Microstructure, Corrosion Resistance and Mechanical Properties of Dissimilar Welded Austenitic, Super-Austenitic and Duplex Stainless Steels

This study aimed to comparatively evaluate the microstructural characteristics, mechanical properties, and localized corrosion resistance of three dissimilar stainless-steel joints: 254 SMO® (UNS S31254)–310S (UNS S31008), 254 SMO® (UNS S31254)–2205 (UNS S32205), and 310S (UNS S31008)–2205 (UNS S32205). The joints were produced by gas tungsten arc welding (GTAW) using ERNiCrMo-3 filler metal and were investigated through macrostructural examination, SEM–EDS analysis, microhardness measurements, transverse tensile testing, and ASTM G48 corrosion testing. All three combinations produced fully penetrated welds without visible macroscopic discontinuities. SEM–EDS revealed Fe–Ni gradients across the fusion boundaries, consistent with local dilution of the Ni-based filler metal, together with Nb–Mo-rich interdendritic constituents and discrete Ti–Nb-rich particles in the weld metal. The 254 SMO–310S joint exhibited the highest tensile strength and elongation (776 MPa and 43.6%), followed by 254 SMO–2205 (742 MPa and 27.7%), with both fracturing outside the weld zone. The 310S–2205 joint showed lower strength and ductility (578 MPa and 12.3%) and fractured within the welded region. ASTM G48 testing showed low mass losses and no pronounced preferential attack of the weld metal or heat-affected zones. ERNiCrMo-3 produced sound dissimilar joints in all three material combinations, although their microstructural, mechanical, and corrosion responses differed with the adjoining base metals.