2.25Cr-1Mo鋼のクリープ損傷進展に及ぼす多軸応力の影響

抄録

Creep damage preferentially extends at a stress concentration portion under multiaxial stress. Therefore, it is necessary to clarify the relationship between the creep damage extension process under the multiaxial stress states. In this study, creep tests using a plain specimen and three kinds of round bar notch specimens with different notch radius (notch tip radius 0.1mm (R0.1) and 0.5mm (R0.5) and 2.0mm (R2.0)) on a 2.25Cr-1Mo steel were carried out. Creep rupture times of the notch specimens were longer than those of plane specimens. Greater number of voids were observed at around 0.1 mm from notch root in R0.1, and around 0.5 mm from notch root in R0.5, and around center of the specimen in R2.0. The finite element creep analysis of the notch specimens showed that triaxial tensile stress yields at the notch root sections with different distribution of the triaxiality factor depending on the notch radius. Creep rupture times of three kinds of round bar notch specimens were accurately predicted by the area average creep damage evaluation method.