Volume 5, Issue 1 (January 2008)

    Fracture Toughness of Hydrided Zircaloy-4 Sheet Under Through-Thickness Crack Growth Conditions

    (Received 16 April 2007; accepted 5 November 2007)

    Published Online: 2007

    CODEN: JAIOAD

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    Abstract

    The susceptibility of fuel cladding to failure in the case of a postulated reactivity-initiated accident may be determined by crack initiation within a hydride blister or rim and subsequent crack growth through the thickness of the cladding. This study has determined the fracture toughness of hydrided cold-worked stress relieved Zircaloy-4 sheet subject to through-thickness crack growth at both 25 and 300°C. The experimental approach utilizes a novel procedure in which a narrow linear strip of brittle hydride blister across the specimen width creates a well-defined precrack upon initial loading. The subsequent crack growth resistance is then characterized by four-point bending of the specimen and an elastic-plastic fracture mechanics analysis. At room temperature, the through-thickness fracture toughness (Kq) is sensitive to the orientation of the hydride platelets and Kq≅25 MPa√m for crack growth through a mixed in-plane/out-of-plane hydride field. In contrast, Kq is much higher (≅75 MPa√m) when the hydride platelets are oriented predominantly in the plane of the sheet and therefore normal to both the crack plane and the crack growth direction. At 300°C, the material exhibits greater ductility as the hydride particles within the matrix resist fracture such that Kq≅83 MPa√m, despite the much lower flow stress of the material.


    Author Information:

    Raynaud, P. A.
    Department of Materials Science and Engineering, The Pennsylvania State University,

    Koss, D. A.
    Department of Materials Science and Engineering, The Pennsylvania State University,

    Motta, A. T.
    Department of Mechanical and Nuclear Engineering, The Pennsylvania State University,

    Chan, K. S.
    Southwest Research Institute, San Antonio,


    Stock #: JAI101183

    ISSN: 1546-962X

    DOI: 10.1520/JAI101183

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    Author
    Title Fracture Toughness of Hydrided Zircaloy-4 Sheet Under Through-Thickness Crack Growth Conditions
    Symposium 15th International Symposium on Zirconium in the Nuclear Industry, 2007-06-28
    Committee B10