Fatigue and SCC Behavior of Sensitized SUS304 Stainless Steel in Pressurized Hot Water at 7.3MPa and 288°C

摘要

Plain fatigue and fretting fatigue tests of sensitized SUS304 stainless steel under pressurized hot water at 7.3MPa and 288°C have been carried out. Fatigue strengths for both fatigue tests almost coincided. Fretting contact could nucleate small SCC cracks near the contact edge in the direction perpendicular to cyclic loading. High R-ratio reduced fatigue strength due to longer exposure time to corrosive environment at high mean stress. From the constant load SCC tests of the specimen with small SCC pre crack induced by fretting contact, it was found that the threshold stress intensity factor for growth of small SCC precrack was 4.1Mpa·m~(1/2), which was significantly lower than that for long crack (10Mpa·m~(1/2)).