Friction stir welding method, and hollow shape member for friction stir welding

摘要

Face plates 11 and 12 of a hollow shape member 10 are abutted against face plates 21 and 22 of a hollow shape member 20 . Grooves 18 formed to said face plates 11 and 12 at the abutted region receive projections 28 formed to said face plates 21 and 22 . A connecting plate 14 orthogonal to said face plates 11 and 12 is provided to the hollow shape member 10 . There is no connecting plate orthogonal to face plates 21 and 22 disposed on the end of the hollow shape member 20 . Friction stir welding heat causes the face plate 21 ( 22 ) to move toward the thickness direction of hollow shape members 10 and 20 , but such movement is suppressed by the groove 18 and projection 28 . Thereby, the abutted region is welded flatly. Since the hollow shape member 20 requires no connecting plate corresponding to plate 14 , the welded members are light in weight.