Arc characteristics and metal transfer behavior of CMT$+$P process for Q235 steel of titanium-steel composite plate

The cold metal transfer (CMT) with addition of pulses (CMT$+$P) process is a new CMT welding method. This paper uses a high-speed camera and electrical signal synchronization acquisition system to perform a CMT$+$P welding test on a 10 mm thick Q235 steel plate, and performs arc characteristic and droplet transfer behavior in the welding process. It has been founded that under relatively small currents and voltages, the CMT$+$P transfer mode is a combination of a projected transfer mode with one droplet in the pulse period and a short circuit transfer mode during the CMT period. The process is stable with little spatter; at relatively large currents and voltages, the transition mode is the combination of pulse transfer, spray transfer and short circuit transfer. It results in one or more droplets that enter the pool both in pulse transfer in the spray transfer mode during the pulse period and in the short circuit transfer mode during the CMT period in a weld cycle.