FRICTION STIR LAP WELDING JOINT METHOD, BACKING JIG AND BONDED JOINT

To provide a bonded joint which unnecessitates positioning of a through-hole provided in material having a high melting point and positioning of a backing jig and has high bonding strength, during execution of bonding by friction stir welding.SOLUTION: A friction stir lap welding joint method is provided in which a low melting point member 20 constituted of metal material and a high melting point member 10 constituted of metal material having a melting point higher than that of the low melting point member 20, and having a plurality of through-holes 11 provided at least in bonding scheduled portions, the friction stir lap welding joint method comprises: an overlapping step in which the high melting point member 10 and the low melting point member 20 are overlapped each other in this order on a backing jig 30 having an uneven surface 33 in such a manner that the bonding scheduled portions correspond to the uneven surface 33 constituted of a plurality of concave portions 31 and a plurality of convex portions 32 ; and a joining step in which the bonding scheduled portions in the low melting point member 20 and in the high melting point member 10, overlapped each other in the overlapping step, are joined by friction stir lap welding joint.SELECTED DRAWING: Figure 1 【課題】摩擦攪拌接合による接合施工時において、高融点側の材料に設けた貫通孔の位置と裏当て治具との位置調整を不要とし、かつ、接合強度が高い接合継手を得る。【解決手段】金属材料により構成される低融点部材２０と、低融点部材２０の金属材料よりも高融点の金属材料により構成され、少なくとも接合予定箇所に複数の貫通孔１１が設けられた高融点部材１０と、の重ね摩擦攪拌接合方法は、複数の凹部３１と複数の凸部３２とからなる凹凸表面３３を有する裏当て治具３０の上に、凹凸表面３３と接合予定箇所が対応するように高融点部材１０及び低融点部材２０を順に重ねる、重ね合わせ工程と、重ね合わせ工程において重ね合わされた、低融点部材２０と高融点部材１０における接合予定箇所を摩擦攪拌接合により接合する、接合工程と、を備える。【選択図】図１