This document discusses aluminium and its alloys. Key points include: - Aluminium is a lightweight metal that is abundant, corrosion resistant, and highly conductive. It is extracted from bauxite via electrolysis. - Aluminium alloys include heat treatable alloys like duralumin that can be strengthened via precipitation hardening as well as non heat-treatable alloys. - Common fabrication methods for aluminium include casting, rolling, extrusion, and welding. Various heat treatments can further influence the properties of aluminium alloys. - Applications of aluminium alloys span transportation, infrastructure, packaging, and more due to its combination of properties like strength, conductivity, and corrosion resistance

1. Non-Ferrous Metals
and Their alloys

2. Aluminium and its alloys

3. Aluminium
• Large growth in use since 1950 (6 times)
• Abundant metal - 8% of earth’s crust
• Light weight SG = 2.7
• Moderate to high strength (depending on alloy)
• Conductivity high (pure metal & low alloys)
• Corrosion resistant (Al2O3 coating)
• Reflectivity high
• Non-magnetic

4. Extraction
• Al2O3 obtained from bauxite by the Bayer process
• Al2O3 reduced electrolytically by the Hall-Heroult process to
make aluminium
– The large energy requirement for this process is the major
proportion of the cost of aluminium, even with cheap
energy sources.
Work Hardening of Aluminium

5. Fabrication
• Ductile metal easily fabricated by rolling and extrusion
– Commercially pure metal can undertake a cold reduction
of 80 - 90% without annealing
– Anneal at 350˚C
• Machineability is good, but limited by the tendency to gall

6. Aluminium alloys
Deformable and heat treatable
1) Al-Cu-Mg-alloys (duraluminium)
2) Al-Cu-Mg-Si-alloys (forgable)
3) Al-Mg-Si-alloys (corrosion resistance)
4) Al-Zn-Mg-Cu-alloys (high strength)
5) Al-Cu-Mg-Ni-Fe-alloys (heat resistance)
Rm → 500 N/mm2
; Rp0,2 → 390 N/mm2
; A → 25%
Deformable and non heat treatable
1) Al-Mn-alloys
2) Al-Mg-alloys (magnalium)
Rm → 300 N/mm2; Rp0,2 → 150 N/mm2; A → 25%
Plane bearing alloys (for mono- and bimetallic bearing shells)
Al-Sn; Al-Ni; Al-Cu-Sb Typical structure of bearing material

7. Aluminium alloys
Cast alloys
1) Al-Si-alloys ↓ Rm (250), A = 1,7 % Pumps and engine
bodies, cylinder heads
2) Al-Cu-alloys Rm ↑ than I group
↓ high temp. strength
Cylinder heads,
apparatures bodies
3) Al-Si-Cu-alloys Rm ↑ than I group
↓ high temp. strength
→ 350 °C
4) Al-Mg-alloys
(magnalium)
Rm, A; good corr. resist.;
↓ castability
→ 100 °C
5) Al- other inclusions high temperature
strength
→ 350 °C
parts of aircraft engines
Rm → 340 N/mm2
; A → 8% (depending on casting mode)

8. Aluminium Lithium
• 1 to 4% Lithium raises strength, raises elastic modulus by up to
6%, lowers density by up to 4%
• Strengthened by Al3Li, Al2CuMg, AL2CuLi precipitates on aging
(depending on composition)
– Up to 585 MPa yield typical
• Good weldability as well as high strength
• Inferior toughness, ductility & stress corrosion performance
• Aerospace applications
Fabrication
• Machineability better than steel
• Cold and hot workability excellent
• Complex extrusion forms common
• Joined by fusion and non-fusion welding, brazing, soldering,
adhesive bonding and mechanical methods

9. Aluminium alloy designations
Deformable alloys
Series 1000 – pure Al
2000 – Al-Cu-alloys (for ex EN-AW-2014)
3000 – Al-Mn-alloys
4000 – Al-Si-alloys
5000 – Al-Mg-alloys
6000 – Al-Mg-Si-alloys
7000 – Al-Zn-alloys
8000 – Al-Fe-alloys
Cast alloys
Series 10000 – pure Al
20000 – Al-Cu-alloys
40000-48000 – Al-Si-alloys (for ex EN-AC-44000)
50000 – Al-Mg-alloys
70000 – Al-Zn-alloys
Designation (chemical composition based)
• deformable alloys – EN-AW...(EN-AW-AlCu4Mg1)
• cast alloys – EN-AC...(EN-AC-AlSi11)
Designation of heat treatment (EN515)
• O – annealed (for ex. 01, 02, 03)
• H – work hardened (for ex. H1, H2...H9)
• W – quenched
• T – heat treated (for ex. T1, T2...T10, T31, T3510)
Mainly used: T4 – quenching + natural ageing
T6 – quenching + artificial ageing

10. 5000 series alloy applications
• Very popular alloys
• Marine, auto and aircraft applications
• Pressure vessels, cryogenics
• Communication towers
• Armour plate
• Some alloys prone to exfoliation or stress corrosion if Al8Mg5
forms in grain boundaries
– Avoid high Mg over 65˚C

11. Alclad
• Many multiphase alloys have inferior corrosion resistance
• These alloys are available as Alclad sheet or plate
• This material has a thin layer of pure aluminium roll bonded
to one or both surfaces to provide corrosion resistance
• Fabrication must be undertaken so as to maintain the
integrity of this coating

12. Alloy types and properties
• Strain hardened alloys (plus solid solution hardening)
• Precipitation (age) hardened alloys
• Dispersion strengthened alloys
• Yield strength from 28 MPa for 1050-O to 455 MPa for 2024-
T815
• Strength increases at low temperature
• No ductile-brittle transition

13. Precipitation (age) hardening
• Solution treatment - α+β
alloy is heated into a
temperature range to
dissolve all B. Quenching
retains B in solution
(supersaturated)
– Soft & ductile condition
• Aging - holding solution
treated alloy at a
temperature at which fine
precipitates of β are formed
– Strengthened condition
T (deg C)
Percentage BPure A
Liquid
L + α
α + β
α

14. Composition effects
• Alloys with low levels of B will only display a weak age
hardening effect
• Alloys with a high level of b, which cannot be dissolved on
solution treatment only display a weak hardening effect
• Alloys with with intermediate levels of B have the highest
strengthening effect
• These alloys only display a narrow temperature range for the
single phase phase field
• These alloys also have a wide solidification range, are likely to
crack during welding, and therefore have low weldability and
castability

15. Heat treatment of Al-alloys
Quenching → water → α-structure Rm, Rp0,2 ↓; A, Z ↑
Ageing: Naturally aged (20 °C) → structure α + Guinier`-Preston zones
artificially aged Rm, Rp0,2↑, A, Z ↓
low (100...150 °C) high (200...250 °C)
(Rp0,2/Rm = 0,6...0,7) (Rp0,2/Rm=0,90...95)
Result –
precipitation
hardening

16. Casting processes
• Die casting
• Permanent mould casting
• Sand mould casting
• Plaster casting
• Investment casting
– Lost wax
• Centrifugal
• Continuous casting

17. Cutting and machining
• Plasma cutting - edges require further dressing
• Shearing
• Sawing
– Extra clearance for chip release
• Planing and milling
– Power plane or rotary tungsten burrs
• Filing and scraping
Joining
• GTAW and GMAW are the most common processes
• OFW and MMAW require powerful fluxes
• Resistance and pressure processes can be used for many
alloys
• Brazing and soldering some application
• Adhesives and mechanical fastening widely applicable

18. • Depends on welding process and alloy composition
• Varies from readily weldable to not recommended
• Tenacious oxide film
• Prone to contamination
by O2, N2, H2
• High conductivity, low
melting temperature
• Slags are tenacious,
corrosive
• Welds tend to under
match strength
• Solidification cracking,
particularly of many
heat treatable alloys
Weldability
Fusion WeldingSolid Phase Welding
• Cold welding - 75% thickness
reduction at lap joint
• Ultrasonic welding - 1.5mm lap
joints
• Explosion welding - cladding and
lap joints
• Friction welding - Low weldability
alloys and dissimilar
combinations,
• Friction-stir welding

19. Brazing
• Restricted range of alloys
– 1000, 3000, 5000 with <2% Mg, 6000
• Al-Si filler materials
• Torch, dip, furnace or vacuum processes
• Clean parts by etching
• Fluxes are fluoride and chloride salts
– Residues MUST be removed
• Temperature control is critical

20. Mechanical properties
• Depend on
– Casting process
– Composition
• Alloy modification with sodium finer grain
– Heat treatment
• Up 435 MPa Yield strength possible
• Ductility up to 20%, but mostly <5%

21. Aluminium Products
• Cast alloys
• Wrought products
– Sheet, plate, foil
– Rod, bar, wire, tube
– Standard and special extruded shapes
– Forgings, impacts (combined extrusion and forging)
• Powder metallurgy (dispersion strengthened) products

22. Structural applications
• Static building structures (AS1664 series)
• Scaffolding and ladders
• Transportation
– Aerospace, road (trucks, buses, trailers), railway
• Machinery and industrial equipment
– Non-sparking tools, roofs to tanks, chemical process
vessels, jigs, patterns, instruments
• Consumer durables
– Structure of appliances: refrigerators, furniture, cooking
utensils

23. Thermal and Electrical
• Electrical
– Pure Al has 200% of the conductivity of copper weight for
weight
– Conductors, heat sinks, capacitors, wave guides,
antennas
• Reflectors
– Mirrors, search lights, loft insulation
Miscellaneous applications
• Packaging
– Drink cans, foil, hermetically sealed packs
• Powders and pastes
– Reflective paint, printing inks, pyrotechnics, thermit
welding

24. Limitations
• Temperature range of -240˚C to +200˚C for normal alloys
• Up to 350˚C for special alloys
• Up to 480˚C for short periods for dispersion strengthened
alloys
• Low modulus of elasticity, requires stiffening
• Inferior wear, creep, & fatigue properties to steel