Investigation of Transition Fracture Toughness Variation within the Thickness of Reactor Pressure Vessel Forgings

    Volume 7, Issue 1 (January 2010)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 22 October 2009

    Page Count: 9


    Lucon, Enrico
    Institute for Nuclear Material Science, SCK•CEN, Mol,

    Leenaers, Ann
    Institute for Nuclear Material Science, SCK•CEN, Mol,

    Vandermeulen, Willy
    Institute for Nuclear Material Science, SCK•CEN, Mol,

    Scibetta, Marc
    Institute for Nuclear Material Science, SCK•CEN, Mol,

    (Received 19 March 2009; accepted 14 September 2009)

    Abstract

    An investigation has been conducted on the influence of the through-thickness sampling position on the tensile and fracture toughness properties of reactor pressure vessel forgings, using material from two actual pressurized water reactor vessels. The aim was to quantify the safety margins entailed by extracting surveillance samples from the 1/4T and 3/4T positions, as recommended by the current legislation. For each forging, seven layers have been considered: Inner surface, 1/8T, 1/4T, 1/2T, 3/4T, 7/8T, and outer surface; for each position, two tensile tests at room temperature and 16 fracture toughness tests in the ductile-to-brittle transition region have been performed. In terms of tensile properties, for both forgings the strength is higher at the surfaces than in the centre, while ductility (elongations and reduction of area) is substantially unaffected. For both materials, fracture toughness is better at the surfaces than in the central portion, although differences in terms of Master Curve reference temperatures are statistically not relevant at the 95 % confidence level. This effect is more pronounced for one of the materials, due to the larger amount of material removed with respect to the original heat-treated forging, and is qualitatively confirmed by metallographic observations. The results obtained from this study are in substantial agreement with similar studies found in the literature, although most authors have reported larger differences between surface and central layers.


    Paper ID: JAI102431

    DOI: 10.1520/JAI102431

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    Author
    Title Investigation of Transition Fracture Toughness Variation within the Thickness of Reactor Pressure Vessel Forgings
    Symposium Ninth International ASTM/ESIS Symposium on Fatigue and Fracture Mechanics (37th ASTM National Symposium on Fatigue and Fracture Mechanics), 2009-05-22
    Committee E08