Effect of filler materials on dissimilar TIG welding of Inconel 718 to high strength steel

Abstract

The increase in demand for the joining of dissimilar materials for various manufacturing industries. Modern technology attracts dissimilar materials to utilize for multiple applications to reduce the cost and weight. However, the joining of dissimilar materials is challenging to attain quality joints. There are several joining methods applied for the fabrication of dissimilar materials based on the applications. However, the conventional welding methods unable to produce successful joints. Tungsten Inert Gas welding is one of the candidate process to weld dissimilar materials. In this study, TIG welding was applied to join the high temperature materials of Inconel 718 to high-strength steel. Two kinds of filler materials were used to join the dissimilar materials and optimize the welding parameters. The metallurgical and mechanical properties of the joints were also analyzed and compared between the two filler materials. The results showed that welding current has a significant influence on the properties of the dissimilar welded joints. Microstructural analysis was revealed the fusion boundary consisting of the martensite phase on high strength steel fusion boundary. Moreover, there are a small number of precipitates in the Inconel 718 fusion line. EDS line scan analysis identified that the formation of γ′ and γ′′, NbC in the weld metal. The tensile strength of the welded joints is higher for the Inconel-based filler than the stainless steel-based filler material.