INVESTIGATION OF SINGLE-SIDED TIG WELDING IN DISSIMILAR AISI 316L AND 304L STAINLESS STEEL JOINTS

Abstract

This study investigates the Tungsten Inert Gas (TIG) welding of dissimilar austenitic stainless steels, AISI 304L and AISI 316L, each with a thickness of 3.2 mm. A single-pass butt joint was welded using a 100 A current with argon shielding gas. The joints underwent mechanical testing, including tensile, bend, impact, and hardness tests. The tensile test revealed a 25% reduction in the weld joint strength compared to the base metal, primarily due to differences in thermal expansion and mechanical properties, resulting in an overall joint efficiency of 75%. Macro and microstructural analyses indicated good fusion without defects, and typical weld metal microstructures were observed. The heat-affected zone (HAZ) of AISI 304L showed larger grains, while AISI 316L exhibited a flaky structure. The hardness test indicated the highest value in the weld zone (191 HV), compared to the HAZ (177 HV) and the parent metal (170 HV), which can be attributed to grain refinement and the use of the SS304 filler rod. Impact tests demonstrated good impact resistance (45 J), with the HAZ exhibiting higher toughness compared to the parent metal. Bend tests revealed no cracks on the weld face, whereas cracks were observed in the root bend tests. The study demonstrated sufficient strength, toughness, and hardness in the dissimilar TIG joint for engineering applications, despite the reduced tensile strength compared to the base metals. © Galati University Press, 2025.