Effect of Welding Parameters on TIG Welding of Inconel 718 to AISI 4140 Steel

The combination of Inconel 718 with AISI 4140 steel joint is in continuous demand for various applications. The difference in the physical and metallurgical properties between the two materials lead to difficulty in joining with conventional fusion welding methods. TIG welding is a suitable welding method to join such materials without any major issues. Therefore, the welding parameter effects on mechanical properties were studied experimentally and using the response surface methodology model. The microstructural characteristics and fracture surfaces of the welds were analyzed using the optical and scanning electron microscope. The reactions between the filler metal and substrates were evaluated by the electron probe microanalyzer for the presence of secondary phases. The formation of equiaxed and cellular dendritic growth of microstructure was observed from the welds. The fractography analysis investigated the ductile mode of failure after lap shear and fatigue tests.