Orientation stability in equal channel angular extrusion. Part II: Hexagonal close-packed materials

Abstract The orientation stability in equal channel angular extrusion (ECAE) of hexagonal close-packed (hcp) crystals using a 90° die is investigated based on the three-dimensional lattice rotation fields from rate-dependent crystal plasticity simulations. The results show that for the major slip and twinning modes considered, the relatively stable orientations in ECAE are distributed along the h1 θ to h6 θ fibers in the Euler space and feature characteristic alignments of the 〈 a 〉- or 〈 c 〉-axis with respect to the macroscopic deformation axes. The application of such simulations is demonstrated by comparing the predictions with experimental ECAE textures in high-purity titanium and other hcp polycrystalline materials, including commercial-purity zirconium, beryllium and magnesium alloys. The simulation results for ECAE are also applied to derive the relatively stable orientations in conventional simple shear deformation.