Hot deformation behavior and dynamic softening mechanism for extreme-cooled 7055 aluminum alloy

An isothermal compression test of extreme-cooled 7055 aluminum alloy was performed on a thermomechanical simulator under the temperature of 250–450 °C and the strain rate of 0.001−1 s −1 . The constitutive model and microstructure evolution of 7055 aluminum alloy during hot compression deformation were studied. We modify the Arrhenius (AR) model considering strain compensation, which can predict the flow stress accurately. The microstructure and dynamic softening mechanism under different deformation conditions were studied using electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The softening mechanism has gradually changed from dynamic recovery (DRV) to dynamic recrystallization (DRX) with increasing the temperature. With the increase of the strain rate, the softening mechanism has also changed from DRX to DRV. The main dynamic softening mechanism of extreme-cooled 7055 aluminum alloy is DRV and DRX. Finally, it is described that the DRX behavior is dominated by continuous dynamic recrystallization (CDRX). Simultaneously, partial discontinuous dynamic recrystallization (DDRX) exists at lower temperature.