Fusion enhancement of hollow tungsten arc coaxially assisted by fiber laser

Abstract

Bead-on-plate experiment was performed on a continuous-mode fiber-laser hollow tungsten coaxial welding platform designed and built by us. The weld bead cross-section was observed by using a optics microscope, and the welding arc image was recorded by using a high-speed camera to track the welding process. The changes in the arc physical field after laser addition were analyzed by conducting numerical simulations to explore the mechanism of increasing the welding depth. The results showed that the coaxial hybrid of fiber laser and hollow tungsten arc can significantly increase the weld depth and thermal efficiency of hybrid arc. When the welding current remained constant at 70 A, the weld penetration increased with an increase in the laser power. However, the growth rate was different under different laser power settings and there were the upper and lower critical values of laser power which were 450 W and 60 W. When the laser power remained constant at 400 W, the weld penetration first increased and then remained constant with an increase in the current, and there was a current critical value of 170 A. The main reasons for the increase in the penetration depth were the increase in the arc temperature, arc pressure and thermal efficiency of hybrid welding.