Study on GMAW assisted by compound external magnetic fields in bogie manufacturing with T-joints and single-bevel grooves

Traditional gas metal arc welding (GMAW) and compound external magnetic field (CEMF)–assisted GMAW were used to manufacture S355J2W steel T-joint bogie structures. The weld formation, microstructure, and mechanical properties of the joints were investigated during welding along with the arc behaviors and temperature distribution. The results show that CEMFs can suppress spatter formation and undercut defects when the welding speed increases by a factor of two. Forward tilting and periodical swinging of the arc create a more uniform temperature distribution of the weld pool, which decreases the Marangoni force. The stirring effect of the CEMFs changes the solidification and crystallization process of the weld pool and eventually results in grain refinement, which improves the microhardness and ultimate tensile strength of the weld joint. Thus, CEMF-assisted GMAW can improve the welding efficiency in bogie manufacturing with T-joints and single-bevel grooves.