Patent ID: 7473864

Claim:
A weldment of different materials, the weldment having a ductile fracture energy of at least 7.5 Joules, comprising: an aluminum or aluminum alloy sheet and an aluminum-coated steel sheet having an aluminum coated layer with a thickness of 15 μm or more, said aluminum or aluminum alloy sheet and said aluminum-coated steel sheet being resistance spot welded, wherein a joined part exists on an interface between the aluminum or aluminum alloy sheet and the aluminum-coated steel sheet, and wherein the area of an intermetallic compound layer in the joined part is 60% or less of the total area of the joined part constituting the intermetallic compound layer and the melted and solidified region created by the resistance spot welding, wherein the aluminum-coated steel sheet comprises a steel substrate containing 0.002% by mass or more of N.