Modeling dynamic recrystallization during hot deformation of a cast-homogenized Mg-Zn-Zr alloy

Hot deformation of a cast-homogenized ZK60 magnesium alloy was studied in terms of dynamic recrystallization (DRX) kinetics. The alloy was isothermally compressed under uniaxial loading at 400 degrees C and 450 degrees C with varying strain rates of 0.001, 0.01 and 0.1 s(-1). The DRX fraction of each deformation condition was determined via electron backscatter diffraction (EBSD) analysis. DRX kinetics during hot deformation was investigated using an Avrami-DRX equation. For the sake of comparison, Avrami-SRX (static recrystallization) modeling was also employed. Both models were calibrated and validated for hot deformation of the alloy. It was observed that the Avrami-DRX model could be successfully used to predict the DRX kinetics except for the lowest DRX fraction (i.e., deformation at 400 degrees C/0.1 s(-1)). Moreover, the Avrami-SRX model was in good agreement with the Avrami-DRX model for deformation at the lowest strain rate (i.e., 0.001 s(-1)). With increasing strain rate, Avrami-SRX model became increasingly less viable. This was mainly attributed to the smaller than 50% recrystallized fractions at 0.01-0.1 s(-1).