STP590

    A Fracture Mechanics Approach to Creep Crack Growth

    Published: Jan 1976


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    Abstract

    A fracture mechanics approach was used to study high-temperature creep crack propagation. Crack growth rates were correlated with the C*-parameter which is an energy rate line integral. For materials conforming to a nonlinear stress and strain rate relationship in the steady-state creep range, specifically, those which can be properly idealized as purely viscous (negligible elastic and transient creep effects), C* characterizes the crack tip stress and strain rate fields.

    Crack growth rate tests were conducted in the creep range on a discaloy superalloy at 1200°F (920 K). Two specimen geometries were tested, a center cracked panel and a compact geometry, to establish the geometry independence of this approach. The results showed that crack growth rate correlated with the C*-integral, while other parameters (K and nominal stress) failed to adequately characterize crack growth rate.

    Keywords:

    crack propagation, stress analysis, mechanical properties, fracture properties, crack initiation, creep rate


    Author Information:

    Landes, JD
    Senior engineer, Westinghouse Research Laboratories, Pittsburgh, Pa.

    Begley, JA
    Ohio State University, Columbus, Ohio


    Paper ID: STP33943S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP33943S


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