Microstructure, Texture Evolution, and Mechanical Properties of Thin AZ31B Mg Alloy Sheets Prepared by Two-Stage Rolling

Magnesium (Mg) sheets that are thinner than 1 mm show significant advantages in the fabrication of shells of electronic equipment, as they are lightweight while also providing excellent electromagnetic shielding. Rolling is the most commonly used method for preparing such thin sheets, but it easily leads to edge cracks and poor mechanical properties related to the evolution of grain structure and texture. To this end, a two-stage rolling process under decreasing temperature conditions is proposed to obtain thin Mg alloy sheets with satisfied surface quality and excellent mechanical properties. The results demonstrated that after two-stage rolling, the thin sheets show satisfied surface quality, basically without edge cracks. The grain structure of the Mg sheets with thicknesses of 1.0, 0.6, 0.3, and 0.1 mm is homogeneous and significantly refined, with the smallest average grain size being approximately 5.3 μm. The 1.0-mm thin sheet exhibits a bimodal texture that transforms into a conventional (0001) basal texture as the rolling process proceeds. This is due to the low deformation temperature during warm rolling, which makes it difficult to activate non-basal slip, and thus, basal slip dominates deformation. Furthermore, based on the effect of inhomogeneous texture components and different Schmid factors in varying directions, all thin sheets show anisotropy in mechanical properties. The 0.6-mm thin sheet indicates a good combination of superior strength and medium ductility, which can be attributed to the combined effect of grain refinement and dislocation strengthening.