Microstructure evolution during friction-stir welding of AZ31 magnesium alloy

The microstructure evolution of a typical hexagonal close-packed (HCP) material (AZ31 magnesium alloy) during friction stir welding was studied in a wide range of welding temperatures. In all cases, the grain structure development was found to be significantly influenced by the formation of a very strong {0 0 0 1} < u w t v > B-fiber texture. Due to limitations imposed by this texture as well as by symmetry of the HCP crystal structure, an extensive lowering of grain-boundary misorientation was found to occur during deformation. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.