Y. S. Sato, Y. Sugiura, Y. Shoji, H. Kokawa, K. Ikeda, Tohoku University, Sendai, Japan; S. H. C. Park, Hitachi, Ltd., Hitachi, Japan

Summary: Relationship between fracture limit strain of plane strain deformation and microstructure in a friction stir welded thin Al alloy 5052 sheet was examined. The excellent fracture limit strain was attributed to the microstructure having both large grain size and a low density of dislocations and subboundaries in the stir zone.