LAP WELDED JOINT BY FSW, AND METHOD OF IMPROVING ITS FATIGUE STRENGTH

摘要

PROBLEM TO BE SOLVED: To provide a lap welded joint by FSW (friction stir welding) in which stress concentration at the toe part or termination part in the welded part by FSW is relaxed, thus fatigue fracture is prevented to improve fatigue strength properties, and the fatigue life is improved.;SOLUTION: The lap welded joint by FSW is obtained by subjecting the platy upper member and lower member which are lapped to FSW by approaching a probe from the side of the upper member to form a welded part between the upper member and the lower member. The lap welded joint by FSW is formed in such a manner that, after the formation of the welded part, the upper member is worked so that it is gradually made thin to the side of the lower member toward the outermost tip part in the toe part or the termination part of the welded part to provide the thin part of the upper member. Thus, stress concentration in the toe part or the termination part of the welded part is relaxed to prevent the fatigue fracture, to improve the fatigue strength properties and to improve the fatigue life therein.;COPYRIGHT: (C)2005,JPO&NCIPI