Hot deformation behavior and 3D processing maps of AA7020 aluminum alloy

Abstract

The hot deformation behavior and microstructural evolution of homogeneous annealed AA7020 aluminum alloy were investigated by isothermal compression tests over the temperatures range of 673–793 K and strain rates range of 0.001–1 s−1. According to the experimental results, the flow stress of AA7020 aluminum alloy exhibits a typical dynamic recovery characteristic, and a six-order polynomial strain compensation of Arrhenius-type constitutive equation is developed to describe the hot deformation behavior of the alloy. 3D processing maps that taking the effect of strain into account was established to investigate the workability of AA7020 aluminum alloy. Based on the 3D processing maps and examination of microstructures, a microstructural characteristic map was established, and it suggests that the recommended processing domains are predicated to be within the temperatures range of 743–793 K and strain rates range of 0.004–0.05 s−1, uniform deformed grains and recovery structures can be found within this domain. Microcrack can be found in samples deformed at high strain rates (>0.1 s−1), and other microstructural characteristics such as partial recrystallization and flow localization can be found in samples deformed within 733−793K/0.001–0.004 s−1 and 673–733 K/0.001–0.1 s−1, respectively. The preponderant soften mechanism is DRV over all the investigated deformation parameter domains, but the role of DRX (includes CDRX and DDRX) is strengthened by deformation at high temperatures with low strain rates, and the maximum volume fraction of recrystallized grains was 3.87% when it was deformed at 793 K/0.001 s−1.