This paper presents a guideline on the procedures for evaluating creep-fatigue crack propagation in fast breeder reactor (FBR) components. The recommendations are based on inelastic fracture mechanics where the fatigue J-integral range, ΔJ{sub}f, and the modified J-integral, J', are employed for predicting the creep-fatigue crack propagation rate per load cycle. Fundamental crack growth tests were performed using test specimens of the representative FBR materials, type 304 and 316FR stainless steels, at temperatures ranging from 400 to 650°C. The test results produced a linear summation type of crack propagation law where contributions from fatigue and creep were respectively expressed by two power laws. A reference stress method with modifications for the secondary stress treatment was proposed as one of the representative schemes to estimate ΔJ{sub}f and J' engineeringly. The proposals were validated by predicting crack growth observed in structural model tests subjected to strain controlled creep-fatigue loads.
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