Low cycle fatigue behavior and life evaluation of a P/M nickel base superalloy under different dwell conditions

Low cycle fatigue (LCF) and fatigue-creep tests were conducted under different dwell conditions at 650 °C on a P/M nickel base superalloy, which was used widely as aero-engine turbine disc. The specimens, taken from a hot isostatic pressing (HIP) disc (Φ180X50mm), were tested under total fully reversed axial strain control. Compared with continuous cycling tests without dwell, the ones with tensile, compressive or tensile-compressive strain dwells showed some shorter fatigue lives. The difference of fatigue lives under different strain dwells reflects the fatigue-creep interactions at elevated temperature. The cyclic deformation and life distribution features were analysed and a lifing model was proposed to evaluate the fatigue life of the alloy. The prediction agrees well with the experimental results.