JOINED BODY OF DISSIMILAR MATERIALS COMPRISING STEEL MATERIAL AND ALUMINUM MATERIAL, AND JOINING METHOD THEREFOR

摘要

To provide a steel-aluminum welded material and a spot welding method therefor having high weld strength. The steel-aluminum welded material 3 includes a steel material 1 and an aluminum material 2 having predetermined widths. The area of a nugget 5 of a spot-welded part is determined as a function of the thickness of the aluminum material 2, and the area of a part of the nugget 5 corresponding to a part having a thickness in a range between 0.5 and 10 µm of an interface reaction layer 6 is defined as a function of the thickness of the aluminum material 2.