Influence of Non-constant Strain Rate Deformation on Flow Behavior and Microstructure Evolution of 7050 Aluminum Alloy
摘要
To study the high-temperature rheological behavior and microstructural evolution of 7050 aluminum alloy under complex loading conditions, isothermal compression tests with constant and non-constant strain rates were conducted using the Gleeble-1500D thermal simulator. The deformation temperature range was 300-480 °C, and the strain rate range was 1-0.01 s−1. An Arrhenius constitutive model based on strain compensation and k-function correction was established, and its prediction accuracy was verified. EBSD was used to characterize the microstructure of the deformed samples, investigating the impact of deformation parameters on microstructural evolution and analyzing the DRV and DRX characteristics of the alloy under different deformation conditions. The results showed that the twice-corrected Arrhenius constitutive model could accurately predict the thermal deformation behavior of 7050 aluminum alloy. During the thermal deformation process of the 7050 aluminum alloy, three DRX nucleation mechanisms occurred: discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization (GDRX). Comparing the microstructural characteristics of samples under different deformation conditions, the samples deformed under non-constant strain rates had a higher DRX volume fraction and more uniform DRX grain size than those under constant deformation conditions, indicating that non-constant strain rate deformation promotes the occurrence of DRX.