The development of microstructure and the influence of processing route during equal channel angular drawing of pure aluminum

A process for imparting large plastic deformation to materials without any significant decrease in cross-sectional area, called equal channel angular drawing (ECAD), has been studied. As-cast aluminum bars of commercial purity (99.9% pure) with extremely coarse grains (of the order of 2000 mu m in size) were subjected to six ECAD passes (resulting in a plastic strain of approximately 3) using three different processing routes, in order to study the potential of ECAD to produce a fine-grained bar of higher strength with special textures. All three processing routes result in considerable strain hardening. Micro banding was a significant mode of plastic deformation. Micron-sized subgrains misoriented by approximately 1-4 degrees are produced in all three routes. The shape of the subgrains varied from elongated to equiaxed depending on the processing route used. Strong deformation textures were not obtained. The suitability of the process to produce a fine-grained commercial purity aluminum bar of increased strength from an initially coarse-grained material is discussed. (C) 1999 Elsevier Science S.A. All rights reserved.