Strain path dependence of texture development in aluminum

Abstract

Polycrystals of aluminum, initially cubic in shape, were deformed in various sequences of free or plane-strain compression increments to three different final shapes: one corresponding to compression, one to tension, and one to no net shape change. The orientation distributions were determined both initially and after the various strain paths. All of the samples exhibited significant changes in texture, in accordance with the total symmetry of each test. The final textures were in quantitative agreement with the results of computer simulations of polycrystal plasticity. The Taylor factors determined by this calculation were used to convert the measured stress-strain curves to crystallographic shear stress vs shear curves; this improved the comparison with experimental stress-strain curves, but the strain hardening in some tests involving path changes remained below that of unidirectional compression. The difference may be attributed to instabilities in the dislocation structure upon a path change.