STP833

    Application of High-Temperature Fracture Mechanics to the Prediction of Creep Crack Growth for a γ-γ′ Nickel-Base Superalloy

    Published: Jan 1984


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    Abstract

    Creep crack growth rates were measured in a γ-γ′ low-carbon Astroloy at 650 to 760°C. A theoretical model based upon the mechanism of cavity nucleation, growth, and coalescence on the grain boundaries near a crack tip was used to predict the creep crack growth rates in Astroloy. The model assumed that creep crack growth was an intermittent cracking process as observed in the experiments. A crack tip stress field of the HRR type in a creeping medium, derived previously by Riedel and Rice, was used for the analysis. The model gave a good prediction of the dependence of the crack growth rates on test temperature and stress intensity factor. The model does not take into account the crack tip stress triaxiality. However, by assuming that the crack tip stress triaxiality was intermediate between the plane strain and the plane stress, a good correlation was obtained between theory and experimental data.

    Keywords:

    creep crack growth, low-carbon Astrology, fracture mechanics, creep cavity, stress intensity factor, C, *-integral, J, -integral


    Author Information:

    Huang, JS
    Pfizer Incorporated, Wallingford, Conn.

    Pelloux, RM
    Massachusetts Institute of Technology, Cambridge, Mass.


    Paper ID: STP32564S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP32564S


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