Numerical study of the influence of gap between plates on weld pool formation in arc spot welding process

Abstract

Arc spot welding is a low heat input process that it is suitable for lap joint welding of thin plates. In a typical arc spot welding process, a controlled short-circuit transfer process, such as cold metal transfer, is used to control the weld pool and/or the heat input to the base metal. In this study, the arc spot welding process is modeled in two dimensions to clarify the metal transfer and weld pool phenomena during the process. In this model, the arc plasma is not calculated and a pseudo arc is set as the conductor of current between the wire and the base metal; the heat input from the arc plasma is given by a simplified heat input model. Droplet formation, droplet transfer, and weld pool formation are included in the proposed model, and the influence of the welding conditions is investigated numerically. First, welding parameters, such as current and the wire feeding speed, are obtained from experimental observation as the input parameters of the model. The calculation result of the weld shape shows good agreement with the experimental result with adjustment of the heat input parameters. The influence of the gap between thin plates is investigated numerically. When a gap exists between the plates, the weld shape differs from that without a gap, and the numerical result is similar to the experimental result. This result shows that the heat conduction between the plates strongly affects the weld shape.