Enhancing stretch formability of rolled Mg sheets by pre-inducing contraction twins and recrystallization annealing

It is commonly accepted that weakening or tilting basal texture is an effective way to improve stretch formability of Mg alloy sheets. In this study, contraction twins (including double twins) were introduced in rolled AZ31 sheet by pre-cold rolling to a thickness reduction of 10%. It was noted that the stretch formability of rolled AZ31 sheet can be greatly enhanced by pre-cold rolling and subsequent recrystallization annealing. The Erichsen value of rolled AZ31 sheet was increased up to 66% by pre-cold rolling and annealing at 400 °C. The improvement in stretch formability was mainly attributed to the formation and growth of recrystallization grains with weak texture nucleated at contraction twins during annealing.