The present study examines the mechanical properties and microstructural characteristics of a dissimilar welded joint between AISI 304H stainless steel and Inconel 617, fabricated using the pulsed gas metal arc welding (P-GMAW) process. A nickel-based ERNiCr-3 (Inconel 82) filler metal was employed to produce the weld joint. Microstructural characterization carried out using optical microscopy and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) revealed a predominantly dendritic austenitic microstructure in the weld metal. The weld metal contained precipitates of NbC and Ti(C,N), which were mainly distributed along the inter-dendritic region which were formed due to the segregation of Nb and Ti during solidification. The welding passes were found to have a pronounced influence on dendritic morphology and precipitate distribution within the weld metal. Consequently, the microstructure varied significantly from the capping pass to the root pass. Near the fusion interfaces, the weld metal primarily exhibited columnar dendritic structures, whereas the central region of the weld showed a mixture of cellular and equiaxed dendrites. The study also identified segregation near the fusion boundaries, leading to the formation of a wide unmixed zone on the AISI 304H side and a partially melted zone on the Inconel 617 side. EDS analysis confirmed elemental diffusion across the interfaces, with significant diffusion of Ni and Fe observed at the AISI 304H interface, while Co, Mo, and Ni diffusion was more prominent at the Inconel 617 interface. The observed microstructural variations across the welded joint had a substantial effect on hardness and Charpy impact toughness. Nevertheless, the P-GMAW process resulted in a refined weld microstructure with a relatively uniform distribution of NbC and Ti(C,N) precipitates within the austenitic matrix, leading to improved mechanical performance. The welded joint exhibited an average tensile strength of 640 ± 7 MPa, Charpy impact toughness of 158 ± 6 J, and microhardness of 239 ± 5 HV. The room-temperature tensile strength of the joint was comparable to that of the AISI 304H base metal but remained significantly lower than that of the Inconel 617 base metal. Elevated-temperature tensile testing showed tensile strengths of 270 MPa and 200 MPa at 650 °C and 700 °C, respectively, with fracture consistently occurring in the AISI 304H base metal region. Charpy impact testing indicated that the weakest region of the welded joint was the Inconel 617 heat-affected zone, which exhibited an impact toughness of 94 ± 4 J. Hardness measurements showed variations from the capping pass to the root pass and across the weld metal from the AISI 304H interface toward the Inconel 617 interface. These results demonstrate the effectiveness of pulsed GMAW in producing a mechanically reliable and microstructurally refined AISI 304H-Inconel 617 dissimilar joint for high temperature applications.
Garga et al. (2026) studied this question.