Research Progress of New Generation Candidate Material SA508Gr.4N Steel for Nuclear Pressure Vessel

Starting from the process flow of SA508Gr.4N steel, the forging process was summarized in order to obtain SA508Gr.4N steel with uniform fine microstructure. The influence mechanisms of alloying elements, cooling rate and heat treatment parameters on the mechanical properties of SA508Gr.4N steel were described. The fatigue properties of SA508Gr.4N steel was summarized by combining the service environment of nuclear pressure vessel. The effects of microstructure evolution, M/A islands and carbides on the fatigue properties, fatigue crack initiation and fatigue crack propagation of SA508Gr.4N steel were analyzed in detail. The influence mechanisms of irradiation hardening and embrittlement and corrosion resistance of SA508Gr.4N steel were summarized. The development direction and further research contents of nuclear pressure vessel materials were prospected in order to improve the service life and ensure its safe operation in harsh environment.