多軸応力条件下における改良12Cr鋼のクリープ損傷評価

抄録

Calculations of creep damage under the multiaxial stress condition were often carried out using either the time fraction rule or the ductility exhaustion rule. In this study, creep tests using 2 kinds of notched round bar specimens of a Modified 12Cr forging steel were performed to investigate the creep rupture strength under the multiaxial stress condition and the distribution of the micro damages such as creep voids. Inelastic analyses using modified theta projection method for considering primary-secondary-tertiary creep low were also performed and calculated the creep damage rate by some creep damage evaluation methods to compare with experimental results. As a result, the predicted creep crack initiation time by the ductility exhaustion rule based on Weiss model showed a good agreement within a factor of 1.5 and the distribution of calculated creep damage agreed with the distribution of creep voids.