A creep-fatigue damage model in air environment of 2.25Cr-1Mo steel (original) (raw)

A phenomenological creep-fatigue damage model is developed using a concept of a continuum damage mechanics. The effect of an environment is included in fatigue and creep damage evolution equations instead of present explicitly as oxidation damage in damage evolution equation under creep-fatigue loading. A creep damage evolution equation is a classical Kachanov’s equation. A fatigue damage evolution equation is the classical Lemaitre’s equation with a frequency-modified term. A damage variable and creep-fatigue interaction rule are derived from a damage decomposition concepts and strain equivalent principle. The model is applied to constant-amplitude uniaxial fatigue and creep-fatigue data of 2.25Cr-1Mo steel at 550oC in an air environment. The prediction results correlate well with the experimental data within a factor of 2 ranges.