P92 steel creep-fatigue interaction responses under hybrid stress-strain controlled loading and a life prediction model

In contrast to conventional strain-controlled creep-fatigue interaction (CCFI) loadings, a novel hybrid stress- and strain-controlled creep-fatigue interaction (HCFI) loadings were developed on P92 steel. Dwell stresses ranging from 140 MPa to 170 MPa, and dwell periods of 300 s, 600 s and 1800 s were employed at 625 °C. The test responses demonstrate that cyclic softening and hardening effects lead to complicated cyclic responses. In addition, the failure life under HCFI loading is observed to be reduced with the dwell stress and dwell period. Finally, a viscosity-based model is proposed to predict the lifetime of both HCFI and CCFI tests.