STP1296

    The Effect of Cyclic Loading During Ductile Tearing on the Fracture Resistance of Nuclear Pipe Steels

    Published: Jan 1997


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    Abstract

    As part of the First International Piping and Integrity Research Group (IPIRG-1) program, a series of 152.4-mm (6-in.)-diameter Schedule 120, A106 Grade B carbon steel and TP304 stainless steel cyclic through-wall crack (TWC) pipe tests were conducted at 288°C (550°F). The conclusion reached from these experiments was that fully reversed loading decreases the ductile tearing resistance of nuclear pipe steels. As part of the Second International Piping and Integrity Research Group (IPIRG-2) program, a series of cyclically loaded compact tension [C(T)] tests were conducted to determine if this effect is present in laboratory specimens and whether these small-scale results can be used to predict larger through-wall crack pipe behavior. The specimens were run in displacement control using several cyclic displacement increments and stress ratios. It was found that as the stress ratio was decreased, i.e., the amount of compressive plasticity is increased, the ductile tearing resistance of the material decreased. Fractographic analysis was performed on several C(T) specimens to determine the cyclic degradation mechanism. It was found that crack tip sharpening and void flattening were observed and could be the mechanisms that contributed to the cyclic degradation. In addition to the laboratory tests, finite element analyses were performed on a cyclic C(T) specimen to verify the ASTM E 1152 procedure used and to calculate the cyclic J-R curves.

    Keywords:

    fracture toughness, cyclic effects, ductile tearing, J, -integral, J-R, curve, finite element analysis


    Author Information:

    Rudland, DL
    Research scientist and senior research scientist, Battelle Memorial Institute, Columbus, OH

    Brust, F
    Research scientist and senior research scientist, Battelle Memorial Institute, Columbus, OH


    Paper ID: STP16246S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP16246S


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