Review about high performance of Austenitic Stainless Steel

Review about High Performance of Austenitic Stainless Steel Tarun Kumar Painkra Student, Bachelor of Engineering Mechanical Engineering Kirodimal Institute Of Technology, Raigarh, Chhattisgarh, India 496001

Kheer Sagar Naik Student, Bachelor of Engineering Mechanical Engineering Kirodimal Institute Of Technology, Raigarh, Chhattisgarh, India 496001

Rajendra Kumar Nishad Student, Bachelor of Engineering Mechanical Engineering Kirodimal Institute Of Technology, Raigarh, Chhattisgarh, India 496001

Prakash Kumar Sen Faculty Department of Mechanical Engineering Kirodimal Institute Of Technology, Raigarh, Chhattisgarh, India 496001

Shailendra Kumar Bohidar Faculty Department of Mechanical Engineering Kirodimal Institute Of Technology, Raigarh, Chhattisgarh, India 496001

Abstract Austenitic stainless steel is the most common type of stainless steel. They are most easily recognized as non-magnetic. They are extremely weld able and formable, and they can be successfully used from cryogenic temperature to the red hot temperature jet engines and various furnaces. Generally in contain 16 to 25% chromium and they can also contain nitrogen in solution. Which increase the property of high corrosion resistance. A small quantity of nickel helps stabilized their austenitic structure.

Keywords: Austenitic stainless steel, temperature, corrosion, high-strength. _______________________________________________________________________________________________________

I. INTRODUCTION Austenite stainless steel combines good mechanical properties of to an excellent corrosion resistance. This combination made austenite stainless steel the most widely used type of stainless steel. Austenite stainless steel has high ductility, low yield stress and relatively high tensile strength, when compared to typical cordon steel. Austenite stainless steel are the most common and familiar type of stainless steel. They are extremely formable and wieldable, and they can be successfully used form cryogenic temperature to red-hot temperature of furnace and jet engine they contain between about 16 and 25% chromium, and they can also contain nitrogen in solution, both of which contribute to their high corrosion resistance. Where it for cost of the nickel that helps stabilizes their austenitic structure, these would be used even more widely.

II. HISTORY Stainless steels were introduced at the beginning of the twentieth century as a result of pioneering work in England and Germany. In the ensuing half century, manufacturers developed a large family of stainless steel that has served the chemical, energy, food and other industries very well. The modern era of stainless steel began in the early 1970s when steel maker introduced new refining and casting technologies. These technologies allowed steel designers and producers to both improve existing “standard grades� and develop new grades with improved performance, including the new HPASS grades.

The new steel making technologies included argon-oxygen decarburization (AOD) and vacuum oxygen decarburization (VOD) processes. They made it economically possible to achieve very low carbon contents, high alloys recovery, and better composition control (especially precisely controlled nitrogen contents). Electro slag remelting (ESR), performed as an alternative or supplemental process, provided improved composition controlled and a more homogeneous microstructure containing fewer inclusions. Continuous casting increased efficiency, further reducing production costs.

One of the first alloys to take advantages of the new technologies, the first member of HPASS, was 904L (N08904) developed by what is now outkumpu stainless steel. Grade 904L employs very low carbon levels to produce a weld able wrought version of an existing cast alloys having very high resistance to strong reducing acids. In 1973, ATI Allegheny Ludlum introduces the first fully seawater-resistant austenitic stainless steel AL-6XÂŽ, containing 6% Mo very low carbon to achieve weld able thin sheet and tubing products. By the mid-seventies, developments in the us and control of nitrogen led to improved 6% MO alloys that

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

were weld able in thick sections and resistant to the formation of detrimental intermetallic phases that reduce pitting resistance.

Representative of these alloys are 254 SM0速 (S31254) by outkumpu stainless and AL-6XN速 (N08367) by Allegheny Ludlum.

Fig 1: HPASS in a fuel gas scrubber application. (Source: outokumpu)[1]

The increasing need for cost-effective, high-performance alloys in emerging environmental and energy industries pushed the required corrosion performance of this stainless steel even higher in the 1990s. Two alloys having extremely high-pitting resistance in aggressive chlorinated water were introduced. Outkumpu stainless introduced alloy 654 SM0速 (S32654), containing 7.3% Mo and 0.50% N, Industeel developed alloy B66 (S31266), containing 6%Mo, 2% W and 0.45% N. these steels approach the performance of some of the highly corrosion-resistant nickel-base alloy at significantly lower cost.[1]

Fig 2: Heat exchanger tube sheet during fabrication [1]

III. ROLE OF ALLOYING ELEMENT A. Chromium (Cr): The alloying element chromium is used to make stainless steel, for unique surface passive film chromium is used to protecting stainless steel in environmental that include moisture, high oxidizing high temperature gases, aggressive water, many acids.

When we need to improve corrosion resistance we increase the quantity of chromium in alloys.

B. Nickel (Ni): In the austenite stainless steel main purpose of nickel is to create and austenite for maintain the austenitic structure nickel is more needed. During cold deformation nickel reduce the rate of work hardening, it also improve corrosion behavior and increase stress corrosion resistance. Hence it is used for cold heading, spin forming, and deep drawing.

C. Molybdenum (Mo): It prevent the alloy from crevice corrosion in fluoride containing environmental and increase resistance to heating it work with nitrogen and chromium with increases corrosion resistance and reducing environment like dilute sulfuric acid, hydrochloric acid molybdenum promote ferrite formation or face. Balance it is oxidation resistance at high temperatures, which make alloy more and give strength.

D. Carbon(C): Carbon is useful alloying element in stainless steel because I give strengthens to austenite, so it used where high temperature attempt like in boiler tube.

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

E. Nitrogen (N): It also strengthens austenite like nitrogen and retards secondary phase formation. it is added in small amount to improve resistance to chlorite pitting and crevice resistance.

F. Manganese (Mn): In stainless steel the small amount of manganese is used like a deoxidizer in molten steel it increases the nitrogen solubility in stainless steel and allow higher nitrogen contain and improve strength and corrosion resistance.

G. Copper (Cu): The role of copper in alloy is to reducing acids like phosphoric acid and sulfuric acid mixture and improves corrosion resistance of stainless steel.

H. Silicon (Si): Function of silicon in stainless steel like manganese as small amount of its effects on the weld ability and corrosion resistance of stainless steel it also used like a deoxidizer.

IV. CHARACTERISTIC PROPERTIES      

Good ductility Very good resistance to uniform corrosion Weld ability is good Very good resistance to pitting crevice corrosion resistance is very good very good resistance to various types of stress corrosion cracking

V. MECHANICAL AND PHYSICAL PROPERTIES The strength and elongation of 904L are similar to those for conventional austenitic stainless steel. The addition of nitrogen in 254 SMO and 4565 gives higher proof strength and tensile strength, see table 1 and 2. Despite the greater strength of these steels, the possibilities for cold as well as hot forming are very good.

Table – 1 Mechanical properties [2]

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

Table – 2 Tensile properties at elevated temperature, minimum value according to EN, Mpa

Table – 3 In table 3 typical values of some physical properties are given for 904L, 254 SMO and the grade 4565.[2] Typical value according to EN 10088[2]

VI. CORROSION RESISTANCE The high content of alloying elements gives the steels 4438, 4439, 904L, 254 SMO®, 4565 and 654 SMO® exceptionally good resistance to uniform corrosion. 904L was originally developed to withstand environments involving dilute sulphuric acid and it is one of the few stainless steels that, at temperatures of up to 35°C, provide full resistance in such environments within the entire range of concentration, from 0 to 100%, Figure 1. 904L also offers good resistance to a number of other inorganic acids, e.g., phosphoric acid, as well as most organic acids. Acids and acid solutions containing halide ions can be very aggressive and the corrosion resistance of grades 4438, 4439 and 904L may be insufficient. Examples of such acids are hydrochloric acid, hydrofluoric acid, chloride contaminated sulphuric acid, phosphoric acid produced according to the wet process (WPA) at elevated temperatures, and also pickling acid based on nitric acid and hydrofluoric acid mixtures. In these cases 254 SMO®, 4529, 4565 and 654 SMO® are preferable and in certain cases they can be an alternative to other considerably more expensive alloys, Figures 2-5 and Tables 5 and 6.[3]

Fig. 3: Isocorrosion curves, 0.1 mm/year, in pure sulphuric acid

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

Fig. 4: Isocorrosion curves, 0.1 mm/year, in sulphuric acid containing 2000 ppm chloride.

Fig. 5: Isocorrosion curves, 0.1 mm/year, in pure hydrochloric acid.

Fig. 6: Isocorrosion curves, 0.1 mm/year, in pure hydrofluoric acid.

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

Fig. 7: Isocorrosion curves, 0.1 mm/year, in pure fluosilicic acid.

VII. THE AUSTENITIC STAINLESS STEELS FAMILY

Fig. 8: Austenitic stainless steel family [3]

VIII. APPLICATIONS OF AUSTENITE STAINLESS STEEL  

In food and beverage Desalination

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Review about High Performance of Austenitic Stainless Steel (IJIRST/ Volume 1 / Issue 9 / 017)

      

Process equipment in chemical industry Flue gas cleaning In the pulp and paper industry like a Bleaching equipment Hydrometallurgy Seawater handling Heat exchangers Pharmaceuticals

IX. CONCLUSION In recent years, new highly corrosion resistant austenitic stainless steel has entered the market place. They have cost effective performance in a variety of harsh and corrosive environment. They have supplied the materials engineers with alloy for demanding new energy environmental needs. Hence this material helps all industries and factories to work. This is very useful metal. This review paper provides basic information about of austenitic stainless steel.

REFERENCE [1] [2]

[3] [4]

Practical guidelines for the fabrication of high performance ASS, source: www.m-tec.uk.com (fabricators), www.photo-genic.com (photo) High performance ASS, www.outokumpu.com High Performance Austenitic Stainless Steel, research.stainless@outokumpu.com outokumpu.com Book’ stainless steel for design engineers, (#05231G)

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