Study on Flow Stress Characteristics of AZ31B under Multi-Stage Hot Deformation

Abstract

In order to improve the understanding of the rheological behavior of magnesium alloy AZ31B under multi-stage hot deformation, a series of isothermal compressing experiments with height reduction of 60% were performed at the temperatures of 250°C, 300°C, 350°C and 400°C and the strain rates of 0.01 s−1and 0.1 s−1 on a Gleeble 1500 thermo-mechanical simulator. The effects of temperature (jump), strain rate (jump), deformation degree and deformation interval time on the flow stress characteristics are investigated and discussed. It is shown that in the dual-stage deformation process with temperature jump or strain rate jump, values of peak stress and peak strain at the second-stage are lower than those at single-stage. The reason for this change is due to the deformation stored energy still retained in the material after its release during the first-stage deformation and deformation interval, such as dynamic recrystallization, meta-dynamic recrystallization, static recovery and static recrystallization The deformation resistance of the multi-stage deformation of AZ31B can be reduced by increasing the deformation degree at the first-stage or the deformation interval because it leads to adequate release of deformation stored energy, which improves the plastic formability of magnesium alloy.