Creep rupture and microstructural analysis of dissimilar welded joints of P92 steel and Alloy 617

Advanced ultra-supercritical plants are recognized for their efficiency and effectiveness in energy production, particularly when operating at elevated steam temperatures (700–720 °C). High-temperature components within these plants, including turbines, pipes, headers, and tubes, typically employ nickel-based alloys like Alloy 617, renowned for their outstanding resistance to corrosion and oxidation. Nevertheless, lower-temperature components (below 620 °C) frequently use less expensive ferritic-grade steels like P91 and P92. Welding these disparate materials balanced the plant’s performance and cost-effectiveness. This study focuses on the creep rupture behaviour of a dissimilar welded joint made through a gas tungsten arc welded joint between P92 steel and Alloy 617, utilizing a Ni-based Inconel 617 filler, at a test temperature of 650 °C under a stress of 140 MPa. A light microscope and a field emission scanning electron microscope were used for microstructural study. The investigation looks at how creep ruptures happen and how the microstructure changes inside the DWJ, and microhardness testing to comprehensively assess the joint’s performance under specific stress and temperature conditions. At 140 MPa and 650 °C, the sample demonstrated a creep rupture time of 54.5 h.