Abstract: The defects of weld profiles in large-current and high-speed welding can be improved by adding alternating magnetic field. In order to obtain the influence of different magnetic excitation parameters on the arc and pool characteristics of DP-TIG (deep penetration TIG) welding, the DP-TIG welding experiment of 12 mm Q345B plate was carried out with additional transverse alternating magnetic field. The arc shapes were observed by a high-speed camera system, the arc pressures were measured through the small hole method, and the weld pool section profiles were analyzed based on the metallographic corrosion method. The results show that, compared with DP-TIG welding without magnetic field, the arc shape of DP-TIG welding with additional transverse alternating magnetic field changes obviously, the peak value of arc pressure first decreases and then increases with the increase of alternating frequency, and the weld pool section profile transits from finger-shape to pot-bottom-shape. In addition, the iron content in the weld surface of Ni-based overlay welding is less than 5%, and the dilution degree of welding material is low.

Key words: DP-TIG, transverse magnetic field, arc shape, pool characteristic