| Abstract: | Effect of the creep fracture toughness on crack initiation and propagation under creep fatigue interaction for three low alloying Cr-Mo-V steels and their micro-fracture proeesses has been mainly investigated. It showed that toughness of the material plays an important role in crack initiation and propagation. In the brittle state, the crack initiation under creep fatigue interaction is faster than that subjected to creep, and there is no remarkable difference of crack growth rate between them. In the ductile state, not only the crack initiation time is shorter, but also its crack growth rate is much faster. On the other hand, the creep fatigue interaction tends to embrittle the steel, which depends on the original toughness value of the steel. All the three Cr-Mo-V steels can be transformed from toughness into brittleness when they are in ductile condition. But, in brittle condition, this transformation is not clear. |
