Investigation on the Effect of Activating Flux on Tungsten Inert Gas Welding of Austenitic Stainless Steel Using AC Polarity

Tungsten Inert Gas (TIG) welding is a popular joining process due to its inherent capability in producing superior quality welding in a wide range of materials. However, lower productivity of it paves the way for introduction of a number of variants of TIG welding, including Flux Bounded TIG (FB-TIG) welding and Activated TIG (A-TIG) welding. In this paper, variations of weld morphology and characteristics with heat input in AC A-TIG welding of both bead-on-plate and butt joining of 6mm thick 316L stainless steel plates using TiO 2 , Cr 2 O 3 and Fe 2 O 3 as activating flux and a stainless steel filler material are investigated. Results are also compared with that obtained in conventional TIG welding. Variations of various weld characteristics viz. depth of penetration, width of weld bead, reinforcement, Reinforcement Form Factor (RFF), and Penetration Shape Factor (PSF) against change in heat input are analyzed and compared. It is observed that TiO2 and Fe 2 O 3 fluxes effectively enhance the penetration due to increase in fluidity and wettability of molten metal and, at the same time, reduce the width of weld bead; whereas, Cr 2 O 3 flux gives inferior results as it reduces penetration instead of increasing it as compared to conventional TIG welding.