Creep-Fatigue Crack Growth Interaction in Nickel Base Supper Alloy

Most engineering components which operate at elevated temperatures are subjected to non-steady loading during service. This paper describes the current fracture mechanics concepts that are employed to predict cracking of Nickel base supper alloy materials at high temperatures under low and high frequency cyclic loading. A model for predicting creep crack growth in terms of C* and the creep uniaxial ductility is presented at low frequency and at high frequency power law relation is used to predict the crack growth rate. When dealing with creep/fatigue interaction a simple cumulative damage concept with fractography evidence is used to predict the crack growth rate. It is shown that these models give good agreement with the experimental results.