Effect of shielding gas and activating flux on weld bead geometry in tungsten inert gas welding of austenitic stainless steels

The aim of this study was to investigate the influence of three shielding gases (argon and argon–hydrogen and argon–helium mixtures) and two activating fluxes (a commercial flux and a TiO₂ based flux) on the geometry of welds produced by the tungsten inert gas (TIG) welding process on several casts of austenitic stainless steel AISI 316, using currents ranging from 100 to 300 A. Penetration depth increases with increasing current for all shielding gases, but weld depth to width ratio is higher for argon than for argon–hydrogen shielded welds. Both activating fluxes produce a substantial increase in penetration depth and in depth to width ratio of the welds. No correlation was found between penetration depth and oxygen content in the melted material. Some interaction exists between activating fluxes and shielding gases, which can affect the weld geometry and/or the defect formation in the welds.