Investigation of dissimilar weld joint between stainless steel grades 204 L and 214, focusing on microstructure, mechanical properties, and pitting corrosion behavior

 This study aimed to characterize dissimilar welding of 200 series austenitic stainless steels (low nickel) between grades AISI 204 L and 214. The welds were produced using the GTAW process for the root side and the GMAW process for the face side, utilizing two types of filler materials: Incoloy 65 and 304 L. The study examined the macrostructure and microstructure, mechanical properties, and pitting corrosion resistance. The macrostructure revealed that the heat-affected zone (HAZ) and the partially melted zone (PMZ) on the 214 base metal side were wider than on the 204 side. The weld metal size was the same for both filler metals. Microstructural analysis showed the formation of delta-ferrite in an austenite matrix in the weld metal using the 304 L filler metal, with solidification occurring in the FA mode. In contrast, the weld metal using the Incoloy 65 filler metal exhibited full austenite, with solidification in the A mode. Microhardness of the Incoloy 65 weld metal was higher than that of the 304 L weld metal for both the face and root sides. Additionally, the root side exhibited higher hardness than the face side for both filler metals. Tensile test results followed a similar trend to the hardness tests. However, the impact toughness of the 304 L weld was better than that of the Incoloy 65 weld, with root sides showing higher toughness than face sides. All fracture toughness tests showed ductile fracture behavior. Regarding pitting corrosion resistance, the Incoloy 65 weld performed better than the 304 L weld, with root sides exhibiting higher resistance than face sides. Pitting initiation occurred at the interface zone between the delta-ferrite and austenite phases, likely due to the low chromium content. This study demonstrates that combining GTAW and GMAW welding processes with a high-nickel alloy filler metal is more quality weldment than using a high-chromium alloy filler metal when welding dissimilar grades of stainless steel from the 200 series.