Temperature effects on low-cycle fatigue behavior of SA533B steel in simulated reactor coolant environments

The low-cycle fatigue (LCF) tests were conducted on SA533B steel at a strain rate of 0.4% s−1 in simulated reactor coolant environments. A significant temperature effect on fatigue life was observed with the specimens tested in the water environment with saturated oxygen; the fatigue lives varied with temperature in the range from 150 °C to 300 °C. However, little or no dependence of fatigue life on temperature was noted in the water environment with oxygen content of 213 ppb. At any test temperature, the steel specimens endured the longest fatigue life when tested in air, but, in contrast, they were observed to have the shortest one in the water environment with saturated oxygen. It implies the fatigue–corrosion interaction plays a significant role in determining the fatigue life of SA533B steel. The results of X-ray diffraction (XRD) analysis showed that the constituents of corrosion products were strongly affected by both temperature and dissolved oxygen content of the water environment. Furthermore, the same factors also affected the fracture appearances of fatigue-tested specimens. The dynamic strain aging (DSA) effect on fatigue life is also discussed in this report.