Effect of electrode radius on expulsion in two pulsed spot welding

Abstract

Since spot welding is quick in production and stable in quality, the joining of thin materials in automobiles and electrical products. The nugget in the joint part took places due to the joule effect of high current. Therefore, the current density at the contact between the base material and the electrode becomes high and weld expulsion is generated in welding for high tensile strength steels with high current during a short time. The authors introduced a numerical model of resistance spot welding and analyzed this phenomenon. In the numerical model, the temperature characteristics of the material were considered. The contact state between the electrode and the base material and that between the base materials depend on the yield stress of the material and the pressure at the contact part. Moreover, the contact resistance depends on the radius of the electrode. The contact resistance was confirmed by performing simulation when the radius of the electrode was changed. The relationship between the electrode radius and the temperature distribution was investigated. The welding condition of two pulsed welding current are induced analyzing its relationship.