime consumption, and dephosphorization rate.

temperature was -0.311 and -0.385, which are important

The sigma (two-tailed) are 0.002 and 0.000, as the signifi-

factors that affect the dephosphorization rate. The results

cance value is less than 0.01, thus there is a significant cor-

of correlation statistical analysis are in agreement with the

relation between the two variables [16].

industrial experimental results of the duplex process with

This indicates that the little variation for lime can affect

a single converter.

Tab.5 - Correlation analysis (**- The correlation was sigma 0. 01 (two-tailed), N-number).

The dephosphorization rate

Consumption of lime (kg)

Endpoint temperature/Â°C

-0.311** 0.002 100

-0.385** 0.000 100

Pearson correlation Sigma (two-tailed) N

Analysis of BOF spatter accident

is significantly lower than the original process.

In the actual manufacturing process of steelworks, the oxygen lance position has no normal operation specifi-

CONCLUSION

cations during the oxygen smelting process and the BOF

(1) Duplex process with a single converter have "low-hi-

converter spatter accident occurs in 4-5 min during the

gh-low" operation specification for oxygen lance. The

smelting process. The high [P] content in the molten iron,

oxygen blowing time was reduced by 62s, which reduced

the low slag viscosity with high slag quantity, and easy slag

the smelting cost.

foam formation lead to a spatter rate of 63.30% in a steel

(2) The new process reduces the metallic charge material

plant. The spatter accident reduces the service life of the

consumption by 2.82kg/t, and also reduces the amount

converter, damages the oxygen lance and shaft, increases

of iron in slag (TFe) by 1.45%, as compared to the original

the security-hidden risk during the converter process and

process.

has a serious risk to the worker's life safety. In the duplex

(3) The industrial data show that after using duplex pro-

process with a single converter, (FeO) content is control-

cess with a single converter, the consumption of lime is

led by changing the oxygen lance position. Meanwhile,

reduced to 4.36kg/t, which is consistent with the results of

the second batch of slag making materials should be ad-

correlation analysis. The new process reduces lime con-

ded in small amounts to stabilize the BOF temperature and

sumption and slag with increased dephosphorization rate.

carbon reduction rate. A slag pouring is carried out in the

(4) The new process reduces the slag amount due to the

smelting process to create a thinner slag layer and redu-

slag pouring in the smelting process. It lowers the risk of

ce the accumulation of (CO2) under the slag layer which is

spatter accident rate to 35.40% and avoids the slag drying.

due to the slag drying and results in explosive spatter. The

It also stabilizes the converter production to ensure the

spatter accident is found to be reduced by 35.40%, which

safety of equipment and workers.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 42

Scientific papers - BOF ACKNOWLEDGEMENT The successful completion of this project is benefited from the financial support provided by National Natural Science Foundation of China (U1760108, 51874001). REFERENCES [1]

Y. Kitamura, S. Ogawa. Improvement of reaction efficiency in hot metal dephosphorization. Ironmaking & Steelmaking, 37 (2002), No. 8, 554-561.

[2]

J. Diao. System assessment of recycling of steel slag in converter steelmaking. Journal of Cleaner Production. 125 (2016), No. 3, 125167.

[3]

Z. Yingjia, L. Jipeng. The technology of less slag steelmaking by double-slagging the 120t BOF of jisco. Henan Metallurgy. 26 (2018), No. 6, 53-56.

[4]

K. Shinya. History and latest trends in converter practice for steelmaking in Japan. Mineral Processing and Extractive Metallurgy. 128 (2018), No.1,34-45.

[5]

L. Zhiguo, Experimental study on dephosphorizing agent containing BOF slag for pretreating molten iron. Journal of Iron and Steel Research, 15 (2016), No. 6, 9-15.

[6]

J. Dejin. Production practice of less-slag smelting in Bensteel. Energy for metallurgical industry. 33(2004), No.5,13-17.

[7]

L. Wei. Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field. High Temperature Materials and Processes. 36 (2017), No. 6,599-605.

[8]

X. Weikang. Practice and Research on Less Slag Smelting of 210t Converter in Rizhao Company of Shangang. Science & Technology Vision. 13(2019), No. 6,70-71.

[9]

Xue.

Phosphorus

vaporization

behaviour

from

converter

slag,

Ironmaking

Steelmaking,

(2019)

DOI:

10.1080/03019233.2019.1630214 [10]

W. Minglin. Dephosphorization in the early stage of converter steelmaking. Ironmaking & Steelmaking. (2019) DOI: 10.1080/03019233.2019.1673546

[11]

K. Yoshida. Development of the Continuous Dephosphorization and Decarburization Process Using BOF, Tetsu-to-hagane, 87 (2001), No. 1, 21-28.

[12]

F. Qiang, G. Xiaochun, W. Zhiqiang, W. Jian. Research and practice of less slag smelting technology in 120 t converter. Steelmaking. 33 (2017), No. 6, 5-8.

[13]

R. Inoue, H. Suito, Phosphorous Partition between 2CaO•SiO2 Particles and CaO–SiO2–FetO Slags. ISIJ International, 46 (2006), No. 2, 174-179.

[14]

F. C. Broseghini. Evaluating the hot metal dephosphorization efficiency of different synthetic slags using phosphorus partition ratio, phosphate capacity and computational thermodynamics. Metallurgy and materials Metalurgia e materiais. 71(2018), No. 2, 217-223.

[15]

Z. Xuejiao. Stability analysis of hydroxyapatite in the system P-Ca-H2O aided prediction of the mechanisms of dephosphorization from the high phosphorus iron ore by hydrometallurgy process. Metallurgy & Metallurgical Engineering. 113(2016), No.3.

[16]

K. SuanChen. Two-tailed Buckley fuzzy testing for operating performance index. Journal of Computational and Applied Mathematics. 361(2017), No.1, 55-63.

La Metallurgia Italiana - November/December 2020

pagina 43

convegno nazionale

trattamenti termici NUOVE DATE: 6-7 MAGGIO 2021 GENOVA • MAGAZZINI DEL COTONE • PORTO ANTICO

www.aimnet.it/tt.htm Il Convegno-esposizione si svolgerà il 6 e il 7 maggio 2021, presso i Magazzini del Cotone di Genova, nel bellissimo contesto del porto antico. Avrà come fulcro l’area espositiva animata da tutte le aziende coinvolte nella filiera del Trattamento Termico, partendo da chi esegue il TT, passando per le aziende di produzione che necessitano di trattamento termico, ai costruttori di impianti, ai fornitori di ausiliari, etc. Il Comitato Organizzatore ha previsto una molteplice offerta, dedicata alle aziende che vorranno prendere parte attivamente al più autorevole e affermato evento italiano, dedicato ai trattamenti termici. Le aziende interessate alla sponsorizzazione e alla partecipazione all’area espositiva, potranno contattare la Segreteria Organizzativa o visitare il sito dell’evento, dove sono disonibili maggiori informazioni e la modulistica.

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Industry news - Stainless steels

La corrosione microbiologica negli acciai inossidabili: una mini-review a cura di: D. Lega - INAIL, DIT, M. Romitelli - libero professionista

La corrosione microbiologica o MIC (microbial induced corrosion) è un fenomeno corrosivo determinato dall’azione diretta o indiretta di diversi gruppi di microrganismi quali batteri, alghe o funghi. Tale tipologia di corrosione costituisce

un grosso problema industriale che interessa prevalentemente le attrezzature che si trovano in un ambiente acquoso

quali per esempio i sistemi di raffreddamento e di stoccaggio, le condutture e le attrezzature sottoposte a prova idraulica. Il processo di corrosione è generalmente inaspettato e veloce, e conduce in tempi molto brevi, dell’ordine di qualche mese, alla perforazione del componente interessato. In questa memoria viene presentato lo stato dell’arte in merito al

fenomeno della corrosione microbiologica negli acciai inossidabili. In particolare vengono analizzati i principali meccanismi di biocorrosione e viene presentata una analisi della morfologia del danneggiamento.

PRINCIPALI MECCANISMI DI BIOCORROSIONE

canali acquosi aperti che consentono gli scambi fra una

I microrganismi sono presenti in tutti gli ambienti acquosi

microcolonia e l’altra. Un biofilm pertanto è una struttura

ed in tutti i fluidi industriali contenenti acqua ed hanno la

complessa che risulta composta dai microorganismi, dai

tendenza ad aderire e crescere sulle superfici metalliche.

prodotti del loro metabolismo, dai materiali polimerici ex-

In condizioni di acque stagnanti o di basso flusso danno

tracellulari prodotti (EPS), dai detriti intrappolati e dai pro-

luogo alla formazione di biofilms. Nel biofilm i microorga-

dotti di corrosione. (fig.1) La formazione di un biofilm offre

nismi sono organizzati in aggregati di microcolonie e sono

ai microorganismi il vantaggio di una maggiore protezione

intrappolati in una matrice polimerica costituita da esopo-

dagli agenti tossici e dai biocidi, ed offre anche l’opportu-

lisaccaridi, proteine e DNA extracellulare da loro prodot-

nità di una maggiore concentrazione dei nutrienti. [1, 2, 3,

ti. All’interno della matrice polimerica sono presenti dei

4, 5 ,6, 7]

Fig.1 - a) formazione e struttura di un biofilm b) immagine FEGSEM di un biofilm su un acciaio AISI 304 [tratto da 4, 8].

Gli effetti corrosivi dei microorganismi su una superficie

la produzione o il consumo di ossigeno, la produzione di

metallica possono esplicarsi mediante una serie di azioni:

acidi organici o minerali, la trasformazione dei composti

La Metallurgia Italiana - November/December 2020

pagina 45

Attualità industriale - Acciai inossidabili dell’azoto o dello zolfo, la fermentazione o le reazioni di

coinvolti nei processi di corrosione degli acciai inossida-

ossido-riduzione. [7, 9, 10] I principali microorganismi

bili sono alghe e batteri così come riassunti nella tabella 1:

Tab.1 - Microorganismi coinvolti nella corrosione degli acciai inossidabili. Regno

Famiglia

Habitat

Caratteristiche

Desulfovibrio, Desulfomaculatum

Tutte le acque comprese quelle marine ed il suolo

Trasformazione dei composti dello S

Gallionella

Acque contenenti sostanza organica e composti del ferro e/o del manganese

Ossidazione del ferro e del manganese ; areazione differenziale

Pseudomonas

Tutte le acque comprese quelle marine ed il suolo

Areazione differenziale; Riduzione dell’ossido di Fe

Alghe verdi e blu-verdi

Acque superficiali e profonde

Areazione differenziale

Batteri

Sphaerotilus sp

Alghe

Dalla tabella 1 si evince che l’influenza di un biofilm sui

sidi di Fe e di Mn. I batteri ossidanti il Fe (Gallionella , Spha-

processi di corrosione di un acciaio inossidabile si esplica

erotilus) trasformano il Fe+2 a Fe+3 con la deposizione di

principalmente mediante la trasformazione dei composti

ossido idrato di Fe+3: Fe(H2O)6+3 (1) il quale ricopre la super-

dello S, l’ossidazione o riduzione del ferro e del mangane-

ficie metallica di uno strato melmoso. Questo idrossido dà

se, l’areazione differenziale. [6, 7, 9, 10, 11].

luogo ad idrolisi determinando localmente una riduzione del pH (2). Alcuni batteri (Siderocapsa) sono inoltre capaci

Ossidazione del Fe e del Mn

di ossidare il Mn+2 a Mn+4 (3) con deposizione di biossido di

Alcuni batteri determinano la biotrasformazione degli os-

Mn, un forte agente ossidante (4). 1) 2) 3) 4)

Gli ossidi ed idrossidi di Fe e Mn così formati danno luogo

nomeno dell’idrolisi determinano un cambiamento locale

alla formazione di depositi insolubili sulla superficie me-

del pH. Questo fenomeno è accompagnato da un aumento

tallica con forma conica a vulcano o a catena montuosa.

della concentrazione degli ioni cloruro che migrano verso

Questi depositi creano delle regioni con differente con-

la zona anodica per neutralizzare la carica positiva generata

centrazione di ossigeno determinando la formazione di

dall’aumento del pH. A questo punto si è generato quindi

pile a concentrazione. La superficie metallica presente

un fenomeno di corrosione localizzata, un piccolo anodo,

sotto il deposito è povera di ossigeno e si trasforma in un

un grande catodo, un ambiente acido e l’accumulo di ioni

piccolo anodo mentre l’ampia superficie che la circonda,

cloruro, ed il processo di corrosione continua in modo in-

più ricca di ossigeno, diviene un catodo. Nella zona anodi-

dipendente dalla specie batterica colonizzante. [9, 10, 11,

ca il metallo si ossida formando ossidi idrati che per il fe-

12, 13, 14, 15, 16] (fig.2)

La Metallurgia Italiana - novembre/dicembre 2020

pagina 46

Industry news - Stainless steels

Fig.2 - schema del processo di corrosione generato da batteri ossidanti il Fe. Areazione differenziale

delle microzone a diverso contenuto di ossigeno ed una

nera facilmente un processo di corrosione per areazione

O2 è maggiore costituisce il catodo e qui avviene la sua ri-

La presenza di un biofilm su un acciaio inossidabile gedifferenziale. Infatti un biofilm agisce come una barriera

fisica alla diffusione dell’O2 ed agisce anche consumando

O2 mediante alcuni processi metabolici. Si generano così

pila a concentrazione. La zona dove la concentrazione di duzione. La zona più povera di O2 costituisce invece l’ano-

do e qui avviene la dissoluzione del metallo. [9, 11, 12, 13] Le reazioni coinvolte sono le seguenti:

(reazione anodica)

(reazione catodica)

Le reazioni di idrolisi degli ossidi idrati determinano una

gradazione dei metalli. Sono batteri anaerobici, presenti

ioni cloruro e generando così un fenomeno di corrosio-

che in presenza di ossigeno purchè in quantità limitate. Il

locale riduzione del pH facilitando così l’ingresso degli ne localizzata che procede anche in maniera indipendente dalla specie batterica colonizzante.

sia nelle acque che nei suoli, che possono svilupparsi anmeccanismo di corrosione è complesso e nel corso degli

anni sono state sviluppate diverse teorie. La teoria classica

è quella della depolarizzazione catodica (1934). [12, 14, 16,

Trasformazione dei composti dello S

I batteri solfato riduttori sono ritenuti i più attivi nella de-

17] Le reazioni coinvolte sono le seguenti:

(reazione anodica)

(reazione catodica)

(metabolismo del batterio solfato riduttore)

Una teoria sviluppata successivamente (EMIC eletrical mi-

sono utilizzare direttamente gli elettroni provenienti dalla

crobial influenced corrosion , 1992) prevede invece l’uti-

ossidazione del Fe per la riduzione del solfato (fig.3b). In

lizzo diretto degli elettroni da parte di alcuni batteri solfato

questo caso le reazioni coinvolte sono le seguenti:

riduttori quali per esempio desulfovibrio. Tali batteri pos(reazione anodica)

10)

(reazione catodica e metabolismo del batterio solfato riduttore) 11)

La Metallurgia Italiana - November/December 2020

pagina 47

Attualità industriale - Acciai inossidabili

Fig.3 - schema dei processi di corrosione dei batteri solfato riduttori: 3a teoria della depolarizzazione catodica; 3b teoria dell’utilizzo diretto degli elettroni [tratto da 19]. Il meccanismo relativo all’ utilizzo diretto degli elettroni rima-

to diretto, l’utilizzo di appendici conduttive denominate pili

ne controverso, le teorie più accreditate prevedono il contat-

(fig.4) oppure l’utilizzo di mediatori elettronici. [19,20]

Fig.4 - micrografia SEM dei pili di un batterio solfato riduttore [tratto da 20]. In presenza di substrati organici naturali alcuni batteri sol-

lecolare ad anidride carbonica. Le reazioni coinvolte sono

fato riduttori, nell’ambito di una respirazione anaerobica,

le seguenti considerando come composto organico di

utilizzano il solfato come accettore di elettroni al posto

esempio lo ione acetato:

dell’O2 e convertono composti organici a basso peso mo(semireazione catodica) 12) (semireazione anodica)

13)

L’acido solfidrico così prodotto è molto corrosivo nei confronti del metallo: 14) Questo meccanismo di corrosione è detto CMIC , Chemi-

Riduzione dell’ossido di Fe

cal microbial influenced corrosion , ed è stato proposto

Alcuni tipi di batteri quali Pseudomonas o Shewanella sono

nel 2006.[16, 18, 20]

in grado di ridurre gli ossidi di Fe e Mn. Pseudomonas è un

La Metallurgia Italiana - novembre/dicembre 2020

pagina 48

Industry news - Stainless steels batterio ferro riducente con alta capacità di adesione che

di ossido insolubile di Fe+3 Pseudomonas produce degli

altera lo strato passivante mediante la rimozione selettiva

agenti chelanti detti siderofori, i quali presentano una ele-

di Fe+3, importante nella struttura dell’ossido misto di un

vata affinità per lo ione ferrico, che catturano e trasportano

acciaio inossidabile. Lo strato passivo può essere quindi

all’interno della cellula batterica. Donatori di elettroni ven-

danneggiato o sostituito da uno meno stabile di metallo

gono considerati l’idrogeno o materiale organico a basso

ridotto che può favorire la corrosione. La biochimica del

peso molecolare secondo la reazione: [12, 13, 21, 22].

processo di riduzione del Fe+3 è poco nota. In presenza 15) Sinergie tra i diversi meccanismi

bile è il seguente: al di sotto di un deposito prodotto da

I processi di corrosione microbiologica sono interattivi ed

batteri ossidanti il Fe ed il Mn si genera una zona povera

i diversi meccanismi generalmente sono spesso sinergici.

di ossigeno dove operano i batteri solfato riduttori. [2, 24]

Uno schema di interazione tipico su un acciaio inossida-

(fig. 5)

Fig.5 - sinergie in un processo di corrosione microbiologica su un acciaio inossidabile [tratto da 23]. Morfologia del danneggiamento

meno della corrosione microbiologica sono gli austenitici

Gli acciai inossidabili sono generalmente resistenti alla

delle serie AISI 300 ed AISI 400, in particolare AISI 303, AISI

corrosione anche in ambienti particolarmente aggressivi

304, AISI 304L, AISI 316, AISI 316L ed AISI 321 stabilizzato

in relazione alla presenza di un film di passività, sono in-

con Ti, i martensitici con 13% di Cr e 1% di Ni ed i ferritici

vece suscettibili alla corrosione microbiologica quando

come AISI 409. [10, 32, 34] La corrosione microbiologica

vengono a contatto con il suolo o con l’acqua. Negli ultimi

negli acciai inossidabili genera un danno localizzato nella

anni sono venuti alla luce numerosi casi di perforazione

forma di vaiolatura o corrosione interstiziale che coinvol-

di componenti ed attrezzature in acciaio inossidabile per

ge soprattutto la zona fusa o la zona termicamente alterata

corrosione microbiologica, in particolare negli scambia-

delle saldature dove sono presenti difetti o ossidazione a

tori di calore, nei sistemi di raffreddamento, negli impianti

caldo (fig.6). La velocità di corrosione è generalmente ele-

antincendio, nelle condutture, nei sistemi di stoccaggio o

vata, per l’AISI 304 viene stimata pari a 0,3 cm/mese. [9, 10,

a seguito di prova idraulica. [10, 25, 26, 27, 28, 29, 30, 31,

13, 25, 35].

32, 33] Le tipologie di acciai inossidabili soggette al feno-

La Metallurgia Italiana - November/December 2020

pagina 49

AttualitĂ industriale - Acciai inossidabili

Fig.6 - a) vaiolature in un sistema di tubazioni in AISI 316L 6 - b) spruzzi di saldatura e vaiolature in un sistema di tubazioni in AISI 304 [ tratto da 30, 29]

Le zone interessate dal processo corrosivo possono presen-

generalmente presenti delle cavitĂ arrotondate di grosse di-

di depositi a forma di catena montuosa generati dai batteri

nizzate in catene o gruppi (fig.8). [9, 10, 11, 13, 34, 36]

tare delle formazioni caratteristiche dette tubercoli, si tratta ossidanti il Fe ed il Mn. (fig. 7) Al di sotto di tali depositi sono

mensioni aventi solo un piccolo foro sulla superficie orga-

Fig.7 - Tubercoli : a) sulla superficie di uno scambiatore di calore in AISI 304 [32] b) sulle tubazioni di un sistema antincendio in AISI 304 [tratto da 29]

Fig.8 - 8a) - cavitĂ sub-superficiali generate sulle tubazioni di un sistema antincendio in AISI 304 [29] e sulle tubazioni in AISI 316L di un impianto petrolchimico [30]

La Metallurgia Italiana - novembre/dicembre 2020

pagina 50

Industry news - Stainless steels A più alti ingrandimenti le zone interessate dalla corrosione presentano una morfologia “skeleton type”. [7, 9, 10,

37, 38, 39]

Fig.9 - Micrografie SEM di una delle zone corrose generate sulle tubazioni di un sistema antincendio in AISI 304 [ tratto da 29] Le analisi metallografiche delle saldature di componen-

loro. Tuttavia l’attacco preferenziale della ferrite delta è

ti interessati da corrosione microbiologica mostrano che

stato sempre osservato in presenza di batteri ossidanti il

l’attacco corrosivo può procedere interessando seletti-

Fe ed il Mn. [9, 10, 38] I depositi generati dalla corrosione

vamente entrambe le fasi presenti, sia la ferrite delta che

microbiologica sono più ricchi di elementi quali S, P, Fe,

l’austenite. Questo indica che i microambienti corrosivi

Mn e Cl. Inoltre è presente un contenuto più elevato di C

nell’ambito dei biofilms possono essere molto diversi fra

determinato dalla presenza della materia organica. [9,10]

BIBLIOGRAFIA [1]

Biologia Ambientale, Bollettino CISBA n.6/1994

[2]

Iwona B. Beech, Cristine C. Gaylarde “Recent advances in the study of biocorrosion : an overview” Revista de Microbiologia (1999) 30:177-190

[3]

Gregory B. Bixlerand, Bharat Bushan “Biofouling :lessons from nature” Philosophical Transactions of the Royal Society (2017) A360 : 2381-2417

[4]

Lewandowski Z and Boltz JP, "Biofilms in water and wastewater treatment," In: Peter Wilderer (ed.) Treatise on Water Science, Oxford: Academic Press 2011 4:529–570

[5]

V.Lazarova, J.Manem “Biofilm characterization and activity analysis in water and wastewater treatment” Water Research, (1995) , 29: 2227-2245

[6]

Hector A Videla, Liz K. Herrera “Microbiologically influenced corrosion :looking the future” International microbiology (2005) 8: 169180

[7 ]

Brenda J. Little, Florian Mansfeld Microbiologically Influenced Corrosion Nace International 1997 Houston Texas

[8]

E. Grande “Tecniche innovative per lo studio della biocorrosione” Tesi di laurea magistrale, Politecnico di Torino settembre 2018

[9]

ASM Handbook vol. 13A. Corrosion, Fundamental, Testing and Protection. Microbiologically Influenced Corrosion.

[10]

ASM Handbook vol. 11. Failure analysis and Prevention. Biological Corrosion Failure.

[11]

Natarajan K.A., “Biofouling and microbially influenced corrosion of stainless steel”, Advanced materials research, vol. 794, 2013, pp.539-551

[12]

Iwona B. Beech, Christine C. Gaylarde “Recent advances in the study of biocorrosion –an overview“ Revista de microbiologia (1999) 30

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Attualità industriale - Acciai inossidabili :177-190 [13]

Marianne Erbs, Jim Spain Microbial iron metabolism in natural environments www.mbl.edu

[14]

Lee J.S. and Little B.J., “A mechanistic approach to understanding MIC by metal depositing bacteria”, Nace Corrosion. August, 18, 2018. www.corrosionjournal.org

[15]

Ray R.I., Lee J.S.and Little B.J., “Iron oxidizing bacteria :a review of corrosion mechanisms in fresh water and marine environmets”, Nace Corrosion 2010 Conference & Expo, March, Sant’Antonio, Texas, USA

[16]

Enning D., Garrelfs J. , “Corrosion of iron by sulfate reducing bacteria: new view of an old problem”, Applied and environmental microbiology, vol.80, n.4, 2014, pp.1226-1236

[17]

Kakooei S., “Mechanisms of microbially influenced corrosion: a review”, World Applied science journal, vol.17, n.4, 2012, pp.524-531

[18]

Dennis R. Enning “Bioelectrical corrosion of iron by lithotrophic sulphate reducing bacteria” PhD Bremen 2012, https://elib.suub. uni-bremen.de/edocs/00102721-1.pdf

[19]

Kato S., “Microbial extracellular electron transfer and its relevance to iron corrosion”, Microbial Biotechnology, 9 (2), 2016, pp.141-148

[20]

Yingchao Li ,Dake Xu,Changfen Chen,Xiaogang Li, Ru Jia, Dawei Zhang, Wolfang Sand, Fuhui Wang, Tingyue Gu Anaerobic microbiologically influenced corrosion mechanisms interpreted using bioenergetics and bioelectrochemistry : a review Journal of material science and technology 34, 2018, 1713-1718

[21]

F. Iacoviello, V. Di Cocco “Corrosione batterica su superfici di acciaio AISI 304 sensibilizzato” Giornate nazionali sulla corrosione e la protezione , IX edizione, 2011, Monte Porzio Catone (RM)

[22]

Ahmad Abdolahi, Esah Hamzah, Zaharah Ibrahim, Shahrir Hashim, Microbially influenced corrosion of steels by Pseudomonas aeruginosa Corrosion review 2014, 32, 129-142

[23]

D. Lega, C. Andenna and M. Romitelli “Microbiologically influenced corrosion: morphology of the damage, characteristics of biofilm and corrosion scale” EPERC International Conference Pressure Equipment Innovation and Safety , Rome 1-3 April 2019

[24]

Iwona B. Beech, Jan Sunner “Biocorrosion : towards understanding interaction between biofilm and metals” Current opinion in biotechnology 2004, 15 : 181-186

[25]

Kobrin G., Lamb S., Tuthill A.H., Avery R.E., Selby K.A., Microbiologically influenced corrosion of stainless steel by water used for cooling and hydrostatic testing. IWC-97-53 www.nickelinstitute.org

[26]

L. Carpen Corrosion of stainless steel in fire protection system , 2008, report research VTT-R-01556-08, www.vtt.fi

[27]

Clarke B.H., Aguilera A.M., Microbiologically influenced corrosion in fire splinker systems, Journal of fire protection engineering, January 2001, pp.955-964

[28]

Hilbert L.R., Carpen L., Moller P., Fontenay F., Mathielsen T. , “Unexpected corrosion of stainless steels in low chloride water”, 6-10 September, European corrosion congress 2009, Eurocorr 2009, Nice, France

[29]

D.Lega, M.Romitelli “ Indagine sulla corrosion localizzata di un sistema di tubazioni facenti parte di un impianto antincendio” , Safap 2018, Bologna 27-29 novembre

[30]

Mohammed Al Muaisub “ Metallurgical investigation of premature failures of 316L austenitic stainless steel pipes” PhD 2018, University of British Colombia, Vancouver

[31]

de Damborenea J.J, Cristobal A.B., Arenas M.A., Lopez V., Conde A., “Selective dissolution of austenite in AISI 304 stainless steel by bacterial activity”, Materials Letters 61, 2007, pp.821-823

[32]

E. Huttunen-Saarivirta, M. Honkanen, T. Lepisto, V.T. Kuokkala,L.Koivisto, C.G.Berg Microbiologically influenced corrosion (MIC) in stainless steel heat exchanger Applied surface science 258 (2012) 6512-6526

[33]

F. Elshawesh, K. Abusowa, H. Mahfud, E. Elagdel “Microbiologically influenced corrosion of type 304 austenitic stainless steel water pipe” Materials Performance 2003, 42 (9) pp 54-57

[34]

Josè R. Ibars, Diego A. Moreno, Carlos Ranninger “Microbial corrosion of stainless steels” Microbiologia SEM 8 (1992) 63-75

[35]

API 571 Damage mechanism affecting fixed equipment in the refining industry, Microbiologically Induced Corrosion.4.3.8

[36]

Brenda J Little, Tammie L. Gerke, Jason S. Lee, “Mini review : the morphology, mineralogy and microbiology of accumulated iron products” Biofouling 2014 , 30 (8) :941-948

[37]

K.R. Sreekumari, Y.Sato and Y. Kikuchi Antibacterial metals-a viable solution for bacterial attachement and microbiologically influenced corrosion” Materials Transaction vol.36 n.7 (2005) pp 1636-1645

[38]

J.J. de Damborenea, A.B. Cristobal, M. A. Arenas, V. Lopez, A. Conde “Selective dissolution of austenite in AISI 304 stainless steel by bacterial activity” Materials Letters 61 (2007) 821-823

[39]

B.J.Little, J.S. Lee, R.I.Ray “ Diagnosing microbiologically influenced corrosion: a state of the art review “ Corrosion 2006 , vol.62, issue n.11, pp 1006-1017

La Metallurgia Italiana - novembre/dicembre 2020

pagina 52

Industry news - Stainless steels

Microbial influenced corrosion of stainless steel : a mini-review 1. The Microbiologically Influenced Corrosion MIC is a re-

the deposition of cathodically reactive ferric and manganic

levant problem, the combination of unexpected attack and

oxides-hydroxides The formation of iron and manganese

rapid failure make MIC a matter of considerable concern

oxide- hydroxide, which generally form insoluble precipi-

in many applications including water handling and manu-

tates and dense insoluble deposit on the surface, promote

facturing processes in power generation, petrochemical,

the formation of region with different oxygen level crea-

gas transmission, paper, wastewater treatment, drinking

ting oxygen concentration cells (Fig. 2).

water supplies, fermentation, pulp and papermaking. Microorganisms are present in all aqueous environment

1.2 Chemical concentration cells.

(seawater, river, lake, ponds, and wells) and all manner of

Stainless steels are known to corrode by differential aera-

aqueous industrial fluids and wastewater. The tendency

tion at occluded surface region. Corrosion is accelerated

for these microorganisms is to attach and grow on the sur-

because the oxygen, that is essential to the stability of the

face of structural metals generating in stagnant or low flow

passive layer, is prevented from diffusing at the occlu-

water discrete colonies or microbial film of varied compo-

ded site. Biofilm can accelerated this process by not only

sition fig.1 The colonies or biofilm influence the corrosion

acting as a physical barrier but also by consuming oxygen

processes. This influence derives from the ability of the

in the metabolism of microorganisms. Under the biofilm,

microorganisms to change the environmental variables

localized respirationâ&#x20AC;&#x201C;photosynthesis can lead to differen-

such as pH, dissolved oxygen, as well as organic and inor-

tial aeration cells and localized anodes and cathodes.

ganic species. The most usual influence is to change the mode of corrosion from uniform to localized and increase

1.3Transformation of Sulphur compound.

the penetration rate.

Sulphate Reducing Bacteria (SRB) are the most widely involved in severe MIC attack on ferrous materials. The-

The microorganisms involved in biocorrosion proces-

re are several generalized explanations for SRB induced

ses of stainless steels are algae and bacteria. They can be

corrosion. The classical cathodic depolarization theory

grouped as shown in table1. The biological influences of

of anaerobic corrosion of iron attributed such corrosion

the biofilm on the corrosion processes of stainless steels

reaction to microbial removal of cathodic hydrogen using

can be divided into the following categories: deposition of

the enzyme hydrogenase. (fig.3a) .Electrical microbiologi-

metals, chemical concentrations cells, transformation of

cally influenced corrosion EMIC is one of the new emer-

Sulphur compound, oxide reductions.

ging explanations of this microbial anaerobic corrosion. SRB bacteria can direct uptake the electrons come from

1.1 Deposition of metals.

the iron oxidation becoming electron consumer (fig.3b)

Many bacteria participate in the biotransformation of the

Chemical microbiologically influenced corrosion CMIC

oxides of metals such as iron and manganese. Iron depo-

mechanism results from corrosion of iron by biogenic

with deposition

H2S. Intracellular oxidation of organic compound by SRB

of Fe hydroxide, this hydroxide undergo hydrolysis and

is coupled to generation of sulphide which, upon diffusion

decrease the pH. Some of these bacteria are also capable

out of the cell, reacts with metallic iron.

siting bacteria, IOB, oxidize Fe

to Fe

of oxidizing Mn

to Mn

with deposition of MnO2, which

is a strong oxidizing agent. Dense accumulation of these

1.4 Reduction of oxides

products on the metal surface may promote corrosion by

Some bacteria such as Pseudomonas or Shewanella are

La Metallurgia Italiana - November/December 2020

pagina 53

AttualitĂ industriale - Acciai inossidabili able to carry out manganese oxide and iron oxide re-

sociation with heat tint area or welding defects. (fig.6) In the

duction. The protective passive layer on stainless steel

case of austenitic stainless steel in water environments the

surface is replaced by less stable reduced metal films that

corrosion influenced by bacteria takes a distinctive form,

allow further corrosion to occur.

that is, the formation of tubercles, that are small rounded prominences, and volcano like deposits (fig.7). Usually the

1.5 Microbial consortia

corroded tubercles were taken as an indication of the me-

Microbial induced corrosion is rarely linked to a single

tal depositing bacteria, iron oxidizing bacteria, IOB and Mn

mechanism or to a single species of microorganisms. The

oxidizing bacteria MOB.

different microbial corrosion mechanisms are often synergistic. Consortia of metal depositing bacteria MDB and

The attack morphology generated by bacteria on stainless

sulphate reducing bacteria SRB often exist as biofilm on

steel takes a distinctive form, that is, large sub-surface ca-

corroding stainless steel surfaces. The oxygen consump-

vities with small-occluded opening or rounded sub-sur-

tion by MDB creates conditions favourable to the growth

face holes in chains or groups (fig.8). At higher magnifica-

of SRB. The joint action of MDB and SRB promote the pit-

tion, the microstructure of the corroded area appears with

ting corrosion of a stainless steel. (fig.5)

a skeletal morphology ( fig.9). Typical MIC failure cases analysed in stainless steel weldments showed preferen-

2. Stainless steels are generally corrosion resistant in dif-

tial attack of either and both Î´ ferrite and austenite phases.

ferent aggressive environments owing to the tenacious

This would indicate that localized conditions under a bio-

passive surface film due to the chromium content, never-

film could vary greatly. Preferential corrosion of Î´ ferrite

theless they are susceptible to various type of microbial

phase is observed with iron depositing bacteria IOB and

corrosion in sub soil, fresh water, sea water etc.The type of

manganese depositing bacteria MOB. Some elements in

stainless steels affected by MIC are austenitic grade of 300

corrosion deposits are indicative of MIC. Deposits asso-

series ( 303, 304, 316), titanium stabilised grade (321), mar-

ciated with MIC caused by SRB usually contain higher le-

tensitic with 13% Cr and 1% Ni, ferritic such as 309. .The

vel of S and P, instead metal depositing bacteria form iron

alloying elements can increase or decrease the suscepti-

and manganese rich corrosion products and moderately

bility to MIC.

higher level of chloride can be expected. An high content of carbon C in corroded area may be due to the organic

In almost all cases, this type of corrosion appears in the

material of cell bodies (bacteria and exopolimer).

form of pitting in weld metal and heat affected zones in as-

La Metallurgia Italiana - novembre/dicembre 2020

pagina 54

Torino, 30 giugno e 1-2 luglio 2021

Industry news - Stainless steels

giornate nazionali

corrosione e protezione

XIV edizione

torino 2021

Organizzate da

Con il patrocinio di

CENTRO INOX

www.aimnet.it/gncorrosione presentazione La XIV edizione delle Giornate Nazionali sulla Corrosione e Protezione si terrà per la prima volta a Torino nei giorni 30 giugno, 1 e 2 luglio 2021, presso il Politecnico di Torino. Le Giornate rappresentano l’evento di riferimento a livello nazionale per la discussione ed il confronto sulle questioni scientifiche, tecnologiche e produttive, nell’ambito della corrosione e protezione dei materiali. In particolare, il Convegno prevede la presentazione dei risultati raggiunti da vari gruppi di studio e da numerose aziende del settore, in forma orale e poster.

aree tematiche principali • • • • • • • • • • • • • • •

Corrosione delle strutture metalliche esposte all’atmosfera Corrosione e protezione delle reti idriche interrate Corrosione negli impianti industriali Protezione catodica: progettazione, collaudo, gestione e monitoraggio Comportamento a corrosione di leghe di titanio, nichel e acciai inossidabili Corrosione delle opere in calcestruzzo armato Corrosione dei beni culturali Corrosione negli impianti Oil & Gas Degrado e rilascio dei biomateriali metallici Rivestimenti e trattamenti superficiali Inibitori di corrosione Impatto delle nuove tecnologie produttive sulla corrosione Tecniche di studio e monitoraggio della corrosione Meccanismi di corrosione Case histories

presentazione di memorie Gli interessati a presentare memorie scientifiche dovranno inviare entro il 29 gennaio 2021, il titolo della memoria, i nomi degli autori con relative affiliazioni ed un breve riassunto. Le memorie potranno essere proposte: - compilando il form online presente sul sito dell’evento: www.aimnet.it/www.aimnet.it/gncorrosione - inviando il riassunto e tutte le informazioni richieste La Metallurgia November/December 2020 a mezzoItaliana e-mail: -info@aimnet.it

segreteria organizzativa Via Filippo Turati 8 20121 Milano t. +39 76021132 · +39 76397770 info@aimnet.it · www.aimnet.it

pagina 55

Experts’ Corner - High strength fasteners

High strength fasteners. Requirements, material selection, heat treatments and properties edited by: Seppo Härkönen, Finland

The properties of fasteners are regulated and steered by international standards. The base standard is ISO 898 Mechanical properties of fasteners made of carbon steel and alloy steel Part 1: Bolts, screws and studs with specified property classes.

Another important standard is EN 10269 Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties. To meet the requirements of fasteners it is important to achieve first the mechanical properties. There is a strict

connection especially with yield strength, toughness and microstructure. Standards may be complicated. Some critical points will be discussed.

Some solutions of problematic cases and references to experience of higher strength fasteners and trials with more exotic materials in fasteners are presented.

KEYWORDS: STANDARDS FOR FASTENERS, CLEANESS OF STEEL, HOMOGENITY OF MICROSTRUCTURE. REQUIREMENTS OF STANDARDS

of which tests are performed during manufacturing or final

ISO 898-1

inspection."

The base standard ISO 898-1 presents the requirements

However according to clause 8.3: "This part of ISO 898 does

on steels and mechanical properties as well as on testing

not mandate which of the tests the manufacturer shall per-

procedures. The part 1 covers bolts, screws and studs in di-

form on each manufacturing lot. It is the responsibility of

mensions M1,6 to M39, but may be applied to sizes outside

the manufacturer to apply suitable methods of his (or her)

the scope (e.g. d > 39 mm), provided all applicable require-

choice, such as in-process test or inspection, to ensure that

ments in accordance with Tables 2 and 3 are met. The stan-

the manufactured lot does conform to all of the applicable

dard is under revision.

requirements." Thus the standard sets to the manufacturer

The essential requirements are given in Table 2 Steels and

a big responsibility for his quality and compliance.

in Table 3 Mechanical and physical properties. Concerning definitions and requirements the Table 2 is abstruse. Many

Importance of microstructure

requirements are presented with footnotes. Requirements

The footnote f of Table 2 requires approximately 90 % mar-

on boron content are contradictory. Many definitions sound

tensite in core after quenching for 8.8 and higher property

homemade, e.g. "carbon steel with additives". It is useful to

classes. This is very essential to guarantee the structure after

observe the footnote i "Caution is advised when the use of

tempering (small inclusions of cementite homogenous di-

property class 12.9/12.9 is considered. The capability of the

stributed in ferrite matrix). This will secure the elongation

fastener manufacturer, the service conditions and the wren-

and impact strength. The tempering temperature will be

ching methods should be considered. Environments can

above the required and thus the yield ratio will be secured.

cause stress corrosion cracking of fasteners as processed

However, it seems, that very few manufacturer of fasteners

as well as those coated."

and heat-treater control and test this requirement.

Following clause introduces the Table 3: "The bolts, screws

The recent experiences show, that the cleanness of steel

and studs of the specified property classes shall, at ambient

seems to have remarkable influence on properties of higher

temperature), meet all the applicable mechanical and phy-

strength fasteners, see case Modified 14.9 class screws.

sical properties in accordance with Tables 3 to 7, regardless

La Metallurgia Italiana - November/December 2020

pagina 57

Scenari - Bulloneria ad alta resistenza ISO 898-1 Tab. 2 - Steels Property class

Chemical composition limit (cast analysis, %)a

Material and heat treatment

°C

max.

min.

Not specified

—

0,003

425

0,003

425

0,003

425

min.

max.

—

0,55

0,050

0,060

0,13

0,55

0,050

0,060

5.8d

—

0,55

0,050

0,060

6.8d

0,15

0,55

0,050

0,060

0,15e

0,40

0,025

0,25

0,55

0,025

0,20

0,55

0,025

0,15e

0,40

0,025

0,25

0,55

0,025

0,20

0,55

0,025

0,20e

0,55

0,025

0,25

0,55

0,025

0,20

0,55

0,025

4.6c d 4.8d 5.6c

8.8f

9.8f

10.9f

Carbon steel or carbon steel with additives

Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered or Carbon steel quenched and tempered or Alloy steel quenched and temperedg Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered or Carbon steel quenched and tempered or Alloy steel quenched and temperedg Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered or Carbon steel quenched and tempered or Alloy steel quenched and temperedg

Tempering temperature

12.9f h i

Alloy steel quenched and temperedg

0,30

0,50

0,025

0,003

425

12.9f h i

Carbon steel with additives (e.g. Boron or Mn or Cr or Molybdenum) quenched and tempered

0,28

0,50

0,025

0,003

380

a. In case of dispute, the product analysis applies.

b. Boron content can reach 0,005 %, provided non-effective boron is controlled by the addition of titanium and/or aluminium.

c. For cold forged fasteners of property classes 4.6 and 5.6, heat treatment of the wire used for cold forging or of the cold forged fastener itself may be necessary to achieve required ductility.

d. Free cutting steel is allowed for these property classes with the following maximum sulfur, phosphorus and lead contents: S: 0,34 %; P: 0,11 %; Pb: 0,35 %.

e. In case of plain carbon boron steel with a carbon content below 0,25 % (cast analysis), the minimum manganese f.

content shall be 0,6 % for property class 8.8 and 0,7 % for property classes 9.8 and 10.9.

For the materials of these property classes, there shall be a sufficient hardenability to ensure a structure consisting

of approximately 90 % martensite in the core of the threaded sections for the fasteners in the “as-hardened” condition before tempering.

g. This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,30 %, nickel 0,30 %, molybdenum 0,20 %, vanadium 0,10 %. Where elements are specified in combinations of two,

three or four and have alloy contents less than those given above, the limit value to be applied for steel class deter-

mination is 70 % of the sum of the individual limit values specified above for the two, three or four elements concerned.

h. Fasteners manufactured from phosphated raw material shall be dephosphated before heat treatment; the absence i.

of white phosphorus enriched layer shall be detected by a suitable test method.

Caution is advised when the use of property class 12.9/12.9 is considered. The capability of the fastener manu-

facturer, the service conditions and the wrenching methods should be considered. Environments can cause stress corrosion cracking of fasteners as processed as well as those coated.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 58

Experts’ Corner - High strength fasteners ISO 898-1 Tab. 3 - Mechanical and physical properties Property class No. Mechanical or physical property

Tensile strength, Rm, MPa

Lower yield strength, ReLd, MPa

Stress at 0,2 % non-proportional elongation, Rp0,2, MPa

Stress at 0,0048d non-proportional elongation for full-size fasteners, Rpf, MPa Stress under proof load, S , MPa f p

Proof strength ratio

4.6

6.8

500

8.8 d≤ 16 mma

600

9.8

d> 16 mmb

800

10.9

12.9/ 12.9

900

1.000

1.200

d≤ 16 mma

400

420

500

520

600

800

830

900

1.040

1.220

nom.c

240

—

300

—

min.

240

—

300

—

nom.c

—

640

720

900

1 080

min.

—

640

660

720

940

1 100

nom.c

—

320

—

400

480

—

min.

—

340e

—

420

480

—

nom.

225

310

280

380

440

580

600

650

830

970

0,94

0,91

0,93

0,90

0,92

0,91

0,90

0,88

—

Percentage elongation after fracture for machined test pieces, A, %

min.

Percentage reduction of area after fracture for machined test pieces, Z, %

min.

Elongation after fracture for full-size fasteners, Af (see also Annex C)

min.

Head soundness

Vickers hardness, HV F ≥ 98 N

Brinell hardness, HBW F = 30 D2

Rockwell hardness, HRC

5.8

min.

5.6

400

nom.c

Sp,nom/ReL,min or Sp,nom/Rp0,2 min or Sp,nom/Rpf,min

Rockwell hardness, HRB

4.8

— —

0,24

—

52 0,22

0,20

— No fracture

min.

120

130

max. min.

160

220g 114

124

max. min.

155

147

152

209g 67

max.

95,0g

190

250

255

290

320

385

250

320

335

360

380

435

181

245

250

286

316

380

238

316

331

355

375

429

—

99,5

—

min.

—

max.

—

Surface hardness, HV 0,3

max.

—

390

435

Non-carburization, HV 0,3

max.

—

Height of non-decarburized thread zone, E, mm

min.

—

1/2 H1

2/3 H1

3/4 H1

Depth of complete decarburization in the thread, G, mm

max.

—

0,015

Reduction of hardness after retempering, HV

max.

—

Breaking torque, MB, Nm

min.

—

in accordance with ISO 898 7

Impact strength, KV i j, J

min.

Surface integrity in accordance with

La Metallurgia Italiana - November/December 2020

—

27 ISO 6157-1l

k ISO 6157-3

pagina 59

Scenari - Bulloneria ad alta resistenza Footnotes for Table 3.

a. Values do not apply to structural bolting. b. For structural bolting d ³ M12.

c. Nominal values are specified only for the purpose of the designation system for property classes. See Clause 5.

d. In cases where the lower yield strength, ReL, cannot be determined, it is permissible to measure the stress at 0,2 % non-proportional elongation Rp0,2.

e. For the property classes 4.8, 5.8 and 6.8, the values for Rpf,min are under investigation. The values at the time of publif.

cation of this part of ISO 898 are given for calculation of the proof stress ratio only. They are not test values. Proof loads are specified in Tables 5 and 7.

g. Hardness determined at the end of a fastener shall be 250 HV, 238 HB or 99,5 HRB maximum.

h. Surface hardness shall not be more than 30 Vickers points above the measured base metal hardness of the fastener i.

when determination of both surface hardness and base metal hardness are carried out with HV 0,3 (see 9.11). Values are determined at a test temperature of 20 °C (see 9.14).

Applies to d ³ 16 mm.

Instead of ISO 6157-1, ISO 6157-3 may apply by agreement between the manufacturer and the purchaser.

k. Value for KV is under investigation.

EN 10269

annealed condition. Because they do not have a pronoun-

The European Standard EN 10269 Steels and nickel alloys

ced transition temperature, which is characteristic of other

for fasteners with specified elevated and/or low temperatu-

steels, they are also useful for application at cryogenic tem-

re properties meets partially the Essential Requirements of

peratures.

Annex 1 of the Pressure Equipment Directive 2014/68/EC.

EN 10269 is useful at the steel users´ point of view. Lot of

One of these essential requirements is the elongation min.

tables may be helpful for instance in designing, as follows:

14 % at the tensile test at the ambient temperature. The steels to be used at lower temperatures shall meet the impact

Mechanical properties at elevated temperatures

strength KV2 at the specified test temperature.

The values in Tables 6 and 7 apply for the 0,2 % proof stren-

The problems when temperature is elevating are the de-

gth at elevated temperatures.

creasing the strength, creep and relaxation, and when the

The values in Tables 8 and 9 apply for the tensile strength at

temperature is more increasing, oxidation and accelerating

elevated temperatures.

of corrosion. Lower temperatures mean risk of brittleness.

Reference data of strength values for 1 % (plastic) creep and

The number of steel grades in the standard is big, but nee-

creep rupture are given in Table C.1.

ded, because temperature range is from -270 to 600 ⁰C. For

Reference data for relaxation properties are given in Table

moderate temperatures non-alloy or low alloy steel grades

D.1.

can be used. Typical alloying elements, when temperature increased, are V and Mo, that form heat resistant precipita-

Mechanical properties at low temperatures

tes. Mo causes secondary hardening when tempering at 500

Low temperature impact energy values are specified in

to 650 ⁰C. Essential for the low temperature steels are low

Tables 10 and 11.

carbon, phosphorus and sulphur contents. Austenitic mi-

Unlike ISO 898-1 this standard defines exactly the manda-

crostructure is insensitive to brittle fracture in the solution

tory tests and their frequency.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 60

Experts’ Corner - High strength fasteners As an example there is a recommendation deducted from the information available in EN 10269: RECOMMENDATION FOR STEEL GRADES Temperature °C

Screw

Nut

600

40CrMoV4-6

21CrMoV5-7

550

X22CrMoV12-1

21CrMoV5-7 500

21CrMoV5-7 25CrMo4

42CrMo4 25CrMo4

400

35B2

350

C35

-50...150

4.6 ... 10.9 (ISO 898-1)

5, 8, 10 (ISO 898-2)

-40

25CrMo4

-100

42CrMo4

C35

The recommendation is based on max. temperatures of

fied min. temperature of EN 10269.

CASES

gap ring connected to the bridge moving mechanism. The

Screws for military bridge

bridge consists of two sections, total length 26 m and mass

A main battle armored vehicle Leopard 2 A4 was modified

10,5 tons. At the installation phase 36 screws M16 carry the

to a bridge vehicle. The original turret was replaced with a

whole load, which means very demanding requirements.

proof stress Rp0,2 and low at temperatures on KV2 at speci-

Fig.1 - Installation of the bridge. The requirements for the M16 screws were: • Rp0,2 min. 1 600 MPa

• KV2

min. 20 J at -30 °C

• Hardness

530 to 580 HV50.

• Rm

1 720 to 1 870 MPa

It was selected the maraging steel X2NiCoMo18-9-5 (Nr.

• A5

min. 8 %

1.6354).

• Z

min 45 % (informative)

La Metallurgia Italiana - November/December 2020

pagina 61

Scenari - Bulloneria ad alta resistenza

STEEL X2NiCoMo18-9-5 (MARAGENING 300) C%

Si %

Mn%

Ni%

Co %

Mo %

0,03

0,10

18,5

9,0

4,8

For the delivery condition the blanks were solution anne-

shape giving - heat treating.

screws were aged 4 hours at 485 °C.

Mo6. Some restrictions to composition were made, for

aled 1 hour at 820 °C, cooling in air. After machining the

The screws are M12 to M16. Material selected is 34CrNiinstance P max. 0,012 %, S max. 0,015 %. The require-

Modified 14.9 class screws

ment on cleanness was K4 ≤ 30 ac-cording to DIN 50602,

neering works were more or less poor. The conditions of

smaller inclusions are counted. The steelmaking process,

200 °C. The end user decided to launch a project in order

continuous casting in protective circumstances were op-

gation was the whole pro-duction chain: steelmaking -

pre-sented in Figures 2 and 3.

The experience of overclassified screws at a Finnish engi-

but it was changed to K3 ≤ 30. Note, that for K3 one class

the applications were alternating load 750 cycles/min at

melting in EAF, vacuum degassing, ladle treatments and

to get good and quality proper screws. Under investi-

timized. Summaries of the cleanness determinations are

Fig.2 - Cleanness of 34CrNiMo6 acc. to K4 DIN 50602, determinations in 2005...2016, 145 casts.

Fig.3 - Cleanness of 34CrNiMo6 acc. to K3 DIN 50602, determinations after 2016, 123 casts.

The heat treatment took place in a low-pressure furna-

tioning in the furnace needed investigation. The QA tests

homogenous martensitic structure after quenching and

tensile tests. Figure 4 is presenting an example of the

ce following gas quenching. The target was to ob-tain a

to avoid big hardening stresses. The charging and posi-

include hardness measure-ments in different stages and hardness distribu-tion over the cross section.

Fig.4 - Hardness check after quenching and distribution after tempering.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 62

Experts’ Corner - High strength fasteners The project set target for the mechanical properties. In

screws have proved to be constant.

Table there is an example of M14 screws. In ser-vice the

MECHANICAL PROPERTIES OF M14 SCREWS Target min.

Actual

Rp0,2, MPa

1 100

1 250

Rm, MPa

1 160

1 350

A5, %

13...15

CONCLUSIONS

The Task group believes that testing of full-size fasteners is

tely it is under revision (in 2018). The Footnote i of Table

production routes differ from those of smaller. In fact, the

The standard ISO 898-1 needs to be discussed. Fortuna2 should be taken seriously: "Caution is advised when the use of property class 12.9/12.9 is considered. The capa-

bility of the fastener manufacturer, the service conditions and the wrenching meth-ods should be considered.

Environments can cause stress corrosion cracking of fasteners as processed as well as those coated."

one of the biggest problems. For these bigger fasteners the

pre-material is not wire rod and cold heading is rare. If a fastener needs a head, it must be hot forged and the quenching and tempering takes place at the final stage. When producing

studs, the quenching and tempering is usually done at the steel works.

The standard EN 10269 has proven to be practical and

Concerning steel grades for 8.8 and higher-class fasteners,

should be completed.

criteria for material selection. Experimental max. diameters

articulate. Information of creep and relaxation properties The presented two cases show the importance of careful planning and investigation. The good durability of the

modified 14.9 class screws may be based on outstanding cleanness of the steel and uniform mi-crostructure. Remarkable is the excellent elongation.

the hardenability and the chemical composition are the main for some of the most common steel grades, when heat treating at a steel work as 6 m long bars: 42CrMo4

Ø ≤ 50 mm

30CrNiMo8

Ø ≤ 100 mm.

34CrNiMo6

Ø ≤ 80 mm

EPILOGUE

The reduction ratio in rolling should be at least 6:1 in order

developing at the moment (November 2020) two new parts

square billet size for instance for Ø 80 mm should be at least

A Task group of ISO Technical Committee 2 (Fasteners) is

to achieve a homogeneous structure. This means that the

for ISO 898. The target is to increase the dimensions range

175 mm.

be ISO 898-11 bolts, screws and studs and ISO 898-12 nuts.

The cleanness should also be specified. It has an important

from M39 up to M100 and perhaps above. The new parts will

La Metallurgia Italiana - November/December 2020

influence on toughness and fatigue strength.

pagina 63

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erambiente Servizi Industriali (Hasi) è la società del Gruppo Herambiente, parte integrante del Gruppo Hera (una delle maggiori multiutility italiane) da sempre a servizio delle imprese nella gestione dei rifiuti industriali, grazie alla propria dotazione impiantistica unica in Italia. Ai servizi di Hasi si affidano oggi oltre 3.000 imprese sul territorio nazionale, di cui 200 operanti nei settori metallurgico e metalmeccanico. Hasi è in grado di trattare tutti i rifiuti prodotti da grandi e medie aziende del comparto, garantendo tempestività di servizio e offrendo soluzioni in grado di massimizzare il recupero degli scarti industriali in chiave di economia circolare. Per gestirli, dispone, tra gli impianti della propria dotazione, di tre piattaforme d’inertizzazione che complessivamente raggiungono una capacità di trattamento autorizzata pari a 265.000 tonnellate all’anno. Fra questi, il solo impianto di disidratazione fanghi Disidrat, che si trova nel polo impiantistico Herambiente di Ravenna, è in grado di trattarne 150.000 tonnellate all’anno. I rifiuti trattati possono ap-

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Dai fanghi materiale riutilizzabile riducendo al minimo il ricorso alla discarica

razie alle sofisticate tecnologie impiegate, fino al 30% dei fanghi in ingresso è recuperato e riutilizzato come copertura per le discariche o come materiale di consolidamento per le miniere. Il materiale restante trattato non recuperabile, in se-

La Metallurgia Italiana - novembre/dicembre 2020

guito è sottoposto a processo di disidratazione. Questo comporta una drastica riduzione dei volumi conferiti in discarica. Tutti i processi del trattamento sono certificati e monitorati per garantire il minor impatto ambientale possibile.

Come funziona il Disidrat

ell’impianto esistono quattro linee di trattamento, specifiche e dedicate alla tipologia di rifiuto in ingresso, che coprono il fabbisogno di trattamento di un ampio ventaglio di comparti produttivi e industriali: - Rifiuti solidi non pericolosi: fanghi da depuratori delle acque reflue urbane e potabilizzatori, industria farmaceutica e chimica, terreni di bonifica;

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rifiuti sono, quindi, introdotti in un reattore/miscelatore in cui si dosano reattivi liquidi e solidi. In alternativa, per conseguire un migliore risultato ambientale, si utilizzano rifiuti con parametri chimici o fisici tali da conferire caratteristiche analoghe al rifiuto così generato.

Successivamente il fango viene trasferito alle filtropresse a piastre, che provvedono alla disidratazione meccanica: le sostanze solide sono trattenute e quelle liquide drenate fino al collettore di scarico.

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La Metallurgia Italiana - November/December 2020

- filtropressatura: il fango liquido, previa aggiunta di reattivi di condizionamento necessari a migliorare l’efficienza della fase successiva, viene spremuto per eliminare fino al 90% dell’acqua presente. Il trattamento consiste

Il fango disidratato è scaricato in un’area sottostante, cinta su tre lati, per essere prelevato e trasportato nei box di stoccaggio. Nel processo di trattamento sono inoltre previste fasi di omogenizzazione e maturazione: il rifiuto è lasciato maturare in apposite aree di stoccaggio, in cui gli agenti chimi-

pagina 65

Pubbliredazionale

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pagina 66

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peggiorata nel 2019 la redditività dell’acciaio: tutti gli indici hanno toccato i valori più bassi dell’ultimo triennio e i tassi di ritorno sugli investimenti e sulle vendite sono in calo. La siderurgia ha risentito, come molti altri settori, del rallentamento registrato negli ultimi mesi dello scorso anno. Nonostante questo, il 2019 ha visto

un modesto miglioramento della solidità del comparto e una stabilità degli indicatori di liquidità. È quanto è emerso dallo studio Bilanci d’Acciaio 2020, ideato dall’Ufficio Studi siderweb, realizzato in collaborazione con i professori Claudio Teodori e Cristian Carini dell’Universi-

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Fatturato

Ebitda

Utile

2018

58.600

4.483

1.656

2019

58.265

3.253

409,4

Variazione % 2018/19

-0,6%

-27,4%

-75,3%*

Fonte: Bilanci d’Acciaio 2020. Dati in milioni di € riferiti alla parte alta della filiera (utilizzatori esclusi). *La sola ArcelorMittal Italia nel 2019 ha fatto registrare una perdita di circa 866 milioni di euro.

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poco solide. È necessario agire sul livello qualitativo - ha sottolineato Claudio Teodori, professore ordinario di Economia aziendale dell’Univer-

La Metallurgia Italiana - November/December 2020

sità degli Studi di Brescia -, puntando all’ottenimento di prodotti caratterizzati da originalità e specificità, in quanto potenzialmente portatori di pagina 67

Pubbliredazionale

maggiore valore aggiunto e marginalità, oltre che di mi-

nore sostituibilità da parte dei Paesi con costi produttivi più

bassi».

Indicatori

2019

2018

2017

ROA (return on assets)

4,3%

5,3%

4,9%

ROS (return on sales)

3,8%

4,5%

4,4%

ROE (return on equity)

6,6%

9,5%

8,1%

Ebitda/fatturato

7,2%

7,6%

8,0%

Valore aggiunto/fatturato

15,3%

15,2%

16,0%

Fonte: Bilanci d’Acciaio 2020. Valori relativi all’intero settore. I RISULTATI DEL QUESTIONARIO

prospettive per il 2021.

ra settembre e ottobre, l’Ufficio Studi siderweb ha somministrato a un campione rappresentativo della filiera nazionale dell’acciaio un questionario che indagasse l’andamento del 2020 e le

2020 - Nel 2020, l’87% delle imprese si aspetta una riduzione del fatturato, anche per valori consistenti. Solo il 4% stima un incremento rispetto al 2019, mentre il 9% una situazione di stabilità.

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Il sondaggio di siderweb: nel 2020 l’87% delle imprese si attende una riduzione del fatturato. Previsto un rimbalzo nel 2021, ma resta l’incertezza a causa della pandemia Il 65% ha fatto richiesta di risorse finanziarie per finanziare il circolante (41%) e per gli investimenti (47%). La fonte principale di finanziamento utilizzata è quella bancaria. Il 55% ha beneficiato o chiesto il finanziamento nell’ambito dei decreti che hanno introdotto forme di garanzia statale. Quanto agli investimenti, il 39% delle imprese ha rinviato i progetti a budget; il 6%, a causa dell’incertezza,

li ha bloccati. Il 41% delle imprese non ha ricevuto richieste di aumento dei giorni di dilazione dei termini di pagamento, mentre il 51% ne ha ricevute inferiori ai 60 giorni. 2021- Il 74% delle imprese ipotizza un fatturato in crescita; il 16% pensa a un’ulteriore riduzione e il 10% a stabilità. Quanto alle operazioni significative previste nel 2021, il 25% identi-

La Metallurgia Italiana - novembre/dicembre 2020

fica come prioritario lo sviluppo di accordi di collaborazione strategici con imprese della filiera; il 14% l’acquisizione di società che vi fanno parte; il 18% la riorganizzazione degli stabilimenti; il 13% la diversificazione dell’attività; l’8% progetti di internazionalizzazione. L’1,4% pensa alla cessione o alla liquidazione dell’attività.

pagina 68

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La Metallurgia Italiana - November/December 2020

pagina 69

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Conference organisers Associazione Italiana di Metallurgia Via Filippo Turati 8 - 20121 Milano, Italy Phone: +39 02.7639.7770 - E-mail: info@aimnet.it www.aimnet.it/htdc.htm

Atti e notizie - AIM news

Eventi AIM / AIM events FaReTra (Fair Remote Training) - FORMAZIONE E AGGIORNAMENTO A DISTANZA Modalità Sincrona 38° CONVEGNO NAZIONALE AIM - Virtual Edition 18-19-20-25-26 gennaio 2021 Giornata di Studio INGEGNERIZZAZIONE DELLE SUPERFICI: DESIGN E CARATTERIZZAZIONE – 17 febbraio Corso FAILURE ANALYSIS 11a edizione - 24-25 febbraio, 3-4-5 marzo

www.aimnet.it

Corso modulare RIVESTIMENTI – III modulo: RIVESTIMENTI PER VIA UMIDA –10-1117-18 marzo Modalità Asincrona

Per ulteriori informazioni rivolgersi alla Segreteria AIM, e-mail: info@aimnet.it, oppure visitare il sito internet www.aimnet.it

Corso ACCIAI AD ALTO CARBONIO SIDERURGIA IN PILLOLE FAILURE ANALYSIS IN PILLOLE – percorso di avvicinamento alla Failure Analysis TECNOLOGIE ADDITIVE IN PILLOLE TECNOLOGIE PRESS & SINTER NON CONVENZIONALI IN PILLOLE MICROSCOPIA ELETTRONICA IN PILLOLE - Principi di base ed utilità della microscopia elettronica per la metallurgia PRESSOCOLATA IN PILLOLE - DIFETTI: POROSITA' DA RITIRO WEB SAFETY PILLS - SICUREZZA IN PILLOLE Giornata di Studio TECNOLOGIA ED INNOVAZIONE NEI FORNI AD ARCO Giornata di Studio CORROSIONE SOTTO SFORZO E INFRAGILIMENTO DA IDROGENO NELLE APPLICAZIONI PETROLCHIMICHE Giornata di Studio RIVESTIMENTI DECORATIVI AL SERVIZIO DELL'ESTETICA DEL PRODOTTO Giornata di Studio STAMPAGGIO: PROPRIETÀ MECCANICHE, TRATTAMENTO TERMICO E MECCANISMO DI DANNEGGIAMENTI Giornata di Studio RESISTENZA A FATICA DEI MATERIALI METALLICI: ASPETTI METALLURGICI ED ASPETTI INNOVATIVI FORMAZIONE E AGGIORNAMENTO IN AULA (*) CONVEGNI 27° Convegno Nazionale Trattamenti Termici - Genova, 6-7 maggio 2021 HTDC - 7th International Conference HIGH TECH DIE CASTING – Vicenza, 23-25 giugno 2021 XIV GIORNATE NAZIONALI SULLA CORROSIONE E PROTEZIONE – Torino, 30 giugno - 1-2 luglio 2021 ESSC & DUPLEX 2021 - 11th European STAINLESS STEEL Conference Science & Market & 8th European DUPLEX STAINLESS STEEL Conference & Exhibition – Bardolino, 6-8 ottobre 2021 ECCC 2020 - 10th European Conference on Continuous Casting - Bari, 20-22 Ottobre 2021 RAW MATERIALS & RECYCLING - Bergamo, 2-3 dicembre 2021 L’elenco completo delle iniziative è disponibile sul sito: www.aimnet.it (*) In caso non sia possibile svolgere la manifestazione in presenza, la stessa verrà erogata a distanza in modalità webinar

La Metallurgia Italiana - November/December 2020

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Atti e notizie - AIM news

Comitati tecnici / Study groups CT PRESSOCOLATA (P)

(riunione telematica del 09 settembre 2020) Manifestazioni in corso di organizzazione • Il convegno internazionale “High Tech Die Casting 2020” è per ora confermato al 23-25 giugno 2021 a Vicenza e con il medesimo format. Titoli e riassunti devono essere inviati entro il 30.10.2020. • Viene confermata la prima “pillola” di formazione online FaReTra dal titolo “Difetti nei getti pressocolati – La porosità da ritiro” per il giorno 23 ottobre 2020. • Si conferma anche il corso “Fatica Termica” – coordinatore Valente – per il 3-4 marzo 2021 presso il KmRosso vicino a Bergamo. Il programma è definito e viene presentato dal coordinatore Valente ai membri del CT. • E’ stato definito e presentato durante la riunione il programma per la GdS “Zama HPDC 2021” – coordinatori Pola e Valente – che si svolgerà presso Metalcom il 16 aprile 2021. Iniziative future • La manifestazione “Getti Strutturali” potrebbe essere trasformata in un corso su due giornate da tenere nell’ottobre 2021. La prima giornata è completamente definita con temi e relatori, mentre per la seconda giornata i presenti discutono sulle possibili tematiche suggerite dai coordinatori. Si dovrà individuare anche la sede dell’evento. • Per la GdS “Sostenibilità nelle fonderie HPDC” – coordinatore Zambelli – alcuni membri del CT confermano di avere ricevuto da importanti gruppi nel settore automotive dei questionari le cui risposte producono un punteggio ed un giudizio che influenza le assegnazioni degli ordini. Nel prossimo meeting si esamineranno questi questionari per capire meglio quali siano le richieste e quindi su quali temi centrare la GdS. Notizie dal Comitato • Un nuovo membro, presente come ospite alla riunione, viene accolto dal Comitato.

CT MATERIALI PER L’ENERGIA (ME) (riunione telematica del 07 ottobre 2020)

Manifestazioni in corso di organizzazione • GdS “Materiali per eolico”: in assenza dell’altro coordinatore Merckling, Gariboldi riferisce che i professori del Dipartimento di Energia del Politecnico di Milano hanno dato la disponibilità per gli interventi introduttivi di carattere generale (aspetti metallurgici, problematiche di fatica e usura su parti di grandi dimensioni, ingranaggi, energie rinnovabili). Gariboldi segnala per contro difficoltà a coinvolgere i piccoli utilizzatori e chi fa i controlli di sicurezza per problemi di riservatezza. Bassani conferma che AIM è in grado di organizzare eventi in streaming con codici e autorizzazioni di accesso riservati, così da garantire i relatori. Si cercherà di organizzare l’evento per febbraio 2021. Iniziative future • La GdS sull’utilizzo delle leghe di Ni in saldatura è al momento programmata per aprile, e si spera di poterla tenere in presenza. • Su suggerimento di Bassani, condiviso dal presidente Gavelli, i membri del CT penseranno e proporranno temi per le iniziative di formazione online FaReTra.

CT CORROSIONE (C)

(riunione telematica del 16 ottobre 2020) Consuntivo di attività svolte Manifestazioni in corso di organizzazione • La manifestazione “Giornate Nazionali sulla Corrosione e Protezione” si terrà a Torino dal 30 giugno al 2 luglio 2021 in collabora-

La Metallurgia Italiana - novembre/dicembre 2020

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Atti e notizie - AIM news

Comitati tecnici / Study groups zione con APCE (Associazione per la Protezione dalle Corrosioni Elettrolitiche) e NACE Italia, e con diversi patrocini. Si auspica che l’evento possa tenersi in presenza ma, nell’eventualità che si debba utilizzare la modalità telematica, i presenti discutono delle loro esperienze con precedenti convegni telematici per ottimizzare la riuscita dalla manifestazione: purtroppo la mancata interazione tra le persone e la mancata convivialità non possono permettere di raggiungere i risultati di un convegno in presenza. Iniziative future • È stato formato un gruppo di lavoro misto con il CT “Controllo e caratterizzazione prodotti” per l’organizzazione del “Corso di corrosione per non corrosionisti”. La manifestazione si dovrebbe sviluppare in due giornate, divise equamente tra i due comitati: la proposta iniziale prevede per la prima giornata gli argomenti: introduzione al meccanismo, forme e ambienti di corrosione, criteri di scelta dei materiali; per la seconda giornata invece: presentazione e approfondimento di casi pratici; rivestimenti organici (pitture), rivestimenti metallici, Oil & gas e costruzioni. Dopo lunga discussione Bolzoni e Cabrini ottengono dal CT il mandato per colloquiare con il gruppo di lavoro per elaborare la proposta definitiva e la bozza del programma. Notizie dal Comitato • Un nuovo membro, presente al momento come ospite, è stato accettato nel CT.

CT TRATTAMENTI TERMICI E METALLOGRAFIA (TTM) (riunione telematica del 19 novembre 2020)

Consuntivo di attività svolte • La GdS “Stampaggio: proprietà dell’acciaio, trattamento termico e meccanismo di danneggiamento” si è svolta in modalità telematica a causa delle restrizioni governative. Il coordinatore Rivolta si ritiene soddisfatto della riuscita della manifestazione, con 45 partecipanti e 12 presentazioni, perfino abbondanti per il tempo disponibile online. Il giudizio dato dai partecipanti è tra buono e ottimo, con particolare risalto per la qualità delle presentazioni e la documentazione. Le interazioni online con i docenti sono naturalmente meno esaustive rispetto alle manifestazioni in presenza. Sono stati raccolti suggerimenti per le future giornate sullo stesso tema. • Il corso “Metallurgia di base propedeutico ai trattamenti termici” si è tenuto per la prima volta in modalità online, con una sessantina di partecipanti. Il giudizio espresso nei questionari di soddisfazione è stato per la grande maggioranza buono, e per il resto ottimo. C’è stato apprezzamento per i docenti, e molti partecipanti hanno proposto suggerimenti per approfondimenti. Il presidente Petta ritiene che il risultato sia positivo. Vicario, una delle coordinatrici insieme a La Vecchia, segnala che sono state ricevute per e-mail diverse domande successive al corso e docenti hanno potuto rispondere a tutti i quesiti. Manifestazioni in corso di organizzazione • Convegno Nazionale Trattamenti Termici: il presidente Petta conferma lo spostamento della manifestazione al 6-7 maggio 2021, sperando che questo intervallo di tempo sia sufficiente ad un pieno recupero della situazione sanitaria. Il programma non subirà modifiche rispetto a quanto già stabilito. Bassani segnala che si continuano a ricevere richieste per l’area espositiva. • Il seminario “Trasmissioni nell’automotive: della acciaieria al processo di pallinatura” si svolgerà a Modugno (BA) il 17 e 18 giugno 2021 presso la Getrag. Morgano, coordinatore della manifestazione insieme a Rosso, presenta la bozza del programma: gli argomenti delle presentazioni sono quasi tutti definiti, e per alcune c’è già il nome del relatore. Si attendono ulteriori contributi dal mondo accademico, in particolare dal Politecnico di Bari, e si cercherà di coinvolgere i grossi stabilimenti industriali del centro sud, oltre che l’Università Federico II di Napoli e l’Università del Salento di Lecce. È prevista una visita allo stabilimento al termine della prima giornata. Iniziative future • La GdS “Il Mondo Industrial - aspetti metallurgici e metodologie di controllo”, più volte rimandata, deve essere tenuta di presenza presso CNH Torino per poter effettuare la visita al Museo Iveco. Per questo motivo si decide di spostare la manifestazione a settembre-ottobre 2021.

La Metallurgia Italiana - November/December 2020

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Atti e notizie - AIM news

Comitati tecnici / Study groups • Il seminario congiunto con il CT “Metallurgia delle polveri e tecnologie additive” è stato rimandato a data da definire, non potendosi al momento svolgere manifestazioni in presenza. • La GdS “Trattamenti termici e modellazione”, presso l’Università di Brescia, viene spostata alla seconda metà del 2021. I coordinatori Pellizzari e Valente hanno comunque preparato il programma che sarà presentato alla prossima riunione. • Nell’autunno del 2021 si terrà in tradizionale corso “Trattamenti Termici. Notizie dal Comitato • Sono stati accettati nel Comitato due nuovi membri in sostituzione di loro colleghi che hanno cambiato posto/mansione.

CT METALLI E TECNOLOGIE APPLICATIVE (MTA) (riunione telematica del 20 novembre 2020)

Manifestazioni in corso di organizzazione • La GdS “Trattamenti per la rimozione del piombo per il riciclo degli ottoni”, già fissata per il 4 novembre a Brescia, è stata spostata a giugno 2021. Il coordinatore Loconsolo segnala che sarà possibile aggiungere altri dati ed informazioni alle memorie. Iniziative future • La GdS “Utilizzo leghe di nichel in saldatura” viene confermata per aprile 2021. Tempistiche e programmi saranno definiti a breve. • La GdS sulla sostenibilità ambientale nel campo delle costruzioni civili è in via di definizione, e alcuni dei presenti fanno proposte per aggiungere argomenti alle presentazioni. Si prevede di tenere la manifestazione nella seconda metà del 2021, forse in modalità telematica. • Il tema legato all’impiego dei metalli nella mobilità elettrica sarà ripreso nella prossima riunione.

La Metallurgia Italiana - novembre/dicembre 2020

pagina 74

Atti e notizie - AIM news

Normativa / Standards Norme pubblicate e progetti in inchiesta (aggiornamento 30 novembre 2020) Norme UNSIDER pubblicate da UNI nei mesi di ottobre e novembre 2020

Prodotti laminati a caldo di acciai per impieghi strutturali - Parte 6: Condizioni tecniche di fornitura per prodotti piani di acciai ad alto limite di snervamento allo stato bonificato per impieghi strutturali.

rivestimento, tubi di produzione e tubi

Tubazioni per raffrescamento - Sistemi di

sbozzati per la produzione di manicotti -

tubazioni flessibili prodotti in fabbrica -

Condizioni tecniche di fornitura.

Parte 3: Sistemi di tubazioni di servizio in plastica non bloccate; requisiti e metodi di

UNI EN ISO 11961:2020

Industrie del petrolio e del gas naturale -

prova. UNI EN 17414-2:2020

Tubazioni per raffrescamento - Sistemi

UNI EN 10219-3:2020

di tubazioni flessibili prodotti in fabbrica

Profilati cavi in acciaio formati a freddo e

- Parte 2: Sistemi di tubazioni bloccate

saldati per impieghi strutturali - Parte 3:

con tubo di servizio in plastica; requisiti e

Condizioni tecniche di fornitura per acciai

metodi di prova.

altoresistenziali e acciai resistenti alla corrosione atmosferica.

EC 1-2020 UNI EN 10025-5:2019

Prodotti laminati a caldo di acciai per impieghi strutturali - Parte 5: Condizioni tecniche di fornitura di acciai con resistenza migliorata alla corrosione atmosferica per impieghi strutturali.

UNI EN 17414-1:2020

Tubazioni per raffrescamento - Sistemi di

UNI EN 10210-3:2020

tubazioni flessibili prodotti in fabbrica -

Profilati cavi in acciaio finiti a caldo

Parte 1: Classificazione, requisiti generali e

per

metodi di prova.

Condizioni tecniche di fornitura per acciai

impieghi

strutturali

Parte

altoresistenziali e acciai resistenti alla

EC 1-2020 UNI EN 10025-4:2019

Prodotti laminati a caldo di acciai per impieghi strutturali - Parte 4: Condizioni tecniche di fornitura di acciai saldabili a grano fine per impieghi strutturali ottenuti mediante laminazione termomeccanica.

Prodotti laminati a caldo di acciai per impieghi strutturali - Parte 3: Condizioni tecniche di fornitura di acciai saldabili a grano fine allo stato normalizzato/ per

UNI EN 13480-3:2020

corrosione atmosferica.

Progettazione e calcolo.

Norme UNSIDER ritirate da UNI nei

Tubazioni industriali metalliche - Parte 3:

mesi di ottobre e novembre 2020

UNI EN 10372:2020

Sistema di tracciamento della qualitĂ per prodotti piani di acciaio attraverso l'utilizzo di un codice a barre - Stampa, lettura e

EC 1-2020 UNI EN 10025-3:2019

laminato

alla corrosione utilizzati come tubi di UNI EN 17414-3:2020

Aste di perforazione di acciaio.

EC 1-2020 UNI EN 10025-6:2019

normalizzato

- Tubi in lega senza saldatura resistenti

poliuretano e rivestimento in polietilene.

impieghi

strutturali. EC 1-2020 UNI EN 10025-2:2019

Prodotti laminati a caldo di acciai per impieghi strutturali - Parte 2: Condizioni tecniche di fornitura di acciai non legati per impieghi strutturali. UNI EN 17415-1:2020

Tubazioni per raffrescamento - Sistemi bloccati monotubo per reti di acqua fredda interrate direttamente - Parte 1: Tubi prodotti in fabbrica con tubi di servizio in acciaio o plastica, isolamento termico in

UNI EN 13480-3:2017

Tubazioni industriali metalliche - Parte 3: Progettazione e calcolo.

trattamento delle informazioni. UNI EN ISO 11961:2019

UNI EN ISO 6931-1:2020

Industrie del petrolio e del gas naturale -

Acciai inossidabili per molle - Parte 1: Filo.

Aste di perforazione di acciaio.

UNI EN ISO 10275:2020

UNI EN ISO 10275:2014

Materiali metallici - Fogli e nastri Determinazione

del

coefficiente

Materiali metallici - Fogli e nastri Determinazione

del

coefficiente

incrudimento durante la prova di trazione.

UNI EN ISO 29001:2020

UNI EN 10270-3:2011

Industrie del petrolio, della petrolchimica e del gas naturale - Sistemi di gestione per

Filo di acciaio per molle meccaniche - Parte 3: Filo di acciaio inossidabile per molle.

la qualitĂ specifici del settore - Requisiti per le organizzazioni fornitrici di prodotti e servizi.

UNI CEN ISO/TS 29001:2011

Industrie del petrolio, della petrolchimica e del gas naturale - Sistemi di gestione per

UNI EN ISO 13680:2020

Industrie del petrolio e del gas naturale

La Metallurgia Italiana - November/December 2020

la qualitĂ specifici del settore - Requisiti per le organizzazioni fornitrici di prodotti

pagina 75

Atti e notizie - AIM news e servizi.

- Fixed steel offshore structures (ISO

— Materials for use in H2S-containing

19902:2020).

environments in oil and gas production — Part 1: General principles for selection of

UNI EN ISO 13680:2010

Industrie del petrolio e del gas naturale

EN ISO 15156-1:2020 Petroleum

alla corrosione utilizzati come tubi di

- Materials for use in H2S-containing

rivestimento, tubi di produzione e tubi

environments in oil and gas production -

Petroleum

sbozzati per la produzione di manicotti -

Part 1: General principles for selection of

— Materials for use in H2S-containing

Condizioni tecniche di fornitura.

cracking-resistant materials (ISO 15156-

environments in oil and gas production —

1:2020).

Part 2: Cracking-resistant carbon and low-

Norme UNSIDER pubblicate da CEN

and

natural

cracking-resistant materials.

- Tubi in lega senza saldatura resistenti

gas

industries ISO 15156-2:2020 and

natural

gas

industries

alloy steels, and the use of cast irons.

e ISO nei mesi di ottobre e novembre

EN ISO 15156-2:2020

- Materials for use in H2S-containing

Petroleum

EN ISO 18796-1:2020

environments in oil and gas production -

— Materials for use in H2S-containing

Petroleum, petrochemicals and natural

Part 2: Cracking-resistant carbon and low-

environments in oil and gas production —

gas industries - Internal coating and lining

alloy steels, and the use of cast irons (ISO

Part 3: Cracking-resistant CRAs (corrosion-

of carbon steel process vessels - Part

15156-2:2020).

resistant alloys) and other alloys.

2020

Petroleum

and

natural

gas

industries

1: Technical requirements (ISO 18796EN ISO 15156-3:2020

1:2018).

Petroleum

and

natural

gas

industries

ISO 15156-3:2020 and

natural

gas

industries

Progetti UNSIDER messi allo studio

dal CEN (Stage 10.99) – novembre e dicembre 2020

EN ISO 35104:2020

- Materials for use in H2S-containing

Petroleum and natural gas industries -

environments in oil and gas production -

Arctic operations - Ice management (ISO

Part 3: Cracking-resistant CRAs (corrosion-

35104:2018).

resistant alloys) and other alloys (ISO

Heat treatable steels, alloy steels and free-

15156-3:2020).

cutting steels - Part 5: Nitriding steels.

EN 15655-2:2020

prEN 10088-1 rev

EN 993-10:2020

Methods of test for dense shaped refractory products - Part 10: Determination of

Ductile iron pipes, fittings and accessories

permanent

- Requirements and test methods for

change

dimensions

Stainless steels - Part 1: List of stainless steels.

organic linings of ductile iron pipes

heating.

and fittings - Part 2: Thermoplastic Acid Modified Polyolefin (TMPO) lining of pipes.

EN ISO 7438:2020 Metallic

prEN ISO 683-5

materials

Bend

test

(ISO

Determination

EN ISO 12004-1:2020

7438:2020).

prEN ISO 16808 rev Metallic materials - Sheet and strip of

biaxial

stress-strain

curve by means of bulge test with optical

Metallic materials - Determination of

measuring systems.

ISO 21736:2020

forming-limit curves for sheet and strip

Refractories — Test methods for thermal

- Part 1: Measurement and application of

shock resistance.

forming-limit diagrams in the press shop

Metallic materials - Uniaxial creep testing

(ISO 12004-1:2020).

in tension - Method of test.

ISO 21051:2020

prEN ISO 3785 rev

ISO 12004-1:2020

Metallic materials — Determination of forming-limit curves for sheet and strip

Construction and installation of ductile

— Part 1: Measurement and application of

iron pipeline system.

prEN ISO 204 rev

Metallic materials - Designation of test specimen axes in relation to product

forming-limit diagrams in the press shop.

texture.

ISO 19902:2020

Petroleum and natural gas industries —

ISO 7438:2020

Fixed steel offshore structures.

Metallic materials — Bend test.

prEN ISO 14556 rev Metallic

materials

Charpy

V-notch

pendulum impact test - Instrumented test

EN ISO 19902:2020 Petroleum

and

natural

ISO 15156-1:2020 gas

industries

Petroleum

La Metallurgia Italiana - novembre/dicembre 2020

and

method.

natural

gas

industries

pagina 76

Atti e notizie - AIM news

Normativa / Standards Progetti UNSIDER in inchiesta prEN e ISO/DIS – novembre e dicembre 2020 prEN – progetti di norma europei prEN ISO 13703-3 Petroleum and natural gas industries Piping systems on offshore production platforms and onshore plants - Part 3: Fabrication (ISO/DIS 13703-3:2020).

steels.

internazionali

prEN 10250-1 Open

die

steel

forgings

for

general

engineering purposes - Part 1: General requirements.

ISO/DIS

–

internazionali

progetti

norma

Piping systems on offshore production platforms and onshore plants - Part 3:

ISO/DIS 13765-7.2

heating.

prEN 15632-4

platforms and onshore plants — Part 3:

Piping systems on offshore production

metal service pipes; requirements and test

Fabrication.

methods.

Refractory

prEN 15632-3

temperature.

District heating pipes - Factory made flexible pipe systems - Part 3: Non bonded system with plastic service pipes; requirements and test methods.

District heating pipes - Factory made flexible pipe systems - Part 2: Bonded system with plastic service pipes; requirements and test methods.

products

compressive

—

strength

Determination at

elevated

Refractory mortars — Part 7: Determination of permanent change in dimensions on

Petroleum and natural gas industries — Piping systems on offshore production platforms and onshore plants — Part 3:

prEN 10250-2

Pre-insulated

flexible pipe systems - Part 1: Classification,

Open

die

steel

forgings

for

general

engineering purposes - Part 2: Non-alloy quality and special steels.

prEN 10250-3

FDIS 10113:2019).

die

steel

forgings

Determination of plastic strain ratio (ISO/ for

general

engineering purposes - Part 3: Alloy special

ISO/FDIS

La Metallurgia Italiana - November/December 2020

— Part 2: Determination of forming-limit curves in the laboratory.

listing elements in steel standards.

ISO/FDIS 23475-1

ISO/FDIS 19905-3 Petroleum

and

natural

gas

industries

–

progetti

ISO/FDIS 15663 Petroleum, petrochemical and natural gas industries — Life cycle costing.

ISO/FDIS 12004-2 Metallic materials — Determination of forming-limit curves for sheet and strip — Part 2: Determination of forming-limit curves in the laboratory.

ISO/FDIS 7989-2

FprEN ISO 10113 Metallic materials - Sheet and strip -

Open

forming-limit curves for sheet and strip

offshore units — Part 3: Floating units.

ISO/DIS 13703-3

FprEN – progetti di norma europei

pipes

investigations.

— Site-specific assessment of mobile

general requirements and test methods.

heating

structures — Part 10: Marine geophysical

General requirements.

ISO/DIS 13765-7.2

Progetti UNSIDER al voto FprEN e ISO/FDIS – novembre e dicembre 2020

District

industries

Testing method for steel tyre cord — Part 1:

Fabrication.

prEN 15632-1

gas

Chemical analysis of steel — Order of

heating.

prEN 15632-2

natural

ISO/PRF 6306

ISO/DIS 22685 of

and

— Specific requirements for offshore

Metallic materials — Determination of

ISO/DIS 13703-3

Fabrication (ISO/DIS 13703-3:2020).

pipe systems - Part 4: Bonded system with

ISO/FDIS 19901-10

ISO/FDIS 12004-2

Petroleum and natural gas industries —

District heating pipes - Factory made flexible

spheroidal carbides — Steels for cold

Petroleum

of permanent change in dimensions on

Petroleum and natural gas industries -

Method for evaluating the nodularity of heading and cold extruding.

Refractory mortars — Part 7: Determination

prEN ISO 13703-3

ISO/PRF 23825

Steel wire and wire products — Nonferrous metallic coatings on steel wire — Part 2: Zinc or zinc-alloy coating.

norma

pagina 77

Atti e notizie - AIM news

Indice Analitico ACCIAI INOSSIDABILI AUSTENITICI / AUSTENITIC STAINLESS STEELS Resistenza a corrosione dell’acciaio inossidabile AISI316L in componenti ottenuti mediante tecnologia SLM pag.2-24

441 (EN 1.4509) per applicazioni automobilistiche: analisi dei parametri di formatura pag.9-39

O. Di Pietro, A. Di Schino

R. Giovanardi, M. Conte, C. Gelsomini, R. Franci

ALLUMINIO E LEGHE DI ALLUMINIO / ALUMINIUM AND

Safety and Lightweight innovations for future mobility by

Resistenza a corrosione di campioni di alluminio, prodotti

using stainless steels pag.3-52

mediante Additive Manufacturing, trattati superficialmente

M. Frigo, S. Lindner

ALUMINIUM ALLOYS

con anodizzazione o PEO pag.2-18

L. Pezzato, M. Dabalà, K. Brunelli

Studio della resistenza alla corrosione di acciai impiegati nell’industria alimentare e delle bevande pag.4-16

Sviluppo di trattamenti termici specifici per leghe di alluminio

G. Tranchida, F. Di Franco, B. Megna, M. Santamaria

prodotte per SLM: effetto sulle tensioni residue e la resistenza

Assessment of the effect of surface finishing processes on the

C.A. Biffi, J. Fiocchi, A. Tridello, C. Colombo, G. Chiandussi,

pitting resistance in saline environments of welded AISI 316L

a fatica pag.2-38

M. Rossetto, D.S. Paolino, L.M. Vergani, A. Tuissi

stainless steel pag.9-07

G. Masi, C. Chiavari, C. Martini, F. Pasini, S. Sessa, N. Gandolfi, M. C. Bignozzi

Heat treatments of EN AW 6082 aluminum forging alloy: effect on micro-structure and mechanical properties pag.3-6

S. Cecchel, D. Ferrario, G. Cornacchia

ACCIAI INOSSIDABILI DUPLEX / DUPLEX STAINLESS STEELS Il test FIMEC per valutare la qualità di giunti saldati in acciaio duplex UNS S31803 pag.3-24

R. Montanari, A. Varone, F. Bonollo, P. Ferro

Studio dell’effetto di trattamento criogenico su una lega AA6012 sottoposta a ECAP mediante nanoindentazione

pag.6-31 C. Paoletti, E. Santecchia, V. Di Pompeo, S. Spigarelli, M. Cabibbo

Studio della resistenza alla corrosione di acciai impiegati nell’industria alimentare e delle bevande pag.4-16

AlSi10Mg

alloy

produced

Selective

Laser

Melting:

G. Tranchida, F. Di Franco, B. Megna, M. Santamaria

relationships between Vickers microhardness, Rockwell

Effect of GTA Welding Parameters on Bead Geometry of

E. Cerri, E. Ghio

SAF2507 Super Duplex Stainless Steel pag.9-18

hardness and mechanical properties pag.7/8-06

C. B. Sekar, S. R. Boopathy, S. Vijayan, S. R. K. Rao

A study of intermetallic phase stability in Al-Si-Mg casting

UNS S32205 Duplex Stainless Steel SED-critical radius

E. Cerri, M.T. Di Giovanni, E. Ghio

characterization pag.9-29

alloy: the role of Cu additions pag.7/8-38

P. Ferro, F. Berto, K. Tang

ALTOFORNO BF-BOF / BLAST FURNACE BF-BASIC

ACCIAI INOSSIDABILI FERRITICI, MARTENSITICI E PH

Detection of Non-metallic Inclusions in 12Mn Steel Continuous

/ FERRITIC, MARTENSITIC AND PH STAINLESS STEELS Deformazione plastica di tubi in acciaio inossidabile ferritico

La Metallurgia Italiana - novembre/dicembre 2020

OXYGEN FURNACE BOF Casting Round Billets pag.5-27

X. Wang, J. Wei, S. Qiu

pagina 78

Atti e notizie - AIM news

AMBIENTE E SICUREZZA / HEALTH AND SAFETY

BIOMATERIALI / BIOMATERIALS

Tornitura criogenica della lega Ti6Al4V pag.7/8-29

R. Sola, P. Veronesi

AUTOMOTIVE

CARATTERIZZAZIONE DEI MATERIALI (OM, SEM, XRF,

Simulation of heat treatment of Jominy specimen to improve quality of automotive gear components pag.1-52

XRD, CT) / MATERIAL CHARACTERIZATION (OM, SEM, XRF, XRD, CT)

E. Morgano, C. Viscardi, L. Valente

Material-dependent aspects for the use of nitriding as a

Neural networks-based prediction of hardenability of high

bearing behaviour of cast irons (part II) pag. 1-40

single or duplex treatment in improving the tribological load-

performance carburizing steels for automotive applications

pag. 1-59

A. Buchwalder, N. Klose, R. Zenker

V. Colla, M. Vannucci, L. Bacchi, R. Valentini

Fenomeni di corrosione delle infrastrutture metalliche di

Heat treatment routes utilizing intercritical annealing of

T. Pastore, M. Cabrini, S. Lorenzi, E. Rizzi, R. Ferrari, L. Cop-

rilevanza storica pag.4-43

automotive medium-mn steel sheets pag.1-66

A. Grajcar, M. Morawiec

Effect of GTA Welding Parameters on Bead Geometry of

Heat treatments of EN AW 6082 aluminum forging alloy: effect on micro-structure and mechanical properties pag.3-6

S. Cecchel, D. Ferrario, G. Cornacchia

swashplate axial piston pumps and motors pag.3-14

R. Sola, P. Veronesi, B. Zardin, M. Borghi

and CP800 ISP and ESP thin slab technology at Acciaieria Arvedi in Cremona, Italy pag.3-43

R. Venturini, A. Bianchi, M. Andraghetti, C. Guarnaschelli, M.C. Cesile, P.E. Di Nunzio

using stainless steels pag.3-52

innovativo

termochimico

–

per

Stato

spegnimento dell’arte

dopo campo

post

Sviluppo di trattamenti termici specifici per leghe di alluminio prodotte per SLM: effetto sulle tensioni residue e la resistenza a fatica pag.2-38

C.A. Biffi, J. Fiocchi, A. Tridello, C. Colombo, G. Chiandussi,

Il test FIMEC per valutare la qualità di giunti saldati in acciaio

Microstructure based strengthening model of a biocompatible WE54 alloy reinforced by SiC pag.5-08

M. Cabibbo, F. F. Průša

D. Petta, E. Morgano e

CARACHTERIZATION

R. Montanari, A. Varone, F. Bonollo, P. Ferro

automotive pag.6-42

Nitrurazione

A. Fava, E. Pakhomova, A. Varone

duplex UNS S31803 pag.3-24

M. Frigo, S. Lindner tempra

interlayer W/Cu depositato con plasma spraying pag.10-16

M. Rossetto, D.S. Paolino, L.M. Vergani, A. Tuissi

Safety and Lightweight innovations for future mobility by

C. B. Sekar, S. R. Boopathy, S. Vijayan, S. R. K. Rao

CARATTERIZZAZIONE MECCANICA / MECHANICAL

Metallurgical design and production of AHSS grades DP800

trattamento

SAF2507 Super Duplex Stainless Steel pag.9-18

Studio degli stress residui mediante diffrazione X di un

A study on PVD coatings for reduction of friction and wear of

Fluido

pola, G. Spirolazzi, G. Pisanelli, C. Cioffi, E. Lizzori

ossidazione

nera

automotive pag.6-50

G. Rovetto (3T Srl Rivoli TO)

La Metallurgia Italiana - November/December 2020

componenti

Studio dell’effetto di trattamento criogenico su una lega AA6012 sottoposta a ECAP mediante nanoindentazione

pag.6-31 C. Paoletti, E. Santecchia, V. Di Pompeo, S. Spigarelli, M.

pagina 79

Atti e notizie - AIM news Cabibbo

CORROSIONE / CORROSION AlSi10Mg

alloy

relationships

produced

between

Selective

Vickers

Laser

Melting:

Resistenza a corrosione di campioni di alluminio, prodotti

microhardness,Rockwell

mediante Additive Manufacturing, trattati superficialmente

hardness and mechanical properties pag.7/8-06

con anodizzazione o PEO pag.2-18

E. Cerri, E. Ghio

L. Pezzato, M. Dabalà, K. Brunelli

UNS S32205 Duplex Stainless Steel SED-critical radius

Recenti sviluppi per l’uso della Spettroscopia a Fotocorrente

characterization pag.9-29

nella Caratterizzazione di Film Passivi su Metalli e Leghe

P. Ferro, F. Berto, K. Tang

Metalliche pag.4-06

A. Zaffora, G. Tranchida, F. Di Franco, M. Santamaria, F. Di Deformazione plastica di tubi in acciaio inossidabile ferritico 441 (EN 1.4509) per applicazioni automobilistiche: analisi dei parametri di formatura pag.9-39

Comportamento a corrosione di armature in acciaio e

O. Di Pietro, A. Di Schino A

new

Ni-base

superalloy:

Quarto

acciaio zincato in una malta ad attivazione alcalina a base di production-microstructure-

properties correlation pag.10-06

G. Angella, A. Serafini, C. Malara, M. F. Brunella

metacaolino dopo carbonatazione accelerata pag.4-22

A. Mobili, C. Giosuè, T. Bellezze, F. Tittarelli Effetti della pre-ossidazione delle armature sulla corrosione indotta dalla successiva penetrazione nel calcestruzzo della

Mechanical characterization of the ASTM A335 P5 steel and

carbonatazione pag.4-27

reliability of radiant tubes after long operating time in a

M. Carsana

petrochemical industry furnace pag.10-45

P. Aliprandi, E. Guglielmino, A. Sili

COMPORTAMENTO

MECCANICO

Corrosione da carbonatazione nel calcestruzzo: valutazione

MECHANICAL

BEHAVIOR Bainitic transformation during the two-step Q&P process in a lean medium Mn steel containing silicon pag.1-6

S. Kaar, R. Schneider, D. Krizan, C. Béal, C. Sommitsch Il test FIMEC per valutare la qualità di giunti saldati in acciaio duplex UNS S31803 pag.3-24

R. Montanari, A. Varone, F. Bonollo, P. Ferro

CONTROLLI NON DISTRUTTIVI / NON-DESTRUCTIVE TESTING Effetti della pre-ossidazione delle armature sulla corrosione indotta dalla successiva penetrazione nel calcestruzzo della carbonatazione pag.4-27

M. Carsana Esposizione all’acqua di mare di provini in c.a. realizzati con materie prime contaminate da cloruri pag.4-67

F. Lollini, M. Carsana, M. Gastaldi, E. Redaelli

La Metallurgia Italiana - novembre/dicembre 2020

del comportamento di un inibitore di corrosione a base nitrato

pag.4-38 F. Bolzoni, MV. Diamanti, M. Ormellese, MP. Pedeferri, G. Cilluffo, W. Franke Fenomeni di corrosione delle infrastrutture metalliche di rilevanza storica pag.4-43

T. Pastore, M. Cabrini, S. Lorenzi, E. Rizzi, R. Ferrari, L. Coppola, G. Spirolazzi, G. Pisanelli, C. Cioffi, E. Lizzori Studio di inibitori “green” su opere in leghe di rame pag.4-49

C. Petiti, B. Elanchezian, S. Goidanich Monitoraggio dello stato di conservazione delle opere d’arte della Collezione Gori pag.4-73

L. Es Sebar, M. Parvis, S. Grassini, E. Angelini Development and characterisation of solvent-borne thermally cured cross-linked TiO2 reinforced Polyceramic coatings for long service-life on industrial metal substrates pag.6-06

O. Tan, O. Çimen, P. Yolcu, B. Çiçek

pagina 80

Atti e notizie - AIM news Mechanical characterization of the ASTM A335 P5 steel and

CORROSIONE

DEGLI

ACCIAI

INOSSIDABILI

STAINLESS STEEL CORROSION Resistenza a corrosione dell’acciaio inossidabile AISI316L in

reliability of radiant tubes after long operating time in a petrochemical industry furnace pag.10/45

P. Aliprandi, E. Guglielmino, A. Sili

componenti ottenuti mediante tecnologia SLM pag.2-24

FATICA / FATIGUE

R. Giovanardi, M. Conte, C. Gelsomini, R. Franci

Il nuovo acciaio da utensile da lavorazione a caldo Studio della resistenza alla corrosione di acciai impiegati

THERMODUR E40K SUPERCLEAN pag.5-48

nell’industria alimentare e delle bevande pag.4-16

E. Prati, A. Magistrelli

G. Tranchida, F. Di Franco, B. Megna, M. Santamaria

CORROSIONE ARMATO

DELLE

OPERE

CORROSION

CALCESTRUZZO

CONCRETE

REINFORCEMENT Innesco e propagazione della corrosione dell’armatura in calcestruzzi fibrorinforzati ad altissime prestazioni (UHPFRC)

pag.4-33

UNS S32205 Duplex Stainless Steel SED-critical radius characterization pag.9-29

P. Ferro, F. Berto, K. Tang

GHISE / CAST IRON Material-dependent aspects for the use of nitriding as a single or duplex treatment in improving the tribological load-

E. Redaelli, B.P. Maffezzoli, D. Redaelli

bearing behaviour of cast irons (part II) pag. 1-40

Fenomeni di corrosione delle infrastrutture metalliche di rilevanza storica pag.4-43

T. Pastore, M. Cabrini, S. Lorenzi, E. Rizzi, R. Ferrari, L. Coppola, G. Spirolazzi, G. Pisanelli, C. Cioffi, E. Lizzori

A. Buchwalder, N. Klose, R. Zenker

ELETTROCHIMICA/ ELECTROCHEMISTRY Sonde di potenziale per applicazioni in protezione catodica: accuratezza della misura del potenziale IR-free pag.4-11

A. Brenna, S. Beretta, M. Ormellese 20 anni di esperienza di protezione catodica e monitoraggio del viadotto sul fiume Adige dell’autostrada A4 pag.4-62

Studio della resistenza alla corrosione di acciai impiegati

P. Marcassoli, D. Pesenti Bucella, C. Vasile, V. Colombo, M.

nell’industria alimentare e delle bevande pag.4-16

Viespoli

G. Tranchida, F. Di Franco, B. Megna, M. Santamaria

Esposizione all’acqua di mare di provini in c.a. realizzati con

Vantaggi nell'utilizzo del monitoraggio remoto per verificare

materie prime contaminate da cloruri pag.4-67

l'efficacia della protezione catodica in aree con presenza di

F. Lollini, M. Carsana, M. Gastaldi, E. Redaelli

correnti vagabonde pag.4-56

CORROSIONE

NEL

SETTORE

PETROLCHIMICO

CORROSION IN OIL&GAS

I. Magnifico 20 anni di esperienza di protezione catodica e monitoraggio

Sonde di potenziale per applicazioni in protezione catodica:

del viadotto sul fiume Adige dell’autostrada A4 pag.4-62

accuratezza della misura del potenziale IR-free pag.4-11

P. Marcassoli, D. Pesenti Bucella, C. Vasile, V. Colombo, M.

A. Brenna, S. Beretta, M. Ormellese

Viespoli

Vantaggi nell'utilizzo del monitoraggio remoto per verificare

Monitoraggio dello stato di conservazione delle opere d’arte

l'efficacia della protezione catodica in aree con presenza di

della Collezione Gori pag.4-73

correnti vagabonde pag.4-56

L. Es Sebar, M. Parvis, S. Grassini, E. Angelini

I. Magnifico

IMPIANTI ED ATTREZZATURE / INSTALLATIONS AND CREEP

La Metallurgia Italiana - November/December 2020

EQUIPMENTS

pagina 81

Atti e notizie - AIM news 20 anni di esperienza di protezione catodica e monitoraggio del viadotto sul fiume Adige dell’autostrada A4 pag.4-62

P. Marcassoli, D. Pesenti Bucella, C. Vasile, V. Colombo, M.

MATERIALI

PER

IMPIEGO

TEMPERATURE

LAMINAZIONE A FREDDO / COLD ROLLING

using stainless steels pag.3-52

approach

ALTA

BASSA

TEMPERATURA / MATERIAL USE AT HIGH OR LOW

Viespoli

New

Safety and Lightweight innovations for future mobility by for

online

tensile-structure

properties

evaluation on HSLA/AHSS steel grades pag.3-32

M. Frigo, S. Lindner

A. Ferraiuolo

MECCANICA

DELLA

FRATTURA

Effetto di trattamenti termomeccanici su acciaio EUROFER97

UNS S32205 Duplex Stainless Steel SED-critical radius

FRACTURE

MECHANICS

per applicazioni in reattori a fusione nucleare pag.10-34

characterization pag.9-29

G. Stornelli, M. Rallini, C. Testani, R. Montanari, A. Di Schino

P. Ferro, F. Berto, K. Tang

LAVORAZIONI

METALLI LEGGERI / LIGHT METALS

PLASTICHE

CALDO

HOT

DEFORMATION Heat treatment routes utilizing intercritical annealing of automotive medium-mn steel sheets pag.1-66

PLASTICHE

FREDDO

Multi Response Optimization of Friction Stir Welding Process Parameters on Dissimilar Magnesium Alloys AZ 31 and ZM 21 using Taguchi-Based Grey Relation Analysis pag.7/8-19

S. Prasath, S. Vijayan, D. Elil Raja

A. Grajcar, M. Morawiec

LAVORAZIONI

COLD

DEFORMATION Deformazione plastica di tubi in acciaio inossidabile ferritico 441 (EN 1.4509) per applicazioni automobilistiche: analisi dei

METALLOGRAFIA / METALLOGRAPHY A study on PVD coatings for reduction of friction and wear of swashplate axial piston pumps and motors pag.3-14

R. Sola, P. Veronesi, B. Zardin, M. Borghi

parametri di formatura pag.9-39

O. Di Pietro, A. Di Schino

METALLURGIA FISICA / PHIYSICAL METALLURGY New

MAGNESIO E LEGHE DI MAGNESIO / Mg BASED ALLOYS Microstructure based strengthening model of a biocompatible

approach

for

online

tensile-structure

properties

evaluation on HSLA/AHSS steel grades pag.3-32

A. Ferraiuolo

WE54 alloy reinforced by SiC pag.5-08

M. Cabibbo, F. F. Průša

new

Ni-base

superalloy:

production-microstructure-

Multi Response Optimization of Friction Stir Welding Process

G. Angella, A. Serafini, C. Malara, M. F. Brunella

properties correlation pag.10-06

Parameters on Dissimilar Magnesium Alloys AZ 31 and ZM 21 using Taguchi-Based Grey Relation Analysis pag.7/8-19

Studio degli stress residui mediante diffrazione X di un

S. Prasath, S.Vijayan, D. Elil Raja

interlayer W/Cu depositato con plasma spraying pag.10-16

A. Fava, E. Pakhomova, A. Varone

MATERIALI PER L’ENERGIA / MATERIALS FOR ENERGY Metallurgical and Mechanical Studies of ASTM A213 T22 / A240 T409 High Frequency Welded Joints pag.9-56

M. Sadeghi, H. Sabet, S. H. Razavi

METALLURGIA DI PROCESSO / PROCESS METALLURGY New

approach

for

online

tensile-structure

properties

evaluation on HSLA/AHSS steel grades pag.3-32

A. Ferraiuolo Studio degli stress residui mediante diffrazione X di un interlayer W/Cu depositato con plasma spraying pag.10-16

Metallurgical design and production of AHSS grades DP800

A. Fava, E. Pakhomova, A. Varone

and CP800 ISP and ESP thin slab technology at Acciaieria

La Metallurgia Italiana - novembre/dicembre 2020

pagina 82

Atti e notizie - AIM news Arvedi in Cremona, Italy pag.3-43

Fenomeni di corrosione delle infrastrutture metalliche di

R. Venturini, A. Bianchi, M. Andraghetti, C. Guarnaschelli,

rilevanza storica pag.4-43

M.C. Cesile, P.E. Di Nunzio

T. Pastore, M. Cabrini, S. Lorenzi, E. Rizzi, R. Ferrari, L. Coppola, G. Spirolazzi, G. Pisanelli, C. Cioffi, E. Lizzori

Microstructure based strengthening model of a biocompatible

WE54 alloy reinforced by SiC pag.5-08

M. Cabibbo, F. F. Průša

MICROSTRUTTURA

CARATTERIZZAZIONE

MICROSTRUCTURE AND CHARACTERIZATION Bainitic transformation during the two-step Q&P process in a

Il nuovo acciaio da utensile da lavorazione a caldo THERMODUR E40K SUPERCLEAN pag.5-48

E. Prati, A. Magistrelli

lean medium Mn steel containing silicon pag.1-6

S. Kaar, R. Schneider, D. Krizan, C. Béal, C.Sommitsch

Surface treatment of Al7075 Matrix by TiC particles via hybrid ball milling and tungsten inert gas cladding pag.6-21

Simulation of heat treatment of Jominy specimen to improve

M. Toozandehjani, F. Ostovan, E. Shafiei, K. R. Jamaludin, A.

quality of automotive gear components pag.1-52

Amrin, E. Hasanzadeh

E. Morgano, C. Viscardi, L. Valente Studio dell’effetto di trattamento criogenico su una lega Heat treatment routes utilizing intercritical annealing of

AA6012 sottoposta a ECAP mediante nanoindentazione

automotive medium-mn steel sheets pag.1-66

pag.6-31

A. Grajcar, M. Morawiec

C. Paoletti, E. Santecchia, V. Di Pompeo, S. Spigarelli, M. Cabibbo

Resistenza a corrosione di campioni di alluminio, prodotti mediante Additive Manufacturing, trattati superficialmente con anodizzazione o PEO pag.2-18

alloy: the role of Cu additions pag.7/8-38

L. Pezzato, M. Dabalà, K. Brunelli Heat treatments of EN AW 6082 aluminum forging alloy: effect on micro-structure and mechanical properties pag.3-6

S. Cecchel, D. Ferrario, G. Cornacchia New

approach

for

online

tensile-structure

properties

A. Ferraiuolo Metallurgical design and production of AHSS grades DP800 and CP800 ISP and ESP thin slab technology at Acciaieria Arvedi in Cremona, Italy pag.3-43

R. Venturini, A. Bianchi, M. Andraghetti, C. Guarnaschelli, M.C. Cesile, P.E. Di Nunzio Effetti della pre-ossidazione delle armature sulla corrosione indotta dalla successiva penetrazione nel calcestruzzo della

M. Carsana

E. Cerri, M.T. Di Giovanni, E. Ghio A

new

Ni-base

superalloy:

production-microstructure-

properties correlation pag.10-06

evaluation on HSLA/AHSS steel grades pag.3-32

carbonatazione pag.4-27

A study of intermetallic phase stability in Al-Si-Mg casting

G. Angella, A. Serafini, C. Malara, M. F. Brunella Effetto di trattamenti termomeccanici su acciaio EUROFER97 per applicazioni in reattori a fusione nucleare pag.10-34

G. Stornelli, M. Rallini, C. Testani, R. Montanari, A. Di Schino Mechanical characterization of the ASTM A335 P5 steel and reliability of radiant tubes after long operating time in a petrochemical industry furnace pag.10/45

P. Aliprandi, E. Guglielmino, A. Sili

MODELLAZIONE

SIMULAZIONE

NUMERICA

MODELING AND NUMERICAL SIMULATION

Simulation of heat treatment of Jominy specimen to improve quality of automotive gear components pag.1-52

E. Morgano, C. Viscardi, L. Valente

La Metallurgia Italiana - November/December 2020

pagina 83

Atti e notizie - AIM news V. Colla, M. Vannucci, R. Valentini Neural networks-based prediction of hardenability of high performance carburizing steels for automotive applications

Effetto di trattamenti termomeccanici su acciaio EUROFER97

pag. 1-59

per applicazioni in reattori a fusione nucleare pag.10-34

V. Colla, M. Vannucci, L. Bacchi, R. Valentini

G. Stornelli, M. Rallini, C. Testani, R. Montanari, A. Di Schino

New

approach

for

online

tensile-structure

properties

PRODUZIONE ADDITIVA/ ADDITIVE MANUFACTURING Comportamento

evaluation on HSLA/AHSS steel grades pag.3-32

alla

corrosione

una

lega

Ti6Al4V

A. Ferraiuolo

per applicazione bio-mediche ottenuta tramite additive

Metallurgical design and production of AHSS grades DP800

C. Testa, M. Cabrini, S. Lorenzi, T. Pastore, D. Manfredi, M.

and CP800 ISP and ESP thin slab technology at Acciaieria

Lorusso, F. Calignano, M. Lombardi

manufacturing pag.2-6

Arvedi in Cremona, Italy pag.3-43

R. Venturini, A. Bianchi, M. Andraghetti, C. Guarnaschelli,

Comportamento elettrochimico di componenti in lega di

M.C. Cesile, P.E. Di Nunzio

titanio Ti6Al4V realizzati con tecnologia direct metal laser

UNS S32205 Duplex Stainless Steel SED-critical radius

A. Acquesta, A. Carangelo, P. Di petta, T. Monetta

sintering pag.2-12

characterization pag.9-29

P. Ferro, F. Berto, K. Tang

Resistenza a corrosione di campioni di alluminio, prodotti

Deformazione plastica di tubi in acciaio inossidabile ferritico

con anodizzazione o PEO pag.2-18

mediante Additive Manufacturing, trattati superficialmente

441 (EN 1.4509) per applicazioni automobilistiche: analisi dei parametri di formatura pag.9-39

L. Pezzato, M. Dabalà, K. Brunelli

O. Di Pietro, A. Di Schino

Resistenza a corrosione dell’acciaio inossidabile AISI316L in

Study on Heat Transfer Characteristics during Solidification

R. Giovanardi, M. Conte, C. Gelsomini, R. Franci

componenti ottenuti mediante tecnologia SLM pag.2-24

of 18-ton Steel Ingot with Large Ratio of Height to Diameter

pag.5-37

AlTiN Coating of Ti6Al4V Alloy Additive Manufactured Parts

Z. Yu, H. Zhang, X. Wang, X. Wu

pag.2-30

Mechanical characterization of the ASTM A335 P5 steel and

Gionda, J. Fiocchi, A. Tuissi

S. Battiston, A. Fiorese, C.A. Biffi, F. Montagner, V. Zin, A.

reliability of radiant tubes after long operating time in a petrochemical industry furnace pag.10/45

Sviluppo di trattamenti termici specifici per leghe di alluminio

P. Aliprandi, E. Guglielmino, A. Sili

prodotte per SLM: effetto sulle tensioni residue e la resistenza

PRESSOCOLATA / DIE CASTING

C.A. Biffi, J. Fiocchi, A. Tridello, C. Colombo, G. Chiandussi,

a fatica pag.2-38

Il nuovo acciaio da utensile da lavorazione a caldo THERMODUR E40K SUPERCLEAN pag.5-48

Knock (and pre-ignition) damage on engine components: case

E. Prati, A. Magistrelli

PROCESSI

TERMOMECCANICI

M. Rossetto, D.S. Paolino, L.M. Vergani, A. Tuissi

studies pag.5-20

THERMO-

MECHANICAL PROCESSES Predizione delle proprietà meccaniche di barre nervate per le costruzioni tramite la combinazione di modelli agli elementi finiti e modelli data-driven pag.10-26

La Metallurgia Italiana - novembre/dicembre 2020

E. Balducci, Parisi, F. Boccia, M. Barichello, L. Ceschini AlSi10Mg

alloy

produced

Selective

Laser

Melting:

relationships between Vickers microhardness, Rockwell hardness and mechanical properties pag.7/8-06

pagina 84

Atti e notizie - AIM news E. Cerri, E. Ghio

pag.2-30 S. Battiston, A. Fiorese, C.A. Biffi, F. Montagner, V. Zin, A.

PROTEZIONE CATODICA / CATHODIC PROTECTION

Gionda, J. Fiocchi, A. Tuissi

Sonde di potenziale per applicazioni in protezione catodica: accuratezza della misura del potenziale IR-free pag.4-11

Development and characterisation of solvent-borne thermally

A. Brenna, S. Beretta, M. Ormellese

cured cross-linked TiO2 reinforced Polyceramic coatings for

20 anni di esperienza di protezione catodica e monitoraggio

O. Tan, O. Çimen, P. Yolcu, B. Çiçek

long service-life on industrial metal substrates pag.6-06

del viadotto sul fiume Adige dell’autostrada A4 pag.4-62

P. Marcassoli, D. Pesenti Bucella, C. Vasile, V. Colombo, M.

SALDATURA/ WELDING

Viespoli

Il test FIMEC per valutare la qualità di giunti saldati in acciaio

Vantaggi nell'utilizzo del monitoraggio remoto per verificare

R. Montanari, A. Varone, F. Bonollo, P. Ferro

duplex UNS S31803 pag.3-24

l'efficacia della protezione catodica in aree con presenza di correnti vagabonde pag.4-56

Surface treatment of Al7075 Matrix by TiC particles via hybrid

I. Magnifico

ball milling and tungsten inert gas cladding pag.6-21

RAME E LEGHE A BASE RAME / COPPER AND COPPER BASED ALLOYS

M. Toozandehjani, F. Ostovan, E. Shafiei, K. R. Jamaludin, A. Amrin, E. Hasanzadeh

Monitoraggio dello stato di conservazione delle opere d’arte

Multi Response Optimization of Friction Stir Welding Process

della Collezione Gori pag.4-73

Parameters on Dissimilar Magnesium Alloys AZ 31 and ZM 21

L. Es Sebar, M. Parvis, S. Grassini, E. Angelini

using Taguchi-Based Grey Relation Analysis pag.7/8-19

RESISTENZA A FATICA / FATIGUE RESISTANCE

S.Prasath, S.Vijayan, D. Elil Raja

Liquid Nitrocarburizing treatment on valves in internal

Effect of GTA Welding Parameters on Bead Geometry of

combustion engines pag.1-78

SAF2507 Super Duplex Stainless Steel pag.9-18

M. Legrand, V. Monteux

C. B. Sekar, S. R. Boopathy, S. Vijayan, S. R. K. Rao

RICRISTALLIZZAZIONE E CRESCITA DEL GRANO /

Metallurgical and Mechanical Studies of ASTM A213 T22 / A240

RECLYSTALLIZATION AND GRAIN GROWTH Heat treatments of EN AW 6082 aluminum forging alloy: effect on micro-structure and mechanical properties pag.3-6

S. Cecchel, D. Ferrario, G. Cornacchia Effetto di trattamenti termomeccanici su acciaio EUROFER97 per applicazioni in reattori a fusione nucleare pag.10-34

G. Stornelli, M. Rallini, C. Testani, R. Montanari, A. Di Schino

RIVESTIMENTI/ COATINGS Resistenza a corrosione di campioni di alluminio, prodotti mediante Additive Manufacturing, trattati superficialmente con anodizzazione o PEO pag.2-18

L. Pezzato, M. Dabalà, K. Brunelli

T409 High Frequency Welded Joints pag.9-56

M. Sadeghi, H. Sabet, S. H. Razavi

SOLIDIFICAZIONE / SOLIDIFICATION Study on Heat Transfer Characteristics during Solidification of 18-ton Steel Ingot with Large Ratio of Height to Diameter

pag.5-37 Z. Yu, H. Zhang, X. Wang, X. Wu

STORIA DELLA METALLURGIA / ARCHAEOLOGICAL METALLURGY Fenomeni di corrosione delle infrastrutture metalliche di rilevanza storica pag.4-43

T. Pastore, M. Cabrini, S. Lorenzi, E. Rizzi, R. Ferrari, L. Coppola, G. Spirolazzi, G. Pisanelli, C. Cioffi, E. Lizzori

AlTiN Coating of Ti6Al4V Alloy Additive Manufactured Parts

La Metallurgia Italiana - November/December 2020

pagina 85

Atti e notizie - AIM news

SUPERLEGHE A BASE NI / Ni-BASED SUPERALLOYS

Neural networks-based prediction of hardenability of high

performance carburizing steels for automotive applications

new

Ni-base

superalloy:

production-microstructure-

properties correlation pag.10-06

pag. 1-59

G. Angella, A. Serafini, C. Malara, M. F. Brunella

V. Colla, M. Vannucci, L. Bacchi, R. Valentini

TITANIO E LEGHE / TITANIUM AND TI-BASED ALLOYS

TRATTAMENTI TERMICI / HEAT-TREATMENTS

AlTiN Coating of Ti6Al4V Alloy Additive Manufactured Parts

High pressure gas quenching: assessment of velocity

pag.2-30

experimental measurements and steps for model validation

S. Battiston, A. Fiorese, C.A. Biffi, F. Montagner, V. Zin, A. Gionda, J. Fiocchi, A. Tuissi

E. Vyazmina, L. Bustamante-Valencia, V. Woimbee, G. Michel, A. Belhajria, Ch. David

Tornitura criogenica della lega Ti6Al4V pag.7/8-29

Influence of gas nitriding conditions on layer structure

R. Sola, P. Veronesi

TRASFORMAZIONI

pag.1-18

formation on grey- and white-solidified cast irons (part I)

FASE

PHASE

TRANSFORMATION Bainitic transformation during the two-step Q&P process in a lean medium Mn steel containing silicon pag.1-6

pag.1-28 A. Holst, A. Buchwalder, R. Zenker New environmental-friendly developments and applications

S. Kaar, R. Schneider, D. Krizan, C. Béal, C. Sommitsch

of the pulsed plasma heat treatment technology in the field

Heat treatment routes utilizing intercritical annealing of

A. Gebeshuber, V. Strobl, T. Müller

automotive medium-mn steel sheets pag.1-66

Non-destructive hardness / microstructure testing of heat-

A. Grajcar, M. Morawiec

treated parts by mass production, with multiple frequency

TRATTAMENTI SOTTO VUOTO / VACUUM TREATMENT AlTiN Coating of Ti6Al4V Alloy Additive Manufactured Parts

pag.2-30 S. Battiston, A. Fiorese, C.A. Biffi, F. Montagner, V. Zin, A. Gionda, J. Fiocchi, A. Tuissi

TRATTAMENTI

SUPERFICIALI

of engine, transmission and power train engineering pag.1-73

magnetic induction method pag.1-82

A. Horsch Fluido

trattamento

tempra

innovativo

termochimico

–

per

Stato

spegnimento dell’arte

dopo campo

automotive pag.6-42

SURFACE

HEAT-

TREATMENTS Material-dependent aspects for the use of nitriding as a single or duplex treatment in improving the tribological loadbearing behaviour of cast irons (part II) pag. 1-40

A. Buchwalder, N. Klose, R. Zenker Liquid Nitrocarburizing treatment on valves in internal combustion engines pag.1-78

M. Legrand, V. Monteux A study on PVD coatings for reduction of friction and wear of swashplate axial piston pumps and motors pag.3-14

R. Sola, P. Veronesi, B. Zardin, M. Borghi

La Metallurgia Italiana - novembre/dicembre 2020

D. Petta, E. Morgano A study of intermetallic phase stability in Al-Si-Mg casting alloy: the role of Cu additions pag.7/8-38

E. Cerri, M.T. Di Giovanni, E. Ghio

TRIBOLOGIA / TRIBOLOGY Material-dependent aspects for the use of nitriding as a single or duplex treatment in improving the tribological loadbearing behaviour of cast irons (part II) pag. 1-40

A. Buchwalder, N. Klose, R. Zenker A study on PVD coatings for reduction of friction and wear of swashplate axial piston pumps and motors pag.3-14

R. Sola, P. Veronesi, B. Zardin, M. Borghi

pagina 86

Atti e notizie - AIM news

Innesco e propagazione della corrosione dell’armatura in calcestruzzi fibrorinforzati ad altissime prestazioni (UHPFRC)

pag.4-33 E. Redaelli, B.P. Maffezzoli, D. Redaelli Development and characterisation of solvent-borne thermally cured cross-linked TiO2 reinforced Polyceramic coatings for long service-life on industrial metal substrates pag.6-06

O. Tan, O. Çimen, P. Yolcu, B. Çiçek

La Metallurgia Italiana - November/December 2020

pagina 87

Atti e notizie - AIM news

Indice Autori Andraghetti, M. pag.3-43

Cioffi, C. pag.4-43

Acquesta, A. pag.2-12

Colla, V. pag. 1-59 - pag.10-26

Aliprandi, P. pag.10-45

Colombo, C. pag.2-38

Amrin, A. pag.6-21

Colombo, V. pag.4-62

Angelini, E. pag.4-73

Conte, M. pag.2-24

Angella, G. pag.10-06

Coppola, L. pag.4-43

Bacchi, L. pag. 1-59

Cornacchia, G. pag.3-6

Balducci, E. pag.5-20

Dabalà, M. pag.2-18

Barichello, M. pag.5-20

David Ch. pag.1-18

Battiston, S. pag.2-30

Di Franco, F. pag.4-06

Béal, C. pag.1-6

Di Franco, F. pag.4-16

Belhajria, A. pag.1-18

Di Giovanni, M.T. pag.7/8-38

Bellezze, T. pag.4-22

Di Nunzio, P.E. pag.3-43

Beretta, S. pag.4-11

Di petta, P. pag.2-12

Berto, F. pag.9-29

Di Pietro, O. pag.9-39

Bianchi, A. pag.3-43

Di Pompeo, V. pag.6-31

Biffi, C.A. pag.2-30 - pag.2-38

Di Quarto, F. pag.4-06

Bignozzi, M.C. pag.9-07

Di Schino, A. pag.9-39 - pag.10-34

Boccia, F. pag.5-20

Diamanti, MV. pag.4-38

Bolzoni, F. pag.4-38

Elanchezian, B. pag.4-49

Bonollo, F. pag.3-24

Elil Raja, D. pag.7/8-19

Boopathy, S.R. pag.9-18

Es Sebar, L. pag.4-73

Borghi, M. pag.3-14

Fava, A. pag.10-16

Brenna, A. pag.4-11

Ferraiuolo, A. pag.3-32

Brunella, M. F. pag.10-06

Ferrari, R. pag.4-43

Brunelli, K. pag.2-18

Ferrario, D. pag.3-6

Buchwalder, A. pag.1-28 - pag. 1-40

Ferro, P. pag.3-24 - pag.9-29

Cabibbo, M. pag.6-31 - pag.5-08

Fiocchi, J. pag.2-30 - pag.2-38

Cabrini, M. pag.2-6 - pag.4-43

Fiorese, A. pag.2-30

Calignano, F. pag.2-6

Franci, R. pag.2-24

Carangelo, A. pag.2-12

Franke, W. pag.4-38

Carsana, M. pag.4-27 - pag.4-67

Frigo, M. pag.3-52

Cecchel, S. pag.3-6

Gandolfi, N. pag.9-07

Cerri, E. pag.7/8-06 - pag.7/8-38

Gastaldi, M. pag.4-67

Ceschini, L. pag.5-20

Gebeshuber, A. pag.1-73

Cesile, M.C. pag.3-43

Gelsomini, C. pag.2-24

Chiandussi, G. pag.2-38

Ghio, E. pag.7/8-06 - pag.7/8-38

Chiavari, C. pag.9-07

Gionda, A. pag.2-30

Çiçek, B. pag.6-06

Giosuè, C. pag.4-22

Cilluffo, G. pag.4-38

Giovanardi, R. pag.2-24

Çimen, O. pag.6-06

Goidanich, S. pag.4-49

La Metallurgia Italiana - novembre/dicembre 2020

pagina 88

Atti e notizie - AIM news Grajcar, A. pag.1-66

Parisi, S. pag.5-20

Grassini, S. pag.4-73

Parvis, M. pag.4-73

Guarnaschelli, C. pag.3-43

Pasini, F. pag.9-07

Guglielmino, E. pag.10-45

Pastore, T. pag.2-6 - pag.4-43

H. Sabet, H. 9-56

Pedeferri, MP. pag.4-38

Hasanzadeh, E. pag.6-21

Pesenti Bucella, D. pag.4-62

Holst, A. pag.1-28

Petiti, C. pag.4-49

Horsch, A. pag.1-82

Petta, D. pag.6-42

Jamaludin, K. R. pag.6-21

Pezzato, L. pag.2-18

Kaar, S. pag.1-6

Pisanelli, G. pag.4-43

Klose, N. pag. 1-40

Prasath, S. pag.7/8-19

Krizan, D. pag.1-6

Prati, E. pag.5-48

L. Bustamante-Valencia, L. pag.1-18

PrĹŻĹĄa, F. F. pag.5-08

Legrand, M. pag.1-78

Qiu, S. pag.5-27

Lindner, S. pag.3-52

Rallini, M. pag.10-34

Lizzori, E. pag.4-43

Rao, S. R. K. pag.9-18

Lollini, F. pag.4-67

Razavi, H.S. pag.9-56

Lombardi, M. pag.2-6

Redaelli, D. pag. 4-33

Lorenzi, S. pag.2-6 - pag.4-43

Redaelli, E. pag.4-67 - pag.4-33

Lorusso, M. pag.2-6

Rizzi, E. pag.4-43

M. Sadeghi, M. 9-56

Rossetto, M. pag.2-38

Maffezzoli, B.P. pag.4-33

Rovetto, G. pag.6-50

Magistrelli, A. pag.5-48

Santamaria, M. pag.4-06 - pag.4-16

Magnifico, I. pag.4-56

Santecchia, E. pag.6-31

Malara, C. pag.10-06

Schneider, R. pag.1-6

Manfredi, D. pag.2-6

Sekar, C. B. S. pag.9-18

Marcassoli, P. pag.4-62

Serafini, A. pag.10-06

Martini, C. pag.9-07

Sessa, S. pag.9-07

Masi, G. pag.9-07

Shafiei, E. pag.6-21

Megna, B. pag.4-16

Sili, A. pag.10/45

Michel, G. pag.1-18

Sola, R. pag.7/8-29 - pag.3-14

Mobili, A. pag.4-22

Sommitsch, C. pag.1-6

Monetta, T. pag.2-12

Spigarelli, S. pag.6-31

Montagner, F. pag.2-30

Spirolazzi, G. pag.4-43

Montanari, R. pag.3-24 - pag.10-34

Stornelli, G. pag.10-34

Monteux, V. pag.1-78

Strobl, V. pag.1-73

Morawiec, M. pag.1-66

Tan, O. pag.6-06

Morgano, E. pag.1-52 - pag.6-42

Tang, K. pag.9-29

MĂźller, T. pag.1-73

Testa, C. pag.2-6

Ormellese, M. pag.4-11 - pag.4-38

Testani, C. pag.10-34

Ostovan, F. pag.6-21

Tittarelli, F. pag.4-22

Pakhomova, E. pag.10-16

Toozandehjani, M. pag.6-21

Paoletti, C. pag.6-31

Tranchida, G. pag.4-06

Paolino, D.S. pag.2-38

Tranchida, G. pag.4-16

La Metallurgia Italiana - November/December 2020

pagina 89

Atti e notizie - AIM news Tridello, A. pag.2-38 Tuissi, A. pag.2-30 - pag.2-38 Valente, L. pag.1-52 Valentini, R. pag.1-59 - pag.10-26 Vannucci, M. pag.1-59 - pag.10-26 Varone, A. pag.3-24 - pag.10-16 Vasile, C. pag.4-62 Venturini, R. pag.3-43 Vergani, L.M. pag.2-38 Veronesi, P. pag.7/8-29 - pag.3-14 Viespoli, M. pag.4-62 Vijayan, S. pag.7/8-19 - pag.9-18 Viscardi, C. pag.1-52 Vyazmina, E. pag.1-18 Wang, X. pag.5-27 Wang, X. pag.5-37 Wei, J. pag.5-27 Woimbee, V. pag.1-18 Wu, X. pag.5-37 Yolcu, P. pag.6-06 Yu, Z. pag.5-37 Zaffora, A. pag.4-06 Zardin, B. pag.3-14 Zenker, R. pag.1-28 - pag. 1-40 Zhang, H. pag.5-37 Zin, V. pag.2-30

La Metallurgia Italiana - novembre/dicembre 2020

pagina 90

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