STP1343

    Direct Observation of the Residual Plastic Deformation Caused by a Single Tensile Overload

    Published: Jan 1999


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    Abstract

    The fatigue crack growth behavior following single tensile overloads at high stress intensity ranges in a cold-rolled austenitic steel has been studied experimentally. After tensile overloads, fatigue cracks initially accelerate, followed by significant retardation, before the growth rates return to their baseline level. The initial acceleration was attributed to an immediate reduction in near-tip closure. Scanning electron micrography and stereophotogrammetric reconstruction of the fracture surface were applied to study the residual plastic deformation caused by a single tensile overload in the mid-thickness of the specimen. The measured residual opening displacement of the crack as a function of the overload is presented and compared with simple estimations. Also, free specimen surface observations of the residual plastic deformation and crack growth rate were performed. In the midsection of the specimens the striation spacing-length, i.e., the microscopic growth rates, were measured before and after the applied overload. It will be shown that the measured plasticity-induced wedges from the single overload and the observed propagation behavior support the significance of the concept of crack closure.

    Keywords:

    residual plastic deformation, single tensile overload, stereophotogrammetric reconstruction, striation spacing, austenitic steel


    Author Information:

    Bichler, C
    Research engineer and interimistic director, Erich-Schmid-Instutut für Festkörperphysik der Österreichischen Akademie der Wissenschaften, Leoben,

    Pippan, R
    Research engineer and interimistic director, Erich-Schmid-Instutut für Festkörperphysik der Österreichischen Akademie der Wissenschaften, Leoben,


    Paper ID: STP15758S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP15758S


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