STRAIN PATH CHANGE EFFECTS IN CUBE TEXTURED ALUMINUM SHEET

The influence of abrupt changes in the direction of straining by uniaxial tension has been measured in aluminium sheet with a well developed cube texture. The path changes produced effects on the flow stress and strain hardening behaviour which depended upon the amount of prestraining, the angle between tensile axes of the prestrain and test and, notably, upon the orientation of the tensile axis of the prestrain in the sheet. The relative contraction in specimen transverse directions was also measured, and these results, together with those of flow stress and hardening rate, indicate that simple concepts of latent and kinematic hardening cannot explain the effects observed. The direction of the tensile axis had a large influence on the formation of a banded microstructure, this was associated with the stability of the orientation involved during deformation. If the band boundaries are considered to be planar regions of high flow stress, then the influence of orientation on the path change effects can be qualitatively explained.