Studies on characteristics of CO2 laser-GTAW hybrid welding of austenitic stainless steel

The present paper describes an experimental hybrid welding study, involving CO2 laser and gas tungsten arc welding, on 6 mm thick austenitic stainless steel sheet. The study focused on real-time plasma monitoring during welding and metallographic examination of the resultant weldments. Coupling of laser-generated plasma and gas tungsten arc was achieved by introducing argon cross jet. The results of the study demonstrated that for obtaining deep hybrid welds, incident laser power density should be above a threshold to generate metal plasma on its own. An increase in arc current with laser power density below the threshold value resulted in broader conduction-limited welds without causing much change in the weld depth. Coupling of arc with laser also served to stabilize and enhance metal plasma formation, which, in turn, facilitated stabilization of the resultant welding process. Best hybrid welds were achieved when arc followed laser beam along the direction of welding.