Improving Room-Temperature Stretch Formability of Mg-4.9Al-0.16Mn (mass%) Alloy Sheet via Optimizing Rolling Temperature

The effect of the rolling temperature on the room-temperature stretch formability, tensile properties, microstructure, and texture of Mg-4.9Al-0.16Mn (mass%) alloy sheet has been investigated. Rolling at 220°C resulted in the formation of a weakly aligned isotropic texture feature, and the annealed sheet showed splitting of (0001) poles to the rolling direction and broadening of (0001) poles to the transverse direction, leading to an excellent Index Erichsen value of 8.2 mm. The alloy sheet also formed a fine-grained structure with average grain size of ~9 µm, achieving isotropic tensile properties with a moderate 0.2% proof stress of ~ 150 MPa. Quasi-in situ electron backscattered diffraction was employed to study the evolution of the texture, revealing that the suppression of dynamic recrystallization, shear-band-related static recrystallization, and grain growth behavior within the shear bands had a significant impact on the texture weakening.