Quantification of microstructure refinement in aluminium deformed by equal channel angular extrusion: Route A vs. route Bc in a 90° die

Microstructures in the centre of two commercial purity aluminium billets extruded through a 90° die either with or without 90° rotations between passes have been investigated using electron backscatter diffraction after eight passes of equal channel angular extrusion. Local heterogeneities in the form of low misorientation regions were present in both samples. The fraction of high-angle boundaries was found to be slightly greater in the sample extruded without rotation.