Abstract
This study explores the potential uses of external sinusoidal alternating longitudinal magnetic field (EMF) assisted K-TIG welding for medium-thick plates. Our research commences with a comprehensive analysis of the distribution characteristics and dynamic variations of the EMF within the welding zone using ANSYS Electronics. Subsequently, experiments were conducted employing a custom magnetic control power supply (MCPS) to weld Y-shaped groove Q345 under EMF at various frequencies. The results indicate that EMF assisted K-TIG offers exceptionally high welding efficiency and quality. The mechanical properties of the welded joints exceed those of the base metal (BM). And we have observed a significant reduction in heat input and an increase in weld bead width under EMF. At an optimal EMF frequency, the stirring effect on the weld pool was particularly evident, resulting in beneficial microstructure and a remarkable increase in impact toughness by up to 100%. Additionally, the magnetic field lines that were perpendicular to the Y-shaped groove surface reduced the strength of the EMF in the longitudinal direction. This reduced the Lorentz force’s electromagnetic stirring effect, only leading to 20A decrease in penetration current, the reduction amplitude is lower than that without a Y-shaped groove (50A). The results of this investigation provide critical theoretical foundations and practical guidelines for improving EMF assisted K-TIG welding methods.