Patent ID: 6983873

Claim:
A friction stir welding method, comprising: in one end of a first member, providing respectively a recessed portion, in a thickness direction, to an outer face at one side of said first member and to an outer face at another side of said first member, opposite said one side and providing a plate extending from said recessed portion at said one side to said recessed portion at said other side, overlapping one end of a second member to the respective recessed portions of the outer faces at said one side and at said another side of said first member, thereby providing an overlapped portion, and under a condition where said first member and said second member at said overlapped portion are supported, carrying out a friction stir welding at said overlapped portion by inserting a rotary tool at said overlapped portion from an outer side of the first member, said rotary tool being inserted so as to overlie a central portion of a width of the plate.