Method of friction stir welding structural body, structural body, and extruded material

The present invention relates to a structural body made of hollow-shaped material and a method of manufacturing the same. For example, the present invention is preferably applied to manufacturing of structural bodies formed from hollow extruded materials made of aluminum alloy which are used in a railway car, a building structure, and the like. The object of the present invention is to weld a hollow-shaped material from one side, regardless of the size accuracy of the hollow-shaped material or the like, and to form the joint with higher strength. Projecting segments of face plates of hollow-shaped materials are friction stir welded from above. Next, a connecting material is placed on the upper face plates of the hollow-shaped materials , and is friction stir welded from above. The welding region exists at the node between a rib connecting the two face plates () and the face plate (). The joint of the connecting material and the face plates are lap joint. Not butt joint. Therefore, the hollow-shaped materials could be welded with ease, even though there exists manufacturing tolerance, or tolerance in arrangement of the hollow-shaped materials