Prediction of flow stress and textures of AZ31 magnesium alloy at elevated temperature

Abstract

The viscoplastic behaviour of magnesium alloys at high temperatures leads to highly temperature-dependent mechanical properties. While at high strain rates a notable strain hardening response is observed, at low strain rates the material shows a smooth plastic response with negligible amount of hardening. This complicated behaviour is due to different deformation mechanisms that are active at different strain rate regimes, resulting in different strain rate sensitivity parameters. In this study we show, by utilizing both numerical simulations and experiments, that this behaviour can be predicted by a model that combines two deformation mechanisms, grain boundary sliding mechanism and dislocation glide mechanism. We discuss the importance of each deformation mechanism at different strain rate regimes based on the findings of modelling and experimental results for AZ3 magnesium alloy. By developing a model that includes the above-mentioned two deformation mechanism, the prediction of flow properties is expanded to a wide range of strain rate regimes compared to previous study. The obtained numerical findings for the stress–strain behaviour as well as texture evolution show good agreement with the experimental results.

Keywords:

• dislocation dynamics
• polycrystalline metals
• mechanical behaviour
• thermal activation of deformation
• texture analysis
• grain boundary sliding
• viscoplasticity

Additional information

Funding

Funding. This publication was made possible by a National Priorities Research Program grant from the Qatar National Research Fund (a member of The Qatar Foundation), [grant number NPRP 09-611-2-236]. The statements made herein are solely the responsibility of the authors.