The evolution of shear deformation texture and grain refinement in asymmetrically rolled aluminum sheets

Abstract

Asymmetric rolling, in which the ratio of upper to lower roll diameter is different, has been used to introduce an intense plastic shear strain for the purpose of obtaining higher plastic strain ratios due to uniform development of shear deformation textures through the thickness and of grain refinement in aluminum sheets. A commercial purity aluminum sheet was asymmetrically cold rolled under various schedules. The textures, microstructures and strengths of the rolled sheets were investigated. When subjected to several passes of asymmetric rolling by over 90%, the textures approaching to the ideal shear deformation texture consisting of {001}<110>, {111}<110> and {111}<112> developed throughout the thickness. Transmission electron microscopy and electron back-scatter diffraction analyses showed that the sheets have fine-grained structures with large misorientations. Unidirectional rolling in which the rolling direction does not change between passes gave rise to more uniformly refined structures than alternating direction rolling in which the rolling direction is rotated through 180° about the rolling direction between passes.