The Influence of Groove Geometry on the Creep Fracture Behavior of Dissimilar Metal Welds between Ferritic Heat-Resistant Steels and Nickel-Based Alloys

This study investigates the influence of groove geometry on the high-temperature creep life and fracture behavior of Dissimilar Metal Welds (DMWs) between low-alloy steel 2.25Cr1Mo and austenitic stainless steel 347H using Inconel 82 nickel-based filling metal. This research aims to reveal the effect of groove geometry, especially the stepped groove, on creep crack propagation path and creep life, through a combined approach of finite element simulation considering stress triaxiality and experimental validation. The study reveals that the stepped groove alters the creep crack propagation path, enhancing the endurance life by deflecting cracks away from the weld/heat-affected zone (HAZ) interface and directing them into regions with higher creep resistance. The experimental results verify the simulation findings, revealing that the stepped groove joints exhibited longer creep life with changes in failure location and mechanism compared to the V-groove joints. However, it was found that the stepped groove intensified the stress concentration at the early creep stage. Thus, a good balance should be achieved between the negative (stress concentration at interface) and positive (changing crack paths) effects of the stepped groove to extend the creep life of DMWs.