1996 年 14 巻 2 号 p. 314-320
The dissimilar spot welding of aluminum and steel sheet with insert of aluminum clad steel sheet was investigated. The study was conducted considering the application to the fabrication of automobile body, which effective to decrease its weight. To clarify the properties of intermetallic compounds to be formed at the steel and aluminum bonding interface, the mechanical properties were measured using the balks of four kinds of intermetallic compound in Fe-Al binary system. The mechanical properties of spot welded joint of aluminum and steel sheet with or without insert of aluminum clad steel sheet were measured using cross tension test and the microstructure of welded joint by this process were observed.
The intermetallic compounds of FeAl and Fe3Al had comparatively higher ductility and the Fe2Al5 and FeAl3 had high hardness and low ductility, so that the Fe2Al5 intermetallic compound were formed at spot welded zone of the aluminum and steel resulting in the deterioration of strength. The dissimilar metal spot welded joint by using insert of aluminum clad steel sheet had excellent tensile strength in cross tension test and fractured in the base metal of aluminum alloy. Two nuggets of aluminum to aluminum and steel to steel were obtained independently by this process. These two nuggets and clad interface by hot rolling contributed to keeping the joint strength. It was confirmed the dissimilar welded joint of aluminum and steel having the strength equal to that of similar welded of aluminum alloy were obtained using this process.