Anisotropic tensile behavior and related yield point phenomena in annealed ultrafine-grained pure aluminum

It is found that tensile flow curves of samples of annealed ultrafine-grained aluminum AA1090 show the development of a yield point and a significant mechanical anisotropy. To rationalize the anisotropic tensile behavior, the orientation data of the annealed material were measured using electron backscatter microscopy. It is found that the inferior mechanical properties of samples tested at 45° to the rolling direction may be attributed to a strong rolling texture effect and that the anisotropic magnitude of the yield drop may be related to the proportion of grains with soft orientations (defined as those with Schmid factor greater than 0.45) in the sample. Additionally, it is found that the anisotropy in tensile ductility is in general agreement with a Considère criterion analysis and that the mechanical anisotropy in the samples is only partly explained by the crystallographic texture, where microstructural anisotropy may also play a role.