The paper presents the results of a probabilistic creep life study on F5001P turbine discs and demonstrates the importance of using physics based probabilistic damage modeling techniques to deal with life prediction uncertainty in forged components. In physics based modeling, the influence of individual microstructural or thermal-mechanical loading factors on metallurgical crack initiation can also be studied with relative ease. In a previous study, Life Prediction Technologies Inc.’s (LPTi’s) prognosis tool known as XactLIFE™ was successfully used to conduct deterministic analysis to establish the fracture critical location of F5001P first stage discs under steady state loads. In this paper, the variability in life is further established as a function of prior austenite grain size. The analysis used typical engine operating data from the field in terms of engine speed and average exhaust gas temperature (EGT). The primary objectives of the case study are to show how prognosis can allow a user to assess fleet reliability for engine specific operating conditions. The lower bound deterministic creep life and probabilistic creep life at 0.1% cumulative probability of failure are very close in magnitude.

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