Study of welding characteristics in CO2 laser-TIG hybrid welding process

In this paper, 304 stainless plates with 4mm thickness were welded with CO2 Laser-TIG paraxial hybrid welding. The arc shapes and weld characteristics were studied under different energy ratios between laser and arc. The experimental results indicated that hybrid welding exists two welding mechanisms---deep penetration welding and heat conductive welding. Because of the action of keyhole induced by laser, TIG arc was fixed and compressed, and the current density and the penetration depth increased dramatically, which took on the weld characteristic of deep penetration welding. When current increased to some degree, the keyhole induced by laser disappeared and arc expanded abruptly, it caused the penetration depth rapidly drop, which took on the weld characteristic of heat conductive welding. Furthermore, the effect of distance from laser to TIC arc and pulsed laser on hybrid welding characteristics were also studied.