Effects of different protective gas on bypass metal transfer in consumable double-electrode gas metal arc welding process

In consumable double-electrode gas metal arc welding process,since the bypass welding wire is connected to the negative electrode of the welding power supply,only gravity promotes the bypass droplet transfer to the weld pool by using pure argon as protective gas. So the size of the bypass droplet is large and the metal transfer process is unstable. A high-speed camera acquisition system and a welding control system of the consumable double-electrode gas metal arc welding have been built to collect and analyze the bypass metal transfer process. On this basis,a welding test was carried out by using the 80% Ar+20% CO₂ mixture gas as protective gas. The results showed that the bypass arc burned stably on the oxide film of bypass droplet formed by CO₂ in protective gas,so the electromagnetic force and the gravity promoted the bypass metal transfer together and the size of the bypass droplet was significantly reduced.