Dissimilar Joining Between Austenitic and Duplex Stainless Steel in Double-Shielded GMAW: A Comparative Study

In the present work, the effect of double-layer shielding and five other process parameters, namely welding voltage, current, primary shielding gas type, its flow rate, and filler material, is studied during dissimilar gas metal arc welding (GMAW) between austenitic and duplex stainless steels (SSs). A simple modification over the GMAW setup is made for additional supply of secondary shielding gas at different flow rates. Two different sets of welding are performed between austenitic and duplex SSs, i.e., AISI 304 with Duplex 2205 and AISI 316 with Duplex 2205, and the contributions of process parameters, their interactions on joint distortion, tensile strength, toughness, and fusion zone microhardness are evaluated. Improvements in joint quality due to the double-shielding environment are also highlighted. Double-layer shielding with secondary shielding by CO2 supply significantly improves tensile strength and toughness and reduces distortion. Fusion and interface zone microstructures are observed by scanning electron microscopy to study the metallurgical behavior of joints fabricated under single- and double-layer shielding environment.