2001 Volume 44 Issue 1 Pages 109-116
A nonlinear damage model, previously developed for creep-fatigue life evaluation of Mod. 9Cr-1Mo steel and 316FR stainless steel in a high vacuum environment was applied to 2 1/4Cr-1Mo steel. In the damage model, the damage accumulation process is considered to be composed of three basic processes: fatigue, creep and creep-fatigue. The fatigue damage process consists of a crack initiation period and a crack growth period. The creep damage process consists of nucleation of creep cavities. Damage interaction is fatigue cracks propagate from creep cavities. Application of this damage model to creep-fatigue tests under complex waveforms and complex strain histories showed a good correlation with the experimental results within a factor of 2.