Numerical investigation on the influence of current waveform on droplet transfer in pulsed gas metal arc welding

A numerical model for pulsed gas metal arc welding (P-GMAW) was established to investigate the influence of the welding current on the fluid flow of arc plasma and filler metal in P-GMAW. Three sets of welding current waveforms with identical peak and base current but different median currents at the drop stage of current were used to conduct the experiment and numerical simulation. Bead-on-plate welding experiments under different current waveforms were conducted and the results showed that the waveform with a median current of 140 A had the best tolerance of the welding speed amongst the three current waveforms. Based on the mathematical modelling, the temperature profile and fluid flow of arc plasma and filler metal under different current waveforms were obtained and compared. The results showed that the waveform with a median current of 140 A could lead to lower droplet temperature and velocity when the droplet reached the workpiece compared with the other two waveforms. The simulated droplet shapes at different moments were compared with the captured images by a high-speed camera and they exhibited good agreements.