Effect of Stretch Bending on the Microstructure and Mechanical Properties of AZ31 Magnesium Alloy

The stretch-bending straightening is an effective way to improve the accuracy of sheet assembly. The effect of stretch-bending on the microstructure, deformation behavior and mechanical properties of the extruded AZ31 alloy sheet is investigated by experiments and finite element analysis. The grain size decreases with increasing deformation, and the upper surface shows a greater of grain size reduction rate than the lower surface due to the tensile and compressive asymmetry of the sheet in the thickness direction. This stress–strain asymmetry has been demonstrated by finite element analysis. In addition, the pole density centers of the (0001), (10 \(\overline{1 }\) $\overline{1}$ 0), (10 \(\overline{1 }\) $\overline{1}$ 1) and (10 \(\overline{1 }\) $\overline{1}$ 2) textures move reciprocally with the loading and unloading of the lower roll along the extrusion direction. The (0001) texture is significantly enhanced affected by the stress loading direction and the “sticking position” of the (0001) grains. The increase of the basal texture intensity and work hardening causes the yield strength and hardness of the sheet to increase by 49 and 26%, respectively, while the plasticity of the sheet decreases.