Hot deformation behavior of novel high-strength Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca alloy

The hot compression behavior of the as-extruded Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca alloy was studied on a Gleeble-3500 thermal simulation machine. The experiments were conducted at temperatures ranging from 523 K to 673 K and strain rates ranging from 0.001 s^–1 to 1 s^–1, respectively. The results exhibited that an increase in strain rate or a decrease in deformation temperature will lead to an increase in true stress. The constitutive equation and processing maps have been obtained and analyzed. The influence of deformation temperatures and strain rates on microstructural evolution and texture were studied with the assistance of electron backscatter diffraction (EBSD). The as-extruded alloy showed a bimodal structure, consisting of deformed coarse grains and fine equiaxed recrystallization structure (about 1.57 μm). The EBSD results of deformed alloys revealed that both the recrystallization degree and the average grain size increase as the deformation temperature increases. In contrast, the dislocation density and the texture intensity decrease. The compressive texture becomes weak with the increase of deformation temperature at the strain rate of 0.01 s^-1. Most grains with {0001} planes tilt away from the compression direction gradually. In addition, when the strain rate decreases both the recrystallization degree and the average grain size increase. Meanwhile, the dislocation density decreases. The texture seems not to be sensitive to the strain rate.