OS2503 EBSD observation and Strain Evaluation for Creep-fatigue Damage Process of Mod.9Cr Steel

Abstract

EBSD (Electron BackScatter Diffraction pattern) observations were conducted on damage samples under creep, low cycle fatigue and creep-fatigue tests for Mod.9Cr heat resistant steel. GOS (Grain Orientation Spread) maps and GROD (Grain Reference Orientation Deviation) maps were obtained and GOS_<ave> and GROD_<ave> were calculated from these maps. Both GOS_<ave> and GROD_<ave> similarly show initial decrease and subsequent stable or small fluctuating trend with increasing damage. GOS_<ave> did not show apparent dependence of pixel size. The "EBSD strain parameter" was introduced as GOS_<ave> multiplied by normalized boundary spacing. The good correlation between EBSD strain parameter and creep strain was obtained from creep and creep-fatigue damage samples.