Microstructure Evolution of ZK61m Magnesium Alloy Sheet during Erichsen Test

ZK-based magnesium alloy has high rigidity and excellent machinability. It is an ideal lightweight material in the field of military industry and has a broad application prospect. Traditional processing technology can't meet the special requirements of local area microstructure adjustment of sheet metal. In the experiment, the same area of the plate was subjected to several reverse Erichsen processes with a certain stamping stroke, and the local deformation area of the plate was subjected to annular tensile and compressive stress. The experimental samples were divided into two groups for microstructure characterization and comparison. The results show that the grain size in the deformed area of the plate is significantly finer than that of the original sample, and ⟨ 10 1 ¯ 2 ⟩ tensile twins appear in some grains. In the repeated Erichsen test, the grain slip leads to the accumulation of dislocations, which increases the dislocation density and KAM value, and plays an obvious strengthening effect on the plate. Compared with the original plate, after repeated Erichsen test for three times, the dislocation strengthening effect of the plate is obvious with ultimate tensile strength increased by 26%.