Abstract
Creep damage and creep -fatigue damage were imposed to the austenite stainless steel SUS304HTB for boiler tube use. EBSD (Electron BackScatter Diffraction pattern) observations were conducted on the creep and the creep-fatigue damaged samples using GROD (Grain Reference Orientation Deviation) maps and Phase maps. Area averaged GROD: GRODave and area fraction of alpha phase f_a(%) were used as the evaluation parameter to creep strain and accumulated creep strainrange. GRODave showed linear relationship with those strains except at final rupture stage. fa showed similar linear relationship with those strains except at the final rupture stage and the initial stage. Proportional relationship was also observed between the equivalent diameter d_v obtained from the creep void area and the estimated creep strain value ε_<cg> obtained from GRODave as well as f_a. These results indicated the EBSD observation could be effective for quantitative evaluation of permanent strain and phase transformation during creep and creep-fatigue damage process.
