Microstructure evolution and deformation behaviors of AZ31 Mg alloy sheets processed by repeated bending−flattening deformation with different die angles

Abstract

AZ31 magnesium alloy sheets were fabricated by repeated bending−flattening deformation (RBFD) using dies of various angles. The microstructure evolution and deformation behaviors of the AZ31 Mg alloy during RBFD were investigated by FEM, OM, EBSD and hardness tester. The results suggest that the 150°/150° die exhibits the superior performance across all three groups. With an increase in passes, the effective strain of the alloy is significantly improved due to the positive impact of shear and bending. After four passes, the average grain size can be significantly refined to 1.7 μm, and a weaker basal texture can be obtained compared to the initial one due to non-basal slips, dynamic recrystallization (DRX), and twinning. Particularly, the pyramidal 〈c+a〉 slip promotes DRX and twinning. The hardness of the alloy reaches HV 77 as a result of the comprehensive effect of microstructure and texture generated by slip, twinning and DRX competition.