Estimation of thermo-mechanical fatigue crack growth using an accumulative approach based on isothermal test data

A procedure to estimate thermo-mechanical fatigue crack growth (TMFCG) rates in a coarse grain nickel-based cast alloy is presented. The implemented model relies on the linear accumulation of temperature dependent and independent crack growth contributions. Isothermal fatigue and creep crack growth experiments were performed to generate the model data base. To quantify oxidation damage, the formation of subsurface γ′-depletion was measured. For validation, TMFCG experiments on corner-crack specimen were conducted. The model gives reasonable estimations for the crack growth of an initial defect. Furthermore it allows the assessment of the causes of the crack growth and associate them to crack propagation characteristics observed from the crack path.