Forming and weld grain growth behavior of arc stud welding driven by rotating magnetic field

Local non-fusion is easy to occur in the process of medium and large diameter hollow stud welding, which reduces the forming quality and mechanical properties of the joint. In this study, a method of arc hollow stud welding driven by external rotating magnetic field is proposed to weld 30CrNi3MoV substrate and Q235 hollow stud. The effects of rotating magnetic field on joint forming and grain growth in weld zone are studied. It was found that under the action of the rotating magnetic field, the charged particles move under the action of Lorentz force, the arc rotates and burns uniformly at the end of the stud, and promotes the expansion of the molten pool, which avoids the local unfused phenomenon and improves the appearance of the joint. The arc rotates and stirs the molten pool under the action of a magnetic field. The undercooling of the molten pool is reduced, the grain size of the weld is refined to 3.06 μm, the proportion of large-angle grain boundaries in the weld area is increased to 41.2 %, and the shear strength and impact toughness of the magnetron stud welded joint are up to 323 MPa and 34.28 J.cm−2, and the microhardness of the weld is up to 325 HV.