Improving the room-temperature bendability of Mg–3Al–1Zn alloy sheet by introducing a bimodal microstructure and the texture re-orientation

A significant enhancement of bendability was achieved by the introduction of bimodal microstructure for AZ31B alloy sheets via pre-compression and subsequent annealing (PCA) process. This combined treatment led to the c-axis of the extracted samples that were inclined by 30° to the rolling direction (30° sample) further shifting toward the rolling direction (RD) and resulting in a higher Schmid factor (SF) value of basal slip under the RD tensile stress. Furthermore, the bimodal microstructure that was introduced by the PCA process broke the damage bands (DBs) in the initial hot rolled AZ31B alloy sheets and gave rise to a more uniform strain distribution in the outer tension region of the bending samples, in which the tensile deformation was accommodated by the equally distributed 10\bar1 2 tension twinning and basal slip. Consequently, the bimodal microstructure, shifted basal texture and the modification of DBs were responsible for the significant enhancement in the bendability of the AZ31 alloys.