Investigating the influence of single and multicomponent activated fluxes on macrostructure, microstructure, and hardness of ATIG welded SS304

This study investigates the effect of activated fluxes TiO₂, SiO₂, and Fe₂O₃ and their mixtures on the microstructure and hardness of tungsten inert gas welded austenitic stainless steel SS304. Regression models were developed for all the responses. Bead-on plate welds were fabricated using optimized process parameters and characterized for microstructure and hardness. The activated fluxes significantly impacted the bead's appearance, shape, microstructure, and hardness. A layer of residual slag was seen over the weld metal for all the fluxes and their mixtures. No critical defect was seen except a little spattering for a few fluxes. Activated fluxes exhibited different impacts on penetration, bead width, and HAZ width without any correlation. SiO₂ produced the greatest penetration and aspect ratio. Penetration varied in direct proportion with the amount of SiO₂ and inversely with the amount of TiO₂ and Fe₂O₃. No such relation could be seen for other responses. Welds displayed the usual vermicular delta-ferrite morphology together with an austenite matrix microstructure without any significant influence of fluxes on microstructure. A marginal change in bead and HAZ hardness was observed for all activated oxide fluxes. Mixture design using analysis of variance is a decent technique for optimizing flux compositions as predicted results are in good agreement with experimental ones.