In process control of weld pool using weaving control in switch back welding

Abstract

The formation of stable back beads in the first layer weld during one side multilayer welding is important to achieve high quality welded metal joints. The authors thus employed the switch back welding method for V groove joints without backing plates. The burn through may take places due to the disturbance, such as the change of the base metal. If the tip of the electrode gets near the root edges, the arc discharged to the root edges of the groove. As a heat of the arc is given to the root edges, the root edges were melted enough and it is difficult to support the weld pool. In order to avoid the burn through, the weaving width was adjusted by detecting the state of the surface of the weld pool, i.e., the authors proposes the control method of weld pool. The validity of the weaving control method was verified by observation of the weld pool and the external appearance of back beads.