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 degrees 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 (Phi 180X50 mm), 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. (C) 2010 Published by Elsevier Ltd.