Abstract: A high-speed video system is used to monitor the changes in droplet transfer mode and plasma morphology as well as to collect the arc and droplet images during welding. An arc analyzer is used to record the signals of arc. The effects of laser power on the arc shape, welding stability and droplet transfer frequency during CO2 laser-metal active gas(MAG) arc hybrid welding are studied. The results show that an increase in welding current reduced the actual distance between laser and arc, which is suitable at 2 mm. The main reasons for the appearance of the turbulence and sharp waveform in the waves of current and voltage are attributed to the disturbance or drift of the charged particles in the main and auxiliary current channels, the skip of welding mode and the change in the droplet transfer mode. The introduction of laser reduces the frequency and stability of the droplet transfer. The frequency of the droplet transfer shows a first decrease and then increase with increasing laser power when the welding current is either 160 A or 180 A, which, however, is between the values of single arc welding under 160 A and 180 A.

Key words: Arc shape, Droplet transfer, Laser power, Laser-arc hybrid welding