| 摘要 |
A method for friction-stir-welding two hollow workpieces. While open end portions of the workpieces butt each other, and an annular support member supports the butt end portions from the inside, the workpieces are joined together by friction stir welding. An annular, radially outward projection is formed on the entire outer circumferential surface of the support member in an intermediate region along the support member width. Support portions to be fitted into corresponding end portions of the workpieces for support from the inside are formed on the support member at corresponding opposite sides of the annular, radially outward projection. While the support portions are fitted into the workpieces, respectively, and end faces of the workpieces abut the annular, radially outward projection, the butt end portions of the workpieces and the support member are friction stir welded from the outside. Thereby, the hollow workpieces are welded without joint defect.
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