Abnormal grain growth in friction stir processed alloys

Abnormal grain growth can be a critical issue during the post-processing heat treatment of friction stir welded or processed aluminum alloys. Various theories have been proposed to elucidate the origin of this behavior. This viewpoint paper addresses the issues with reference to the mechanisms involved and their implications for friction stirred microstructures. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.