Recrystallization mechanisms and texture evolution of AZ31 alloy by gradient caliber rolling

A single-pass gradient caliber rolling of a conical-shaped AZ31 Mg alloy was performed at 723 K to obtain a transitional microstructure with strain ranging from 0 to 30%. The recrystallization mechanisms involved and the evolution of texture during the deformation were specifically investigated. The results show that the recrystallization extent increases with strain. The isolated fine grains at 5% strain were formed by the particle stimulated nucleation, which tended to randomize the texture. A large number of {10 1¯ 2} extension twins at 10% strain effectively divided and refined the grains, but no twin-induced dynamic recrystallization was found. Some {10 1¯ 1}-{10 1¯ 2} double twins and {10 1¯ 1} compression twins were activated at 15% strain, which to a certain extent facilitated dynamic recrystallization nucleation. Meanwhile, the continuous dynamic recrystallization and discontinuous dynamic recrystallization mechanisms also occurred at various strains. In particular, the discontinuous dynamic recrystallization was more prominent due to the higher deformation temperature, and the recrystallization grains were evidently different from the orientations of their parent grains. In addition, with increasing strain, the overall texture component of the deformed samples gradually transitioned from the initial (0001) basal texture to the [11 2¯ 0]-[10 1¯ 0] non-fiber component, then tended to form the [11 2¯ 0] fiber orientation eventually.