World of Aluminium Slides- 14th November 2023 by Aluminium Federation

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World of Aluminium Modular Course

World of Aluminium July 2023 alfed.org.uk

Intermediate level

World of Aluminium

Modular Course Intermediate level Part 1 alfed.org.uk

Your presenter…

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www.alfed.org.uk Jan Lukaszewski, Technical Manager JLukaszewski@alfed.org.uk Direct Tel: +44 (0) 333 240 9735

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But now I have seen the light

Al Aluminium alfed.org.uk

Housekeeping ▪ Domestic Arrangements – breaks, lunch, timings, toilets, smoking, ▪ Fire escapes & assembly point and alarm test ▪ This workshop – note book, handouts, product literature, Properties Book ▪ It’s all about you!

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Copyright Where relevant the copyright and source of relevant photographs or videos is attributed to owners either with the text of each slide or by specific reference ▪ Photographs in the public domain are not credited ▪ In all other cases the Aluminum Federation has received permission from the owners or has applied to use the materials

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Intellectual Property The Intellectual Property and/or Patent and/or Product Design ownership throughout this entire document is identified on each slide by the Logo of the respective organisation, thus: ▪ Aluminium Federation

▪ International Aluminium Institute ▪ Alimex ▪ Hydro Extrusions

▪ Impression technologies alfed.org.uk

Introductions ▪ ▪ ▪ ▪ ▪ ▪

Who are you? Who do you work for? Describe your job? What is your level of understanding of Engineering, Metallurgy, Aluminum? What do you want to get out of today? Specific interest?

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Aluminium- “Young Metal”

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Roman Metallurgists Roman metallurgists refined, alloyed and worked with seven metals ▪ Iron ▪ Lead ▪ Tin ▪ Copper ▪ Silver ▪ Gold ▪ Mercury Seven metals were either found as pure metals or were smelted by charcoal or wood fires so prehistoric man discovered them in his camp fires

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Aluminium Metallic Aluminium is not found in nature as it is extremely reactive and forms an oxide, ▪ Aluminium oxide white ceramic ▪ Melting point 2,072 °C ▪ Cannot be smelted or reduced by carbon of a camp fire ▪ Unknown to ancient man ▪ 120 year history ▪ “Young Metal”

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Pliny the Elder Pliny the Elder, a Roman scientist, in his book “Historica Naturalis” told the story of a first century craftsman presenting to Tiberius, the Roman Emperor, a cup made of an unknown metal looking like silver, but too light to be silver, ▪ Tiberius promptly beheaded the craftsman, because the metal would have devalued Gold and Silver ▪ In “Historica Naturalis” Pliny the Elder, gave the name ‘Alumen’ to alum, a mineral containing a compound of Aluminium and Sulphur. ▪ Pliny the Elder died on August 25, AD 79, while attempting to rescue a friend from the eruption of Mount Vesuvius

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Roman Metallurgists Since the Romans we learnt how to make; ▪ Metals hotter ▪ Purer ▪ Hit them harder

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Alumina In 1595, Andreas Libavius, German doctor and chemist, demonstrated that an undiscovered earth is part of alum and named it “Alumina” ▪ Many attempts continued in later part of 18th century to establish the nature of Alumina and by end of 18th century, alumina was considered a metallic earth ▪ Correct chemical formula AL2O3 was established by German chemist Eilhard Mitscherlich in 1821

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Alumen 1808 Sir Humphry Davy, the English chemist, postulated that Aluminium could be produced by electrolytic reduction from Alumina, Aluminium oxide, ▪ Although he never managed to prove his theory in practice, he named “Aluminum” after alum, which is called ‘Alumen' in Latin. ▪ The lack of availability of electricity prevented Davy proving his theory

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Aluminium – Precious Meta In 1845, German chemist Friedrich Wöhler successfully produced small pieces of the metal and is credited as the discoverer of Aluminium. ▪ Friedrich Wöhler established many of the metal's properties, including the remarkable lightness, that truly excited researchers ▪ Wöhler’s method could not yield large amounts of aluminium so was comparable to Gold! ▪ 1863 Aluminium and gold helmet worn by King Frederick VII of Denmark.

“Aluminium, the Magic Metal”, Thomas Y Canby, National Geographic, August 1978

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Henri-Etienne Sainte-Claire Deville In 1856 Henri-Etienne Sainte-Claire Deville using the Woehler process started industrial production of Aluminum in Rouen (France) in 1856. ▪ During 1855-1890 200 tonnes of Aluminium were produced ▪ It was considered to be a precious metal for ornaments

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Jules Verne 1865: Science fiction writer Jules Verne describes an Aluminum space rocket in his novel, Journey to the Moon.

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Commercial Pressure ▪ In 1882 Aluminium was the same price as silver ▪ Aluminium and gold baby’s rattle made for the son of Napoleon III

“Aluminium, the Magic Metal”, Thomas Y Canby, National Geographic, August 1978

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Diane de Gabes Diane de Gabes Aluminium casting was produced in Paris in 1859 at the works of Paul Morin ▪ One third replica of a full size Greek marble statue in the Louvre ▪ Casting was made using the lost wax process with Aluminium made by the sodium process. ▪ Oldest Aluminium casting in existence ▪ Now on permanent display at the Science Museum in London by permission of The Aluminium Federation.

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Hall-Heroult Process In 1886 the development of an electrolytic production method independently by a French engineer Paul Heroult, and an American student Charles Hall, established Aluminium as a viable metal. ▪ Electrolysis involved the reduction of molten Aluminium Oxide in Cryolite but required enormous amount of electric power, not commercially available at that time. ▪ Thus the growth of Aluminium was powered by the growth in electricity generation

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Eros Sculptor Alfred Gilbert was commissioned to create a memorial to Anthony Ashley-Cooper, the 7th Earl of Shaftesbury, in 1886 ▪ Erected in 1892 and unveiled on 29 June 1893 ▪ Statue is actually of Anteros, the god of requited love, twin brother of Eros ▪ Cast in Aluminium by George Broad & Son at the Hammersmith Foundry

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Bayer Process The Bayer process for refining Aluminum ore to make pure Aluminium oxide, Alumina, was developed in 1888 and was the last key stage that completed the viable and economic production of Aluminium ▪ Bauxite to Alumina ▪ Alumina to Aluminium

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Aluminium Pioneers 1897 San Gioacchino, Rome, ▪ Raffaele Ingami Aluminium Dome

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Karl Benz 1899 Karl Benz presented the first sports car with an Aluminium body at an exhibition in Berlin ▪ Recognising Aluminium potential to the Automotive Industry.

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Aluminium Age Hardening Alfred Wilm in 1901, a German research metallurgist discovered age hardening of aluminium alloys.

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Wright Brothers Flyer The 1903 Wright Flyer had an Aluminum crankcase, the first use of Aluminium in aircraft construction. ▪ Crankcase was cast by the Buckeye Iron and Brass Works. ▪ Buckeye sourced Aluminium from the Pittsburgh Reduction Company, renamed Alcoa in 1907, then the world’s leading producer of Aluminium. ▪ Precipitation hardening Aluminium 8% Copper alloy

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Decorative Aluminium 1905 St Mary, the Virgin, Great Warley ▪ Architect C. Harrison Townsend with Sir William Reynolds-Stevens

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Duralum 1909 Duralumin, the corner foundation stone of Aluminium invented ▪ Duralumin, with addition of Copper, Magnesium and Manganese was as lightweight, as Aluminium, but significantly exceeded it in strength, hardness and elasticity meaning. ▪ Alfred Wilm, a German scientist took seven years to alloy it. ▪ Duralumin quickly dominated aviation with the first all-metal plane, the Junkers J1, launched in 1915.

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Aviation boom 1930’s Germany pioneered aviation, with age-hardened Aluminium alloys ▪ 2000 series alloyed with Copper, Manganese and Magnesium

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Spitfire Britain’s first Aluminium-bodied Aeroplane, the 1936 Spitfire. ▪ The Second World War established Aluminium as the “Strategic Metal”. ▪ Joseph Stalin, the leader of the USSR, wrote to Franklin Roosevelt, in 1941: 'Give me 30 thousand tonnes of Aluminium, and I will win the war‘.

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Japanese Zero Zero 1936 ▪ Mitsubishi's chief designer Jiro Horikoshic understood that the Zero aircraft had to be as light as possible. ▪ Every possible weight-saving measure was incorporated into the design. ▪ Aircraft was made from a top-secret aluminium alloy developed by Sumitomo Metal Industries, called Extra Super Duralumin ▪ Extra Super Duralumin Zinc Alloyed 7075

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Diffusion 1947 Ernest Kirkendall discovered solid state diffusion of alloy elements through a pure metal ▪ Kirkendall Effect

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Land Rover 1948 with a great steel shortage, surplus Aluminium from aircraft was used to produce the original Land Rover vehicle. ▪ Second a major step-up in the use of Aluminium occurred in n 1961, when the Rover company started casting Aluminium V-8 engine b

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Sputnik 1957, the USSR launched the first artificial satellite into orbit. The satellites hull consisted of two separate Aluminium semi-spheres joined together

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First Aluminium Skyscraper 1952 30-storey Alcoa Building in Pittsburgh, USA, Clad in untied open-jointed Aluminium panels. ▪ Architect: Harrison & Abramovitz

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Civil Aviation Airframe of modern commercial aircraft is 80% Aluminum by weight. ▪ Assembled from sheets and extrusions riveted together. ▪ Predominant alloy is 7075, Aluminium, zinc, magnesium and copper.

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Into Space 1981 Aluminum used for Apollo spacecraft, the Skylab, the space shuttles and the International Space Station. ▪ Lockheed Martin has chosen an Aluminum-Lithium alloy for the primary structures of NASA’s new Orion spacecraft

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Coca-Cola® and Pepsi® The “Aluminum” drinks can the symbol of every “Red Bodied” male emerged in the USA in 1958. ▪ Cans invention was shared between Kaiser “Aluminum” and Coors. ▪ Coors was not only the first company to sell beer in “Aluminum” cans but also started “recycling” organising the collection of empty cans. ▪ Coca-Cola® and Pepsi® in1967 started to sell their drinks “in “Aluminum” cans.

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Aluminium Intensive Volume Cars JLR pioneer of Aluminium car bodies – Alcan – Ford research in 1990s ▪ XE / XF / F-Pace / F-Type / Range Rover Sport / Range Rover

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Aluminium Conclusion Aluminium components within a maintained interior, such as a church of library, appear to have an infinite life expectancy. ▪ Aluminium components exposed to weather including sun and rain have a life expectancy of over 120 years. ▪ Aluminium should no longer be thought about as a new material. It has a rich and successful track record in architecture and the built environment, with a performative role and a key place in material culture.

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Aluminium Strategic Metal for Society Aluminium is unique among all other metals, in that its alloys, engineering and metallurgical properties have been systematically designed and developed through the application of metallurgy, within its short history of just one century, in response to known engineering gaps and to the specific needs of society. ▪ It is a developed, not a discovered metal! ▪ From its inception, matching its developments Aluminium has been recycled not consumed, so beyond doubt leads and is at the forefront of the “Circular Economy”! ▪ Truly the holistic and versatile properties of Aluminium are establishing it as global designers’ metal of choice, substituting and displacing other strategic metals, materials, plastics, and carbon fibre!

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Demand is Growing across all Sectors Aluminium is a “Traded Metal” in London Metal Exchange and Shanghai Metal Exchanges ▪ Aluminium global price matches demand ▪ Supply matches demand, Balanced

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Metals

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Simplification Of Metallurgical Mechanisms Apologies to Metallurgists and those “GEEKS” that inhibit dark back rooms, whilst the metallurgical reactions, mechanism and theories have been simplified throughout this presentation, overall the effects are correct

Metallurgist is a material scientist or technician who specializes in metals such as steel, Aluminum, iron, and copper working with the knowledge of Metallurgy.

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Elements & Symbols Symbol Ag Ar Ba Be B Ca Cl Cr F Fe H He K Li alfed.org.uk

Element Silver Argon Barium Beryllium Boron Calcium Chlorine Chromium Fluorine Iron Hydrogen Helium Potassium Lithium

Symbol Element Magnesium Mg Manganese Mn Nitrogen N Sodium Na Niobium Nb Nickel Ni Oxygen O Phosphorus P Lead Pb Silicon Si Tin Sn Titanium Ti Zinc Zn Zirconium Zr

Elements and Compounds Atom is the smallest unit of matter ▪ Each element is a unique atom

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Elements and Compounds Atom is the smallest unit of matter ▪ Each element is a unique atom ▪ An element is a substance that cannot be broken down to other substances by chemical reactions

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Elements and Compounds Atom is the smallest unit of matter ▪ Each element is a unique atom ▪ An element is a substance that cannot be broken down to other substances by chemical reactions ▪ A compound is a substance consisting of two or more elements ▪ Most metals do not occur in their natural state, found as compounds such as oxides, sulphides and halides

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Atomic Number E

An Elements is defined by its atomic number, which is the number of its protons. ▪ Each element has a nucleus of a different number of positively charged Protons,

NP PP N PN N PNP

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Protons E

Atomic Number E

An Elements is defined by its atomic number, which is the number of its protons. ▪ Each element has a nucleus of a different number of positively charged Protons, ▪ Nucleus surrounded by an equal number of orbiting negatively charged Electrons

NP PP N PN N PNP

Protons E

Electrons

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Atomic Number E

An Elements is defined by its atomic number, which is the number of its protons. E ▪ Each element has a nucleus of a different number of positively charged Protons, ▪ Nucleus surrounded by an equal number of orbiting negatively charged Electrons Neutrons ▪ In the nucleus the protons are spaced by non charged Neutrons

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NP PP N PN N PNP

Protons E

Electrons

Atomic Number! E

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NP PP N PN N PNP

Protons E

Electrons

Protons & Electrons ▪ Protons carry a positive charge

+ve

▪ Electrons carry a negative charge

-ve

▪ Opposite charges attract

+ve

▪ Same charges attract repeal

+ve

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-ve

+ve

1.3 Shell Orbits Electrons orbit around the nucleus three dimensionally within a “Shell”

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Negative Electrons Negative electrons repeal each other are separated within orbits ▪ Each orbits can accommodate a set numbers of electrons ▪ So depending on atomic number atoms can have many electron orbits

-ve

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-ve

Metallic Bond The outer most orbit of electrons are called valence electrons ▪ Valence electrons participate in the formation of chemical bonds E E E

NP PP N PN N PNP

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Metallic Bond The outer most orbit of electrons are called valence electrons ▪ Metals shed and share their valence electrons as a fast moving cloud between all their atoms

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NP PP N PN N PNP

Metallic Bond The outer most orbit of electrons are called valence electrons ▪ Metals shed and share their valence electrons as a fast moving cloud between all their atoms

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Metallic Bond Loss of the valence electrons to cloud means nucleus, protons become positive +ve ▪ Nuclei are positive so individual metal atoms are not bonded to each other ▪ Valance electrons carry a negative charge so cloud is negative -ve ▪ Opposites attract ▪ Attraction of positive protons to negative election cloud forms the “Metallic” Bond that holds metals together -

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Metal ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪

Metal from Greek An element, Strong “Metallic Bond”, Expand and contract, métallon Melt, Fusible, able to be fused, Hard, High strength (behave elastically and plastically), Malleable and ductile, Shiny, High electrical conductivity High thermal conductivity.

μέταλλον

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Metals Dominate The Periodic Table The atomic number of an element is the number of its protons

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Electricity Conduction Electric current is the flow of electrons, so metals are a good conductors of electricity because of metallic bonding ▪ Fundamentally one election in is one electron ejected hence electrical flow

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Thermal Conduction Heat is energy and energy excites/increase the motion/vibration of the electron cloud ▪ This excited vibration is transmitted across the metal hence thermal conduction

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Thermal Expansion When a metal is heated the kinetic energy of its atoms increases. ▪ Electrons vibrate more vigorously forcing a greater separation between the atoms. ▪ Thus the metals expand ▪ Increasing temperature increases separation decreasing strength of metallic bond

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Ductility Ductility is a metal’s ability to be plastically drawn out or permanently stretched without breaking. ▪ It is a measure of a metal’s ability to withstand plastic deformation under load without rupture. ▪ The greater the strain/elongation/stretch the more ductile a metal ▪ Fundamental property essential to the ability of a metal to be cold worked.

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Module 3 Crystals

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Face Centred Cubic Lattices Aluminium atoms arrange themselves into “Face Centered Cubic” lattices ▪ Atom at each corner ▪ Atom in the middle of each Face

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Face Centred Cubic Lattices Aluminium atoms arrange themselves into “Face Centered Cubic” lattices ▪ Atom at each corner ▪ Atom in the middle of each Face

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Metallic Bond Electron cloud is three dimensional so shared between all atoms of cube maintaining metallic bond in all directions

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Aluminium Crystals Adjacent Atoms repeat the “Face Centered Cubic” lattices to form crystals ▪ Repetitive translation of the unit cell along its principal axes in three dimensions creates symmetrical crystal lattices

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Planes of Atoms Adjoining Face Centred Cubes align into planes of atoms

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Planes of Atoms As individual atoms are not bonded to specific atoms but held together by the charge of electron cloud, planes of atoms can slip easily past one another, ▪ Thus metals are ductile and malleable

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Metallic Bond Metallic bond is not broken by slip of planes of atoms ▪ Bond is between positive charged atoms and negative electron cloud

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Liquid Metals & Solidification

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Liquid Metals When a metal is melted the metallic bond breaks down ▪ Atoms are randomly mixed together and are free to slide around. ▪ Atoms are held together only by weak forces of attraction so liquid lacks cohesion, will flow and pour

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting”

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting”

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting” Liquidus lines

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting” Liquidus lines

Solid + Liquid

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting” Liquidus lines

Solid + Liquid

Solidus Line

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting”

Solid + Liquid

Solidus Line

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All Solid

Metal Alloys When metals are melted, the metallic bond is dissolved forming liquids ▪ Lesser volume, “Solute”, metal is dissolved into the greater volume “Solvent” metal ▪ As liquids virtually all metals are soluble in each other

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Liquid Metal Limitations Virtually all metals are soluble in each other in liquid form ▪ Melting point of one metals can be higher vaporisation temperature of second metal e.g. Tungsten and Aluminium ▪ Difference in specific weight can be so great that they separate into two distinct liquids with a narrow boundary layer e.g. iron and Aluminium

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Solidification As molten metals cool, the metallic bonds forms between atoms and atoms bond together forming single cells throughout the liquid.

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Solidification As molten metals cool, the metallic bonds form between atoms and atoms bond together forming single cells throughout the liquid. ▪ Cells are randomly orientated

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Crystal Growth As cooling continues the single cells progressively grow. in the direction of their principal axis’s that of the random orientation of the seed cell

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Grain Structure Eventually the crystals will impinge against each other, but, because of the mismatch of their different orientations they cannot grow together so develop into individual grains ▪ Distinct boundaries form between adjacent grains

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Grain Structure On final solidification a network of boundaries forms between and surrounding all the grains ▪ Grain Boundaries

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Grain Boundaries Grain boundaries are therefore physical barrier so planes of weakness

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Effect of Grain Size ▪ Fine grains have large grain boundary contact areas so disrupt crack propagation. ▪ Each time you encounter a new grain you have to start a new crack ▪ Large grains have minimum grain boundary contact areas between them so offer clear crack propagation paths ▪ Therefore yield and tensile strength increase with decreasing grain size

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Solid Solubility of Metals In the solid state there is limited solubility of solute metal atoms within the solvent metal atoms! ▪ Metals form “Solid Solutions” of solute in solvent atoms ▪ Metallic bond forms between different metals

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Limited Solid Solubility On solidification the excess solute metal atoms are pushed by the growing grains into the grain boundaries ▪ Solid Solutions have only limited solubility

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Sizes of Atoms Atomic radii decrease across the Periodic Table because as the atomic number increases, the number of protons increases so does the number of electrons ▪ Effectively nuclear charge towards the outermost electrons increases, drawing the outermost electrons closer. ▪ Thus electron cloud contracts and the atomic radius decrease.

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Size of Metal Atoms No two elements have atoms of the same size

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Substitutional Solid Solution Strengthening Atoms of an alloying element are dissolved in the liquid solvent metal on solidification. ▪ Solute atoms “Substitute” in the crystalline Aluminium lattice.

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Metallic Bond Metallic bond forms across solvent and solute atoms

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Substitutional Solid Solution Strengthening The solute atoms “Substitute” for aluminium atoms in the crystalline lattice ▪ No two elements have the same size atoms ▪ The substituted solute alloying atoms distort the crystalline lattice

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Substitutional Solid Solution Strengthening The different size atoms distort the lattice hampering the free slip of planes of atoms ▪ Slip requires more force to occur ▪ Hence alloy atoms strengthen alloy

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Diffusion & Solid Solubility of Metals

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Self Diffusion Individual metal atoms are not bonded to each other but are held in the “Metallic Bond” by the clouds of electrons ▪ Even at ambient temperature metal atoms migrate around, they defuse through solid state structures with time

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Time

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Mobility of Metal Atoms Even at ambient temperature metal atoms migrate around, they defuse through the structures ▪ Individual metal atoms are not bonded to each other but are held in the “Metallic Bond” by the clouds of electrons

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Mobility of Metal Atoms Individual metal atoms are not bonded to each other but are held in the “Metallic Bond” by the clouds of electrons ▪ Increasing the temperature expands the lattices electrons move out separating atoms more ▪ Increasing the temperature, increases the mobility of atoms increasing freedom of movement. ▪ Increasing temperature increase mobility increase the rate of diffusion ▪ Diffusion is thus a function of time and temperature

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Theory of Diffusion Diffusion is phenomenon of material transport by atomic motion ▪ Atoms move from an area of higher concentration to an area of lower concentration

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Theory of Diffusion Atoms move from an area of higher concentration to an area of lower concentration ▪ Atoms re-distributed within the microstructure until an equilibrium is achieved ▪ Atoms can be re-distributed between different alloys ▪ Atoms can be added from external materials or environment ▪ Atoms from the alloy can be discharged to the environment, e.g. Hydrogen

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Solubility & Temperature Increasing temperature increases solubility of solute atoms ▪ So solute metal are taken into solid solution out of the grain boundaries

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Solid Solutions The solid solubility of solute atoms will increase with temperature up to the onset of melting, the solidus lines

Solid Solution of B Atoms in A

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Eutectic or Solidification Diagram Eutectic - Greek word for “easy Melting” Liquid

Liquidus Lines Temperature °C

α + liquid

β + liquid

β Solidus Lines

Solvus line

Solid

0% 100%

100% 0%

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Hot & Cold Working

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Mechanical working of Metals As individual atoms are not bonded to specific atoms but held together by the charge of electron cloud, planes of atoms can slip easily past one another, ▪ Mechanical working slips planes of atoms

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Metallic Bond Metallic bond is not broken by slip of planes of atoms ▪ Bond is between positive charged atoms and negative electron cloud -

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Cold Working Cold working is the physical deformation of a metal at ambient temperature, by mechanically changing its shape ▪ Bending or reducing its cross-sectional area, through drawing, rolling, stamping etc, ▪ As volume of the metal cannot change, the reduction of area translates into metal spread or elongation in the direction of work

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Cold Working Cold working slips the planes of atoms past each other, metallic bond does not break the electron cloud just reconfigures

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Cold Working Cold working slips the planes of atoms past each other, metallic bond does not break the electron cloud just reconfigures ▪ Slipping of the planes of atoms results in the grains being permanently compressed and elongated in the direction of work.

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Cold Work Hardening & Strain Hardening In cold working as the planes of atoms slip, they lock up ▪ New flattened shape is more resistant to further deformation ▪ Forces to required to induce more slip increase with increasing deformation, ▪ Causing a strength increase ▪ Hence “Work Hardening or “Strain Hardening.“

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Strain Hardening Any mechanical cold work deforms grains ▪ Cold work involves reshaping, reforming and cutting at room temperature ▪ Cold work strain work hardens a metal

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Directionality Cold working distorts the grains in the direction of major deformation that is rolling or drawing ▪ Grains stretch in direction of work ▪ Induce strong directionality ▪ Transverse to longitudinal properties will be different

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Strain Hardening The greater the cold deformation the higher the strength increase ▪ Ductility is the reciprocal of strength

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Strain Hardening The greater the cold deformation the higher the strength increase ▪ As deformation increases strength increase

and ductility

reduces

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Strain Hardening The greater the cold deformation the higher the strength increase ▪ Brittle failure during cold work will resultant when ductility is exhausted

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Annealing and Recrystallisation In the fully work or strain hardened condition aluminium has high strength but no ductility

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Annealing and Recrystallisation If we heat the cold-worked metal to above the “Recrystallisation Temperature”, approximately 50% of the melting temperature, and hold on temperature, new grains, are seeded, start to grow

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Annealing and Recrystallisation If we heat the cold-worked metal to above the “Recrystallisation Temperature”, and hold on temperature for prolonged times, new grains grow, consuming all the plastically-deformed grains. ▪ Once all the new grains have formed, the structure is fully “annealed”, ▪ Strength and ductility are restored to their original levels.

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Annealing and Recrystallisation The process of recrystallising the cold worked grains is “annealing” ▪ Once all the new grains have recrystallised the structure is fully “annealed”, and strength and ductility are restored to their original levels

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Annealing In the cold or work hardened state heavily deformed grains have high strength but low ductility

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Annealing Once all the new grains have recrystallised the structure is fully “annealed”, and strength and ductility are restored to their original levels

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Aluminium at Elevated Temperatures At relative low elevated temperatures yield and strength of Aluminium are significantly reduced ▪ Higher temperature thermal expansion weakens metallic bond so yield and strength reduce ▪ Force to work Aluminium reduces significantly to very low levels

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Aluminium at Elevated Temperatures At these low hot working temperatures Aluminium becomes extreme ductility ▪ Enables high reductions and change in shape without failure at low working forces

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Hot Working Hot working is when metals are mechanically deformed above their Recrystallisation temperature. ▪ That is above about 50% of its melting temperature or higher ▪ Above the Recrystallisation temperature, metals constantly recrystallise during deformation, so do not strain or cold-work harden. ▪ Effectively the hot worked metals automatically anneal growing new grains

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Elastic & Plastic Behaviour of Metals

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Tensile Strength & Stress A load hanging on a wire, a filament or object, puts it into tension or stresses it! ▪ Depending on its strength that filament will stretch, elongate and so be strained

Load

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Tensile Strength & Stress A load hanging on a wire, a filament or object, puts it into tension or stresses it! ▪ Depending on its strength that filament will stretch, elongate and so be strained ▪ The heavier the weight the greater the stress so stretch

Load

Load alfed.org.uk

Stress & Strain Stress is a measure of strength the ability to withstand a force

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Stress & Strain Strain is a measure of stretch or elongation

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Stress & Strain Loading or stressing a filament will stretch or elongate it

Weight

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Stress & Strain Increasing the load or stress will result in the filament stretching or elongating more. ▪ The higher the stress the greater the strain

Weight

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Load

Metals Behave Elastically When loaded or stressed metals, Aluminium will stretch or elongate

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Metals Behave Elastically When loaded or stressed metals, Aluminium will stretch or elongate ▪ Atomic lattices stretch

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Metals Behave Elastically Under a load grains elastically stretch

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Metals Behave Elastically Under a load grains elastically stretch

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Metal – Elastic Behaviour On removal of the load, metals, Aluminium springs back to original shape, no permanent deformation ▪ Metals behave “Elastically” they spring!!!

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Metal – Elastic Behaviour On removal of the load, grains spring back, they behave “Elastically”!!!

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Yield Stress As the stress is increased, suddenly the elongation changes and there is a large increase for a small increase in stress ▪ This is the yield stress or yield point

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151

Yield Point or Stress Once the applied stress exceeds the yield stress the deformation becomes permanent ▪ Planes of atoms have slipped

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Yield Point or Stress Up to yield stress elastic stretch is a straight line relationship between Stress and Strain ▪ Follows straight line equation 𝑦 = 𝑚𝑥 + 𝑐

𝑆𝑡𝑟𝑒𝑠𝑠 = 𝑆𝑙𝑜𝑝𝑒 𝑥 𝑆𝑡𝑟𝑎𝑖𝑛 + 𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡

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Yield Point or Stress Once the applied stress exceeds the yield stress the deformation becomes permanent

No longer springs back to start, zero

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Yield Point or Stress Once the applied stress exceeds the yield stress the deformation becomes permanent ▪ The planes of atoms have slipped ▪ Permanent deformation is “Plastic”

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Yield Point Terminology Text books refer to the yield point of metals by many terms with the same meaning ▪ Yield Stress ▪ Yield point ▪ Elastic Limit

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Yield point Terminology Aluminium has a poorly defined yield point so for engineering purposes it taken as the stress required to produce 0.2% permanent deformation.

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Yield Point Terminology ▪ Yield Stress ▪ 0.2% permanent deformation.

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Designing Products Products are designed to be subjected to stresses in service below the yield stress with a safety margin ▪ Within elastic stress

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Plastic Deformation Once a metal has yielded, on release of the stress, it is permanently plastically deformed

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Plastic Deformation Once a metal has yielded the grains are plastically deformed ▪ The deformation of the grains is permanent

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Plastic Deformation Once a metal has yielded, the grains have been permanently deformed so the metal has been permanently work or strain hardened

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Cold Work Hardening & Strain Hardening Once the metal has yielded the plastic deformation is cold working as the planes of atoms slip and lock up ▪ The deformed shape is more resistant to further deformation ▪ Forces to required to induce more slip increase with increasing deformation, ▪ Causing further strength increase ▪ Hence “Work Hardening or “Strain Hardening.“

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Work or Strain Hardening As the stress increases so does deformation of the grains and the degree of work or strain hardening ▪ Increasing resistance to further deformation

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164

Work or Strain Hardening As the stress increases so does deformation of the grains and the degree of work or strain hardening ▪ Increasing resistance to further deformation

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165

Work or Strain Hardening As the stress increases so does deformation of the grains and the degree of work or strain hardening ▪ Increasing resistance to further deformation

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Work or Strain Hardening As the stress is increased the slip in the planes of atoms is so great that the metallic bond fails and the atoms start to pull apart ▪ Eventually cross-sectional area is reduced so cannot support applied stress ▪ Stress plateau levels out

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Maximum Breaking Stress Plateau is maximum stress, load, or force, that the metal can support ▪ This is the maximum stress

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Maximum Breaking Stress Plateau is maximum stress, load, or force, that the metal can support

Text book terms for plateau

▪ Tensile Strength ▪ Maximum breaking load

▪ Maximum breaking stress

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Maximum Breaking Stress Plateau is maximum stress, load, or force, that the metal can support

Text book terms for plateau

▪ Tensile Strength ▪ Maximum breaking load

▪ Maximum breaking stress

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Final Failure On exceeding the maximum breaking stress the grains part and the stress falls off ▪ Parting grains reduce cross-sectional area, resulting in localised necking ▪ Final failure

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Ultimate Elongation Following failure, the permanent plastic deformation is termed Ultimate elongation ▪ Ultimate elongation is normally expressed as a percentage increase over the original gauge length after failure

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Tensile Testing

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Tensile Testing Machine In the Tensile test a sample is subjected to a controlled tension until it fails.

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Tensile Testing Machine ▪ The basic machine consists of two cross beam that support the test piece grips.

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Tensile Testing Machine ▪ Attached to the cross beams are two vices that grip the test piece

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Tensile Testing Machine ▪ The vices clamp the test piece being tensile tested

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Tensile Testing Machine ▪ A force is applied to the test piece by moving beams apart either mechanically or hydraulic.

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Tensile Testing Machine ▪

A force is applied to the test piece by moving beams apart either mechanically or hydraulic. ▪ The force is applied through the clamps into the test piece loading or stressing it

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Tensile Testing Machine ▪ The basic machine consists of two cross beam that support the test piece grips. ▪ A force is applied to the test piece by moving beams apart either mechanically or hydraulic. ▪ The applied force is measured using a load cell electronically and displayed

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Tensile Testing Machine ▪ Combining the measurements of the applied force with the moment of the movable cross beam allows us to create a graph of stress vertical axis and strain horizontal as described in the module on elastic and plastic behaviour ▪ Thus we can measure yield and maximum breaking forces

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Measuring Stress and Strain Up to the yield point the elastic movements are small so are measured electronically using an “Extensometer” ▪ The extensometer is clamped onto the test piece ▪ Once the metal has yielded the extensometer is removed and we measure plastic movement from the cross beams

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Measuring Stress and Strain Thus we can construct a graph of Stress against Strain

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Yield Point Terminology ▪ Yield Stress ▪ 0.2% permanent deformation.

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Maximum Breaking Stress Plateau is maximum stress, load, or force, that the metal can support

Text book terms for plateau

▪ Tensile Strength ▪ Maximum breaking load

▪ Maximum breaking stress

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Tensile Test Pieces Standard test pieces for tensile testing are either turned or machined.

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d0 d1 L0 Lt h

diameter of specimen diameter of grip gauge length (L0 = 5 d0)Lc total length height of grip

a b B h L0 Lc

thickness of specimen width of specimen width of grip (» 1.2 b + 3 mm) height of grip (« 2 b + 10 mm) gauge length parallel length

Unit of Force The newton (symbol: N) is the SI unit of force. It is named after Sir Isaac Newton because of his work on classical mechanics. ▪ The force resulting from the action of gravity on 1 kg weight is 9.81N

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Stress Stress Is a function of load hanging on the object and the cross-sectional area of that object

High Stress

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Low Stress

Unit of Stress The pascal (symbol: Pa) is named after the French polymath Blaise Pascal. It is the SI derived unit of pressure used to quantify stress. It is defined as one newton per square metre.

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Stress Tensile force is the measurement of force or load applied to a filament or component ▪ Stress “σ”, is the tensile force “Fn” divided by the nominal cross-section of the specimen “A”

𝐹𝑛 𝜎= 𝐴 ▪ Engineering Stress is measured in N/mm² or more correctly MPa

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Strain Engineering Strain is the measure of stretch or ductility or elongation ▪ Engineering strain “ε, is “ΔL” is the change in gauge length, “L0“ is the initial gauge length, and “L” is the final length, normally expressed as percentage

∆𝐿 𝐿 − 𝐿0 𝜀= = 𝐿0 𝐿0

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Grain Flow Any wrought product will exhibit grain flow in the direction of major plastic metal flow Compressio n

Rolled Sheet Cast Slab

Minor Grain Flow

Major Grain Flow

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Directionality Depending on degree of rolling and of cold work or strain hardening mechanical properties will vary between longitudinal and transverse directions ▪ Yield and tensile stresses will be greater in longitudinal direction, major grain flow ▪ Ductility will be greater transversely, minor grain flow

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Elongation Most EN and BS specify tensile test elongation be expressed as a percentage over a gauge length, typically A50mm, meaning that the original gauge length should be 50mm ▪ Check certificates for method of calculation ▪ Elongation is a function of gauge as the thicker the gauge the greater the amount of metal to draw out so the Ultimate Elongation ▪ Check minimum elongation is applicable to your gauges

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Hardness Testing

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Principle of Hardness Tests All hardness tests involve pressing a dimensionally very accurate indenter under a known load into a metal or component and measuring the resultant plastic deformation ▪ Hardness is thus a measure of resistance to plastic deformation, so can be used to estimate tensile strength

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Hardness Tests Hardness are therefore a non destructive method of confirming mechanical properties ▪ Tensile strength ▪ Heat treatment,

▪ Degree of ageing ▪ Product checking ▪ Sorting tool

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Rockwell Hardness Test The Rockwell hardness test, indicates hardness by using a dial gauge to measure the depth of the impression. ▪ For Aluminium the “B” scale is used which uses a 1/16 inch ball indenter and a force of 100 Kg ▪ The method of testing is to apply a minor load to remove surface effects and zero the depth gauge, then the major load is applied. ▪ The major load is then removed and the depth of the impression is indicated as a Hardness Rockwell Number, “HRB” ▪ Very quick and low skill.

▪ Perfect for sheet Aluminium

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Brinell Hardness Test The Brinell Harness test, calculates hardness by measuring the diameter of the impression with a microscope. ▪ For Aluminium a 10mm ball indenter and a force of 500 or 1000kg ▪ The results are quoted as Hardness Brinell or “HB” or Hardness Brinell Number “HBN” ▪ The Brinell is used on coarse surface such as castings or large grains that will affect the accuracy of the Rockwell or Vickers tests ▪ Suited for castings, forgings and plates alfed.org.uk

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Hardness Test Method Abbreviations Brinell Hardness test ▪ HBW, Brinell Hardness number using a tungsten carbide ball ▪ HBS Brinell Hardness number using a steel ball Rockwell Hardness test ▪ HRB, Hardness Rockwell number using “B” scale ▪ HRA, Hardness Rockwell number using “A” scale ▪ HRS and HRT, Hardness Rockwell number using superficial “R” and “T” scales

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Equotip Equotip uses dynamic testing principle. ▪ An impact body with a hard metal test tip is propelled against the surface of the test piece by spring force ▪ When the impact body hits the test surface, surface deformation takes place resulting in loss of kinetic energy. ▪ The loss of energy is measured electronically and displayed as a harness value

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Webster Hardness Tester Webster portable hardness tester type ”B” for Aluminium ▪ Quick and easy test, the hardness value can be read out directly from the indicator with a simple clamp ▪ Uses spring to compress indentor ▪ Simple ”Go No-Go”.

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Hardness Conversion Chart

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Test Certificates & Certificates of Conformity

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Certificates Certificates report test values of a product against a specification in terms of: ▪ Chemical Composition ▪ Mechanical Properties ▪ Tolerances ▪ Non Destructive testing ▪ Surface condition or finish ▪ Life time warranty ▪ Specified other e.g. fatigue life Set by National & International Standards organisations such as BSI, ASTM or customer ▪ Beware they only certificate against the written requirements of the specification

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Conformity Certificate Certificate of Conformance / Letter of Guarantee ▪ Can be issued by anybody ▪ Limited value

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Types of Certificate Indicative Certificates, EN10204 / 2.2/ DIN 50049 / 2.2 ▪ Typical or Average values over production runs ▪ Not batch specific ▪ Gives average values from a mill over a period

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Types of Certificate Batch Specific certificates EN10204 / 3.1/DIN 50049 / 3.1B ▪ Issued by the mill ▪ Actual product test results ▪ Cannot be issued in retrospect

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Types of Certificate Third part witnessed EN10204 / 3.2 DIN 50049 / 3.1C ▪ Same as 3.1 above but with testing witnessed by an independent inspector, e.g. Lloyds, DNV, ▪ Essential for critical applications

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Aluminium Strategic Metal for Society

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Aluminium Metal Atom ▪ An element, one of nature’s building blocks ▪ A metal Wide and versatile properties of Aluminium are establishing it as global designers’ metal of choice ▪ Substituting for displacing other strategic metals, materials, plastics and carbon fibre!

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Aluminium a Strategic Metal Aluminium is one of five strategic metals that shape the world; ▪ ▪ ▪ ▪ ▪

Copper Iron, that is Steel Titanium Magnesium Aluminium

Strategic to UK Infrastructure

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Aluminium Light Metal Aluminium, low density ▪ ▪ ▪ ▪

30% Density of Copper 34% Density of Steel 60% Density of Titanium 155% Density of Magnesium Steel Magnesium Aluminium Titanium (Iron) Copper Density g/cm³

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1.738

2.7

4.506

7.874

8.96

Aluminium a Strategic Metal Magnesium

Aluminium

Titanium

Steel

Copper

Symbol

Density g/cm³

1.738

2.70

4.506

7.874

8.96

Melting Point °C

650

660

1668

1538

1084

Youngs Modulus GPa

116

211

110/128

Bulk Modulus GPa Aluminium:

110

170

140

Thermal Conductivity ▪ 34% W/(m.k) Density of Steel

156

237

21.9

80.4

401

µm/(m.k)can °C Thermal Expansion (at 25 24.8 of the automotive 23.1 8.60 11.8 16.5 ▪ Strength match many and architectural steel Electrical Resistance nΩ.m (at 20 °C)

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43.9

28.2

420

96.1

16.78

Low Density, Light Weight & Strength Weight in a shopping bag is as important as in the design of a car

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Automotive & Architectural Aluminium Aluminium alloys and tempers exist that match ductility and strength of body in white, chassis automotive and architectural steels

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Design for Weight Saving

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High Strength To Weight Ratio Typically 45% weight saving over steel

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2035 RIP Internal Combustion Engine

Aluminium will not be an alternative for an EV, it will be mandatory to compensate battery weight

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Aluminium a Strategic Metal Magnesium

Aluminium

Titanium

Steel

Copper

Symbol

Density g/cm³

1.738

2.70

4.506

7.874

8.96

Melting Point °C

650

660

1668

1538

1084

Youngs Modulus GPa

116

211

110/128

Bulk Modulus GPa

110

170

140

Thermal Conductivity W/(m.k)

156

237

21.9

80.4

401

Thermal Expansion µm/(m.k) (at 25 °C

24.8

23.1

8.60

11.8

16.5

Electrical Resistance nΩ.m (at 20 °C)

43.9

28.2

420

96.1

16.78

Aluminium: ▪ 60% Thermal & electrical conductivity of Copper

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Electrical Conduction Aluminium has 61% the conductivity of Copper on a volume basis, ▪ 200% the conductivity of Copper on a weight basis.

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Aluminum “Non Magnetic” Normally Aluminium is non Magnetic! ▪ Magnetism can pass trough Aluminium ▪ Electrical flow through any conductor causes a magnetic field ▪ Magnetic fields can induce eddy currents in Aluminium and so create magnetic fields

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Thermal Conductivity Aluminium has 57% the thermal conductivity of Copper on a volume basis, but nearly 200% the conductivity of copper on a weight basis. ▪ Properties of high thermal conductivity, low weight and good formability ▪ Optimal for heat exchangers, car radiators, cooking utensils and engine cylinder heads.

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Thermal conductor Good Thermal Conductor ▪ Non magnetic ▪ Semiconductor heat sinks

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Low Melting Point Aluminium has one of the lowest melting temperatures of all metals ▪ Low energy ▪ Low thermal losses during melting

Steel Magnesium Aluminium Titanium (Iron) Copper Mg Al Ti Fe Cu Melting Point °C 650 660 1668 1538 1084 alfed.org.uk

High Fluidity Aluminium is a light metal so in its molten state, particularly its Silicon alloys, exhibits high fluidity, approaching that of water! ▪ Optimal for casting ▪ For casting fine details

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Castings In the United Kingdom 40% of all Aluminium used goes into castings ▪ Aluminium has 40% melting temperature of steel ▪ Liquid metal engineering

▪ Low energy process

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Low Temperature Performance Aluminium alloys have no ductile-to-brittle transition ▪ As the Aluminium atoms contract their metallic bond attraction increase ▪ Tensile and yield strengths increase with decreasing temperature ▪ Ductility, slightly increases with decreasing temperature

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Low Temperature Performance Aluminium alloys increase in strength and ductility with decreasing temperature ▪ Used extensively in cryogenic applications ▪ Transportation of liquid gases

▪ No Ductile to brittle transition

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Aluminium at Elevated Temperatures When metals are heated they expand and their metallic bond is weakened At working temperatures up to 100°C the mechanical properties of most Aluminium alloys and tempers are not affected. ▪ Reduction by 200°C to 80% of proof stress ▪ Reduction by 300°C to 30% of proof stress

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Aluminium at Elevated Temperatures Aluminium at moderate temperatures circa 500°C becomes super ductile ▪ ▪ ▪ ▪

Unique and most important property of Aluminium Enables Aluminium to be hot worked at low temperatures To produce complex shapes Ideal for extrusion forging and Superforming

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Aluminium Thermal Expansion/Contraction ▪ Thermal expansion double that of steel

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Easy to Shape Manipulate ▪ Extrudable ▪ Formable ▪ Bendable ▪ Hot

▪ Cold

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Joinable/Weldable ▪ Welds ▪ Bonds ▪ Mechanical joints

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Ultra-Violet Light Totally resistant to Sunlight degradation ▪ No Heat Warping ▪ No Ultraviolet light degradation

▪ Impervious to Ultraviolet radiation ▪ Protects package contents ▪ Colour fast

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Packaging & Containers ▪ Non Toxic ▪ Long life ▪ Recyclable

▪ Colourfast ▪ Strong!!!!!!!

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Odour Less Aluminum foil, made solely from rolled aluminum, is 100% dense and impervious to light, odour and taste. ▪ No effect on the taste or smell of food wrapped in it.

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Pharmaceuticals Unrivalled barrier properties of Aluminium totally exclude the penetration of moisture, oxygen, aromas and other gases, as well as micro-organisms and light. Even with 0.007 mm thickness of aluminium foil, it is still impermeable ▪ Light proof ▪ Bacteria proof ▪ Impervious to air ▪ Infinite life

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Aluminium is “Non Sparking” Aluminium is always covered with a microscopic layer of oxide which is extremely hard and chemically inert.

▪ Aluminium is already oxidised, so oxidised that sparking cannot occur!

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Aluminium Mirror Reflectivity Aluminium can reflect up to 90% of white light and heat ▪ “Walkie Talkie” tower, 20 Fenchurch Street

▪ Each day for a period of up to two hours sun shines directly onto the building, which acts as a concave mirror focusing light onto the streets to the South, melting cars!

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Heat Reflectivity High reflectivity of aluminium does not absorb radiant heat and low absorption heat. ▪ During summer maintains interior cooler and during winter warmer

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Expanded Screen Filters Aluminium “Rhomboid” apertures are fabricated at an angle to create a brise-soleil ▪ Strong and light ▪ Blocking sunlight during the hottest days of the year ▪ Allow the sun to penetrate the facade during the winter..

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Sound Proof Aluminium is an excellent reflector of sound waves as well as electromagnetic waves. ▪ Does not ring! ▪ Does not allow external noise to enter buildings and contains interior sounds ▪ Soundproofing

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Corrosion Resistant

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Corrosion Resistant Eros ▪ Sculptor Alfred Gilbert was commissioned to create a memorial to Anthony Ashley-Cooper, the 7th Earl of Shaftesbury, in 1886 ▪ Erected in 1892 and unveiled on 29 June 1893

▪ Cast in Aluminium by George Broad & Son at the Hammersmith Foundry

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Built to last Bodleian Library, still has original Aluminium windows installed in 1939

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Aluminium Vital Constituent of Steel Aluminium is used for deoxidizing and grain refining in steels. ▪ Without Aluminium “NO” high quality steels

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Aluminium Oxide (Alumina)

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Aluminium Oxide Aluminium reacts with the Oxygen of air to form Aluminium Oxide Al2O3

▪ Commonly called Alumina ▪ Natural state of Aluminum in Nature ▪ Forms instantly on Aluminium surface ▪ Oxide is self healing

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Aluminium Oxide “Alumina” Aluminium oxide, Alumina

▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪

Corrosion resistant Transparent Bonding is “IONIC” not metallic An inclusion in Aluminium metal. Ceramic Brittle An electrical insulator. High Hardness High Strength Young’s Modulus 393 GP (Aluminium 70 GPa) High Melting Point 2,072 °C (Aluminium 660.32 °C) alfed.org.uk

Primary Aluminium Production

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Aluminium most Abundant Metal in Earth’s Crust Oxygen Silicon Aluminium Iron Calcium Sodium Potassium Magnesium Titanium Hydrogen Phosphorus

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46.46% 27.61% 8.07% 5.06% 3.64% 2.83% 2.58% 2.07% 0.62% 0.14% 0.12%

Natural Aluminium Metallic Aluminium is not found in nature, it occurs in the form of hydrated oxides or silicates, clays ▪ To difficult to economically extract Aluminium from most clays ▪ Common clay brick wall contains 10 to 20 kilograms of Aluminium per square metre ▪ China Clay kaolin ▪ Bauxite clay is only viable source of global Aluminium

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Bauxite Mineral Source of Aluminium Bauxite is a rock formed from laterite soil that has been severely leached over millennia of silica and other soluble materials in wet tropical or subtropical climate ▪ Bauxite has no specific composition, it is a mixture of hydrous Aluminium oxides, Aluminium hydroxides, clay minerals and insoluble materials ▪ Minerals include iron which gives Bauxite red colour ▪ Bauxite reserves estimated at 28 Billion tons

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Origin of Bauxite Bauxite was discovered in 1821 by the French geologist Pierre Berthier near the village of Les Baux in Provence southern France ▪ In 1861, the French chemist Henri Sainte-Claire Deville named the mineral “Bauxite"

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Bauxite Sources Global Bauxite mining ▪ Australia 31% ▪ China 16% ▪ Brazil 14% ▪ Indonesia 12% ▪ Guinea 7% ▪ India 6%

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Rehabilitation & Reforestation Bauxite is typically found in top five metres of the topsoil. ▪ Ore acquired through environmentally responsible stripmining operations ▪ Bauxite mining has reached stage where it is sustainable and ‘land area footprint neutral’ ▪ 97% of all Bauxite mines have formal rehabilitation procedures ▪ Topsoil, seeds and seedlings from mining site are stored to be replaced during rehabilitation process ▪ Reforestation is progressive and starts as soon as a mining strip is closed

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Extraction of Aluminium from Bauxite Extraction of Aluminium from bauxite is carried out in three stages ▪ Ore dressing, cleaning ore by means of separation of the metal containing mineral from the waste ▪ Chemical treatment of bauxite through Bayer process converting the hydrated Aluminium oxide to pure Aluminium oxide Al2O3 ▪ Reduction of Aluminium from Aluminium oxide by the Hall-Heroult electrolytic process

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Bayer Process Dissolution ▪ Crushed and ground bauxite is mixed with hot sodium hydroxide solution, which dissolves the Aluminium Hydroxide, forming solution of sodium aluminate. ▪ By product of Bayer process is “Red Mud” a mixture of sand, Iron Oxide and Silicates :

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Bayer Conversion to Alumina ▪ The supersaturated Aluminium Hydroxide is precipitated out of solution, washed, and filtered. ▪ The spent liquor is reheated, treated with caustic and recycled. ▪ The Aluminium Hydroxide crystals are dried by heating to between 1300 & 1500 C. ▪ Drying, calcining converts Aluminium Hydroxide into Alumina Al2O3 2Al(OH)3 → Al2O3 + 3H2O

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Aluminium Oxide “Alumina” Aluminium metal in air or oxygen instantly forms a surface oxide Al2O3, Alumina.. ▪ Oxide is self healing ▪ Ceramic ▪ Brittle ▪ An electrical insulator. ▪ High Hardness 1400 Vickers Hardness Number ▪ High Strength Young’s Modulus 393 GP (Aluminium 70 GPa) ▪ High Melting Point 2,072 °C (Aluminium 660.32 °C)

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Reduction of Aluminium Oxide Alumina Aluminium cannot be reduced from its oxide, Alumina, by simple thermal reduction so the only alternative process is electrolysis ▪ The reduction of Aluminium Oxide to pure Aluminium requires three electrons so is high electricity demand process

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Hall-Heroult Process Aluminium oxide is very poor conductor of electricity so electrolysis has to be is carried out in a bath of molten cryolite, (cryolite is a mineral, containing sodium Aluminium fluoride, Na3AlF6 ▪ Cryolite is electrically conductive, and dissolves Alumina Al2O3 ▪ Alumina Al2O3 dissolved in Cryolite melts at 1012C and the solution is a good electrical conductor. ▪ Heavy electrical currents are passed between the anodes and the cathode through the cryolite ▪ Aluminium oxide is reduced to metallic Aluminium deposited at the cathode and oxygen liberated at the anode

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Electrolysis Reactions Electrolysis is carried out in a steel cell, lined with graphite which form the cathode and Graphite rods are used as anodes.

▪ The overall reactions is 4Al3++ 6O2- + 3C → 4Al + 3CO2 ▪ Hence carbon anodes are consumed by the reaction and converted to Carbon Dioxide. ▪ Molten Aluminium metal is produced at the cathode, and sinks to the bottom of the cell.

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Hall-Heroult Electrolysis Cells Aluminium is often referred to as solid electricity because of the large amounts of power required to transform alumina into refined metal.

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Carbon Anodes Consumable Carbon Anodes and cell linings react to produce heavy CO2 emissions!

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Hall-Heroult Cells Continuously Operated Hall-Heroult cells are continuously operated so molten Aluminium Is sucked out of cells and taken to Cast-house for refining and casting

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Conversion Rate Bauxite to Aluminium

Bauxite 4 Tons

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Alumina 2 Tons

Aluminium 1 Ton

Raw Materials to Produce One Kilogram Aluminium

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Aughinish (Ireland) Alumina Production United Kingdom only source of Alumina is Aughinish in Ireland

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Scottish Primary Smelter ▪ United Kingdom has one smelter producing 45,000 tons of primary Aluminium per annum ▪ Alvance Aluminium ▪ Lochaber generates is its own hydroelectricity

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Aluminium Growth & Electricity Fundamentally the Hall-Heroult electrolysis, Aluminium refining process dependents on Electricity ▪ Historically growth in Aluminum has been extricable linked with the growth in electricity generation

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Aluminium Smelting Energy Consumption Most modern smelters use approximately 12.8 kW·h/kg of Aluminium

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Electricity Generation Growth Fuels Aluminium Production Renewables and natural gas are the fastest growing sources of electricity generation but coal is still expected to fuel the largest share by 2040 ▪ Coal generation of electricity requires steady base load demand

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Aluminium Reliance on Electricity Aluminium smelters located close to sources of economical, reliable and plentiful long term power. ▪ Hydropower supplies around 40% globally of the industry’s energy consumption, ▪ Middle East use surplus gas to generate electricity ▪ China has vast Coal reserves and despite gross generating overcapacity is building more power stations

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Regional Energy Smelting Intensity China with modern smelters operates the most energy efficient smelters

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Global Aluminium Energy Consumption World's Energy Demand to Create / Recycle Aluminium

$70 Billion Dollars Per Year on Aluminium 2.0% 1.8%

Aluminum Production, 1.8%

1.6% 1.4% 1.2% 1.0% 0.8% 0.6% 0.4% 0.2%

0.0%

Energy to Create Aluminum

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Energy to Reuse Aluminium

Carbon Free Smelting Alcoa Corporation and Rio Tinto have announced revolutionary process to make Aluminium that produces oxygen and eliminates all direct greenhouse gases emissions from traditional smelting process. ▪ New process releases oxygen instead of carbon dioxide using an advanced conductive material. ▪ Joint venture Elysis, headquartered in Montreal will develop and license the technology so it can be used to retrofit existing smelters or build new facilities. ▪ Elysis anode and cathode materials, last more than 30 times longer than traditional components

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Global Primary Aluminium Production ▪ Predicted reserves to last 100 years

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Global Growth of Aluminium

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Primary Production 2000 (25MT)

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Primary Production 2010 (42MT)

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Primary Production 2022 (65 MT)

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Aluminium End Uses Transport has overtaken architecture as the dominant use of Aluminium

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Total Global Demand 1000s tons

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Aluminium Global Demand

▪ ▪ ▪

Predicted Year 2021 demand 95 Million Tons Extrapolated Year 2030 demand 160 Million Tons Demand supported by Primary and Recycling!!!!

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Module 11 Infinitely Recyclable Aluminium

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Sustainable development: “meets the needs of the present without compromising the ability of future generations to meet their own needs”

Brundtland Report, 1987

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Our Purpose

“to shape a sustainable future through innovative Aluminium solutions”

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Aluminium Infinitely Cycled Aluminium is “NOT” consumed is it infinitely “Cycled

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”

Aluminium is Stored Energy ▪ Recycling uses only 5% of the original energy used to produce primary Aluminium ▪ Recycling uses only 5% of the water used during production of primary Aluminium ▪ Recycling creates only 5% of the original Carbon Dioxide released during production of primary Aluminium ▪ No Red Mud “Cradle to Cradle”, Aluminium in use is stored energy

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Aluminium “Longevity” ▪ 75% of all Aluminium ever produced still in Use

▪ 50% of all Aluminium in “First Use”

Million Tonnes Al (cumulative)

1,000 800

IN USE

600 400 200 0 1950

1960

1970

1980

1990

2000

2010

-200 -400

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In Use "First Life"

Recycled & In Use

Construction

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Recycled Aluminium Indistinguishable Recycled Aluminium indistinguishable from Primary Alloys ▪ Chemistry is totally indistinguishable ▪ Heat Treatment and Strain hardening response identical ▪ Mechanical properties no loss ▪ Corrosion performance comparable

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Sources of Aluminium Scrap Aluminium for recycling originates from a wide diversity of sources ▪ Process or primary scrap, known alloys ▪ End of Vehicle Life, known alloys ▪ Can and packaging, known alloys ▪ Architectural, readily analysable ▪ Domestic, ▪ White goods ▪ Swarf, heavily contaminated

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Driving Forces of Recycling One and a quarter billion tonnes of primary produced since 1888 ▪ Almost one billion tonnes in products in use Proven Aluminium service lives ▪ Buildings 75 Years ▪ Aircraft 30 Years ▪ Power transmission 35 Years ▪ Cars 15 Years ▪ Consumer white Goods 7 Years ▪ Cans 1 Year ▪ Foils 1 Year

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Automotive Demand Growth

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Automotive Recycling Since 2015, the “End of Life Vehicles Legislation” sets a target of a 85% of all raw materials, including metals must be recycled ▪ Recycling the Aluminium in a one car saves approximately one ton of Carbon dioxide ▪ In Europe that equates to 15 million cars scrapped or tons of Carbon Dioxide saved

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Recycling Aircraft Recycling the Aluminium from an A320 aircraft at the end of its life saves 300 tons of Carbon Dioxide

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Architectural Scrap Limited number of Aluminium grades ▪ Large bulky ▪ Few metallic contaminants

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Every Can Counts ▪ Can are infinitely recycled ▪ Can to can recycle is 60 days ▪ 69% of all Aluminium cans are cycled

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Recycling Aluminium Packaging Food cartoons and foils and ancillaries ▪ Aluminium packaging is recovered from incinerator bottom ash (IBA). ▪ 2015 IBA accounted for around 16% of recycling performance. ▪ Volumes set to grow dramatically as new plants come on stream

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Bicycle from Recycled Aluminium Coffee Pods Nespresso and Czech bicycle producer Festka have joined hands to come up with a unique product to promote Aluminium recycling. • Festka recycled the ubiquitous Aluminium coffee capsules from Nespresso to fabricate a unique bicycle called the Festka Doppler. The bicycle was sold at a charity auction held during Mercedes-Benz Prague Fashion Week.

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Aluminium Star of Circular Economy

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Production Scrap Segregation Production scrap resulted from metal forming and pressing operations is kept strictly segregated during production in “Aluminium Grades”

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Scrap Sorting into Aluminium alloys Modern scrap sorting can result in over 95% alloy segregation for remelt feed stock ▪ Organics, coffee, dried and physical shaken off sent for fertilizer ▪ Plastic electrostatically sorted ▪ Steel extracted by magnetism ▪ Non Ferrous Copper removed using eddycurrents ▪ Aluminium sorted into “Aluminium Alloy Series” by X-ray Florescence

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Valuable Scrap Aluminium Scrap Aluminium is a valuable commodity Scrap recovery should be part of costing a product!!!! ▪ G1,litho,new extrusion scrap 1000-1050 £/tonne) ▪ Pure cuttings scrap 820-880 £/tonne ▪ Baled old rolled scrap 700-750 £/tonne ▪ Old cast scrap 730-780 £/tonne ▪ Cast wheels 1000-1040 £/tonne ▪ Turnings 420-480 £/tonne ▪ Al UBC baled 610-660 £/tonne ▪ LM24 ingot 1250-1320 £/tonne ▪ LM6/25 ingot 1490-1540 £/tonne ▪ Al-5%Cu-0.5%Ag ingot 4000 £/tonne alfed.org.uk

United Kingdom Recycling Twenty Aluminum recyclers in the United Kingdom Output ▪ Ingot 220,000 tons ▪ Remelt 580,000 tons ▪ Total 800,000 tons

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Recycling of Wastes & Slags Slags are recycled into environmental beneficially “Green” products ▪ Aluminium Metal ▪ Potash “Fertiliser” ▪ Salt

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Sustainable use of Aluminium Global Vision – responsibly sourced (primary and secondary) Aluminium – mainly sustainable bauxite extraction and refining, and low-emission smelting ▪ ALFED is a member, as are big companies such as JLR, Audi, Novelis, Bridgnorth Aluminum and Arconic

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Aluminium Recycling Growth Availability of short life cycle scrap will result in 26.5 million tons of globally recycled Aluminium by 2023

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Total Global Production 2023 ▪ Primary 65 million tons ▪ Recycled 25 million tons 1000s tons

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Production of Secondary Aluminium

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Aluminium Melting & Casting Selected Aluminum scrap and master alloys are melted in a “Melting Furnace” ▪ High Melting rate furnaces ▪ Dirty furnace

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Sows Sows are the feed stock for secondary Aluminium Production

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Drossing Fluxes are added to the molten Aluminium and stirred in ▪ Impurities, oxides and inclusions float to the top of the liquid Aluminium ▪ Skimmed off top of melt and out of furnace ▪ Dross sent for recycling

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Alloying & Purification Clean molten Aluminium is transferred via a launder to a second holding Furnace

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Holding Furnace Second holding furnace ▪ Clean furnace eliminates risk of contamination ▪ Molten Aluminium is sampled and analysed ▪ Additions of master alloys and alloying elements made to correct analysis to required specification

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Filtration Once analysis has been corrected to required alloy specification, molten Aluminium is filtered to remove inclusions and degassed then cast

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Ingots for Castings Aluminum for castings is metered into ingots and solidified

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Direct Chill Casting Slabs & Logs Most common method for semi-continuously producing Aluminium slabs or logs is “Direct-chill (DC) Casting” Molten Aluminium is poured through a bottomless water cooled mould, where it’s outer surface rapidly solidifies to take the shape of the mould and enables it to be extracted as a solid from below Aluminium is ideal ▪ Low melting point ▪ High fluidity ▪ High thermal conductivity

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Direct Chill Casting Slabs & Logs Most common method for producing Aluminium slabs or logs is “Directchill (DC) Casting” ▪ Molten Aluminium is poured through a bottomless water cooled mould, ▪ Supporting stool bottom of mould descends ▪ Outer surface rapidly solidifies to take the shape of the mould ▪ Extracted as a solid from below

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Bottomless Mould ▪ Direct Chill Casting uses a water cooled round or rectangular mould ▪ Water is allowed escapes through the bottom of the mould bottom to cascade as a shower curtain around the base ▪ The bottom of the mould is closed with a “Stool” that moves downwards Water Cooled Mould Water shower

Stool Bottom of Mould

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DC Casting Sequence ▪ Molten Aluminium is poured into the mould

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DC Casting Sequence ▪ Aluminum in contact with Mould walls and Stool instantly solidifies forming a solid cup like crust

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DC Casting Sequence ▪ ▪ ▪ ▪

Stool descends downwards drawing down the forming log of Aluminium Log walls are solid crust Core is molten Aluminium held with crust cup Debris float upwards on liquid

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DC Casting Sequence • • •

Core Solidifies All debris floated to top Top and bottom of slab discarded

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DC Casting Floor

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Mini Casting Mills Approximately 300 twin roll casters operate globally ▪ Capacity of 10,000 tons per year ▪ Molten Aluminium melt is fed through a ceramic nozzle into the gap between two rotating water-cooled rolls. ▪ Melt cools down and solidifies between the rolls. ▪ Additionally the solid strip exerts hot rolling

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Direct Cast Slabs Direct Cast Slabs for: ▪ Plate ▪ Sheet ▪ Foil

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Direct Cast Logs Direct Cast Logs for: ▪ Forgings ▪ Extrusions

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Cast Structures As cast Aluminium ▪ Heterogeneous ▪ Variable stratified alloy analysis ▪ Variable mechanical properties ▪ Heterogeneous grains ▪ Core alloy segregation ▪ Shrinkage ▪ Porosity ▪ Inclusions

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Aluminium & Health

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Aluminium in the Body Human body contains around 35 mg of Aluminium, of which approximately 25% is in the soft tissues, 25% in bone and the rest in the lungs, probably as inhaled dust particles. ▪ No known biological role for Aluminium - it does not appear to be an essential trace element ▪ Body has highly effective barriers to exclude Aluminium. ▪ Only a minute fraction of Aluminium in the diet is taken up from the gut, and in healthy individuals, most of this absorbed Aluminium is excreted by the kidneys. ▪ Brain is vulnerable to many metals, including Aluminium, but there is a ‘blood-brain barrier’ which prevents most of the Aluminium in blood from entering this organ. When blood Aluminium levels are high, bone appears to act as a ‘sink’, taking up Aluminium and releasing it slowly over a long period

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Aluminium in Drinking Water Aluminium sulphate is widely used around the world in the treatment of water supplies. It is added as a flocculating agent to remove suspended particles, including the spores of some infectious organisms which are difficult to remove by other means. ▪ Most of the Aluminium is removed in the later stages of treatment and the final concentration is usually much less than two hundred parts per billion. ▪ Thus, drinking water contributes only a very small fraction, less than 1%, of the Aluminium which we take in each day.

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Medical Problems Associated with Aluminium Following the North Cornwall water pollution incident at Camelford, it was claimed by a few scientists that there would be long-term adverse health effects, two government reports by an independent team of medical and scientific experts concluded that Aluminium was not the cause of symptoms reported by the local population

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Medical Problems Associated with Aluminium When the natural barriers which limit the absorption of Aluminium are bypassed, or when the ability of the kidneys to excrete Aluminium is impaired, the accumulation of this metal in the body may sometimes be associated with adverse health effects. ▪ Patients with kidney failure are unable to excrete Aluminium. Toxicity associated with exposure to Aluminium in the dialysis fluid, or with the long-term medical use of Aluminium compounds in this patient group, are now recognised. ▪ In extremely rare cases, long-term exposure to massive levels of flake powdered Aluminium in the work-place has been shown to cause toxic effects. Modern occupational hygiene practices, which are enforced by health and safety legislation, now prevent the occurrence of such exposures in the work-place.

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Scientific Committee on Consumer Safety & Aluminium EU, Commission’s independent Scientific Committee on Consumer Safety (SCCS) published its opinion on Aluminium in cosmetics such as lipstick, deodorants and toothpastes on the 11-042014 ▪ Aluminium is a known systemic toxicant at high doses. After studying the available literature on exposure, SCCS expressed several considerations. ▪ No plausible evidence that use of Aluminium containing cosmetics and skin care products can increase the risk of breast cancer or Alzheimer’s disease, Parkinson’s disease and other neurodegenerative diseases. ▪ No evidence that using antiperspirants can lead to levels of Aluminium that would be harmful to health. ▪ Regarding safe concentration limits, SCCS concluded that there was too little data to draw conclusions

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Aluminium & Pregnant Workers Employers must assess the risks to women of a childbearing age as part of their general workplace risk assessment. • Once an employer is notified that a worker is pregnant, has given birth in the last six months, or is currently breastfeeding, they must complete an individual risk assessment, which should include exposure to any harmful substances. • Employers should be managing any significant risks in their workplaces, and are best placed to assess whether or not they need to do anything additional for pregnant workers or new mothers. • It is not known if aluminium dust or fume will cause birth defects in humans. However, aluminium in large amounts has been shown to be harmful to unborn and developing animals by causing delays in skeletal and neurological development. • Employers may choose to take a precautionary approach, and avoid exposure to aluminium fume and dust in the workplace. • HSE provides guidance on protecting pregnant workers and new mothers in the workplace https://www.hse.gov.uk/mothers/ alfed.org.uk

Aluminium and Alzheimer’s No medical evidence of a link between Aluminium and Alzheimer’s ▪ Main cause of Alzheimer’s seems to be predisposition ▪ Some Alzheimer’s sufferers do have a slightly elevated level of Aluminium in their brain ▪ Aluminum is present in soil, so most exposure comes from foods we eat and the water we drink.

▪ NOT from pots & pans, foil packaging ▪ Biggest single source is Indigestion Remedies

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Aluminium and Cosmetics Aluminium in the levels in cosmetics is unlikely to be carcinogenic ▪ In cosmetics, they function as pigments and thickening agents ▪ Aluminum salts are used as antiperspirants to control sweat, they coat and plug the sweat glands

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Aluminium & Fire

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Solid & Molten Aluminium Non-Combustible Aluminium metal and all its alloys, in both solid and molten states, including all products forms – wire, extrusion, sheet and foil – are “non-combustible”, meaning they do not burn or combust when exposed to fire. ▪ Combustible materials are those capable of burning. ▪ Flammability is the ease with which a combustible material ignites. ▪ Solid Aluminium is a non-combustible material and therefore inflammable, so cannot catch fire.

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Aluminium Behaviour in Fires Investigation of major detailed accounts of Aluminium behaviour in fires concluded there is no evidence that Aluminium burned or contributed to the damage! ▪ Collision of USS Belknap and Kennedy in 1975, when the entire superstructure of the Belknap was engulfed in flames from ruptured fuel lines on the Kennedy. ▪ Sinking of four British Royal Navy warships in the Falklands War 1982; British Admiralty concluded that there was no evidence that Aluminium contributed to the loss of any vessel. ▪ Damage to the USS Stark frigate by Iraqi missiles 1985.

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Building Regulations Fire safety: Approved Document B Building regulations in England, “Fire safety: Approved Document B”, additionally consider the propagation of fire, so consider both the spread of flames and the amount of heat added to a fire by the energy output of burning materials. ▪ Aluminium is Classed as A1 Noncombustible and does not flame or cause any rise in temperature” ▪ Class 0 is the highest category for surface spread of flame of a material ▪ A material of limited combustibility will achieve a Class 0

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Aluminium Melting Aluminium alloys have melting points between 550°C and 660°C so if exposed to a prolonged fire environment, provided that the metal's temperature passes the melting point, they will melt, without releasing harmful gases, not burn. ▪ Latent heat of melting lowers fire temperature. ▪ Molten Aluminium will flow as liquid. ▪ Liquid Aluminium will solidify rapidly away from heat source.

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Heat Dissipation When aluminium is exposed to fire, its high thermal conductivity allows it to quickly dissipate heat from the flames and absorb even more thermal energy from the centre of the fire, ‘cooling’ the environment and limiting hot spots! ▪ Heat dissipation is comparatively greater than that of other metals therefore Aluminium offers a comparatively higher response time to fire fighters. ▪ Hence use in Oil rigs!

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World of Aluminium

Modular Course Intermediate level Part 2 alfed.org.uk

Wrought Aluminium International Specifications

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International Alloy Designation The Aluminum Association (based in Washington DC) in 1954, introduced a four digit system register entitled :‘International Alloy Designation and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys’ ▪ Most international aluminium committees and companies in 1970 adopted the AA system ▪ Sensibly, recent Euronorm Standards follow the Aluminum Association system, “therefore AA 3105 / BS EN 3105 / NF EN 3105 / DIN EN 3105 are the same alloy with the same chemical composition limits” Register is commonly known as “Teal sheets”

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Teal Sheets ▪ International Alloy Designations and Chemical Composition Limits for Wrought “Aluminium” and Wrought “Aluminium” Alloys ▪ This registration record is the defining source for the designations and chemical composition limits for wrought “Aluminium” and wrought “Aluminium” alloys referenced in a number of standards and specifications worldwide. ▪ http://www.Aluminium.org/sites/default/files/TEAL_1_OL_2015.pdf

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Wrought Alloys Classification Codes ▪ ▪ ▪ ▪

The four digit coding system classifies wrought aluminium alloys by chemical composition The first number of the four digits defines the alloy group, according to the major alloying element The second digits describe further secondary alloying elements The third and fourth digits separate the alloys ▪ 1xxx Unalloyed (pure) greater than 99% Aluminium ▪ 2xxx Copper ▪ 3xxx Manganese ▪ 4xxx Silicon ▪ 5xxx Magnesium ▪ 6xxx Magnesium and Silicon ▪ 7xxx Zinc ▪ 8xxx Other elements (Tin and Lithium) alfed.org.uk

Alloys Overview

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XXX”A” Some alloys have been modified but not sufficiently to justify a four-digit new number, a letter is added to differentiate the modified alloy ▪ Lower Silicon Si in 2014A makes it easier to extrude, and results in slightly lower yield Stress

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British Standards Wrought Alloy Designation European Standards and British Standards have adopted the Aluminum Association and follow the system.

▪ The system is described by BS EN 573 part 3 “Aluminium and aluminium alloys. Chemical composition and form of wrought products”

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Aluminium Alloys Chemistry In the EN BS Standards part 3 dealing with the chemistry of alloys • The chemical composition of Aluminium and Aluminium alloys is specified in percentage by mass • Limits of impurities are expressed as a maximum • Limits of alloying elements shown as a range, so minimum and maximum • Aluminium is specified as a minimum for unalloyed aluminium, 1XXX series and as a remainder for Aluminium alloys

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Classification of Aluminium Alloys Aluminium and its alloys are divided into two broad classes: ▪ Wrought Aluminium alloys, “those worked by rolling, extrusion, forming or forging into the desired shape.” ▪ Wrought Aluminium is sub-divided into non-heat treatable and heat treatable alloys. ▪ Aluminium casting alloys, “those which are poured in a molten state into a mould producing a cast shape.” ▪ Some casting alloys are also strengthened by heat treatment, but in this case the distinction is not used as a sub-division.

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Aluminium Non Heat Treatable Alloys Non Heat treatable alloys can only be strengthened by cold work or strain hardening

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Aluminium Heat Treatable Alloys Certain Aluminium alloys can be strengthened through heat treatment ▪ Aluminium alloy heat treatment is called “Age Hardening” and/or “Precipitation hardening” ▪ Heat treatable can also be strained or by a combination of strain hardening and Age hardening

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Casting Alloys

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European Casting Alloy Designation Designation systems for casting alloys and castings differ significantly between British Standards and the Aluminum Society ▪ BS EN 1780-1:2002 Aluminium and aluminium alloys. Designation of unalloyed and alloyed aluminium ingots for remelting, master alloys and castings-Numerical designation system ▪ British use five digit system designation system for casting alloys and castings the

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BS 1490:1988 Aluminium Ingots and Castings British Standard 1490:1988 “Aluminium and Aluminium Alloy Ingots and Castings for General Engineering Purposes” ▪ Obsolete specification but widely used by UK foundries and ingot suppliers. ▪ Grades LM0 to LM31 ▪ LM abbreviation for “Light Metal” ▪ First published in 1948.

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Module

Heat Treatment of Aluminum

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373

Aluminium Heat Treatment Definitions European Standard BS EN 515:1993 defines all temper designations for: ▪ Different heat treatments as termed “Tempers” ▪ All forms of wrought Aluminium and Aluminium alloys

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Basic Temper Designations Designations are added after the 4-digit alloy designation to explain how the physical properties of alloys are modified by heat and/or mechanical treatment

5052

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Basic Temper Designations Designations are added after the 4-digit alloy designation to explain how the physical properties of alloys are modified by heat and/or mechanical treatment

5052-H32 First letter of the designation indicates the treatment used to produce the properties. ▪ ▪ ▪

▪

O Annealed - Used after cold-working to soften work hardening alloys (1xxx, 3xxx and 5xxx series). H Strain Hardened - This applies to non heat-treatable alloys (3xxx, 4xxx and 5xxx series) that are cold worked or strain hardened. W Solution Treated -This applies to heat treatable alloys which have only been solution treated (2xxx, 6xxx and 7xxx series) T Heat Treated - This applies to heat treatable alloys which have been solution and aged alfed.org.uk

Aluminium Non Heat Treatable Alloys Non Heat treatable alloys can only be strengthened by cold work or strain hardening

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Strain Hardening & Cold work Annealed Aluminium grains are normally semi round and uniformly shaped ▪ Grains deform, flatten and stretch when cold worked by rolling, stamping, drawing or any mechanical reshaping process ▪ Flattened shape is more resistant to further deformation so Aluminium become harder and stronger ▪ Working harden or strain harden

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Temper Designation Cold Work -H1X For non heat treatable alloys the temper code denotes cold or strain hardening by using the letter H followed by numbers. H1x The first number indicates how the temper is achieved. The second number after H indicates degree of strain-hardening ▪ O

Annealed, soft

▪ H12 Strain-hardened, quarter-hard ▪ H14 Strain-hardened, half-hard

▪ H16 Strain-hardened, three-quarter hard ▪ H18 Strain-hardened, fully hard ▪ H19 Strain-hardened, extra hard

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Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation.

0 alfed.org.uk

Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation.

H12

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Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation.

H14

H12

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Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation.

H16 H14

H12

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Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation. H18

H16 H14

H12

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Temper Designation Cold Work -H1X The higher the cold work the higher the developed yield and tensile stress, but lower the corresponding ductility/elongation. H18

H16 H14

H12

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Annealing and Recrystallisation When a cold-worked metal is heated to between its “Recrystallisation Temperature”, new grains form, consuming all the plastically-deformed grains. ▪ Once all the new grains have formed, the structure is fully “annealed”, and strength and ductility are restored to their original levels.

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Temper Designations Strain-hardened and Partially Annealed -H2X Fully cold worked Aluminum lacks sufficient ductility for further working such as pressing So British Standards have designated H2X to products that have been strainhardened and then reduced in strength to the desired level by partial annealing. H2x tempers have the same minimum ultimate tensile strength as the corresponding H1x tempers and slightly higher elongation. ▪ ▪ ▪ ▪

H22 Strain-hardened, partially annealed, quarter hard H24 Strain-hardened, partially annealed, half hard H26 Strain-hardened, partially annealed, three quarter hard H28 Strain-hardened, partially annealed, fully hard

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