2004 Volume 54 Issue 7 Pages 293-297
In this study, resistance spot welding was applied to make a dissimilar-metal joint between Mg alloy AZ31B plate and commercially pure Al plate. Factors affecting the cross tensile strength of the joint and the effect of Ag insert on the joint strength were investigated. The main results obtained in this study are as follows.
The strength of the dissimilar-metal joint of Mg/Al increased with increasing welding current, however, the strength was very low and was about one forth to one fifth that of the similar-metal joint of Mg/Mg made under the same condition.
By using insert metal consisting of four layers of Ag foil with 0.1 mm thickness, the strength of the Mg/Ag joint increased about 1.5 times than that of the Mg/Ag joint without the insert metal.
With increase in the thickness of the foil-layered Ag insert metal, the thickness of an intermetallic compound formed at the interface between Mg and Ag decreased and the thickness of a eutectic reaction layer between Ag and Al increased, resulting in the increase in the Mg/Al joint strength. However, when the insert metal of 5-layers Ag foil was used, the strength of the Mg/Ag joint decreased because non-bonded regions occurred in the eutectic reaction layer.
