Enhancement of the mechanical properties of textured AZ31 Mg alloy sheets by bimodal-orientation microstructure: Basal orientation and RD-texture

In the present study, a bimodal-orientation microstructure including the basal orientation and RD-texture was prepared by twinning deformation of an AZ31 Mg alloy sheet. Experimental results show that 21%-24% of tension twin boundaries are produced and that the recrystallization content decreased by up to 30.5%-52.0% after hot deformation. The variant selections of island twin and parallel tension twin pairs conform to the Schmid law, while the connected twin pairs and the twin transmitting are controlled by the strain coordination. Twin-free grains are observed because of the accommodation strain controlled by the hard deformation mode. After final post-annealing, the bimodal-orientation microstructure is balanced with a tension twin boundary fraction and recrystallization content of 16.6%-22.2% and 45.0%-74.3%, respectively. Finally, the anisotropy weak-ening, and improvement of formability are obtained due to the orientation adjustment and work hardening elimination, with the average Lankford values (r) decreasing from 2.84 to 0.43 and the IE value increasing from 2.25 to 4.63.