Hot deformation characteristics of CaO-added AZ31 based on kinetic models and processing maps

Hot deformation characteristics of CaO-added AZ31 were studied using hot torsion tests based on kinetic models and processing maps. The alloy exhibited deformation characteristics comparable to those of a commercial AZ31 alloy. Compared with those of the AZ31 alloy, the flow stress of the CaO-added AZ31 alloy increased, the failure strain decreased, and the volume fraction of dynamically recrystallized grains increased under the same deformation conditions. The processing maps revealed that the hot deformation characteristics of the CaO-added AZ31 alloy varied with the temperature and strain rate. At high temperature, the deformation efficiency, shown in the processing maps of the CaO-added AZ31 alloy, was relatively uniform irrespective of the strain rate. Microstructural observation revealed that Ca-bearing second phases were formed in the matrix and these contributed to the differences in the hot deformation characteristics of the CaO-added AZ31 alloy.