Weldment Properties of S355 Unalloyed Steel and 304L Stainless Steel Sheets

Abstract

S355 unalloyed structural steels are exploited in constructions and in huge parts because of their low costs, while much more expensive high-alloyed 304L austenitic stainless steels are preferred in areas where high corrosion resistance is a concern. These two types of steels can be used together in applications primarily due to economic considerations. For instance, in furnaces, 304L alloy is used inside the furnace, and S355 alloy is used outside. Bolting and welding techniques are frequently preferred for joining these two distinct alloys. In the present study, S355 and 304L steel sheets are joined with the Tungsten Inert Gas (TIG) welding method by argon shielding gas via ER309L TIG welding rods. As-received pearlitic and ferritic microstructure of S355 alloy was transformed into the needle-like and dendritic carbides, while the as-received microstructure of 304L, having a majority of austenite and minor amounts of delta ferrite became regular equiaxed austenite grains upon solidification and recrystallization after welding. The highest microhardness values were obtained in weld metal regions as a consequence of the ER309L TIG rod having higher chromium and molybdenum contents over the two base metals, owing to its hard carbides. The mechanical and microstructural tests revealed that the conventional TIG welding method can satisfactorily and effectively be used in joining these two distinct steel groups.