Enhanced microstructural and mechanical performance of dissimilar stainless steel joints using hybrid-flux activated GTAW

Abstract Dissimilar welding of stainless steels is extensively used in chemical, petrochemical, food-processing, and power-generation industries, where improved weld quality and mechanical performance are essential. The present study investigates the influence of TiO₂, SiO₂, and hybrid TiO₂+SiO₂ activated fluxes on the microstructural and measured hardness response of SS304–SS316 dissimilar joints produced by Gas Tungsten Arc Welding (GTAW). weld morphology, calculated heat input, surface morphology, localized elemental composition, diffraction response, and microhardness were evaluated using optical examination, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Vickers microhardness testing. The hybrid TiO₂+SiO₂ activated flux produced the deepest weld penetration (3.0 mm), the narrowest bead width (3.8 mm), and the highest measured microhardness (95 HV) compared with conventional GTAW. SEM observations revealed differences in surface morphology among the investigated welding conditions, while EDS analysis indicated differences in elemental distribution across the analysed regions. XRD analysis revealed additional diffraction peaks associated with flux-assisted welding; however, definitive phase identification requires further quantitative analysis. Overall, the hybrid TiO₂+SiO₂ activated flux demonstrated the most balanced combination of weld penetration, bead geometry, microstructural characteristics, and hardness, indicating its potential for improving the quality of dissimilar stainless-steel welds.