Creep-fatigue behavior analysis of the 310 NBN steel: Experimental and life prediction

With the increasing challenge of extending the service life of structural steels components subjected to high-temperature environments, there is an urgent need to investigate the mechanisms of creep-fatigue and to develop new steels that can effectively withstand these complex loading regimes. This study examines the creep-fatigue behavior of a novel 310 NbN austenitic stainless steel, enhanced with nitrogen and niobium, under high-temperature conditions. Specimens were subjected to tests at 675°C with varying hold-times of 0, 5, 60, and 600 s. Results indicated that longer hold times significantly increased crack growth rates and reduced cycles to fracture, highlighting a time-dependent crack propagation. Fracture surface analysis revealed a shift from transgranular to intergranular fracture with longer hold-times, indicating predominant creep damage. Predictive models, including the strip-yield model, aligned well with experimental data, emphasizing the critical role of hold-time in designing high-temperature steel components for improved durability. • Investigation of the creep-fatigue behavior of 310 NbN steel under high temperature • Conducted creep-fatigue crack growth at 675°C with varying hold-times on C(T) samples • Longer hold times increased crack growth rates and decreased cycles to failure • Fracture surfaces showed shift from transgranular to intergranular with hold-time • ASTM E2760 and strip-yield model effectively predicted creep-fatigue behavior