STP942: Prediction of Crack Growth Under Creep-Fatigue Loading Conditions

    Nikbin, KM
    Imperial College, London,

    Webster, GA
    Imperial College, London,

    Pages: 12    Published: Jan 1988


    Abstract

    Crack growth data are presented on a brittle and a ductile low alloy steel and a nickel base superalloy which have been subjected to combined static and cyclic loading at elevated temperatures. The cyclic tests have been conducted between fixed load and fixed displacement ranges. Distinct regions of fatigue and creep dominated cracking have been identified. It is shown that crack growth eventually ceases because of load relaxation in the constant displacement amplitude tests. Fracture of a component made of the ductile steel is unlikely to occur under this type of low-cycle fatigue loading, but significant cracking is possible with the brittle steel. Where cyclic crack growth is creep controlled, it is shown that crack propagation rates can be predicted from static creep data using the creep fracture mechanics parameter C*.

    Keywords:

    creep-fatigue crack growth, fracture mechanics, C, * parameter, low-cycle fatigue


    Paper ID: STP24487S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP24487S


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