Numerical simulation of multipoint capacitor discharge welding of AISI 304 bars

Capacitor discharge welding (CDW) is able to weld with cooling rates greater than 106 K/s which produce a very narrow heat-affected zone with no thermal deformations. The physics of the process consists in an accumulated high current, discharging through a transformer to the welding area and vaporizing a protrusion machined at the centre of one of the joint surfaces. The vaporization of the protrusion produces the heat required for welding. In this paper the authors present a numerical investigation on the influence of CDW process parameters on AISI 304 welds. In order to improve the welding capability, some modifications of the welding surface profiles were proposed. In particular, two different contact geometries were proposed as alternatives to the single protrusion geometry. A numerical model investigated the effects of the geometry and the interactions between the electrical and mechanical parameters on the thermal cycle and distortions. Since the welding surface profiles had more than one contact point, the authors named this process ‘multi-point capacitor discharge welding’.