STP857

    Computerized Near-Threshold Fatigue Crack Growth Rate Testing at Cryogenic Temperatures: Technique and Results

    Published: Jan 1985


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    Abstract

    A computerized near-threshold fatigue crack growth rate (FCGR) test method has been applied at cryogenic temperatures. Near-threshold FCGR tests were conducted at room and cryogenic temperatures as low as 4.2 K (−452°F) on JBK-75 (modified A-286) stainless steel (base and autogenous gas-tungsten arc weld metal). Near-threshold crack growth rates in both the base and weld metal tended to decrease with decreasing temperatures from 297 to 4.2 K (75 to −452°F). At each temperature, the JBK-75 base material typically demonstrated a higher threshold stress intensity range than the weld material. Unlike the room temperature results, at 77 and 4.2 K (−320 and −452°F) near-threshold crack propagation rates were insensitive to load ratio (R = Pmin/Pmax). The decreased dependence of near-threshold FCGR data on load ratio at low temperatures appears to be in agreement with a crack closure model.

    Keywords:

    fatigue tests, near-threshold tests, computerized tests, cryogenic tests


    Author Information:

    Liaw, PK
    Metallurgy Department of the Westinghouse R&D Center in PittsburghNuclear Services Integration Division (NSID) of the Westinghouse R&D Center in Pittsburgh, PAPA

    Logsdon, WA
    Metallurgy Department of the Westinghouse R&D Center in PittsburghNuclear Services Integration Division (NSID) of the Westinghouse R&D Center in Pittsburgh, PAPA

    Attaar, MH
    Metallurgy Department of the Westinghouse R&D Center in PittsburghNuclear Services Integration Division (NSID) of the Westinghouse R&D Center in Pittsburgh, PAPA


    Paper ID: STP32754S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP32754S


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