Study on the joint formation mechanism and performance of resistance rivet welding of Mg/steel dissimilar materials

Abstract

In this paper, a new resistance rivet welding process (RRW) is used to achieve the joining of Mg alloy and steel. A rivet is utilized to pierce the upper Mg plate during the welding process and then welded to the lower steel plate. It realizes a metallurgical bond between the rivet and the steel plate, and a hybrid rivet-welded joining between the steel plate and the Mg plate. The joint morphology, forming mechanism, microstructure, and mechanical performance of RRW joints were investigated. And the role of welding current variations on the failure mode and mechanical properties of the joint was studied. The results showed that at welding currents between 11 kA and 13 kA, the main bearing area of the joint was primarily the Mg plate base material. As the welding current increased, the bonding location between the Mg refilled into the rivet cavity and the Mg plate could also be subject to more load, significantly affecting the mechanical properties and failure mode of the joint. The RRW joints achieved a tensile-shear load of 6.08 kN and an energy absorption value of 8.95 J at the optimum parameters.

Keywords

• Resistance rivet welding
• Mg/steel dissimilar materials
• Joint formation mechanism
• Tensile shear performance
• Failure mode transition