Isothermal and thermomechanical fatigue behavior of Inconel 718 superalloy

The fatigue behavior and damage mechanisms of Inconel 718 are investigated and discussed under thermomechanical fatigue (TMF) and isothermal fatigue (IF) test conditions. The experimental results show that cyclic temperature accelerates fatigue degradation compared to isothermal equivalents, and the fatigue life under inphase (IP) TMF mode is shorter than that under out-of-phase (OP) mode. The S-N data can be fitted by Coffin-Manson equation under LCF condition, and TMF lifetime can be predicted by the model based on hysteresis loop energy with a comprehensive consideration of mechanical and thermal strains.