STP821: Use of a Constant ΔK Test Method in the Investigation of Fatigue Crack Growth in 288°C Water Environments

    Van Der Sluys, WA
    Technical Advisor and Research Engineer, Babcock & Wilcox, a McDermott Company, Alliance, Ohio

    DeMiglio, DS
    Technical Advisor and Research Engineer, Babcock & Wilcox, a McDermott Company, Alliance, Ohio

    Pages: 27    Published: Jan 1984


    Abstract

    To characterize environmental fatigue crack growth properties of reactor pressure vessel steels, experiments were conducted by a computer-controlled constant alternating stress intensity factor (ΔK) test technique over a wide range of R-ratios and loading frequencies in 288°C water environments. Compact fracture specimens of two nuclear pressure vessel steels were tested over a range of ΔK-values from 16 to 55 MPa √m. Loading frequencies ranged from 0.0017 to 10 Hz, and R-ratios from 0.16 to 0.72.

    As many as 22 separate experiments were conducted on a single specimen. The constant ΔK test method permitted crack growth rate measurements to be made with a high degree of confidence over long intervals of crack extension.

    A simulated pressurized water reactor (PWR) environment plays only a minor role in the enhancement of fatigue crack growth rates. The applied ΔK was the primary rate-controlling variable, while R-ratio and loading frequency were secondary.

    In high-purity deoxygenated water, the environment had a very significant effect on crack growth rates. The loading frequency was a primary rate-controlling variable at low loading frequencies. At high loading frequencies crack growth rates were ΔK-dependent.

    Keywords:

    fatigue, fatigue crack growth, corrosion fatigue, fracture mechanics, environmental fatigue crack growth, fatigue crack growth rate test methods, reactor pressure vessel steels, constant Δ, K, test method


    Paper ID: STP34448S

    Committee/Subcommittee: G01.09

    DOI: 10.1520/STP34448S


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