Effect of external magnetic field on arc characteristics and weld bead formation in metal-cored arc welding

Abstract This study aimed to clarify the influence of a longitudinal external magnetic field (EMF) on arc characteristics, metal transfer behavior, and weld bead formation in metal-cored arc welding (MCAW) process. The work focused on comparing two distinct conditions: without EMF (0 mT) and with EMF applied at a magnetic flux density (MFD) of 6 mT, evaluated by high-speed video observations and numerical simulation models for a welding current of 320 A. Experimental results indicated negligible changes in droplet transfer frequency between the two conditions, but significant differences were observed in arc behavior and weld pool characteristics. The application of EMF intensified arc brightness and increased weld penetration depth from 3.7 mm (no EMF) to 4.2 mm (EMF 6 mT). Simulation results revealed that EMF induced rotational plasma flow and reduced pressure at the arc column center, which resulted in an increased plasma velocity directed toward the weld pool surface. Consequently, a depression was observed at the weld pool surface to enhance the weld bead penetration. The findings highlight the potential of EMF as a valuable tool to optimize MCAW processes, particularly when precise penetration control and improvement of weld quality are required.