The variation law and mechanism of titanium alloy MIG welding process under the synergistic effect of coaxial dual channel gas path

Abstract

MIG welding still had a lot of potential in the titanium alloy industry with many advantages. How to achieve stable process and forming was still a hard nut to crack for titanium alloy MIG welding. The conventional MIG welding torch had a small coverage of shielding gas which causes an obvious insufficient capability of isolating air. Therefore, this study introduced the fluid field composite MIG process, proposed a novel strategy of titanium alloy MIG welding process under the synergistic effect of coaxial dual channel gas path, and had explored the impact of the synergistic effect of internal gas flow(Q) and external gas flow(q) on the welding process from three aspects: droplet transfer characteristics and weld surface morphology, weld cross-section. The results showed that the form of “one large droplet + several small droplets” was always maintained during transition process. Q mainly impacted on the variation law of the droplet transition; however, the length of transition period was mainly affected by q. In addition, the arc length was reduced meanwhile the geometric parameters of welds’ cross-section had more regular changes after adding q. The surface morphology was the worst when Q acted solely; however, it was straight and uniform after adding q. When q = 40L/min and Q = 15L/min, the coverage and protective effect of shielding gas was excellent, no turbulence was generated, and no pores generated in the cross-section of the weld. It was easier to obtain a more stable forming of titanium alloy MIG welding when Q and q worked together.