Al-0.42mg-0.50si-0.99cu Alloy Industrial Profiles Thermal Deformation Behavior And Organization, Performance Studies

In this paper, the alloy composition has been optimized on basis of Al-Mg-Si alloy and a new Al-Mg-Si-Cu aluminum alloy was prepared by addition of the alloying element Cu and the microalloying elements Gr,Mn,Zn to Al-Mg-Si alloy and application of proper smelting,extrusion and heat treatment process. The effects of teat treatment and corrosion on the microstructures and properties and hot deformation behaviors and microstructure evolution of Al-0.42Mg-0.50Si-0.99Cu aluminum alloy were detailed investigated by using of Optical Microscopy, Scanning Electron Microscope, Transmission Electron Microscope and electronic universal testing machine and the mechanisms were discussed. Through the series of investigation, we drew these conclusions as follows:(1) In the process of isothermal compression of the alloy, flow stress is controlled by strain rate and deformation temperature. The flow stress increases with strain rate increasing and decreases with deformation temperature increasing. The alloy shows the phenomenal of dynamic recovery with a few dynamic recrystallization. The flow stress of the alloy during high temperature deformation can be represented by Zener-Hollomon parameter.(2) The Al-0.42Mg-0.50Si-0.99Cu aluminum alloy has excellent extrusion performance with the hot deformation activation energy 190 kJ/mol.(3) The safest deformation condition is 300℃～500℃and 0.002 S-10.032 S-1.(4) The best heat treatment parameter:solution at 520℃for 1 hour, water-quenched, then aging at 175℃for 9 hours. The corresponding mechanical properties:σbis 315.7MPa,σ0.2 is 274.1MPa,δis 15.49%.(5) The delay aging time should be controlled in 3 hours.(6) The main precipitates and constituent phases of the Al-0.42Mg-0.50Si-0.99Cu aluminum alloy are GP zone,β"(Mg5Si6), Q'(Al4Cu2Mg8Si7), In T6 under-aging condition the precipitates are GP zones with high density, in T6 peak-aging condition the precipitates areβ" phase with high density and small amount of Q'phase in matrix, with the aging time increasing, Q'phase increases and coarsens. The precipitation sequence is SSSSâ†'GPzoneâ†'β"+Q'+σ'â†'β'+Q'â†'Q+β+σ.(7) The Al-0.42Mg-0.50Si-0.99Cu aluminum alloy has the tendency to intergranular corrosion. In T6 under-aging condition there was no distinct corrosion behavior; in T6 peak-aging condition it has the serious tendency to intergranular corrosion; with the aging time increasing, corrosion resistance increased; in double aging condition the corrosion resistance is obviously improved while tensile strength is a little decreased.