Numerical study of the effects of short-circuiting current on a controlled short-circuit transfer process

Abstract

Gas metal arc welding has wide industrial applications so that there is a high demand for increased efficiency and quality for it. A controlled short-circuit transfer process, which means a process realized by appropriate current and wire feed control in this paper, is a low heat input gas metal arc welding process. In this process, short-circuit transfer is stably and periodically repeated to enable the low heat input and the high deposition rate. Recent years, this type of process has been investigated to be applied to dissimilar materials welding, wire arc additive manufacturing and lap joint welding of thin plates of high tensile strength steel, these are current important topics. However, control factors of the process are not clear enough because of the complexity of its welding phenomena and the lack of investigations for them. In this study, a controlled short-circuit transfer process is modeled in two-dimensions to clarify the metal transfer and weld pool phenomena during the process. In this report, the effects of short-circuiting current on the process are investigated. We revealed that the electromagnetic force induced by short-circuiting current has a large effect on the weld formation process. Short-circuiting current induced the high pressure in the liquid column that is formed between electrode and base metal while short-circuiting, and the strong convection flow induced by the large pressure gradient between the liquid column and the weld pool promoted the weld formation. We also revealed that the electromagnetic force affects on the droplet transfer process. Short-circuit transfer cycles became more instable when the short-circuiting current is higher.