A constitutive model incorporating the interplay of dynamic recrystallization and twinning during hot deformation of AZ31 magnesium alloy

Abstract

Dynamic recrystallization (DRX) and deformation twinning play a pivotal role in stress partitioning during hot deformation of magnesium alloy. However, the influence of twinning on stress is diverse, and the interaction between DRX and twinning is intricate. Existing constitutive models cannot simultaneously describe the relationship between DRX and twinning, as well as their effects on stress. In this study, the hot compression tests were conducted to study the flow behavior and microstructure evolution of AZ31. The obtained flow curves and microstructure revealed that AZ31 alloy undergoes simultaneously DRX softening and twinning hardening during hot deformation. Furthermore, texture evolution was significantly influenced by both DRX and twinning behaviors. As a result of DRX behavior, there was a decrease in twin volume fraction in the later stages of deformation. Consequently, a twin volume fraction model that incorporates the inhibitory effect of DRX was proposed. According to the experimental results of high temperatures and low strain rates, a constitutive model incorporating work hardening, dynamic recovery (DRV), and DRX was established. Additionally, the influence of twinning on flow stress was incorporated into the model, resulting in a constitutive model that considers both DRX and twinning simultaneously. Finally, the proposed model's reliability was validated through the wedging spinning process, successfully predicting both macroscopic deformation and microstructure evolution of the spinning parts.

Keywords

• Magnesium alloy
• Hot deformation
• Dynamic recrystallization
• Twinning
• Constitutive model