2.25Cr-1Mo鋼の長時間クリープ挙動に及ぼす酸化の影響

抄録

Using the constitutive equations derived from a strain rate versus creep strain relationship, the extrapolation of creep life from an accelerated creep range to a long-term creep range was made of a 2.25Cr-1Mo steel, and the results were compared with the long-term creep data. It was found that the extrapolated creep life is in good agreement with the long-term creep data below 823K. However, the extrapolated creep life becomes much longer than the measured one above 823K. To explain the discrepancy between them, the effect of oxidation during creep on the life was numerically examined with the aid of the constitutive equations and an empirical equation for the reduction of cross-sectional area given as a function of expose time and temperature. It was made clear that the creep life compensated by the effect of oxidation is well in accordance with the measured one at any temperatures. These results suggest that the effect of oxidation on creep life is much larger than the effect of structural degradation on a long-term creep life.