Influence of rolling routes on press formability of a rolled AZ31 Mg alloy sheet

Microstructure, tensile properties and press formability of AZ31 Mg alloy sheets processed by unidirectional rolling, reverse rolling and cross rolling were investigated. The intensity in (0002) plane texture for the reverse-rolled and the cross-rolled specimens was lower than that for the unidirectional-rolled specimen. In addition, the Erichsen values of the formers were larger than those of the latter. The superior press formability for the formers could not be explained from the viewpoint of the elongation to failure, n-value, average r-value and planar anisotropy of the r-value, but it was related to a reduction in directional dependence of the thickness-direction strain and width-direction strain normalized by the tensile-direction strain (epsilon(1)/epsilon(L) and epsilon(w)/epsilon(L)). Therefore, it is suggested that the minor texture formation due to reverse rolling and cross rolling gives rise to the reduction in anisotropy of strain, resulting in the superior press formability for the reverse-rolled and cross-rolled specimens.