Volume 6, Issue 2 (February 2009)

    Stress-Triaxiality in Zr-2.5Nb Pressure Tube Materials

    (Received 23 November 2007; accepted 14 November 2008)

    Published Online: 2009

    CODEN: JAIOAD

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    Abstract

    The crack growth resistance of irradiated Zr-2.5Nb pressure tubes is controlled by the initiation of voids and their subsequent growth and coalescence. The presence of particles that contribute to void nucleation is determined by the operating conditions/history of the pressure tube and by the concentration of pre-existing species, which is a function of the manufacturing process. The susceptibility of the pressure tubes to void nucleation is determined by the number and distribution of particles, the deformation properties of the matrix, and the stress state at the crack tip. The effect of irradiation on zirconium material is to increase the yield stress but to reduce the work hardening ability of the matrix and to promote strain localization, which, in turn, leads to void nucleation. Void nucleation is also enhanced by high values of stress triaxiality at or near the crack tip. For irradiated pressure tube material, both small-scale curved compact tension specimens and large-scale burst test sections are used to characterize the crack growth resistance. However, the measured fracture toughness can depend on the specimen geometry due to differences in constraint. The present investigation uses three-dimensional finite element analyses to characterize stress triaxiality at the crack tip in these different specimen geometries. Results of the numerical analyses are compared to the experimental evidence that provide qualitative evidence of differences in stress triaxiality at the crack tip for different specimen geometries.


    Author Information:

    Leitch, B. W.
    Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, ON

    St. Lawrence, S.
    Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, ON


    Stock #: JAI101555

    ISSN: 1546-962X

    DOI: 10.1520/JAI101555

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    Author
    Title Stress-Triaxiality in Zr-2.5Nb Pressure Tube Materials
    Symposium Seventh International ASTM/ESIS Symposium on Fatigue and Fracture Mechanics (36th ASTM National Symposium on Fatigue and Fracture Mechanics), 2007-11-16
    Committee E08