A New Life Prediction Model Based on Ductility Exhaustion Theory for High Temperature Low Cycle Fatigue of Turbine Disk Alloys

Based on ductility exhaustion theory and the generalized damage parameter, a new viscosity-based life prediction model is put forward to account for creep and mean strain or stress effects in a low cycle fatigue regime. The mechanisms of loading waveform and cyclic hardening effects are also taken into account within this model. It assumes that damage accrues by means of viscous flow and ductility consumption relates only to plastic strain and creep strain under high temperature low cycle fatigue conditions. The proposed model provides a better prediction on the fatigue behaviors of Superalloy GH4133 than the Goswami’s ductility model and the generalized damage parameter. Compared with the proposed model and the generalized damage parameter, the Goswami’s model cannot properly account for creep and mean stress effects on the low cycle fatigue life. Under non-zero mean strain conditions, the proposed model provides more accurate predictions of GH4133 Superalloy than that with zero mean strains.