Creep-fatigue behavior of various alloys used in power industry and their predictability

Material behavior under creep-fatigue interaction has been receiving wide attention in association with the development of fast reactor plants. A considerable effort has been undertaken for developing methods which can predict failure life with reasonable accuracy. However, no established consensus seems to have been reached yet, for creep-fatigue liofe prediction due to its more complex nature compared to failures under pure creep or pure fatigue conditions. This paper summarizes the results of creep-fatigue tests performed on several alloys used in the power generation industry and clarifies common characteristics and differences concerning their behavior. Then the representative failure prediction methods are applied to tension-hold creep-fatigue tests of these materials to study their performances for various types of alloy. Inter-relations existing between the stress-based and strain-based approaches for creep damage calculation and their consequence on life predictability are also discussed.