Stretch formability at elevated temperature of a cross-rolled AZ31 Mg alloy sheet with different rolling routes

Cross-roll rolling with different rolling routes (unidirectional rolling and reverse rolling) was carried out on a commercial AZ31 Mg alloy sheets. In the cross-roll rolling, the roll axis was tilted by 7.5° against the transverse direction. As a result of the Erichsen tests at 433–493 K, the stretch formability of the reverse cross-rolled specimen was higher than that of the unidirectional cross-rolled specimen. The reverse cross-rolled specimen showed lower average Lankford value and higher thickness-direction strain compared with the unidirectional cross-rolled specimen. This is likely to be responsible for the enhanced stretch formability of the reverse cross-rolled specimen. The higher thickness-direction strain was attributed to more random grain distribution which may promote prismatic 〈a〉 slip toward thickness direction.