Microstructure and plastic anisotropy in rolled AA1200

The directionality of tensile behaviour in cold rolled AA1200 commercial purity aluminium has been investigated. This material initially had a strong 'cube' texture which remained the dominant component up to rolling strains greater than 0.5. There was a marked dependence of behaviour on the degree of prior rolling strain and on the direction of the tensile axis relative to the rolling direction. Part of the directionality was due to crystallographic texture effects, notably the contribution to work hardening- and so elongation- from the change in preferred orientation occurring in tension at 45degrees to the rolling direction. There was also a significant difference in plastic behaviour between tension at 0degrees and 90degrees to the rolling direction. This could not be due to texture effects, but was caused by the directionality in deformation substructure generated during the rolling which led to characteristic strain path change effects. The effect of static recovery on this behaviour has been investigated to help clarify the relationship between substructure and the directionality of plastic response in pre-strained aluminium. It seems that the thickness of the aligned planar dense dislocation regions has a large effect on the mechanical behaviour.