New insight into the phenomenon of the abnormal grain growth in friction-stir welded aluminum

Abstract In this work, the annealing behavior of friction-stir welded aluminum alloy 6061 was studied. Due to essential grain refinement and dissolution of secondary particles, this material usually exhibits relatively low stability against abnormal grain growth during post-weld solutionizing treatment. In the present study, it was found that the abnormal microstructural coarsening actually develops during the heating stage of the tempering process, i.e., during material warming from the ambient condition to the solutionizing temperature.