Influence of Pulsed Current for Heating Characteristic of Groove in Ultra-narrow Gap Welding with Sheet Tungsten Electrode Arc Constricted by Insulating Solid Wall

The new method for welding of SUS304 austenitic stainless-steel is proposed to improve the heating characteristics of pulsed current sheet tungsten electrode arc constricted by insulating solid wall on groove in ultra-narrow gap. The bottom, side and corner in ultra-narrow gap groove could obtain good fusion in lower heat input by this method. Meanwhile the heating mechanisms of pulsed current sheet tungsten electrode arc constricted by insulating solid wall on ultra-narrow gap groove would be understood by comparative analysis of transverse weld morphology, geometric parameters with variation of pulse current frequency, duty cycle and average welding current, thermal cycle curve, peak pressure of pulsed arc and arc shape. The results show the synergistic effects of pulse current frequency, duty cycle, average welding current and constriction by insulating solid wall on sheet tungsten electrode arc would determinate the heating characteristics on groove in ultra-narrow gap; the raise of pulse current frequenc