Aluminium Light Training Course- 17th October 2023 by Aluminium Federation

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An Introduction into Aluminium & Aluminium Applications Modular Course

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Module 1 Aluminium

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Topics Aluminium Strategic metal Properties of Aluminium Applications Global demand

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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 Mg Al Ti Fe Cu Density g/cm³ alfed.org.uk

1.738

2.7

4.506

7.874

8.96

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

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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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Aluminium “Non Magnetic” Normally Aluminium is non Magnetic! ▪ Magnetism can pass through Aluminium

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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 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 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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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 alfed.org.uk

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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Diamond Hard “Alumina” Aluminium when exposed to the oxygen of the air forms an oxide layer called Alumina. Alumina imparts to Aluminium its unique corrosion resistance ▪ ▪ ▪ ▪ ▪ ▪ ▪

Transparent Self healing Ceramic An electrical insulator. High Hardness High Strength High Melting Point

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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 Non-Combustible Aluminium metal and all its alloys, both solid and molten do not burn

▪ All products forms, wire, extrusion, sheet and foil are “non-combustible”

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

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Global Demand 1000s tons

▪ Demand is growing across all sectors alfed.org.uk

Aluminium Infinitely Recyclable Recycled Aluminium indistinguishable from Primary Alloys ▪ Chemistry is totally indistinguishable ▪ No loss of mechanical properties ▪ Corrosion performance comparable

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Module 2 Aluminium Production & Global Demand

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Topics Sources of Aluminium Refining and production Growth & relationship with electricity Low carbon recyclability

Supply matching demand

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Aluminium the most Abundant Metal Aluminium is the third most abundant element in the earths crust

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Oxygen

46.46%

Silicon

27.61%

Aluminium

8.07%

Iron

5.06%

Natural Aluminium Metallic Aluminium is not found in nature, it occurs as clays ▪ Too 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 the only viable source of global Aluminium

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Bauxite Mineral Source of Aluminium Bauxite is a rock that has been severely leached of silica and other soluble materials

▪ Found in wet tropical or subtropical climate ▪ Bauxite is a mixture of Aluminium oxides, iron, clay minerals ▪ Iron gives red colour

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Bauxite Sources Global Bauxite mining ▪ Australia 31%

▪ China 16% ▪ Brazil 14% ▪ Indonesia 12% ▪ Guinea 7% ▪ India 6% alfed.org.uk

Rehabilitation & Reforestation Bauxite mining is sustainable and ‘land area footprint neutral’ ▪ Ore acquired through environmentally responsible stripmining operations ▪ 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 alfed.org.uk

Extraction of Aluminium from Bauxite Extraction of Aluminium from bauxite is carried out in three stages ▪ Ore dressing, 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 ▪ Reduction of Aluminium oxide to Aluminium metal by the Hall-Heroult electrolytic process

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Bayer Process Dissolution Crushed and ground bauxite is mixed with hot sodium hydroxide solution; Aluminium oxide is precipitated out of the solution and calcined, that is dried

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Hall-Heroult process Aluminium can only be reduced from its oxide, Alumina, through electrolysis In 1886 independently a French engineer Paul Heroult, and an American student Charles Hall, developed an electrolytic production method which established Aluminium as a viable metal. ▪ Electrolysis requires enormous amount of electric power ▪ Thus growth of Aluminium is powered by the growth in electricity generation

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Electrolysis Reactions Electrolysis is carried out in a bath of molten cryolite, a mineral, containing sodium Aluminium fluoride ▪ Electrolysis is carried out in a steel cell, lined with graphite which form the cathode, and Graphite rods are used as anodes.

▪ 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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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

Aluminium Smelting Consumption Modern smelters use approximately 12.8 kilowatt hours of electricity to produce one kilogram of Aluminium

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Aluminium Growth & Electricity Growth in Aluminium has been inextricably linked with the growth in electricity generation

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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.

▪ Middle East use surplus gas to generate electricity ▪ China has vast Coal reserves and despite gross generating overcapacity is building more power stations ▪ Smelters use surplus off-peak electricity, perfect base load for generators

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Aluminium Star of Circular Economy

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

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Aluminium “Longevity” ▪ 75% of all Aluminium ever produced still in Use ▪ 50% of all Aluminium in “First Use”

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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 Aircraft Power transmission Cars Consumer white Goods Cans Foils

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75 Years 30 Years 35 Years 15 Years 7 Years 1 Year 1 Year

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

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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

Recycled Aluminium Indistinguishable Recycled Aluminium indistinguishable from Primary Alloys ▪ Chemistry is totally indistinguishable ▪ Heat Treatment response identical

▪ Mechanical properties no loss ▪ Corrosion performance comparable

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Aluminium is Stored Energy “Cradle to Cradle”, Aluminium in use 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

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Aluminium Recycling Growth

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Production of Secondary Aluminium

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

▪ Impurities, oxides and inclusions float to the top and are drossed off

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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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Direct Chill Casting Slabs & Logs Most common method for producing Aluminium slabs or logs is “Direct-chill (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 alfed.org.uk

Direct Chill Casting

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Sows Sows are the feed stock for secondary Aluminium Production

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

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Pigs Ingots for re-melting into casting

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

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Grain Boundaries During casting solidification atoms from the liquid Aluminium grow into crystals until they impinge onto another crystal ▪ The impingement between crystals forms distinct lines of demarcation or “Grain Boundaries”

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Cast Macrostructures Cast Aluminium is extremely heterogeneous ▪ Large localised variations in chemical analysis ▪ Segregation

▪ Porosity ▪ Variable mechanical properties

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Module 3 Wrought Aluminum and Applications

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Topics Classification of Aluminium Alloys Alloy series and their applications Aluminium and Fire Aluminium and Health

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Alloy An alloy is a metal made by combining two or more metallic and/or non metallic elements to develop a substance with properties that are significantly different and much enhanced over those of the pure constituent elements ▪ ▪ ▪ ▪ ▪ ▪ ▪

Greater strength Toughness Fatigue life Corrosion resistance Appearance Machinability Formability

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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.”

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International Alloy Designation The Aluminum Association, based in Washington DC, in 1954, introduced a fourdigit system register for all Aluminium wrought alloys “International Alloy Designation and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” ▪ The Aluminum Association Register are known as “Teal Sheets”

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British Standards Alloy Designation British Standards have adopted the Aluminum Association four digit system and follow the system ▪ The system is described by BS EN 573 “Aluminium and aluminium alloys. Chemical composition and form of wrought products”

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Cast & Wrought Aluminium Cast Aluminium has coarse grains, extremely heterogeneous with variable chemistry and properties ▪ Through mechanical work we wrought or break up the coarse structure and then anneal to form fine new evenly distributed homogeneous grains with much stronger uniform mechanical properties

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Alloy Designation System for Wrought Aluminium Wrought Aluminium is classified by chemical composition using the four-digit system. ▪ The first of the four digits in the designation indicates the alloy group, according to the major alloying elements. ▪ Further digits explain other alloying elements Unalloyed (pure) greater than 99% Aluminium ▪ 1xxx Copper ▪ 2xxx Manganese ▪ 3xxx Silicon ▪ 4xxx Magnesium ▪ 5xxx Magnesium and Silicon ▪ 6xxx Zinc ▪ 7xxx ▪ 8xxx Other elements (Tin and Lithium) alfed.org.uk

Alloys Overview

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1000 Series Pure Aluminium Pure Aluminium, high purity, 99.0% minimum ▪ Not Heat Treatable ▪Mechanical properties can only be increased by strain hardening. Properties ▪ High ductility ▪ Excellent conductors ▪ Excellent formability and weldability ▪ Good appearance ▪ Great for anodising ▪Good corrosion resistance Uses

▪ Foil, electrical busbars, chemical tanks, piping alfed.org.uk

Alloy 1050 Litho Plate ▪ Each coil is batch annealed in a fully computerised environment in order to achieve optimum mechanical properties and maximum on-press plate performance

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1XXX Alloys 1050 ▪ Supplied in sheet form; also available as foil, bar, tube, extrusions ▪ End uses include chemical process plant, food containers, reflectors, architectural flashing 1350 ▪ Special high electrical conductivity grade ▪ Used in overhead cable for both low and high voltage lines, on its own or as part of an Aluminium conductor steel reinforced, “ACSR” system.

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1XXX Electrical ▪ Electrical Switch Gear ▪ Cabinets ▪ Bus bars

▪ Switch Gear ▪ Trunking

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Aluminium in Electric Vehicle Drives ▪ Batteries ▪ Cables ▪ Battery cooling ▪ Powertrain

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2000 Series Aluminium - Copper Alloys Main Alloying Element is Copper ▪ Heat Treatable ▪Originally known as ‘Duralumin’ Properties ▪ Strong ▪ Machinable ▪ Poor corrosion resistance ▪ Poor formability ▪ Difficult to weld ▪ Good strength at temperatures up to 150 °C Uses ▪ Aerospace, Military vehicles, Rocket fins alfed.org.uk

Duralumin Duralumin, the foundation stone of Aluminium as an engineering metal ▪ Aluminium alloy with addition of Copper, Magnesium and Manganese ▪ Alfred Wilm, a German scientist took seven years develop in 1909 ▪ First all-metal Duralumin airplane, the Junkers J1, launched in 1915.

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2XXX Alloys 2017 ▪ Original “Duralumin”, an Al-Cu-Mg alloy 2014A ▪ Addition of silicon to 2017 lead to the development of 2014 ▪ Much stronger and stiffer than 2017 ▪ Widely used in structural parts, 2024 ▪ Increasing magnesium levels lead to the development of 2024 ▪ much stronger and tougher than 2017 ▪ Strong Aluminium alloy for fatigue critical end uses 2618A ▪ Al-Cu-Fe-Ni alloy with improved strength at high temperature 100ºC, used for airframe of Concorde

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3000 Series Aluminium - Manganese Alloys Main Alloying Element is Manganese ▪ Not Heat Treatable ▪Mechanical properties can only be increased by strain hardening Properties ▪ Formable ▪ Corrosion resistant similar to 1000 series ▪ Weldable ▪20% Stronger than 1000 series Uses ▪ Radiators, air conditioning condensers, evaporators, heat exchangers.

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Aluminium Cans 3004 and 3104 are used for light weight can bodies ▪ Maintain sufficient integrity with the thinnest possible wall. ▪ After forming beer can bodies have a wall thickness of 100 microns at thinnest point

5182 are used for pull tabs for strength that allows use of the riveted pull tabs

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4000 Series Aluminium - Silicon Alloys Major Alloying Element is Silicon ▪ Silicon lowers the melting range so Aluminium-Silicon alloys are used in welding wire and as brazing alloys for joining Aluminium, where a lower melting range than that of the base metal is required ▪ Not Heat Treatable Properties ▪ Formable ▪ Corrosion resistant ▪ Weldable

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4000 Aluminium Uses ▪ Welding wire, brazing and filler wires ▪ 4043 is a common welding wire alloy

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4000 Series Specialist Alloys Not widely used in extruded form, except: ▪ 4032 Forging stock for pistons where wear resistance and thermal stability are required ▪ 4021 ABS brake components, machinable, strength close to 6061 and 6082

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4XXX Cladding Alloys Common cladding alloys for brazing sheet ▪ 4004 ▪ 4045

▪ 4104 ▪ 4343

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5000 Aluminium Main Alloying Element is Magnesium ▪ Magnesium more effective than manganese as a hardener and lighter ▪ Not Heat Treatable ▪Mechanical properties can only be increased by strain hardening Properties ▪ Strong ▪ Formable ▪ Extremely high corrosion resistance ▪Good Weldability Uses ▪ Automotive, truck, train bodies, marine and chemical tankers

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5083 5083 Aluminium alloy with magnesium and traces of manganese and chromium. ▪ Highly resistant to attack by seawater and industrial chemicals ▪ Alloy 5083 retains exceptional strength after welding.

▪ Highest strength of the non-heat treatable alloys ▪ Not recommended for use in temperatures in excess of 65 °C

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RC5754 Following the research project ‘REALCAR’, a new 5xxx Aluminium alloy was developed by JLR for XE; RC5754

▪ RC5754 specifically a recycled alloy ▪ All future Jaguar Land Rover vehicles will utilise it ▪ Recycled “RC” 50,000 tonnes of Aluminium scrap, produced 200,000 XE body shells, captured as closed-loop during 2015/16

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6000 series Aluminium-Magnesium-Silicon Alloys Main Alloying Elements are Silicon and Magnesium ▪ Extremely Heat Treatable Balanced properties ▪ Strong, but not as strong as most 2xxx and 7xxx alloys ▪ Formable ▪ Good corrosion resistance ▪ Good Weldable Uses ▪ Most widely used alloy for Extrusions alfed.org.uk

6000 Alloy for Anodising 6463 / 6463A − Specialized “6063” type to give bright finish after chemical brightening.

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7000 Aluminium Main Alloying Element is Zinc with Magnesium & Silicon ▪ Heat Treatable, comparable strengths to steel Properties ▪ Very high strength ▪ Machinable ▪ Poor to reasonable corrosion resistance prone to stress corrosion ▪ Poor weldability ▪ Limited extrudability Uses ▪ Aerospace, armoured vehicles, bicycle frames alfed.org.uk

Japanese Zero Zero 1936 ▪ Mitsubishi's chief designer Jiro Horikoshic understood that the Zero aircraft had to be as light as possible. ▪ 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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7075 Very high strength alloy ▪ 7075 has poor corrosion resistance, with risk of stress corrosion

▪ Direct contact by dissimilar metals can cause galvanic corrosion ▪ Good machinability ▪ Anodising is good

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Consumer Electronics Apple® popularised Aluminium laptops in 2003 with the introduction of the Aluminium PowerBook G4. and their latest is the iPhone 7® and the Apple Watch® ▪ iPhone 7 and Apple Watch use 7XXX alloys for strength

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8000 Series Aluminium alloys The 8XXX series covers a wide range of alloys that do not fit into any other group.

▪ This includes the Lithium alloys that contain up to 2.45% lithium. ▪ Lithium atoms are lighter than Aluminium, so every 1% Lithium added reduces the density of the resulting alloy by 3%, and increases tensile strength by 5%. ▪ A growing use of 8XXX series alloys is for electrical cables.

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8000 Series Applications ▪ Nuclear power resistance to corrosion at elevated temperatures and pressures, 8001 ▪ Bearings for cars and trucks, 8081, 8280 ▪ Electrical conductors, 8017, 8030, 8076, 8176

▪ Food industry, 8011, 8079 ▪ Medical, 8011, 8079 ▪ Heat exchangers, 8011 alfed.org.uk

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” ▪ They do not burn or combust

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Aluminium Melting Aluminium alloys have melting points between 550°C and 660°C so if exposed to a prolonged fire, they will melt ▪ Not Burn ▪ Will not release harmful gases.

▪ Melting lowers fire temperature ▪ Liquid Aluminium will flow and solidify rapidly away form heat source.

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Aluminium & Health

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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 April 2014 ▪ Aluminium is a known systemic toxicant at high doses. ▪ When the ability of the kidneys to excrete Aluminium is impaired, in those patients with kidney failure, the accumulation of this metal in the body may sometimes be associated with adverse health effects.

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Scientific Committee on Consumer Safety & Aluminium 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 and Alzheimer’s No medical evidence of a link between Aluminium and Alzheimer’s Disease ▪ Main cause of Alzheimer’s seems to be a predisposition.

▪ Some Alzheimer’s sufferers do have a slightly elevated level of Aluminium in their brain . ▪ Aluminium 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. alfed.org.uk

Module 4 Strengthening Aluminum

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Topics Definition of Tempers Non Heat Treatable Alloys Work Hardening Heat Treatable Alloys

Solution & Age Hardening

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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 (1xxx, 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 Any mechanical cold work deforms grains ▪ Cold work ▪ Strain hardens a metal

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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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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 ▪ Lower the corresponding ductility

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Strain Hardening The greater the cold deformation the higher the strength increase ▪ Lower the corresponding ductility

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Strain Hardening The greater the cold deformation the higher the strength increase ▪ Lower the corresponding ductility

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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

0 alfed.org.uk

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”, 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.

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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 When a cold-worked metal is heated to above 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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Annealing Once all the new grains have Recystallised the structure is fully “annealed”, and strength and ductility are restored to their original levels.

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

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1.4 Temper Designation - Strainhardened and Partially Annealed H2X Fully cold worked Aluminium H1x lack sufficient ductility for further working such as pressing or manipulation ▪ Fully cold worked Aluminium H1x products have insufficient ductility they risk brittle during service in components subjected to elastic movements such as in suspension or in bridges ▪ Aluminium in the H1x strain hardened conditions exhibits high elastic spring back it is difficult to manipulate ▪ Fully cold worked Aluminium H1x is not thermally stable if subjected to elevated temperatures, such as during welding or paint curing it will start recrystalise in a noncontrolled manner ▪ Partial annealing enables strain-hardened alloys to be reduced in strength to the desired strength and ductility level ▪ Partial annealing gives thermal stability alfed.org.uk

Strain-hardened and Partially Annealed -H2X Partial annealing of the strain hardened condition, allows the strength and ductility of non-heat treatable alloys 1xxx, 3xxx and 5xxx to be tailored to the require levels ▪ Increased ductility for forming ▪ Reduced spring back on forming

▪ Thermally stable on welding British Standards have designated the temper H2X to indicate strain hardened and partially annealed tempers The second digit after the H2 indicates the degree of partial annealing H2X ▪ H28 Strain-hardened, partially annealed, fully hard ▪ H26 Strain-hardened, partially annealed, three quarter hard ▪ H24 Strain-hardened, partially annealed, half hard ▪ H22 Strain-hardened, partially annealed, quarter hard alfed.org.uk

Temper Designation - Strainhardened and Partially Annealed H2X In the fully work or strain hardened condition aluminium has high strength but no ductility ▪ H28 fully hard condition

H28

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Temper Designation - Strainhardened and Partially Annealed H2X If we heat the cold worked aluminium to about 50% of its melting temperature or higher, for a short period of time new grains start to seed

H26 Recovery

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Temper Designation - Strainhardened and Partially Annealed -H2X

If we continue to hold the strain hardened aluminium above the recrystallisation temperature for longer times new grains start to grow ▪ Reduction is strength is marked as is increase in ductility

H24 Partial Recrystallisation

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Temper Designation - Strainhardened and Partially Annealed H2X After holding the strain hardened aluminium above the recrystallisation temperature for prolonged times there is significant growth of new grains ▪ Marked reduction in tensile strength reduces and ductility increases

H22 Significantly Recrystalised

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Strain-hardened and Partially Annealed -H2X After a prolonged period of of time above the recrystallisation temperature all new grains have grown, Structure is fully “annealed” and strength and ductility are restored to their original levels.

O Fully Annealed

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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”

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Heat Treatable Alloys In heat treatable grades alloying elements combine with Aluminum during heat treatment to increase the strength of the alloys The alloying elements are ▪ ▪ ▪ ▪

2xxx 6xxx 7xxx 8xxx

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Copper Magnesium and Silicon Zinc Other elements (Tin and Lithium)

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

7075

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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 treatment

7075 -T6 First letter of the designation indicates the treatment used to produce the properties. ▪ ▪

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 (2xxx, 6xxx and 7xxx series)

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Temper Designations Heat treatment -TX British Standard uses the letter T to indicate the thermal treatment, followed by one or more digits: ▪ T1 Cooled from an elevated temperature shaping process and naturally aged. ▪ T3 Solution treated, cold worked and naturally aged to a substantially stable condition. ▪ T4 Solution treated, naturally aged to substantially stable condition. ▪ T5 Cooled from and elevated temperature shaping process and then artificially aged. ▪ T6 Solution treated and then artificially aged. ▪ T7 Solution treated and over aged / stabilised.

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Heat Treating Aluminium In the normal state some alloying element atoms exist within the Aluminium grains but the excess beyond the solubility limits within the grain boundaries ▪ Structures are weak and very ductile

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Solution Treating First stage of heat treatment is to “Solution Treat” that is to heat Aluminium up towards but well below melting temperature and hold on temperature ▪ Alloying atoms move out of the grain boundaries dissolve into the grains of aluminium

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Quenching The next stage of “Solution Treating” is to rapid quench the aluminium to low temperature ▪ Quenching freezes and traps the alloying atoms within the grains

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Quenching Quenching dependent on alloy can be; ▪ Water ▪ Polymer ▪ Air Spray or tank quenching

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Solution Heated “W” condition In solution treated quenched condition trapped alloy atoms slightly increase tensile strength ▪ Solution treated quenched is termed “W” condition ▪ In W condition alloy is still ductile with slight strength increase

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Ageing Reheating “W” condition to an intermediate temperature for long periods of time allows the trapped atoms to migrate together to form “precipitates” ▪ Long heating times up to 100 hours hence called “Ageing”

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Precipitate Strengthening Precipitates form within the grains

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Ageing or Precipitation Hardening Precipitates grow together within the grains ▪ Precipitates strengthen the grains internally so they resist deformation increasing strength ▪ Precipitates are sub microscopic so invisible

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Natural Ageing T3 Tempers Certain 2XXX alloys naturally age very quickly at room temperature, T3 temper

▪ 2017A and 2024 age to a substantially stable condition within 2 to 3 days ▪ Known as naturally ageing alloys

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Ageing T4 Tempers As Ageing proceeds with time number of precipitates grow within grains ▪ Yield and Tensile strength increase with increasing precipitates T4

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Ageing T5 Tempers As Ageing proceeds with time number of precipitates grow within grains ▪ Yield and Tensile strength increase with increasing precipitates T5 T4

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Ageing T6 Tempers As Ageing proceeds with time number of precipitates grow within grains ▪ Yield and Tensile strength increase with increasing precipitates T6 T5 T4

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Peak strength T6 Temper Peak ageing with maximum yield and tensile strength is termed T6 temper ▪ Minimum ductility T6

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Over Ageing T7 Tempers As ageing continues precipitates grow into large coarse colonies and reduce in number ▪ Strength reduces but ductility increases T6 T7

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Over Ageing Tempers Overaged tempers are more stable, more ductile with greater resistance to stress corrosion

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Minimum Specified Temper Properties Properties specified in standards for a temper are minima, so are not an exact temper point

▪ Therefore mechanical properties can be satisfied by a temper range

Minimum T6 Properties

T6 temper range that satisfy minimum properties

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Module 5 Elastic & Plastic Behaviour of Metals

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Topics Elastic & Plastic Behaviour Yield & Tensile Stress Tensile Testing Hardness Testing

Units of Stress and Strain

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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

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

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

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Metal Elastically 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 Behave Elastically Under a load grains elastically stretch

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

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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

▪ Grains have been cold worked, strain hardened ▪ Permanent deformation is “Plastic”

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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, grains have been work or strain hardened and so deformed through cold work ▪ Plastically elongated

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Plastic Deformation Once a metal has yielded, grains have been work or strain hardened and so deformed through cold work ▪ Plastically elongated

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Yield Point or Stress Once yield stress is exceeded, deformation of grains becomes permanent on release of stress

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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 Stress ▪ Yield Stress ▪ Yield point ▪ Elastic Limit

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Yield point Terminology Aluminium has a poorly defined yield point so for engineering purpose it taken as the stress required to produce 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 ▪ Spring zone

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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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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 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 more grains stretch, eventually cross-sectional area is reduced so cannot support applied stress ▪ Stress plateaus levels out

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

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

Text books term for plateau

▪ Ultimate 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

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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 ▪ Theses vices clamp the test piece being tensile tested

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

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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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In the Tensile test a sample is subjected to controlled tension through loaded beams until it fails. ▪ 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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1.1 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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1.1 Measuring Stress and Strain Thus we can construct a graph of Stress against Strain

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Tensile Test

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Units of Stress ▪ 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

▪ 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”

𝜎=

𝐹𝑛 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 − 𝐿 0 𝜀= = 𝐿0 𝐿0

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

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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Global Tensile Test Variations In Europe accepted mill practice to cut a transverse tensile test piece

▪ Marginally greater ductility, marginally lower yield and Tensile strength In the USA and Japan mill practice to cut a longitudinal tensile test piece in direction of rolling extrusion ▪ Marginally greater ductility, marginally lower yield and Tensile strength

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Global Tensile Test Piece Variations Between Europe and USA there are variations in the location from which the test piece is cut

▪

Europe ⅓ width

▪

USA

½ width

In thickness tensile tests the centre of thick test piece should be cut from the ¼ thickness

▪ Thin products ½ thickness

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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

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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Webster Hardness Conversion

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Module 6 Production of Wrought Aluminium

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Drag Tails Drag tails all aligned in the same direction, inclusions dragged out by rolling

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Module 7 Extrusion of Aluminium

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Topics Theory of Extrusion Direct & Indirect Extrusion Products Extrusion Defects

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Theory of Extrusion

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High Temperature Ductility of Aluminium At moderately low temperatures 450 to 500°C, about 80% of its melting point, Aluminium loses strength and becomes extremely ductile ▪ Flow stress of Aluminium alloys is very low and by applying a pressure through a ram Aluminium can be “Extruded” through a steel die

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Versatile Extrusions Ability to be readily and easily extruded sets Aluminium apart from other metals ▪ Most versatile of all metal forming process. ▪ Designers ”Can Put Metal Where They Need It” ▪ The Ultimate “Nett Shape Process”

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Homogenisation First stage of extrusion is to heat the billets to extrusion temperature ▪ “Homogenise” the cast structure to form an uniform grain structure ▪ Extrusion temperatures are those of Solution Heat treatment

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Direct & Indirect Extrusion

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Direct Extrusion Direct extrusion also called forward extrusion is the most general extrusion process. ▪ Operation includes the placement of the billet in a container, ▪ Ram is used to push the billet through the die. ▪ Most common process in the UK Ram

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Container

Billet Die

Direct Extrusion Billet being inserted in Container

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Limitations of Direct Extrusion Major disadvantages of direct extrusion is the force needed for extrusion because of the friction of the billet having to move the container's entire length. ▪ Limited dimensional stability and control ▪ Greatest force is required at the start of the process, decreasing slowly with use up of billet. ▪ Friction between cylinder walls and billet pull back peripheral extrusion flow so flow is core forwards ▪ Back and front end defects

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Indirect Extrusion Indirect Extrusion also called backwards extrusion ▪ In this process, the die is constant whereas the billet & container move together.

Container

Die

Stem

Billet alfed.org.uk

Limitations of Indirect Extrusion Indirect Extrusion also called backwards extrusion ▪ In this process, the die is constant whereas the billet & container move together. ▪ The final and maximum extrusion length is decided by the stem's column strength ▪ As the billet movement is with the container, all the frictional forces are easily eliminated. Die

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Stem

Indirect Extrusion Disadvantages of Indirect Extrusion ▪ This process is not as versatile as the process of direct extrusions, as the cross-sectional area is confined by the stem's maximum size. ▪ Defects and impurities on the billet's surface affect the extrusion's surface. ▪ For anodising or or if its aesthetics are important, the billets have to be wired brushed, chemically cleaned or machined before being used ▪ High cost of dies

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Extrusion Press

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Extrusion Solution Heat Treating On exiting the die the extrusion is at solution heat treatment temperatures so is quenched using air or water to form solid solutions

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Extruded Profiles

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Extrusion Press Stretcher Profiles are transferred to a “Stretcher” where they are plastically Stretched by 1 to 2 % ▪ To straighten and correct any misalignments

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Final Ageing The extrusions are then cut to length and aged in a conventional furnace

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Open Sections Direct Extrusion Simple solid bars and open sections are extruded by direct extrusion through a solid flat die.

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Complex Hollow Sections To extrude complex hollow sections a “Port-Hole” die is used. ▪ Billet is extruded through a die that splits the flow into two or more streams, ▪ Streams are shaped through a bridge ▪ Pressure welded together to emerge as an extrusion

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Extrusion Shape Difficulty

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Extrusion Products

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Vee Grooves Or Decorative Features

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Extruded Heat Sinks Extruded semi conductor heat sinks, enable lap tops and desktops ▪ Aluminium Good Thermal Conductor ▪ Non magnetic

▪ Finned Designs

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Click Snap lock Permanent Lock

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Click Snap-Fit Lock Snap Fit

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Locking Profiles

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Interlocking Profiles Fastening devices for fixing and locking profiles that are part of a joint.

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Interlocking Profiles

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Corner Joints

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Thermal Breaks Thermal bridges introduce an insulating material between two sections interrupting the high heat conduction of Aluminium, two methods

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

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Extrusions 2016 – new Fleetwood Town FC training centre ▪ Aluminium powder coated extrusions and window systems

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Lighter Trucks HYDRO, (Sapa) designed and extruded the Aluminium that helped create the lightweight chassis vehicle for DAF ▪ The brief was to make a new chassis that will provide a minimum weight saving of 30% compared to the conventional steel chassis currently produced.

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Extrusions Demand Extrusions enable simple high strength snap to together assemblies ▪ No welding low energy assembly, recyclable ▪ Battery Electric Vehicles are heavy, and weight limits driving range.

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Extrusion Defects

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Extrusion Defects ▪ Straightness ▪ Poor dimensional control

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Channel type extrusions will exhibit predominantly longitudinal grain flow ▪ Depending on die design some minor grain flow will follow the walls ▪ In the curvatures grain flow will be longitudinal ▪ Hence tensile strength and ductility are maximised in the longitudinal direction

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Minor Grain Flow

Channel Extrusion Grain Flow

Die lines Deep longitudinal Carbon cut marks ▪ Scratches

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Carbon Black Pencil lines Caused by residual graphite lubricant traces ▪ During coating, frequently not removed by pre-treatment

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Shadowing In 6xxx Series alloys ▪ Hot spots, Mg2Si precipitation

▪ Shadowing

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Grain Growth Overheated during extrusion resulting in grain growth, “Orange” peel effect

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Surface Staining Lubricant or chemical contamination of die or billets

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Die or Profile Resultant Streaks Die Pressure lines

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Surface Texture Variable grain size

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Billet to Billet Welding

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Direct Extrusion Back Coring Direct Extrusion defect, where insufficient end has been cut

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Extrusions are Limited only by Imagination Some of the images used today are courtesy of Hydro Extruded Solutions

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Module 8 Drawing Shaping & Forming Aluminium

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Topics Forging Forged Products Cold Drawing

Wire and Rod Production Sheet Metal Forming and Pressing Joining

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Forging Aluminium

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High Temperature Ductility of Aluminium At moderately low temperatures 450 to 500°C, Aluminium loses strength and becomes extremely ductile so easily forged

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Forging Grain Orientation As the metal is shaped during the forging process, its internal grains deform, to follow the general shape of the part. ▪ Grain flow is continuous throughout the part, giving improved strength characteristics ▪ Stronger then cast or machined ▪ Highest strength components

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Forging Most Aluminium is closed die forged ▪ Start with round billet ▪ Heated in furnace ▪ Homogenise and bring to forging temperature ▪ Forge in between two die halves ▪ Most modern forges are hydraulic rather then actual hammers

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Forging Die Forgings can be from grams to several hundred tons in weight

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Hydraulic Piston

High Deformation

Head

Cross Head

Forging is above recrystallisation temperature ▪ High deformations possible ▪ No Cold Work ▪ Deformed grains instantly recrystalise ▪ Eliminate any segregation ▪ Close up any porosity ▪ Highly homogenise fine grains

Die Top

Die Bottom

Base

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Hydraulic Piston

High Deformation

Head

Cross Head

Die Top

Die Bottom

Base

alfed.org.uk

High Deformation

Head

Hydraulic Piston Forging is above recrystallisation temperature ▪ High deformations possible ▪ No Cold Work ▪ Deformed grains instantly recrystalise ▪ Eliminate any segregation ▪ Close up any porosity ▪ Highly homogenise fine grains

Cross Head

Die Top

Die Bottom

Base

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High Deformation

Head

Cross Head

Die Top

Die Bottom

Base

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Forged Products Forged products are used for highly stressed and fatigued applications ▪ Safety critical

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Upsetting Forging of Bolt Starting blank is drawn or extruded wire. ▪ Cut blank to length ▪ Homogenised Annealed ▪ Upset Forge

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Bolt Manufacture Roll thread between two reciprocating dies ▪ Solution Heat treat and final age

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Cold Drawing

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Cold Drawing Cold drawing is cold or strain hardening ▪ Bar wire or tube are pulled through a die ▪ High precision process ▪ High dimensional tolerances

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Bar Cold Drawing Drawing Die

Simplest operation on a draw bench

Dog with Gripping Teeth

Extruded Rod

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Cold Drawing Cold drawing is cold or strain hardening ▪ Only method of strengthening non heat treatable alloys ▪ High fatigue strength

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Cold Drawing ▪ Prototypes

▪ Small production runs ▪ Thinner wall to Diameter then extrusions ▪ Shapes such as Spirals and Flutes are possible

▪ Tubes can be heat treated after cold drawing

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Wire Drawing Wire drawing is a process used to reduce the cross-section of a wire by pulling it through a single, or series of drawing dies. ▪ As the wire is drawn through the die, its volume remains the same, so as the diameter decreases, its length increases. ▪ The starting stock can either be a hot rolled or extruded rod

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Multistage Wire Drawing For high reduction rates several dies can be used in tandem, each separated by a “Bull Block”

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Cold Drawn Tubes Tubes are cold drawn to produce ▪ Smaller diameters then possible through extrusion ▪ Thinner wall ▪ Thin wall large diameter ▪ Extreme precision Tubes are cold drawn between a die and an internal mandrel.

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Cold Drawing Bench Tubes are drawn on a bench ▪ Pulled through a die by a “Dog” on an endless chain

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Aluminium Spinning In Aluminium metal spinning a disc or extrusion or tube is rotated at high speed in a lathe and cold flow formed by a pressure roll or nib tool over a mandrel into an axially symmetrical part. ▪ High speed rotation of the part and the point contact of the tool flow form the metal.

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Spinning Parts produced are seamless, typical uses include Rocket cone noses, cookware and gas cylinders. ▪ Forming parameters and part geometry can be altered quickly. ▪ Tooling costs are low ▪ Minimal metal waste

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Forging & Spinning Wheels Optimal grain flow

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Sheet Metal Forming and Pressing

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Non Heat Treatable Alloys Ductility Non heat treatable alloys 1xxx. 3xxx, 4xxx and 5xxx ▪ Good ductility and bendability in the annealed condition “O”, ▪ Low ductility and limited bendability upon Strain Hardening ▪ Extract from BS EN 485 - 2 : 1994 - Sheet, Strip and Plate - Mechanical Properties

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Heat Treatable Alloys Ductility Heat treatable alloys 2xxx. 6xxx and 5xxx ▪ Reduced ductility and bendability in the annealed condition “O”, ▪ Heat treated bendability has to be carefully considered ▪ Extract from BS EN 485 - 2 : 1994 - Sheet, Strip and Plate - Mechanical

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Deep Drawing Process

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Deep Drawing of Cans

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Stamping or Press Forming “Stamping” or more correctly “Press Forming” forms an Aluminium sheet, into a net shape between a male and female die surface in a stroking or reciprocating press ▪ Press forming uses a multitude of operations, including shearing, piercing, blanking, embossing, bending, flanging, coining and drawing.

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Body in White Press Formed Parts

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Superforming At Elevated temperatures Aluminum become super forming ▪ High ductile ▪ Low strength

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Superforming In Superforming, Aluminium sheet is formed over a heated single surface form tool by “Controlled Air Pressure” Aluminium Sheet

The superplastic forming process (courtesy of Research Gate).

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Superforming

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Hot Form Quench HFQ® HFQ® is disruptive technology for stamping complex-shaped Aluminium components from High-Strength alloys and simultaneously heat treating ▪ Combines Heat Treatment, Press Forming and cold die quenching.

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Hot Form Quench HFQ® HFQ® is a disruptive technology for stamping complex-shaped Aluminium components from High-Strength alloys ▪ Combines Heat Treatment, Press Forming and cold die quenching. ▪ Superform hot part

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Hot Form Quench HFQ® Size and set in the tool whilst in the “Solution Treated” condition ▪ Perfect size

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Hot Form Quench HFQ® Final age in oven to develop properties

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Joining of Aluminium

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Clinching Clinching is cold punching, used to create friction interlocking, high strength joints. ▪ Clinched joint is significantly “Strain Hardened“, so stronger than the surrounding parent Aluminium. ▪ A punch through impact extrusion causes local incision, and then compresses the Aluminium to create the clinch.

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Hemming Simple cold-forming process, were the edge of one sheet is folded over another to form a mechanical joint. Particularly used to join the outer skin panels of car doors to the frames. Two methods are used: ▪ Hemming pressing, normally a three-stage operation to fold forward and hem ▪ Robot rolling In modern production a sealant or adhesive is inserted into the joint, to weather-proof and seal against galvanic corrosion.

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Self Piercing Rivets Self-piercing riveting are high-speed mechanical fastening process for point joining Aluminium ▪ Steel rivets zinc plated ▪ A single-step technique, that clinches the sheets. together in a mechanical joint ▪ Jaguar car uses 3000 rivets

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Aluminium Rivets Given that the 7XXX series of Aluminium used extensively for aircraft and in aerospace cannot be easily welded such structures are riveted ▪Rivets are manufactured from cold drawn tube Alloys 2017, 2024, and 2117 used for structural ▪ Solution treated and frozen ▪Riveted and then allowed to naturally age Alloys 1100, 3003 and 5052 used for non structural ▪ Work harden through riveting

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Mechanical Fixture Joining of Aluminium Aluminum can be mechanical joined using every known type of mechanical fixture, special consideration has to be given to ensure no crevice or galvanic corrosion ▪ Bolts ▪ Huckbolts ▪ Screws ▪ Flowdrills ▪ Flow Drill Screws

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Metal Gas Arc Welds Metal Inert Gas (MIG) and Manual Gas Arc Weld (MGAW) use non heat treatable 4xxx and 5xxx filler alloys. ▪ Welds created by melting filler metal in the joint gap ▪ Large weld beads require to compensate for loss of strength

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Tungsten Inert Gas Tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable Tungsten Electrode to melt the parent metal to form the weld ▪ The weld area is protected from oxidation by an inert shielding gas Argon or Helium ▪ A filler rod can be used but not normally for Aluminium

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Resistance Spot Welding

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Spot Welds in Typical Car

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Laser Welding Laser welding uses a focused coherent light beam to produce the highest energy concentration of any known source of energy. ▪ High power density of the order of 1 MW/cm2, resulting in micro-heat affected zones and high heating and cooling rates. ▪ The welding spot size of the laser is small of the order of 0.2mm.

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Friction Stir-Welding Friction Stir-Welding is a solid state welding process, ▪ No melting, where a rotating tool plastically mixes metal from one side of the joint to the other.

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Adhesive Application technology

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Bonded Extrusion Joints Extruded mechanical joints provide maximum contact area for bonded joints and can be readily design to eliminate the risk of peel.

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Module 9 Corrosion & Protection of Aluminium

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Topics Corrosion Corrosion Types Galvanic Series Protection Methods Anodising

Powder Coating

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Corrosion Corrosion is a natural process that converts a refined metal to a more stable form, such as its oxide, hydroxide, or salt.

▪ It is the gradual destruction/dissolution of a metal by a chemical and/or electrochemical reaction with its environment.

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Aluminium and Corrosion Metallic Aluminium is very reactive with atmospheric oxygen, and forms a surface passivation film of Aluminium oxide Al2O3 (alumina). ▪ Alumina gives Aluminium exceptional corrosion resistnce ▪ Alumina “Self Heals”, oxidises if damaged Acid

▪ Chemical stable

▪ Will not corrode within PH 4.0 to 8.5 ▪ Will not corrode in mild acid or alkali alfed.org.uk

Alkali

Aluminium is 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 in middle of Trafalgar square

▪ No coating nor protection ▪ Favourite place for pigeons

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Aluminium Oxidation in Air High resistance of Alumina to corrosion begins to form immediately the metal is exposed to air and slowly increases in thickness ▪ Slowly increases resistance to corrosion ▪ Humidity affects the rate of growth and thickness ▪ Prolonged exposure to a moist atmosphere causes slight white to grey corrosion.

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Relative Corrosion Resistance of Aluminium Alloys ▪ ▪ ▪ ▪ ▪ ▪

1xxx series 3xxx series 5xxx series 6xxx series 7xxx series 2xxx series Alloy Type

(pure) (Mn) (Mg) (Si/Mg) (Zn/Mg) (Cu) 1XXX

3XXX

Good Good Good – Very good Moderate - Good Poor - Moderate Poor 5XXX

6XXX

7XXX

2XXX

7XXX

Corrosion Resistance

CHEMICAL CODE

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AL Mn

Al Mg

Al Mg SI Al Zn Mg

Al Cu Mg Al Zn Mg Si Cu

Atmospheric Corrosion In normal rural atmospheres, and in moderately industrial atmospheres, Aluminium’s durability is excellent. ▪ In highly sulphurous atmospheres, minor pitting may occur. ▪ The presence of salts in the air reduces Aluminium’s durability, so pitting corrosion may occur, ▪ Maximum pit depth is generally only a fraction of the thickness of the material..

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Aluminium Corrosion in Water Aluminium is particularly resistant to rain and dew both are acidic

▪ Alloys are frequently found in sea water with 5XXX performing the best but also used are 1XXX, 3XXX & 6XXX series ▪ Copper 2XXX & 7XXX are less resistant and not suitable to sea water

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Stagnant Water Rain water washes off corrosion agents thus protecting Aluminium ▪ Pigeon poo!!!! Poor drainage results in standing stagnant water ▪ Stagnant water is free from oxygen ▪ Prevents prevent Alumina film forming ▪ Stagnant water builds up pollutants ▪ Problems with shielded buildings Design water run off’s

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Crevice Corrosion Crevice corrosion occurs in narrow, liquid-filled crevices, particularly marine atmospheres where oxygen is excluded and electrolytes concentrated

▪ Stagnant Oxygen free Water

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Filiform Corrosion Filiform is a type of crevice corrosion that can occur under organic coatings, paint or powder. ▪ Caused by stagnant water trapped ▪ Starts at edges or coating defect and travels beneath the coating in irregular tunnels, ▪ Cosmetic problem & is rarely associated with substantial metal loss

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Resistance to Chemicals Aluminium has good resistance to many chemicals. ▪ Inorganic acids and strong alkaline solutions are very corrosive for Aluminium. ▪ In moderately alkaline water solutions, corrosion prevented by silicate inhibitors such as found in Dish Washer detergents!

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Bacterial Corrosion Due to the formation of passive oxide film Aluminium is one of the most resistant metals to attack by bacteria

▪ Bacterial colonies can produce corrosive chemicals ▪ Can cause oxygen depletion stagnant water ▪ Production of water soluble organic acids

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•

More Noble Cathode +Ve – Platinum – Gold – Carbon – Silver – Stainless steel (passive) – Nickel alloys (passive) – Copper alloys – Tin – Lead – Titanium – Cast iron – Steel – Cadmium – Aluminium – Zinc – Magnesium

•

Less Noble Anode –Ve

Galvanic Corrosion Galvanic corrosion is “Electrochemical” process in which one metal corrodes preferentially when it is in contact with a different metal, when both are in an “Electrolyte” ▪ Metals act as battery and preferential corrosion is accelerated

▪ Least noble metal in the combination becomes the anode and corrodes whilst most noble of the metals becomes the cathode and is protected against corrosion. ▪ Aluminium is the least noble or anodic metal in most combinations with other metals, so is at a greater risk of galvanic corrosion. alfed.org.uk

Soot Galvanic Corrosion Soot is strongly cathodic with so will cause galvanic corrosion of anodic Aluminum ▪ Main threat is carbon or soot from diesel engines ▪ Soot also acts as a sponge for bacteria

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Corrosion Protection

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Corrosion Protection Methods of protecting Aluminium: ▪ Barrier Coating, seal the surface against attack ▪ Modify surface to resist attack – Aluminium Oxide – Alumina

▪ Galvanic protection – Make Aluminium more Noble – Insulate against stray electrical currents ▪ Modify the environment – Add an inhibitor alfed.org.uk

Barrier Coatings Barrier coatings prevent corrosion, by physically separating the environment from the Aluminium ▪ Paints ▪ Lacquers

▪ Anodising ▪ Powder coat

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Cladding with Pure Aluminium Roll cladding produces a three layer sandwich with a core of a poor corrosion resistant alloy such as 2XXX series or 7xxx series, protected by thin outer skins of corrosion resistant pure Aluminium 1XXX series

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Modify Corrosion Environment Eliminate attacking species or interrupt the chemical process Add inhibitors to aqueous electrolytes ▪ Inhibitors in dish washing

▪ Car cooling system anti-freeze ▪ Machining coolants ▪ Prevent stagnation of water

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Modify Corrosion Environment Dry atmosphere, remove aqueous electrolytes ▪ Humidity is controlled in clean rooms, in airplanes Correct Acidity/Alkalinity/PH ▪ Agriculture modify growing environment on global scale

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Sacrificial Protection Make Aluminium more noble by use of Magnesium sacrificial anodes ▪ Deliberate connect Aluminium to sacrificial Anode of Magnesium ▪ Extensively used in marine industry Electroplate with Zinc, (normally over pure Aluminium)

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Electrical Protection Pass an electrical current through Aluminium to stop Galvanic action ▪ Negative Earth in cars

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Electrical Insulation Where Aluminium is used in combination with another metal galvanic corrosion can be prevented by electrically insulating them from each other.

▪ The insulation has to break all contact between the metals.

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Coatings

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Reasons to Coat Aluminium Reasons for coating include; ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪

Aesthetic Appearance Colouring Reflectivity, polishing, brightening PH outside range, resulting in corrosion risk Severe environment Improved engineering surfaces Heat transfer, black for absorbing, white for reflectivity Adhesive bonding, "flash” anodizing Screen printing

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Wet Coil Painting Continuous wet coil coating is the most common process for rolled Aluminium products. ▪ Coil is unwound at a constant speed, passing through pre-treatment, coating baths and curing furnaces before being recoiled.

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Electropaint E-Coating is the dominant Automotive Electropaint method. ▪ Water based paint ▪ Uses electrical current to “Condense” the paint onto part ▪ Oven Baked after electrodeposition to crosslink ▪ Automotive companies give guarantees of 10 years against underbody corrosion

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Anodising

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Anodising Anodising is an electrolytic-chemical process, that converts the Aluminium surface into, Alumina. ▪ Article is made the anode of an electrolytic cell with sulphuric acid as electrolyte ▪ Electric current is passed through cell releasing oxygen on the surface of the article oxidising it into Alumina

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Colouring Anodised Surface Anodised coating is porous

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Colouring Anodised Surface Anodised coating is porous so can be in-coloured ▪ Dye colouring, freshly anodised part is immersed in a liquid solution of dye, absorbing dye ▪ Electrolytic Colouring, after anodising, the metal is immersed in a bath containing a metal salt. Current is applied which deposits the metal salt into pores.

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Sealing anodised Coat To prevent ingress of contaminants or leaching out of colours, porous Anodic coatings are sealed by immersion in water at 98°C ▪ Converts the anodised layer into “Boehmite” actually Aluminium Oxide Hydroxi

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Recommended Anodised Film Thicknesses ▪ ▪ ▪ ▪ ▪ ▪

100µm Special extreme applications 25µm Severe abrasion and corrosion 20µm Normal outdoor buildings or transport or for food uses 15µm Severe indoor abrasion in a clean environment 10µm Normal indoor applications 5µm Indoor cosmetic

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Advantages of Anodising ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪

No risk of Filiform corrosion Highly durable Self Healing Ceramic Proven Architectural service lives in excess of 50 years Won’t chip, flake, peel or chalk Maintains metallic appearance of Aluminium Environmentally friendly, No VOC’s No heavy metals Inexpensive to produce and maintain

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Architectural Anodising Architectural finish used in permanent, exterior and static situations were both appearance and long life are important.

Cambridge University Library: 1934 - anodised Aluminium windows manufactured by James Gibbons alfed.org.uk

East Street Exchange Red corrugated Aluminium extension named East Street Exchange, has been added to a 1960s library in southeast giving it "a new lease of life". ▪ Created by “We Made It” architects as part of renovation of the East Street Library in Walworth, the striking red structure is designed to contrast with the existing building ▪ Striking red facade of East Street Exchange is anodised

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Built environment ▪ Aluminium façade; Anodised discs on Selfridges building

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Powder Coating

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Powder Coating Powders are organic thermoset coatings that are applied electrostatically as free flowing dry powders and then cured under heat to flow and form hard

▪ Thermoset Powders once cured cross link to form strong molecular chains so do not melt on reheating

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Pre-treatment Critical to the powder coating process is pretreatment which creates an air and watertight ‘seal’ to the Aluminium. ▪ Minimum pre-treatment should include degreasing, acid, or alkaline etching of the surface, and then passivation. ▪ Passivation can include hexavalent chromate, non- chromate treatments or pre-anodising.

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Application of Powders Powders are electrostatically sprayed onto Aluminium. ▪ Powder is electrostatically charged, whilst the work piece and supporting rack are electrically grounded ▪ Charged powder is electrostatically are attracted to grounded work piece, ensuring an even coating.

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Powder Coating Bake Cure The electro-deposited powder is then polymerised, ▪ Baked in an oven at between 180 to 210º C ▪ Melts and flows into a smooth continuous pore-free coating ▪ Forms chemical cross links ▪ Profiles exit the oven and are allowed to cool naturally.

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Powder Coating Advantages ▪ Coating layer adhered to the metal ▪ Wide range of colours ▪ Different textures available ▪ Wide range of different glosses available ▪ Good corrosion resistance ▪ Wear resistance ▪ High chemical resistance ▪ Dirt repelling properties depend on finish chosen ▪ Powder coatings contain no solvents and release little Volatile Organic Compounds (VOC) into the atmosphere.

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The Shard Cladding and ceiling tiles ▪ Architect Renzo Piano

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Canaletto Cladding & extrusions ▪ Architect UN Studio

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Lowe House Health Centre, St Helens White rendered building with perforated aluminium panels in various colours offering vertical brise soleil solar shading

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Egypt, GIZA Museum ▪ Architect: Heneghan Peng

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Coating Performances Film thicknesses of the applied coatings and their respective durability under external conditions.

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Module 10 Casting Technologies

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Topics Liquid Metal Engineering Casting Structures Aluminium

Casting Technologies

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Liquid Metal Engineering Casting most cost effective way of producing a wide range of components in metal ▪ Cost effective way of producing high volumes of repetitive components ▪ Simplest forming method for metal parts ▪ Only method to manufacture components with complex internal cavities and hollow channels

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Size Does Not Matter Casting is virtually independent of size producing from tiny macroscopic components to colossal

▪ World's largest steel castings, weighing approx. 350 tons, poured from almost 600 tons of liquid steel

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Cast Macrostructures Cast Aluminium is extremely heterogeneous ▪ Large localised variations in chemical analysis ▪ Segregation

▪ Porosity ▪ Variable mechanical properties

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Casting Products ▪ Art ▪ Automotive

▪ Mass transport ▪ Aerospace ▪ Architecture ▪ Medical ▪ Telecommunications ▪ Pumps and valves ▪ General engineering alfed.org.uk

Aluminium 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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Aluminium Casting Processes 100,000

VACUUM DIECASTING HIGH PRESSURE DIECASTING

75,000 Components Per Annum 50,000

GRAVITY CASTING SQUEEZE CASTING AUTOMATIC SAND CASTING

25,000

INVESTMENT CASTING SAND CASTING

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Tooling/Die Costs

Sand Casting A wooden or steel pattern a replica of the casting to be made ▪ Sand is packed and rammed around the pattern.

▪ The pattern is withdrawn to leave a cavity in the mould. ▪ Channels are cut through the mould to allow the liquid metal to enter, to form reservoirs and feeders ▪ Cores are inserted into mould cavity for holes in casting. ▪ Finally mould washes are applied

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Sand Casting Manufacture of sand mould

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Sand Castings Advantages ▪ Low tooling and pattern costs ▪ Largest size castings possible by any casting method ▪ Suited to complex shapes and cores ▪ Very low gas porosity is possible

▪ Slow, even cooling rate

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Sand Castings Disadvantages ▪ Low production rate ▪ 5mm minimum wall thickness ▪ Poor linear dimensional tolerances e.g. 4mm / m ▪ Rough surface finish

▪ Coarse grain size compared to die casting ▪ Casting weights in the range of 0.1 Kg - 10,000 Kg ▪ Economical production range 1 - 1000 castings.

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Sand Castings

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Gravity Die Casting Gravity die castings are produced by pouring molten Aluminium into permanent steel moulds ▪ A simple steel die, coated with a refractory wash. ▪ A cheaper alternative is cast iron. ▪ Good dimensional stability and thermal fatigue resistance.

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Gravity Die Casting Advantages ▪ High Volume, compared to sand casting ▪ Lower set up cost than Pressure Die castings ▪ Can employ cores ▪ Low gas porosity levels

▪ Fine grain sizes ▪ Near net shape; less finishing than for sand castings. ▪ Heat treatable

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Gravity Die Casting Disadvantages ▪ Minimum wall thickness 3-5mm ▪ Linear tolerance is approximately 3 mm/m ▪ Surface finish better than sand casting ▪ Limited shape complexity

▪ Casting weight range 0.1 Kg - 50 Kg ▪ Economical production range 500 - 2500

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Gravity Die castings

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Low Pressure Die Casting ▪ Metal injected slowly into die by pressurised gas, usually air ▪ Pressure is maintained until solidification complete.

▪ Slow filling promotes high integrity castings. ▪ Good surface finish ▪ Relatively slow process ▪ Often used for wheels ▪ Wheel cycle times up to 5minutes

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Low Pressure Die Casting Advantages ▪ Thin wall thickness possible 2 to 3mm ▪ Closer tolerances than gravity casting ▪ Surface finish better than gravity but worse than pressure die casting stand ▪ Low Porosity

▪ Castings are heat treatable ▪ Sand cores may still be used to allow complex castings ▪ Die costs lower than for pressure die casting

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Low Pressure Die Casting Disadvantages ▪ Production rates up to 30 per hour ▪ Size of casting limited by machine size ▪ Feeding thin sections through thick sections is not recommended ▪ Casting weight range 5 Kg - 25 Kg

▪ Economic production rate more than 1000 parts

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Low Pressure Die Cast Engine cylinder heads, heat treated

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High Pressure Cold Chamber Die Casting In High pressure cold chamber die casting, molten Aluminum is injected into metal moulds • High pressures of the order of 1000psi. • Molten Aluminium is poured into the shot chamber and then injected into the mould by the “Piston” through a narrow “Gate” • Component is allowed to cool between 7-35 seconds

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High Pressure Die Casting Advantages ▪ Fast reduction rates can be high in the order of 200 per hour ▪ Thin wall thickness of 1mm possible ▪ Best surface finish is produced by this casting method ▪ Very near net shape, reducing machining requirements

▪ Very fine grain structure produced ▪ Castings have high strength in the as-cast condition ▪ Good linear tolerances and repeatable properties are obtained

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High Pressure Die Casting Disadvantages ▪ Size of castings limited by the machine ▪ Shrinkage-free, thick sections are difficult to cast, Porosity can be a concern ▪ Liquid metal fired in at about 40 m/s. Leads to air entrapment ▪ Castings cannot be heat treated because of porosity,

▪ High start up and capital costs ▪ High tooling costs ▪ Casting weight range 0.01 Kg - 25 Kg ▪ Economic production rates more than 10,000 per annum alfed.org.uk

High Pressure Die Cast Engine blocks not heat treated

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Vacuum Assisted Die Casting Technically reduced atmospheric pressure casting

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Vacuum Assisted Die Casting Advantages ▪ Rejections due to porosity are reduced. ▪ Cold Shuts reduced. ▪ Casting can be heat treated. ▪ Excellent surface quality is ensured. ▪ Product density and strength are increased. ▪ Larger, thinner, and more complex castings are made possible.

▪ Die life is extended. ▪ Flash is reduced or eliminated. alfed.org.uk

Vacuum Assisted Die Casting Disadvantages ▪ High capital costs ▪ High running costs ▪ High die costs ▪ High maintenance costs ▪ Difficult and long set up periods

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Vacuum Assisted Die Castings

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Squeeze Casting Squeeze Casting also known as liquid-metal forging. ▪ In squeeze casting process an accurate measure of molten Aluminium is injected slowly into the mould via a wide “Gate” ▪ Pressure continues to be applied to molten metal until it has solidified. ▪ Feeders are heated to ensure shrinkage is fed with liquid Aluminium.

▪ Because the high pressure is applied during solidification, porosities caused by both gas and shrinkage can be prevented or eliminated.

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Squeeze & High Pressure Die Casting Differences

High Pressure Die Casting ▪ Small Gate Area ▪ High fill speeds ▪ Aluminium Sprayed into die ▪ Rapid cooling / solidification ▪ High production rate ▪ Near nett shape alfed.org.uk

Squeeze Casting ▪ Large Gate Area ▪ Slow fill speeds 1.5 - 4.0 seconds ▪ Fluid / laminar flow of Aluminium ▪ Slow solidification under pressure ▪ High casting mechanical integrity

Squeeze Casting Advantages ▪ Improved near “Nett Shape”

▪ Almost no shrinkage porosity ▪ Superior mechanical properties ▪ Improved fatigue life ▪ Heat treatable components ▪ High dimensional stability ▪ Faster cycle times over gravity & low pressure ▪ Complex shapes, thicker wall sections alfed.org.uk

Squeeze Casting Disadvantages ▪ Slower than high pressure die casting ▪ High capital and tooling costs ▪ Casting weight range 0.01 Kg - 25 Kg ▪ Economic production rates more than 10,000 per annum

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Squeeze Castings

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Investment Casting Investment casting uses complex "wax pattern" to create complex ceramic moulds. ▪ A wax model is made of part by carving or pouring wax into a mould.

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Investment Casting ▪ Wax model is dipped in a refractory slurry ▪ Wax is melted out of the mould to leave exact cavity.

▪ Refractory mould is furnace baked

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Investment Casting ▪ Molten Aluminium is then poured into the mould cavity ▪ Allowed to solidify

▪ Mould broken away from the casting

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Investment Casting Advantages ▪ Can form complex shapes and fine details ▪ Very good surface finish ▪ Extreme accuracy

▪ Minimal secondary machining

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Investment Casting Disadvantages ▪ Expensive, high labour and tooling costs ▪ Only small castings ▪ Time-consuming process

▪ Economical production rates 1 to 1000

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Investment Die Castings

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Additive Manufacturing Additive manufacturing process uses a high-powered laser in an Argon atmosphere to directly melt together successive layers of powdered metals and resins into three-dimensional solid parts. ▪ The more complex the component, the more economical the process ▪ Complex geometries and precise internal features that cannot be made by traditional machining ▪ Multiple, identical parts can be built on a single platform at one time

▪ Minimum of material waste ▪ Fully dense

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Direct Metal Laser Melting

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Additive Manufactured Heat Exchanger

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Additive Manufacturing Developments Casting moulds and inserts ▪ Optimal for prototypes ▪ Low cost production steel moulds ▪ Sand moulds can be additive produced ▪ No shape limitations ▪ No machining constraints, internal shapes and complex webs possible ▪ Internal cooling channels and ducts can follow shapes, not limited by boring and plugging

▪ One piece were machining access might require multiple assemblies ▪ No tooling costs alfed.org.uk

Additive Manufacturing Aluminium is not optimal metal for additive manufacturing ▪ Extreme affinity for oxygen to form Alumina ▪ High Conductivity requires very high powered lasers ▪ High conductivity accurate temperature control to prevent secondary melting ▪ Suited for prototypes

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Questions