The purpose of this study is to investigate environmental effects on low cycle fatigue crack growth of SUS316. Low cycle fatigue test and periodical observation on inner surface of a hollow specimen was conducted by developing new type of replica observation. The crack growth in PWR environment was measured and the investigation of environmental effects on crack initiation and propagation was conducted. Crack initiation rate of fatigue test in PWR environment is faster than in air condition. Crack pr...
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Environmental Effect on Low Cycle Fatigue Crack Growth of SUS316

The purpose of this study is to investigate environmental effects on low cycle fatigue crack growth of SUS316. Low cycle fatigue test and periodical observation on inner surface of a hollow specimen was conducted by developing new type of replica observation. The crack growth in PWR environment was measured and the investigation of environmental effects on crack growth was conducted. Crack initiation rate of fatigue test in PWR environment is faster than in air condition. Crack initiation is estimated ...
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Environmental Effect on Low Cycle Fatigue Crack Growth of SUS316

The purpose of this study is to generalize P-curve for strain range condition focusing on crack initiation life and crack growth life. The fatigue tests under different constant strain range conditions were conducted in air and the observation of fatigue cracks on specimen surface was also conducted. Using data derived from experiment, dispersion of cry using two-parameter Weibull distribution. Furthermore, the relationship between strain range and shape parameter or scale parameter of crack initiation mo...
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Study on fatigue crack initiation model in air for type 316 stainless steel

The purpose of this study is to investigate environmental effects on low cycle fatigue crack growth rate of SUS316 in different strain rate condition. The fatigue tests were conducted under different strain rate (0.4%/sec and 0.004%/sec) in simulated PWR environment with interrupting tests and the surface of specimens was observed. By the investigation of fatigue cracks growth, the effect of strain rate on crack growth rate was evaluated. From the results of tests, the followings were confirmed; ・Fatigu...
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Influence of Strain Rate on Fatigue Crack Growth in SUS316 under Reactor Coolant Environment

To prevent degradation at Nuclear Power Plants (NPPs) by maintenance activity, fatigue evaluation should be improved to be more accurate. Studies of crack growth under equi-biaxial fatigue which is caused by thermal stress have been conducted for these purposes. Previous study shows that crack growth rate under equi-biaxial stress is faster than under uniaxial one. But the comparison is not quantitative. In this study, the difference of crack growth rate between equi-biaxial and uniaxial is confirmed q...
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Study on the Behavior of Fatigue Crack Growth of Austenitic Stainless Steel under Equi-biaxial Stress

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℃...
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Influence of Temperature on the Fatigue Crack Initiation and Growth in Reactor Coolant Environment

Cumulative Usage Factor (CUF) is currently used for fatigue design and management to prevent fatigue failure. Fatigue damage is evaluated by CUF but CUF doesn’t show the real extent of fatigue damage and cannot be used for probabilistic index for risk assessment. Therefore, in order to clarify relation between CUF and damage state, the introduction of postulated crack growth curve (P-curve) of stainless steel was examined by Kamaya [1]. This curve was defined by single crack growth curve made from fati...
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Study on Fatigue Crack Growth Prediction Model of Carbon Steel based on Surface Observation of Fatigue Test Specimen