Modelling of flow stress characterizing dynamic recrystallization for magnesium alloy AZ31B

Based on the Gleeble-1500 thermomechanical simulation tests of magnesium alloy AZ31B, a new model of flow stress characterizing dynamic recrystallization (DRX) for magnesium alloy was put forward. Theoretically, in the flow rule the atomic diffusibility and the driving force of dislocation migration are dependent on the temperature, and the dislocation density and the cumulation of grain boundary energy are dependent on the strain rate. So, the peak stress is taken as the function of the temperature and the strain rate according to the creep equation. Since the DRX is a thermally activated process, the recrystallized volume fraction can be regarded as the function of strain through Avrami equation. The descending of flow stress is mainly dominated by the recrystallized volume fraction. On the base of this idea the flow stress at different strain is regarded as the function of the peak stress and the strain. This new model expresses the dependence of the flow stress on various temperatures, strain rates and strains. Statistical analysis shows the standard deviation of this model is 2.32% approximately.