A characterization for the dynamic recrystallization kinetics of AZ80 magnesium alloy based on flow curves

The true stress-strain curves of as-cast AZ80 magnesium alloy were achieved by a series of isothermal compression tests,which would be taken as the basic data for characterizing the evolution of dynamic recrystallization(DRX).In order to obtain the activation energy of DRX and some other essential parameters,the conventional hyperbolic sine equation was adopted and solved by regression analysis.Based on the analysis of work hardening plots before and after the peak points of stress-strain curves,three potential key points were identified as following: the critical strain for DRX initiation,the strain for peak stress and the strain for maximum softening rate,which contributes to characterizing DRX evolution.The modified Avrami type equation representing the evolution of DRX volume fraction was adopted,and a dimensionless intermediate parameter,was further introduced to couple the effect of deformation temperature,strain rate,strain and DRX volume fraction.Result shows that DRX volume fraction increases gradually until a constant value of 100%.At a constant strain rate,the strain corresponding to the same DRX volume fraction increases with decreasing deformation temperature.