Coarsening of precipitates and degradation of creep resistance in tempered martensite steels

Three modified Cr steels were investigated for the types, sizes and volume fractions of precipitates. It is shown that precipitation of V in the form of fine M2X-particles provides high short-term creep resistance, but causes relatively fast degradation of creep resistance due to Ostwald ripening. In the later stages, precipitation of Z-phase and related phenomena accelerate the degradation.