STP445: Influence of a Synthetic Seawater Environment on the Fracture Behavior of HP 9-4-25 and HP 9-4-20 Alloy Steels

    Clark, WG
    Senior engineer and manager of fracture mechanicspersonal member, Westinghouse Research LaboratoriesASTM, Pittsburgh, Pa.

    Wessel, ET
    Senior engineer and manager of fracture mechanicspersonal member, Westinghouse Research LaboratoriesASTM, Pittsburgh, Pa.

    Pages: 22    Published: Jan 1969


    Abstract

    The influence of a synthetic seawater environment upon the crack-notch fracture characteristics of 180-ksi yield strength HP 9-4-25 and HP 9-4-20 alloy steels was investigated and the results presented in terms of the stress intensity fracture toughness parameter. Data were generated in both air and seawater under rising-load tension, short-time (½ h) sustained tension, and tension-tension cyclic loading conditions with 2-in.-thick wedge-opening-loading crack toughness specimens. Results show that a synthetic seawater environment does not influence the rising-load or short-time sustained loading fracture characteristics of either alloy. In addition, no significant difference in fatigue crack growth rate was observed for the HP 9-4-25 alloy tested in air and seawater. Limited data for the HP 9-4-20 alloy indicate that the fatigue crack growth rate in seawater exceeds that in air. However, the fatigue crack growth rate for HP 9-4-20 in seawater was equivalent to that observed for HP 9-4-25 in air. In view of the higher toughness and comparable resistance to fatigue crack growth, HP 9-4-20 steel appears more attractive than HP 9-4-25 for hydrospace structures.

    Keywords:

    toughness, fracture mechanics, fatigue, environment, steels, crack propagation, corrosion, evaluation, tests


    Paper ID: STP32018S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP32018S


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