Influence of Temperature on the Fatigue Crack Initiation and Growth in Reactor Coolant Environment
三澤 樹 Tatsuru MISAWA 北田 孝典 Takanori KITADA 中村 隆夫 Takao NAKAMURA 竹田 敏 Satoshi TAKEDA 釜谷 昌幸 Masayuki KAMAYA
Crack CoalescenceCrack InitiationCrack Propagation RateEnvironment Assisted FatigueTemperature
It has been clarified that the fatigue life is reduced in the fatigue test of high-temperature and high-pressure water that simulates PWR reactor coolant environment compared to that in the tmosphere, and temperature, strain rate，etc. affect the decrease of fatigue life. In this study, the influence of crack growth behavior on fatigue life of SUS316 in simulated PWR reactor coolant environment of different temperature was investigated. Fatigue tests were conducted under different temperatures (325℃ and 200℃) in simulated PWR reactor coolant environment with interrupting tests, and cracks generated on the specimen surface were observed with two step replica observation. From the results of observation, the influence of crack growth behavior in different temperature on the fatigue life was clarified. As a result, it was confirmed that the decrease of fatigue life due to high temperature is mainly caused by the increase in crack propagation rate and the acceleration of crack propagation rate by crack coalescence due to the increase of crack initiation number.