Hot Deformation Characteristics and Processing Parameter Optimization of Al–6.32Zn–2.10Mg Alloy Using Constitutive Equation and Processing Map

Abstract

Hot compression tests over the temperature range from 350 °C to 500 °C and strain rates range from 0.001 s−1 to 1 s−1 for homogenized Al–6.32Zn–2.10Mg alloy were carried out on a Gleeble-3800 thermal simulation machine to characterize its hot deformation behavior. At the same time, a modified Arrhenius constitutive equation was established to describe the flow behavior of the alloy, whose average absolute error is 2.89%, which proved to have an excellent predictive effect on the flow stress of the alloy. The hot processing map of the alloy was established, and the stability processing parameters were 460–500 °C and 0.01–0.08 s−1. Then, the Z parameter processing map and activation energy processing (AEP) maps were established for further optimization. Eventually, the optimal processing parameters of the alloy was 460–500 °C (0.03–0.08 s−1). Then, the microstructure of specimens was observed using electron backscatter diffraction. Based on the findings the reasonability of the AEP map and Z parameter map was verified. Finally, electron backscatter diffraction (EBSD) techniques were used to analyze the evolution of the grain structure during the deformation process. It was found that dynamic recovery (DRV) was the main softening mechanism of Al–6.32Zn–2.10Mg. Continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) operated together with the increase of strain, but CDRX was confirmed as the dominant DRX mechanism.