Abstract
In this paper, creep-fatigue properties of modified 9Cr and SUS316FR steels are studied under several conditions of creep-fatigue tests at high temperature considering the use in energy equipment. Durations of stress holding, i.e., durations of creep were different among the experiments. The experiments were stopped when the specimens reached to the same strain for observation of the microstructures. The differences among macroscopic creep-fatigue properties under several creep-fatigue conditions were discussed in terms of the effects of the durations of stress holding. The electron backscatter diffraction (EBSD) was used to observe the microstructures such as grain size and deformation inside grains. Even if the macroscopic strains were same, the microstructures were different from each other especially in modified 9Cr steel. The microstructures were related to the effects of the creep-fatigue conditions.
