Development of high-basicity SMAW electrodes for dissimilar welding of duplex stainless steel 2205 and API X70 pipeline steel

The present study investigates the development and evaluation of high-basicity SMAW electrodes containing CaO–CaF 2 –TiO 2 –ZrO 2 –SiO 2 coatings for welding API X70 pipeline steel to DSS 2205. Twenty-seven electrode formulations were developed, characterized, and benchmarked against a commercial ER309L electrode. Welds fabricated using the optimized laboratory-developed electrode exhibited a more balanced weld-metal chemistry, notably with reduced carbon and silicon levels. Tensile testing indicated that the weld-metal strength was comparable to that achieved with the commercial electrode, whereas ductility was slightly lower and impact toughness was higher. Microhardness measurements showed uniform hardness across the weld zone, with the DSS HAZ displaying a higher hardness. Microstructural analysis revealed a desirable ferrite–austenite balance, along with chromium enrichment in ferrite and nickel enrichment in austenite. Potentiodynamic polarization testing in 3.5% NaCl solution demonstrated enhanced corrosion resistance for welds produced with the optimized electrode.