Influence of microstructure uniformity on fracture behavior of magnesium alloy rolling sheet based on slip trace analysis

The nonuniform microstructure of magnesium alloy rolled sheets tends to influence their plastic deformation capacity. This study employed multi-pass restricted rolling to successfully prepare AZ31 magnesium alloy rolled sheets with a uniform microstructure, enhancing their mechanical properties. Quasi-in-situ tensile EBSD was used to investigate the effect of microstructure uniformity on the plastic deformation and fracture behavior of magnesium alloy. The results demonstrate that the nonuniformity of the magnesium alloy microstructure intensifies the strain asynchrony between adjacent grains, leading to relative misalignment and crack formation. Fine grains cannot coordinate the strain within their adjacent coarse grains, resulting in ledge formation at their common grain boundaries. Moreover, low-angle grain boundaries (LAGB) influence fracture behavior, rendering fine grains penetrated by LAGB more susceptible to becoming strain concentration areas that promote intergranular fracture and even transgranular fracture.