Material Properties of High Cr-Mo Steel (IV); Creep and Creep-Fatigue Properties of HCM12A(2001) in Liquid Sodium (Interim Report)

Kato, Shoichi ; Yoshida, Eiichi; Ishigami, Katsuo*; Yaguchi, Katsumi*

A high Cr-Mo steel is a candidate for structural materials of future advanced fast reactors, because of good thermal properties and high creep strength. In this study, creep, creep-fatigue and corrosion tests were carried out to confirm the long-term extrapolation of sodium environmental, effects on the mechanical properties of HCM12A (2001). The exposure to sodium was conducted using a sodium test apparatus constituted by austenitic steels. For the conditions of in-sodium test, the sodium temperature was 550 deg-C and the oxygen concentration in sodium was below 2 ppm. The creep and creep-fatigue strength data in sodium, and in the carburized sodium were within the scattered range of those in air under the same conditions. It is considered that the creep damage in the bulk of the material was dominant. The creep and creep-fatigue life calculated using the usual rule for air showed good agreement with the sodium experimental results. The maximum corrosion rate of HCM12A (2001) was 0.4 micro-m/year at 550 deg-C, and it was almost same as SUS304 and Mod.9Cr-1Mo steels. Corrosion allowance of HCM12A (2001), therefore, can be estimated conservatively by the equation defined in "the elevated temperature structural design guide of prototype fast reactor".