Abstract:The flow behavior and microstructure evolution of 6A82 aluminum alloy (Al-Mg-Si-Cu) with high copper content were studied on a Gleeble-1500 system by isothermal hot compression test in the temperature range from 320 to 530 °Cand the strain rate range from 0.001to 10 s^-1. The results reveal that the flow stress of the alloy exhibits a continuous flow softeningbehavior at low temperatures of 320-390 °C, whereas it reaches steady state at high temperatures (≥460 °C), which are influenced greatly by the Zener-Hollomon parameter (Z) in the hyperbolic sine with the hot deformation activation energy of 325.12 kJ/mol.Microstructure characterizations show that prominent dynamic recrystallization and coarsening of dynamic precipitation may be responsible for the continuous flow softening behavior. Due to deformation heating at high strain rates (≥1 s^-1), dynamic recrystallization is more prominent in the specimen deformed at 530 °C and 10 s^-1 than in the specimen deformed at 460°C and 0.1 s^-1 even though they have very close ln Z values.

Key words: Al-Mg-Si-Cu aluminum alloy; isothermal hot compression; flow stress; dynamic recrystallization;dynamic precipitation