STP868

    Axial Fracture Toughness Testing of Zr-2.5Nb Pressure Tube Material

    Published: Jan 1985


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    Abstract

    A complete flaw evaluation of a longitudinal defect in a CANDU (CANada Deuterium Uranium) reactor pressure tube requires knowledge of the axial fracture toughness of the material. This paper addresses the problem of measuring fracture toughness of thin pressure tube material. Compact tension specimens (∼4 mm thickness) are prepared from flattened and stress-relieved Zr-2.5Nb pressure tube material. Axial crack growth resistance curves (Ja) and crack opening displacement (COD) are determined at room temperature and 150°C using the unloading compliance method. The latter is shown to give excellent estimates of crack extension for side-grooved specimens (≤2% variation) and for plane specimens at room temperature (≤7% variation for Δa > 1.5 mm). However, for plane specimens at 150°C and short crack extensions (Δa < 1.5 mm), the compliance calculated crack length underestimates the true crack extension by approximately 20%. The Ja curves and COD are shown to be in good agreement with previous results of Simpson.

    Keywords:

    elastic-plastic, fracture, Zr-2.5Nb, pressure tube, compact tension specimen, J, -integral, crack opening displacement, thickness effect


    Author Information:

    Davies, PH
    Research Engineer and Technologist, Ontario Hydro Research Division, Toronto, Ontario

    Stearns, CP
    Research Engineer and Technologist, Ontario Hydro Research Division, Toronto, Ontario


    Paper ID: STP34260S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP34260S


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