Equal channel angular sheet extrusion (ECASE) as a precursor of heterogeneity in an AA6063-T6 alloy

Abstract

We study the deformation inducing heterogeneity in an aluminum alloy 6063-T6 in the form of a sheet processed at room temperature by equal channel angular sheet extrusion (ECASE) up to a maximum equivalent strain of 1.86 following route C. The through thickness strain distribution showed higher strains in the edge vicinities than in the sheet core. The texture was heterogeneous between the edges and the sheet core with a strong cube component in the initial deformation stages, and a rolling texture with the S component in the sheet edges. Different microstructural characteristics, like grain size, average misorientation, and fraction of high angle grain boundaries (HAGB), decreased by increasing the deformation. The geometrically necessary dislocation (GND) calculations corroborated the existence of a heterogeneous microstructure along the sheet thickness, giving rise to gradients of plastic deformation which allowed to obtain a good strength-ductility relationship. It was demonstrated that ECASE process was a good alternative to produce heterogeneous microstructures. The material heterogeneity was found not to be randomly distributed across the sheet thickness but rather showing higher dislocation concentration and bigger grain size reductions in the edge’s vicinities than in its middle zone.