This study investigates the dissimilar welding of austenitic stainless steel AISI 304L and ferritic stainless steel AISI 409 M using Tungsten Inert Gas (TIG) welding. Welding experiments were designed using a Taguchi L9 orthogonal array considering welding current, shielding gas flow rate, and travel speed as process parameters. Butt joints were fabricated and evaluated through visual inspection, X-ray radiography, tensile testing, and microstructural characterization. The results indicate that tensile strength of the welded joints varied significantly with process parameters and ranged from 522 to 644 MPa. Among the samples, specimen S6A exhibited the highest tensile strength (644.5 MPa) with 30.6% elongation due to the formation of a refined ferrite-austenite microstructure with reduced dendritic spacing. Microstructural analysis revealed the presence of lacy and vermicular ferrite within the austenitic matrix along with Widmanstätten ferrite near grain boundaries. Taguchi optimization identified the optimal welding condition as C2G3S3 corresponding to 105 A welding current, 20 L/min shielding gas flow rate, and 3 mm/s travel speed. The study establishes a correlation between welding parameters, heat input, microstructural evolution, and mechanical performance in dissimilar stainless-steel TIG welding. Unlike previous studies, the present work establishes a direct correlation between heat input, solidification behavior, and resulting microstructural features in AISI 304L-409 M dissimilar welds. The study provides new insight into the process-structure-property relationship specific to ferritic-austenitic stainless steel combinations.
Ghosh et al. (Thu,) studied this question.