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Alloy Designation System

Alloy Designation System. Wrought aluminium alloys were standarized by Aluminium Association in 1954. X X X X. Alloy Group. Impurity Limit. Min. Al % after decimal point. 1060: 1xxx series having 99.60% Al. Designation Table. Temper Designation-I.

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Alloy Designation System

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  1. Alloy Designation System • Wrought aluminium alloys were standarized by Aluminium Association in 1954. X X X X Alloy Group Impurity Limit Min. Al % after decimal point 1060: 1xxx series having 99.60% Al.

  2. Designation Table

  3. Temper Designation-I Five basic tempers: F denotes as Fabricated; O denotes annealed, Recrystallized; H denotes strained hardened; T for heat treated and W as Solution heat treated F: Tempering done by normal manufacturing process. O: The softest temper H: Mechanical properties increased by cold working. Hxyz: H1yz: Strained hardened only. H2yz: Strain hardened and partially annealed - Purpose??? H3yz: Strained hardened and stabilized – Purpose??? y: Amount of cold working H18z: Full hardened;H14z: Half hardened z: identifies a special set of mechanical properties AV-485

  4. Temper Designation-II W: Alloys which spontaneously age at RT after solution treatment. T: Thermally treated with or without supplementary SH. Produces stable tempers. Followed by numbers from 2 to 10. T2: Annealed for cast products only T3: Solution heat-treated and then cold worked T4: Solution heat treated and naturally aged to stable state T5: Artificially aged T6: Solution heat treated and artificially aged T7: Solution treated and then stabilized T8: Solution treated, cold worked and then artificially aged T9: Solution treated, artificially aged and then cold worked T10: Artificially aged and then cold worked 4

  5. Aluminium Copper (2xxx)-I Interesting reading from AVp485 5

  6. Al-Cu System (Al-Rich) Al-Mg System (Al-Rich) Cu-Mg System Simple Phase Diagrams Even for simple 2xxx alloy (Al-Cu-Mg), need data for 3 binaries and information about ternary phases S - Al2CuMg, T - Mg32(Al,Cu)49, V - Al5Cu6Mg2, Q - Al7Cu3Mg6 Ternary Phases MTDATA predicted phase diagrams Real, commercial Al-alloys may contain > 10 alloying elements! See HDB-Al1-pdf

  7. Cliq1 Csol1 Cliq2 Csol2 Cliq3 Csol3 Solidification Microstructures Solidification occurs rapidly under non-equilibrium conditions However, given certain assumptions, thermodynamic calculations and the equilibrium phase diagram can still be used to predict solidification microstructure Microstructure Scheil Solidication Model - Assumptions: C0 (i) Local equilibrium exists at the solid/liquid interface (ii) No diffusion in the solid phases (iii) Uniform liquid composition (iv) No density difference between solid and liquid Liquid Csol0 T Solid % Solute

  8. Temperature RD 50nm Microstructural Changes Time Cast Homogenized Rolled Solutionized Aged

  9. Aluminium Copper (2xxx)-II Duralumin -2017 oldest of all heat-treatable aluminium alloys having 4% Cu. Widely used for aircraft construction. NA alloy – has to be refrigerated after solution treatment – Good formability in the solution treated condition – subsequent precipitation increases the strength and hardness. 2014 has higher Cu and Mn content and susceptible to artificial ageing. In artificially aged condition 2014 has higher YS, TS but lower elongation than 2017. 2024 with 4.5%Cu and 1.5% Mg highest strength of any NA 2xxx series. Mainly used for aircraft structures, rivets, hardware, truck wheels and screw machine products. 13

  10. Aluminium Copper (2xxx)-III Adding of Mg reduces the formability and makes it more difficult to fabricate. Increase of silicon in cast alloy increases the fluidity and hence thin sectioned castings are made with ease. 14

  11. Aluminium Manganese (3xxx)-I L β + L 660 C α + L α α + β 1 4 2 AVp489 Although solubility decreases with decreasing temperature, not age hardened – why? 15

  12. Aluminium Manganese (3xxx)-II Not used as major alloying elements in any casting alloy, used only for wrought alloys. 3003 – good formability, corrosion res. And good weldability. Used as utensils, storage for food, oil, gasoline and pr. vessels. beverage cans (3XXX) Al-Mn or Al-Mn-Mg 16

  13. Aluminium Silicon (4xxx)-I AVp489 17

  14. Aluminium Silicon (4xxx)-II Have excellent castability and resistance to corrosion. Typical use for intricate casting and marine fittings. 4032 containing 12.5% Si used for automotive pistons owing to its low coeff. of thermal expansion and good forgeability. 18

  15. Aluminium Magnesium (5xxx)-I 19

  16. Aluminium Magnesium (5xxx)-II Good weldability, Corrosion resistance and moderate strength. 5005 (0.8%Mg): architectural extrusions; 5050 (1.2% Mg): automotive gas and oil lines; 5052 (2.5% Mg): aircraft fuel and gas lines 5083 (4.5% Mg): marine and welded structural applications 20

  17. Al-Mg-Si (6xxx)-I 22

  18. Al-Mg-Si (6xxx)-II More workable than other heat treatable alloys. Excellent corrosion resistance. Automobile body, furniture, vacuum cleaner turbine and architectural applications. 23

  19. Al-Zn (7xxx)-I Put phase diagram from Internet and explain from AVp492 24

  20. Dispersoids Al3Zr dispersoid particles in 7050 after homogenization • Fine Al3Zr dispersoid particles precipitate during homogenization of 7050 • Dispersoid particles are important for the control of grain structure during processing • Act to “pin” grain boundaries

  21. Al-Zn (7xxx)-II 7075 and 7079 produce highest tensile strength obtainable in aluminium alloys. Used where high strength and good corr. res is required. Aircraft structural parts. 26

  22. Some Issues Automotive Applications Corrosion Resistance Precipitation Hardening Strain Hardening

  23. Automotive Applications Al alloys Low C Steel Excellent formability at RT Formability at RT 2/3 of Steel Good surface finish Warm forming with 5xxx and 6xxx alloys Low cost 5xxx Exhibit higher strength BUT suffers from Ludering 6xxx Have the advantage of pptn hardening after forming 28

  24. Aluminium Alloys in Aerospace 2XXX (Cu-containing, 500 MPa) 7XXX (Zn+Mg+Cu-containing, 600 MPa)

  25. Design Requirements • Components must be • Lightweight • Damage tolerant • Durable (corrosion resistant) • Cost effective • Requires careful balance of material properties

  26. Critical Material Properties

  27. Aluminium Alloys • Pure aluminium has • Low density (rrelative Al=2.7, Fe=7.9) • Readily available (Al is 3rd most abundant element in Earth's crust) • Highly formable (FCC crystal structure) • Low strength and stiffness (EAl=70GPa, EFe=211GPa) • Low melting point (Tm=660oC) • Alloy with other elements to improve strength and stiffness - results in alloys with properties well matched to aerospace requirements

  28. B C E A A) Slats - 2618 B) D-Nose Skins - 2024 C) Top Panel - 7150 D) Bottom Panel - 2024 E) Spars / Ribs - 7010 F) Flap Support - 7175 G) Flap Track - 7075 H) Landing Gear - 2024 H F G D Aerospace Al-Alloys • Dominated by “high strength” wrought alloys • Two main alloy series in particular • 2xxx alloys (Al + Cu, Mg) UTS~500MPa • 7xxx alloys (Al + Mg, Zn, (Cu)) UTS~600MPa Alloys used in typical wing structure

  29. Next Generation Aircraft Bigger.... Airbus A380 > 950 seats ...Faster Boeing sonic cruiser > Mach.95

  30. Goals • Next generation aircraft rely on advances in materials and assembly methods • Weight reduction is critical • Alloy optimization • Increase strength and stiffness and/or reduce density whilst maintaining other properties • Assembly optimization • Reduce weight associated with joints between components

  31. Alloy Design • Traditionally, alloy and process development largely by trial and error based on metallurgical experience • Recently, emphasis has changed to designing alloys and processes to meet specific property goals • Improved understanding of relationships between processing, microstructure and properties • Development of models to predict alloy microstructure and performance

  32. Questions • Discuss how micro alloying influences the precipitation reactions in aluminium alloys? Polmear P49. • Principle of formation of PFZ and its role in controlling mechanical properties • Dislocation precipitate interaction and its effect on strength and work hardening • Notes on Non-Heat treatable Aluminium Alloys. Polmear 130 • Notes on 2XXX alloys – consider both cast and wrought • Notes on 6xxx alloys - consider both cast and wrought • Alloy design and properties for Aircraft alloys • Alloy design and properties for Automotive sheets and structural alloys • Alloy design and properties for Shipping • Alloy design and properties for Superplastic alloys

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