EFFECT OF OXIDATION ON THE LONG-TERM CREE P-BEHAVIOR OF A 2.25CR-1MO STEEL

Using the constitutive equations derived from a strain rate versus cre ep strain relationship, the extrapolation of creep life from an accele rated 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 l ife becomes much longer than the measured one above 823K. To explain t he discrepancy between them, the effect of oxidation during creep on t he life was numerically examined with the aid of the constitutive equa tions and an empirical equation for the reduction of cross-sectional a rea given as a function of expose time and temperature. It was made cl ear that the creep life compensated by the effect of oxidation is well in accordance with the measured one at any temperatures. These result s suggest that the effect of oxidation on creep life is much larger th an the effect of structural degradation on a long-term creep life.