Modeling strain rate sensitivity and high temperature deformation of Mg-3Al-1Zn alloy

Abstract

Abstract Increasing the plastic deformation temperature of Mg alloys results in higher strain rate sensitivity, easier activation of secondary slip modes, and impeded twinning. In this study, the strain rate sensitivity is estimated for each deformation mode, and visco-plastic self-consistent modeling is used to reproduce the plastic deformation behavior of an Mg-3Al-1Zn O-temper plate from 150 to 450 °C. Twinning and basal slip have relatively low strain rate sensitivity, whereas secondary slip modes are highly strain rate sensitive at high temperature. The texture evolution and plastic anisotropy are modeled at different temperatures and strain rates. Results show that when the strain rate sensitivity is taken into account, compared with rate independent critical resolved shear stresses, the material parameters and predictions are different. In particular, this study shows that, for hot deformation, there is a critical strain rate above which secondary slip modes predominate, and beyond which tension twinning is activated. A similar transition is expected for modes that have different strain rate sensitivity.