Time-incremental creep-fatigue damage rule for single crystal Ni-base superalloys

In the present paper a damage model for single crystal Ni-base superalloys is proposed that integrates time-dependent and cyclic damage into a generally applicable time-incremental damage rule. A criterion based on the Orowan stress is introduced to detect slip reversal on the microscopic level and the cyclic damage accumulation is quantified using the dislocation loop immobilization mechanism. Further, the interaction between cyclic and time-dependent damage accumulation is incorporated in the model. Implementation in a multi-scale constitutive framework for Ni-base superalloys enables simulations for a wide range of loading conditions, showing adequate agreement with experimental results.