The Influence of Superimposed Creep Loadings on the Thermal-Mechanical Fatigue Behaviour of the Ni-Base Superalloy IN 792 CC

The effect of superimposed creep loadings on the cyclic deformation andthe lifetime behaviour of the Ni-base superalloy IN 792 CC underout-of-phase TMF loadings is presented and discussed. The mean stressand the stress amplitude are not affected significantly by the creeploading. A slight cyclic hardening is observed even for cycles withsuperimposed creep loadings at a maximum temperature of 920°C whichmeans that the work hardening processes occurring under TMF loading arenot fully compensated by recovery during the creep phase. The plasticstrain amplitude increases with increasing creep stress. Using theManson–Coffin relationship, it is possible to calculate the influence ofthe superimposed creep loadings on the lifetime behaviour in goodaccordance with the experimental results.