Studies on residual stresses and structural integrity of the dissimilar gas tungsten arc welded joint of sDSS 2507/Inconel 625 for marine application

摘要

Abstract This study examined the structural integrity and residual stresses of dissimilar welding between super duplex stainless steel (sDSS 2507) and Inconel 625 using ER2594 filler wire and gas tungsten arc welding (GTAW). The mechanical properties of the weldments were assessed through various tests, such as hardness, impact, and transverse tensile tests, at different heat inputs, i.e., 0.73 and 1.4 kJ/mm. Optical and scanning electron microscopes with energy-dispersive spectroscopy studied base metal and weld zone/interface microstructure evolution. Additionally, the study analyzed the effects of heat input on residual stresses and evaluated those stresses using deep-hole drilling methods. In the weld metal and IN625 HAZ, Nb-rich Laves phases were irregularly distributed. Line mapping and electron probe micro-analysis showed Cr, Mo, and Nb enrichment, which precipitated as segregation at the weld interface. EDS studies also demonstrated Mo- and Nb-rich phases segregating in the inter-dendritic region of the weld zone, with the highest weight percentage at high heat input weldment. The Nb-rich Laves phases in the inter-dendritic regions reduced mechanical performance, and both weldments fractured at the weld zone during tensile testing. High heat input increased residual longitudinal and transverse stresses by 16 and 19, respectively.