A discussion on the weldability of Inconel and carbon steel dissimilar joints

Available studies indicate that optimised welding parameters, Ni-based fillers, buffer layers, and post-weld heat treatments can partially mitigate cracking and improve microstructural stability. However, research on direct Inconel 718-carbon steel joints remains limited and fragmented, with much of the understanding derived from analogous systems such as Inconel 625 overlays and Inconel-stainless steel welds. Significant knowledge gaps persist in long-term degradation mechanisms, fatigue and fracture behaviour, corrosion-assisted failure, and service-life prediction. Advanced approaches – such as functionally graded interlayers, solid-state welding, in-situ monitoring, and computational thermomechanical modelling – are identified as key strategies for improving weldability and reliability. Overall, this review highlights the need for systematic, mechanism-driven investigations to enable the reliable application of Inconel-carbon steel dissimilar joints in demanding industrial environments.