Abstract
Hybrid welding was carried out on Type 304 stainless steel plate under various conditions using a YAG laser combined with a TIG arc, and the effects of various welding conditions on the penetration and porosity formation were investigated for respective arrangements of a YAG laser beam or TIG torch ahead in hybrid welding, and the welding results were compared with the ones obtained with a TIG arc only or a YAG laser alone. In most cases the hybrid weld beads were deeper and wider in comparison with the YAG laser ones; however, this fact did not always take place. It was consequently found that a laser beam should be shot inside the molten pool made readily with a TIG arc alone to produce deeper weld beads effectively. It was also confirmed that, under the focused condition, the hybrid weld beads at the arc current of 200 A had a smaller amount of porosity than the YAG laser ones. The behavior of arc plasma and laser-induced plume as well as the relationship between a laser-shot spot and the molten pool made with TIG arc only was observed through a CCD camera and a high-speed camera during arc and hybrid welding to understand the hybrid welding phenomena and factors affecting penetration.
