Friction stir welding method

A method of manufacturing a structural body comprising the steps of:

• inserting a projecting portion of an end portion of a plate of a first frame member into a recessed portion of an end portion of a plate of a second frame member, wherein at the end portions of each of said respective plates a raised portion, which protrudes in a thickness direction of the first and second frame members, is provided, and wherein the recessed portion extends into one of the raised portions, and the projecting portion extends from the other of the raised portions;
• at said insertion-into portion, inserting a rotary tool from one face side of said plate into the raised portions, from a side of the raised portions, and carrying out flatly a friction stir welding on another face side of said plate;
• and
• positioning a face of said one side of a structure which has been obtained by the friction stir welding as an outer face of a structural body.

A method of manufacturing a car body comprising the steps of:

• inserting a projecting portion of an end portion of a plate of a first frame member into a recessed portion of an end portion of a plate of a second frame member, wherein at the end portions of each of said respective plates a raised portion, which protrudes in a thickness direction of the first and second frame members, is provided, and wherein the recessed portion extends into one of the raised portions, and the projecting portion extends from the other of the raised portions;
• at said insertion-into portion, inserting a rotary tool from one face side of said plate into the raised portions, from a side of the raised portions, and carrying out flatly a friction stir welding on another face side of said plate;
• and
• positioning a face of said one side of a structure which has been obtained by the friction stir welding as an outer face of a car body.