Comparative analysis of filler metals on microstructure and mechanical performance of TIG-welded AISI 201 austenitic stainless steel joints

In this study, 4-mm thick AISI 201 austenitic stainless steel butt joints were fabricated using the tungsten inert gas (TIG) process with ER309L, ER316L and ER2209 filler rods. TIG welding was performed using a current of 100 A, voltage of 14 V, with pure argon as the shielding gas at a flow rate of 10 L/min, and filler rod diameters of 2.4 mm. The microstructural and mechanical properties were analysed. ER2209 and ER316L promote an austenitic structure in the fusion zone. ER316L filler produced the finest grain structure (9.39 μm) and the lowest δ-ferrite content (25.85%) in the weld zone. Welds made of ER316L exhibited the highest hardness (314 HV), ultimate tensile strength (857 MPa) and yield strength (448 MPa). ER316L welds also demonstrated superior strain-hardening capacity (0.91) and impact toughness (19.8 GPa). Fracture analysis revealed finer dimples in the ER316L welds, indicating improved ductility and strength compared to other welded joints.