STP1298

    Evaluation of Effects of LWR Coolant Environments on Fatigue Life of Carbon and Low-Alloy Steels

    Published: Jan 1997


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    Abstract

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figure I–90 of Appendix I to Section III of the Code specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Recent test data indicate a significant decrease in fatigue life of carbon and low-alloy steels in LWR environments when five conditions are satisfied simultaneously, viz., applied strain range, temperature, dissolved oxygen in the water, and sulfur content of the steel are above a minimum threshold level, and the loading strain rate is below a threshold value. Only a moderate decrease in fatigue life is observed when any one of these conditions is not satisfied. This paper summarizes available data on the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, and sulfur content on the fatigue life of carbon and low-alloy steels. The data have been analyzed to define the threshold values of the five critical parameters. Methods for estimating fatigue lives under actual loading histories are discussed.

    Keywords:

    fatigue crack initiation, strain vs. life (S-N) curve, LWR environment, carbon steel, low-alloy steel, strain rate, dissolved oxygen, sulfur content


    Author Information:

    Chopra, OK
    Metallurgist and Associate Director, Argonne National Laboratory, Argonne, IL

    Shack, WJ
    Metallurgist and Associate Director, Argonne National Laboratory, Argonne, IL


    Paper ID: STP19965S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP19965S


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