Patent ID: 7951465

Claim:
A steel-aluminum welded material formed by a process comprising welding together a steel material having a thickness t 1 in a range between 0.3 and 2.5 mm and an aluminum material having a thickness t 2 in a range between 0.5 and 2.5 mm by spot welding and forming an interface reaction layer comprising intermetallic compounds of Al 3 Fe and Al 19 Fe 4 Si 2 Mn, wherein a nugget formed in spot welded parts has an area in a range between 20 t 2 0.5 and 70 t 2 0.5 mm 2 , and a part of each nugget in a thickness in a range between 0.5 and 10.5 μm of an interface reaction layer has an area not smaller than 10 t 2 0.5 mm 2 .