改良9Cr-1 Mo鋼部材のクリープ損傷評価 : (第2報, ボイド観察による溶接継手の評価)

抄録

The voids were observed in the fine grained heat affected zone of the creep damaged modified 9Cr-1 Mo steel welded joint. And, the correlation between creep damage and area fraction of void was obtained. The area fraction of void increased as the creep damage increased depending on the creep conditions. The theoretical formula of the correlation among the area fraction of void, creep damage and creep conditions was derived based on the creep deformation kinetics. The distribution of voids was not uniform along the radial axis of the round bar creep specimen. The stress state under creep was analyzed by FEM and the effect on the distribution of voids was investigated. In the fine grained heat sffected zone, the tri-axial stress state was realized under the uni-axial creep test and it was shown that the creep damage by axial stress played an important role on the distribution of voids.