Influence of strain rate on hot deformation behaviour and texture evolution of AZ31B

Abstract

In the present work, the effects of strain rate on the flow behaviour and microstructure evolution of AZ31 Mg alloy were studied by compression testing over a wide range of strain rates (0·01–100 s⁻¹) and temperatures (300–450°C). In addition, the influence of different strain rates on the dynamic recrystallisation (DRX) mechanisms and texture evolution was investigated. The results showed that with increasing strain rate, the twin induced DRX fraction increased at a constant temperature, and the contribution of continuous DRX decreased. On increasing the strain rate, the formation of twins and subsequent twin induced DRX intensified the basal texture in the deformed sample. In addition, the recrystallised volume fraction increased significantly with strain rate. The flow behaviour was fitted to two types of constitutive equations: power law and hyperbolic sine. Average activation energies of about 162 and 135 kJ mol⁻¹ were obtained for the peak and steady state strain respectively.