Deformation behavior, microstructure evolution, and dynamic recrystallization mechanism of an AZ31 Mg alloy under high-throughput gradient thermal compression

Abstract

A high-throughput gradient thermal compression process was adopted to investigate the effects of thermal deformation parameters on the deformation behavior and microstructure evolution of a rolled AZ31 Mg alloy. The results showed that with increasing deformation degree, the flow stress-strain curves of the double-cone samples compressed along the normal direction (ND), transverse direction (TD), and rolling direction (RD) of rolled Mg alloy rapidly reached their peak value, then decreased gradually, and finally maintained a trend of horizontal change. Under the same strain condition, the dynamic recrystallization (DRX) degree of the double-cone sample increased gradually with increased deformation temperature. Twins were more likely to occur when compression occurred in the TD and RD, rather than along ND. With increasing temperature or strain, the number of twins that formed during compression gradually decreased. At deformation temperatures of 250 °C and 300 °C, continuous dynamic recrystallization was the main DRX mechanism in the double-cone samples compressed along the ND, TD, and RD. Furthermore, the twin-assisted DRX mechanism also occurred in the double-cone samples compressed at 250 °C along the TD and RD. During compression at 350 °C and 400 °C along the ND, TD, and RD, discontinuous dynamic recrystallization occurred in the double-cone samples, indicating that the DRX mechanism changed with increasing compression temperature.