Texture effects on development of shear bands in rolled AZ31 alloy

Abstract

We investigate the effects of texture on shear banding in highly textured Mg–3Al–1Zn alloy. The plates with different textures were rolled to 10% reduction in thickness at various temperatures, and the microstructure, texture and misorientation distributions within the regions undergoing shear banding were analyzed with optical microscopy and X-ray diffraction and electron backscattering diffraction techniques. It is found that texture prior to rolling significantly affects the various features of shear bands such as the formation frequency of shear bands, the inclined angle of shear bands to the rolling plane, and orientations of grains in shear bands. We infer that shear bands in AZ31 rolled to a relatively low strain occur as a result of geometric (texture) softening. Shear banding is most pronounced in the plate with conventional strong basal texture, whereas the plate oriented favorably for the prism 〈a〉 slip shows no sign of shear banding. The inclined angle of shear bands in the plate with basal texture is around 30°, while those in the plates oriented for basal <a> slip or tension twinning is around 55°. The regions of shear bands receive more strain than the region outside the bands, which results in significant lattice rotation of the grains in the bands, leading to off-basal texture.