Microstructural evolution and elemental variation across the fusion interface of AISI 904L and Inconel 625 dissimilar weldments

Abstract In the current scenario, welding between two different metals is broadly utilized in various industrial applications owing to their cost-effective potentials. During welding, the elemental variation across the weld interface is inevitable due to the difference in their melting ranges of micro-constituent. In this research work, the microstructural growth and the effect of precipitation due to elemental variation across the fusion boundary is analysed. PCGTA welding were employed to join alloys AISI904L and Inconel 625 using ERNiCrCoMo-1 and ERNiCrMo-4 (enriched Ni-Cr-Mo) fillers. The optical microscopy and SEM images were employed to disseminate the microstructure characters of these joints. Micro-segregation and un-mixed zone are noticed in the HAZ of both the weldments. Multi-directional competitive grain growth containing fine equi-axed grains in the weld centreline along with cellular and columnar dendrites in the weld zone are observed for both the weldments. Migrated and solidification grain boundaries are distinctly observed in the ERNiCrCoMo-1 fusion zone. The research outcomes form the present work based on the elemental variation across the fusion interfaces (micron level) recommended the ERNiCrMo-4 filler to join these candidate alloys.