STP942

    Fatigue Life and Short Crack Propagation of Turbine Rotor Steels under Variable Strain Loading

    Published: Jan 1988


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    Abstract

    Fatigue behavior of steam turbine rotor steels with and without defects has been investigated at 550°C with emphasis on the effects of service loadings. It is shown that the life of defect-free materials is reduced remarkably by a factor of 10 to 100 due to the accumulation of the plastic strain range, which becomes conspicuous under a programmed fatigue test which simulates service loadings. A linear damage cumulative law in terms of the plastic strain range to estimate the fatigue life is presented. It is also shown that in order to evaluate the effect of defects, the conventional low-cycle fatigue test is not appropriate but a variable strain test is necessary. The fatigue life of the material with a defect is discussed in light of crack initiation and growth periods.

    Keywords:

    fatigue (materials), high temperature fatigue, service loadings, turbine rotor steels, 1Cr-Mo-V steels, 12Cr steels, stress-strain diagrams, crack propagation, short-crack, defects, inclusions, life prediction


    Author Information:

    T, Mori
    Technical Development Group, Kobe Steel, Ltd., Kobe,

    H, Toyoda
    Technical Development Group, Kobe Steel, Ltd., Kobe,

    S, Ohta
    Technical Development Group, Kobe Steel, Ltd., Kobe,


    Paper ID: STP24535S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP24535S


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