Study of twin tungsten electrode – wire electrode indirect arc welding assisted by alternating magnetic field
Liming Liu, Yanli Zhu, Runtao Liu
Abstract
In this paper, an alternating parallel magnetic field was applied to assist twin tungsten electrode – wire electrode indirect arc welding (TTW IAW), aimed to improve the spreading of its weld bead. The arc behavior, droplet transfer process, and weld pool morphology were recorded by high-speed camera. Results showed that under the magnetic field, the arc and droplet of TTW IAW swung periodically, but the deflection directions of the both were opposite. Besides, the weld bead was smooth and successive, and the columnar dendrite was partly changed into equiaxed dendrite in the fusion zone of weld bead. Additionally, with the increase of the external excitation current, the swung amplitude of arc and droplet increased accordingly, which promoted the transverse convection of molten metal . When the external excitation current was 39 A, the wetting angle of weld bead could decrease 31.5 %, and the weld width could increase 20.2 %, where the spreading of weld bead was evidently improved. Furthermore, the stirring on the weld pool was promoted with the increase of the external excitation frequency , while the spreading of weld bead was lowered when the external excitation frequency exceeded 10 Hz.