A new phenomenological model describing the compressive thermal deformation flow stress of cast-rolled AZ31B Mg alloy

In this research, the isothermal compression tests were carried out to study the hot deformation behaviors of cast-rolled AZ31B Mg alloy. The modified Arrhenius model was solved by expressing the effects of strain on the material constants. Regressive analysis was performed on the Zerilli-Armstrong (ZA) model for HCP metals based on dislocation mechanism of heat activation. The relationships between stress and strain, strain rate and temperature were analyzed for proposing a new phenomenological model. The predictive ability of the three models was assessed by calculating the goodness-of-fit as well as the error in the relative instability zone. The results show that only in the small strain zone (ε < 0.4) can the modified Arrhenius model have certain predictive ability. Both the ZA model and the new phenomenological model can well describe the hot compressive deformation behaviors of Mg alloy over a wide range of the deformation conditions, and the new phenomenological model has a reasonable number of material constants, as well as a higher predictive accuracy.