Characterising the Texture and Temperature Effects on the Deformation Mechanism of Magnesium Alloy AZ31: A Simulation Study of the Interplay between Slip, Twinning, and Dynamic Recrystallisation

Abstract

Two viscoplastic self-consistent (VPSC) models were developed to investigate the temperature and texture effects of a hot-rolled magnesium alloy AZ31. These models are coupled with a composite twin grain model and dislocation density based hardening laws to predict the activation and evolution of the deformation mechanisms found within magnesium. At moderate temperatures, there are a variety of active mechanisms in magnesium: ⟨a⟩ basal, ⟨a⟩ prismatic, and ⟨c+a⟩ pyramidal slip, {101 ̅2} tensile twins, and {101 ̅1} compressive twins. The validation of the models is done using an experimental study, realised on a hot-rolled AZ31 Mg alloy over a temperature range of 25 °C to 200 °C and under uniaxial tensile loads parallel, perpendicular, and 45° offset from the c-axis of the material. The first developed VPSC model, VPSC-T, incorporates drag stress and interaction matrix as temperature dependent parameters to predict the deformation behaviour of Mg AZ31 at moderate temperatures. The simulation results obtained with this new mode are in good agreement with the experimental results up to 150 °C, where a softening behaviour, due to dynamic recrystallisation, starts to be observed experimentally. Consequently, the second developed VPSC model, VPSC-DRX, incorporates dynamic recrystallisation into the temperature sensitive model, VPSC-T. The simulation results of the new DRX model are in close agreement with the experimental results for temperatures above 150 °C. Additionally, a parametric study has been conducted to investigate the importance of the various parameters needed to accurately predict DRX.