Using arc pressure to investigate the effects of energy source distance on arc plasma behaviour in pulsed Nd:YAG laser/tungsten inert gas (TIG) arc hybrid welding

This work is aiming at studying the effects of arc pressure based interenergy sources distance on the dynamic behaviour of arc plasma in pulsed Nd:YAG laser/tungsten inert gas (TIG) arc hybrid welding process. First, the effect of process parameters such as height of tungsten electrode, inclination angle of TIG torch and arc current on the arc pressure on workpiece surface was investigated experimentally in order to get a quantitative understanding of the influences of TIG arc welding parameters on the arc-pressure based inter-energy sources distance, d, of hybrid welding process. And then hybrid welding experiments were conducted with five different d: -0.75, -0.25, 0.25, 0.75 and 1.25 mm. During hybrid welding processes, transient evolution of arc plasma was recorded by a high speed charge-coupled device (CCD) camera. Under the conditions considered in this paper, strongest contraction of arc plasma was observed in the welding process with d being -0.25 mm. With d is less than -0.25 mm, arc plasma would become fluctuant during laser pulse duration. When d is greater than -0.25 mm, however, the increase of inter-energy sources distance resulted in the weakening of arc plasma contraction.