Investigation of the microstructure, residual stresses, and mechanical behavior of Inconel 59 and AISI 904L fusion joint using single pulse GMAW with post-weld cryogenic treatment

Inconel 59 and AISI 904L are widely used in chemical processing and systems for flue gas desulfurization due to their superior corrosion resistance and mechanical strength. This study evaluates dissimilar joints formed by Single Pulse Gas Metal Arc Welding (SP-GMAW) using ERNiCrMo-13 filler. Microstructural analysis revealed coarse grains in the heat-affected zone on the 904L side, with the fusion zone showing columnar and cellular grains. The heat-affected zone was larger on the AISI 904L side (280 µm) than on the Inconel 59 side (180 µm). SEM/EDS analysis indicated minimal secondary phases, with molybdenum (Mo) enrichment and nickel/iron depletion in the fusion zone. Mechanical testing showed fracture occurring in the AISI 904L base metal, while deep cryogenic treatment contributed to notable improvements in yield strength, tensile strength, and elongation. The fusion zone hardness was 224 HV, exceeding Inconel 59 by 16% and AISI 904L by 23%, attributed to Mo segregation. Impact toughness in the weld zone averaged 85 J, 26% lower than Inconel 59 but 47.36% higher than AISI 904L. Residual stress analysis revealed compressive stresses in the fusion zone and tensile stresses in the base metals. SP-GMAW, combined with deep cryogenic treatment, achieved a refined microstructure and enhanced mechanical properties.