抄録
Creep-fatigue tests of SUS304 stainless steel were conducted and creep cavities initiated on grain boundaries inside the specimen were observed on the longitudinal cross-section by means of a scanning laser microscope. The results obtained were as follows. (i) The shape of cavities was almost spherical when they were small. (ii) There was no preferential direction of grain boundaries for the cavity initiation. (iii) Since cavities preferentially grew and coalesced along grain boundaries perpendicular to the stress axis direction, the shape became slit-like. Based on the experimental determination of cavities, four kinds of creep damage parameters, such as area fraction of cavities on cross-section, fraction of cavities on grain boundary lines, areal cavity density, and A-parameter were evaluated.
