Effects of additional compensation shielding gas on high-speed pulsed MIG welding seams

Aiming to provide a solution to frequently occurring weld defects such as, undercuts and humping beads, an additional compensation shielding gas technique has been adopted for the first time. A shielding gas branch channel has been specially built near the end of rear protective gas hood of the pulsed MIG welding gun nozzle. By using a three-way air valve, to control the flow of the compensation shielding of gas as to conduct manual intervention to facilitate the formation of high-temperature solid and liquid welding seams that have just left the welding gun nozzle and provide secondary protection for the seams. The surfacing plate test in which the 18-8 austenitic stainless steel plate has been used as the base metal, has been conducted. The test results have shown that the introduction of appropriate additional compensation shielding gas not only improves the formation of welding seams apparently but also tracks and protects the welding seam surfaces in time, which significantly reduces the weld defects that frequently occur during the use of the high-speed pulsed MIG welding technique and substantially increases the welding efficiency. Therefore, the technique is worth being studied further theoretically and in technological practice.