Effect of the initial texture of AZ31 Mg alloys on their microstructure and texture evolution during single pulse laser shock peening

Because of their hexagonal close-packed structure, magnesium alloys exhibit anisotropy, leading to a lack of independent slip systems and thus inferior formability and mechanical properties at room temperature. Among the various methods used to address this issue, the weakening of the texture is effective, with particular attention paid to adjusting the stress direction based on the material texture to form deformation twins. This study investigated the effects of laser shock peening (LSP) as a practical alternative to traditional surface-hardening processes, focusing on the influencing role of the initial texture of AZ31 Mg alloys. Rolled alloys with a strong basal texture and extruded alloys with c-axes perpendicular to the extrusion direction showing basal fiber texture showed distinct differences in the types and fractions of deformation twins and Schmid behavior upon LSP application. Therefore, the type of twins activated depends on the orientation relationship between the loading direction and the c-axis, with the extruded alloy exhibiting greater activation of the {10-12} tension twins than the rolled alloy owing to the tensile stress states along the c-axis. Moreover, the variation in the behavior of the {10-12} tension twin formation in areas with different stresses resulted in one pair of twin variants in the rolled alloy and two in the extruded alloy. This study demonstrates the potential of LSP to control the texture of Mg alloys, with the initial texture essential in determining the direction of the process.