Development of through-thickness texture gradient and persistence of shear-type textures during annealing of commercial purity aluminium sheet processed by accumulative roll-bonding

Ultrafine-grained commercial-purity aluminum (AA1070) sheets produced by four cycles of accumulative roll-bonding (ARB) without lubrication are subjected to annealing treatments in the temperature range from 250 degrees C to 400 degrees C. Microstructures and microtextures in the surface and center regions of the ARBed and annealed sheets are measured by electron backscatter diffraction. The results show that annealing treatments at 325 degrees C or above lead to a reduction in the microstructure gradient but a significant through-thickness texture gradient different from that in the as-deformed state. The center region is featured by the development of a strong cube texture at the expense of rolling components. In the surface region, shear-type components are either enhanced or largely retained, showing a high persistency upon annealing. While the grain structures are restored predominantly by continuous recrystallization in the surface region, a mixture of continuous and discontinuous recrystallization is envisaged for the center region. (C) 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.