Effect of Different Magnetic Field Types on Microstructure and Properties of Deposited Metal Prepared from High-Strength Steel Wire

In this paper, 800 MPa high-strength steel wire is used to prepare a kind of deposited metal with good toughness by magnetic field-assisted MAG welding. A high-speed camera is used to observe the arc morphology and melt drop transition during the welding process assisted by different types of magnetic field. The microstructure evolution of deposited metal is characterized by means of OM and EBSD, whose effects on mechanical properties also are analyzed. The results show that the transverse magnetic field can change the arc morphology and melt droplet trajectory, reduce the formation of PF, and refine the grain size. The low-temperature impact toughness of deposited metal is increased to 128 J, with a 28% improvement compared to non-magnetic fields. Under the influence of a longitudinal magnetic field, the arc is compressed and the frequency of the transition of the melt drops slows down, resulting in the growth of spatter. It also reduces the amount and size of pre-eutectic ferrite and side-plate lath ferrite, resulting in grain size refinement. The low-temperature impact toughness of the deposited metal was increased to 113 J, an improvement of 13%. In addition, low-temperature impact toughness of the deposited metal was increased by 61% due to the application of an alternating magnetic field, which enabled the welding arc to be characterized by both non-magnetic and longitudinal magnetic field shapes, accelerated the frequency of the melt droplet transition, and reduced the average grain size by 12.7%