Effect of bypass coupling on droplet transfer in twin-wire indirect arc welding

The bypass coupling technique was employed on twin-wire indirect arc welding (TWIAW) to improve its penetration. In bypass coupling twin-wire indirect arc welding, the cathode current can be adjusted by changing the cathode-wire feeding speed. The melting efficiency increases with the cathode-wire current. At the same total current, the deposition and dilution rates of twin-wire indirect arc welding with bypass coupling is twice and a third those of conventional gas metal arc welding, respectively, which are good for low-heat input welding, such as surfacing. High-speed camera observation indicated that the cathode droplet transfer mode changes from free transfer to contact transfer with the increase of the cathode-wire current. The repulsion force of the anode droplet to the cathode wire increases with the increase of the cathode-wire current.