Low cycle fatigue behaviour of T91 martensitic steel at 300 °Cin air and in liquid lead bismuth eutectic

In this paper, the low cycle fatigue (LCF) behaviour at 300 °C in air and in liquid lead bismuth eutectic (LBE) of the T91 martensitic steel is studied. From LCF tests in the range Δεt 0.4–2.4%, it is shown that the cyclic stress response consists of a cyclic softening. Monotonic and cyclic stress–strain curves do not change with the environment, whereas the fatigue life is reduced after LCF in the high strain range in LBE compared to air. Metallographic and fractographic observations suggest that the reduction in the fatigue resistance is due to a liquid metal enhancement of the crack propagation rate.