Influence of shear deformation during asymmetric rolling on the microstructure, texture, and mechanical properties of the AZ31B magnesium alloy sheet

Abstract

In this study, the changes in the microstructure, texture, and mechanical properties of the AZ31B magnesium alloy sheet after asymmetric rolling (ASR) in different shear deformations during each pass are reported. A high shear strain is induced along the sheet thickness when the velocity ratio of the upper and lower rollers is 1.8. In the case of the sheet processed via ASR in the reverse shear deformation along the rolling direction (RASR), the grain refinement, weak basal texture, and improved structural homogeneity result in better mechanical properties than those of the sheet processed via symmetric rolling (SR). However, in the case of the sheet processed via ASR in the single shear deformation along the rolling direction (UASR), shear bands containing dynamically recrystallized grains and larger numbers of dislocation are formed, tilting the peak intensity of the pole figure away from the normal direction. Moreover, the shear band with an average grain size of 5 μm causes severe structural inhomogeneity, which results in bad mechanical properties than the other two sheets. Furthermore, the twin mode changes from the double twin of the SR sheet to the extension twin of the ASR sheet under shear strain. The extension twin contributes to the optimization of the mechanical properties. Finally, the strength and elongation of the sheets processed via RASR are simultaneously improved to 250.3 MPa and 12.5%, respectively.