JOINED BODY OF DIFFERENT KINDS AND METHOD FOR RESISTANCE SPOT WELDING

摘要

PROBLEM TO BE SOLVED: To provide a joined body of different kinds and a method for a spot welding in which a joining having a high breaking energy and strong joining is available at a high efficiency. SOLUTION: The joined part 3 of an aluminum-plated steel plate 1 and an aluminum plate 2 is composed of an intermetallic compound layer 3a which exists in a region in which a part of a plated layer 1b exists before the joining and a molten part of aluminum 3b which so exists on the side of the aluminum plate 2 to enclose the inter-metallic compound layer 3a, and the atoms existing on the surface of the molten part of aluminum 3b are metallic-bonded with atoms which exist on the surface of the steel plate 1 except in the region in which the intermetallic compound layer 3a exists by a flat face view. Further, the area of the intermetallic compound layer 3a is limited to 60% or lower of the whole area of the joined part 3 at the boundary plane between the aluminum plated steel plate 1 and the aluminum plate 2. Thus, the area of the molten part of aluminum 3b exceeds 40% of the whole area of the joined part 3.