抄録
CrMoV turbine rotor steel is strengthened by dispersed fine carbides, however carbides precipitated and coarsened at grain boundary during creep exposure. The carbide structure also changes from Fe_3C to M_<23>C_6 type carbide as coarsening. The carbide structure was electrochemically isolated by solving the matrix and analyzed with X-ray diffraction analysis. The X-ray peak intensity ratio of M_<23>C_6 to Fe_3C is tentatively defined as J-parameter. In order to evaluate the efficacy of J-parameter for creep damage evaluation, creep interruption test was conducted. The J-parameter increased with increasing creep and also correlated well to mean interparticle spacing. The change in J-parameter was affected by the chemical composition of the steel.
