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    International Round Robin Test on Master Curve Reference Temperature Evaluation Utilizing Miniature C(T) Specimen

    Published: 29 August 2014

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    The Master Curve (MC) method is a promising technique for evaluating the fracture toughness of ferritic steels. It enables the determination of the reference temperature, To, of a probabilistic fracture toughness curve using small specimens. The Central Research Institute of Electric Power Industry (CRIEPI) investigated this capability of the MC method using different size of C(T) specimens, and it was found that 0.16T-C(T) specimen with the dimensions of 4 by 10 by 9.6 mm, hereafter called “Mini-CT specimen,” can be used to obtain valid To values. The advantage of this Mini-CT specimen technique is that multiple specimens can be machined from one of the broken halves of Charpy size specimens, which are used in a standard surveillance capsule of a reactor pressure vessel (RPV). In order to ensure the robustness of this technique, a round-robin test was planned. The idea is to perform MC tests using Mini-CT specimens by different investigators to see if consistent To values can be obtained. All the specimens used were machined and pre-cracked by one fabricator from unique RPV material to avoid any possible effect of specimen preparation on To values. Seven institutes participated in this exercise, and obtained valid To values. No specific difficulty was found in the MC tests performed in accordance with the ASTM E1921-10el protocol. The scatter of the obtained To values was well within the uncertainty range defined in Appendix X4.2 of ASTM E1921, indicating the robustness of the Mini-CT specimen technique in terms of the testing procedure. Throughout this activity, we could obtain 182 KJc(1Teq) for a single material. We investigated the statistics of this large database, and found that there is no remarkable difference not only in the To values, but also in the fracture toughness distribution between the Mini-CT specimen and the standard 1T-C(T) specimen results.


    the Master Curve method, reactor pressure vessel material, fracture toughness evaluation

    Author Information:

    Yamamoto, Masato
    Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa

    Onizawa, Kunio
    Japan Atomic Energy Agency, Tokai, Ibaraki

    Yoshimoto, Kentaro
    Mitsubishi Heavy Industries LTD., Takasago, Hyogo

    Ogawa, Takuya
    Toshiba Co., Yokohama, Kanagawa

    Mabuchi, Yasuhiro
    Hitachi-GE Nuclear Energy LTD., Hitachi, Ibaraki

    Valo, Matti
    VTT Technical Research Centre of Finland, Metallimiehenkuja, Espoo

    Lambrecht, Marlies
    SCK·CEN, Belgian Nuclear Research Centre, Boeretang, Mol

    Viehrig, Hans-Werner
    Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße, Dresden

    Miura, Naoki
    Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa

    Soneda, Naoki
    Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa

    Committee/Subcommittee: E10.02

    DOI: 10.1520/STP157620140020