STP445

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

    Published: Jan 1969


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    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


    Author Information:

    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.


    Paper ID: STP32018S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP32018S


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