Investigation of transition fracture toughness variation within the thickness of reactor pressure vessel forgings

Enrico Lucon, Ann Leenaers, Willy Vandermeulen, Marc Scibetta

    Research outputpeer-review


    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.
    Original languageEnglish
    Pages (from-to)1-9
    Number of pages9
    JournalJournal of ASTM International
    Issue number1
    StatePublished - Jan 2010
    EventJoint ASTM-ESIS Symposium on Fracture and Fatigue - ASTM, Vancouver
    Duration: 1 May 20091 May 2009

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