Dissimilar Welding Between Inconel 617 Superalloy and 310 Stainless Steel and Evaluation of the Joint Properties Dissimilar welding between Inconel 617 nickel base superalloy and 310 austenitic stainless steel (SS) has been investigated in this research. Three types of filler materials including ERNiCr3, ERNiCrCoMo and ER310 were used for this purpose. Sever restraint was imposed to the joints to simulate the actual industrial welding conditions in the experiments. The joint microstructures including the weld metals, heat affected zones, interfaces and unmixed zones were characterized by utilizing optical and scanning electron microscopy. The joint's weldability was examined via the weldability Varestraint test. Moreover, the mechanical properties such as tensile strength, impact resistance and hardness and fracture surfaces of the specimens were investigated. Since this joint is usually used at high temperature, its mechanical properties and microstructures were investigated after aging at 1000 ?C for 120 hour. The results showed a dendritic structure in the nickel base weld metal without any cracks. The cellular-dendritic microstructure of 310 SS weld metal comprised low melting point particles that their effect along with the presence of thermal stresses led to the formation of cracks in the weld metal and in the unmixed zone of 310SS base/weld metal interface. Niobium carbide and Laves eutectic phases were found in the Inconel 82 weld metal as well as severe Nb segregation to interdendritic zones and grain boundaries migration. A fine structure and Mo segregation in the interdendritic zones were observed in Inconel 617 weld metal. After aging treatment, the precipitated particles increased in Inconel 617 and 310SS weld metals, especially in the form of chromium and molybdenum carbides. In the tensile tests, all specimens were ruptured in a ductile manner from the 310 SS base metal. In addition, the Inconel 617 filler metal made superlative strength and elasticity before aging treatment. The welded specimens of Inconel 617 and 310SS filler metals showed the maximum and minimum hardness values, respectively. Aging treatment caused hardness to increase in weld metals and 617 base metal, but it was vice versa for the 310 SS base metal. The maximum value of fracture energy was pertained to Inconel 617 weld metal (about 205 J).
