Resistance rivet welding of magnesium/steel dissimilar materials

Welding of magnesium (Mg)/steel faces huge challenges due to the extremely low mutual solid solubility. In this paper, the resistance rivet welding (RRW) was used to join Mg alloy to steel for the first time, and a metallurgical-mechanical hybrid joint was formed among the semi-tubular rivet, Mg alloy and sheet steel. A steel hollow sphere weld was formed by fusion welding between steel rivet and lower steel sheet, with re-solidified Mg alloy maintained inside it. The microstructure of the hollow sphere weld consisted of lath-like martensite. The welds present both interfacial fracture (IF) mode and button pullout fracture (BPF) mode in tensile shear tests and the strength reaches the maximum of 4381 kN at 7 kA-200 ms with BPF mode. The failure mechanism of the hollow sphere weld for IF shows the ductile characteristic, and the fracture characteristics of Mg sheet for BPF show the mixture of ductility and brittleness. This study provided an alternative technology for welding Mg/steel immiscible materials. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The resistance rivet welding (RRW) was used for the first time to join Mg alloy to steel, forming a metallurgical-mechanical hybrid joint with a hollow sphere weld. The strength of the weld reached a maximum of 4381 kN, showing both IF and BPF fracture modes. The failure mechanism of IF mode exhibited ductile characteristics, while the fracture characteristics of BPF mode showed a mixture of ductility and brittleness.