抄録
EBSD(Electron BackScatter Diffraction pattern) observations were conducted on damaged Mod.9Cr steel obtained by the creep and the creep-fatigue tests as well as unused material. In order to quantify accumulated strains due to creep and creep-fatigue damage, "EBSD strain parameter M_<εKAM>" was introduced based on KAM(Kernel Average Misonentation) maps obtained by the EBSD observations. Here, M_<εKAM> was defined as the product of area averaged KAM: KAM_<ave> and boundary spacing/pixel size ratio. As a result, M_<εKAM> showed a good linear correlation with creep strain components for creep and creep-fatigue damaged materials under the optimal magnifications and grain boundary identification conditions in the EBSD observations. Therefore, M_<εKAM> was thought as a good parameter corresponding to the creep strain component. M_<εKAM> was also successfully applied to evaluate the creep strain components in the area containing the vicinity of creep voids and creep-fatigue crack tips on the failed materials by creep and creep-fatigue.
