The Effect of Environments on the Fatigue Life of Pressure Vessel Steel in High-Temperature Water

Low cycle fatigue (LCF) tests in room temperature air and in high-temperature oxygenated water were performed to clarify environmental effects on the fatigue life of SA508 Cl.3 reactor pressure vessel steel. In room temperature air, the cyclic stress responses showed an initial hardening and a moderate cyclic softening during deformation. On the other hand, for tests performed in high-temperature water, the cyclic stress responses were observed to induce an enhanced hardening, that is a secondary hardening due to dynamic strain aging (DSA). Fatigue life in high-temperature oxygenated water was shorter than that in room temperature air. The main reason of the life decrease may be a synergistic effect between environmental parameters and loading parameters. It may be considered that the reduction of the fatigue life was related to slip oxidation/dissolution and hydrogen embrittlement.