Effect of Increasing Oscillation Width on the Arc Characteristics and Droplet Transfer Behavior of X80 Steel in the Overhead Welding Position of Narrow Gap P-GMAW

Abstract

In the welding process of thick plate narrow gap pulse gas metal arc welding (P-GMAW) overhead welding station, the arc characteristics and droplet transfer behavior that become more complex due to the combined effects of narrow gap groove, gravity, and welding torch oscillation. The welding stability is more difficult to control. High-speed imaging and electrical signal acquisition systems were established to observe and record the arc behavior and droplet transfer during the welding process at different oscillation widths, further revealing the formation mechanism of welding seam in narrow gap P-GMAW overhead welding station. Research has found that with an increased oscillation width, the arc deflects towards the sidewall from a trumpet-shaped symmetrically distributed around the center of the groove at an increasing deflection angle, and the droplet transfer changes from one droplet per pulse to multiple droplets per pulse, resulting in defects such as lack of sidewall fusion and undercutting of the weld seam. Based on the welding process discussed in this study, it is recommended to use an oscillation width of 2.6 mm.