Applicability of smaller than Charpy specimens for fracture toughness characterization with the VTT method

Kim Wallin, Matti Valo, Tapio Planman, Rauno Rintamaa

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific


    The term fracture toughness usually refers to the linear elastic fracture resistance parameter KIC. In the case of structural steels, the estimation of KIC is limited to the lower shelf of toughness or require extremely large specimens. This specimen size requirement has been one major obstacle for applying fracture mechanics in structural integrity assessment outside aviation, nuclear and off-shore industries. During the last decade, a statistical data treatment methodology, based on a micro-mechanistic cleavage fracture model, combined with elastic plastic finite element analysis has enabled the fracture toughness to be characterized with small specimens in the ductile-to-brittle transition region. The methodology is known as the VTT method or the Master Curve procedure. The development has led to a new testing standard for fracture toughness testing of ferritic steels in the transition range. Here, the premises for the methodology are described and its validity range is discussed. Presently the methodology has been validated for as small as 10.10 mm² bend specimens, but the use of even smaller specimens is under investigation. Specifically, results obtained with three different sub-Charpy specimen configurations are presented and discussed.
    Original languageEnglish
    Title of host publicationIrradiation effects and mitigation
    Subtitle of host publicationWorking material
    Place of PublicationVienna
    PublisherInternational Atomic Energy Agency IAEA
    Publication statusPublished - 1997
    MoE publication typeB3 Non-refereed article in conference proceedings
    EventIAEA Specialists' Meeting on Irradiation Effects and Mitigation - Vladimir, Russian Federation
    Duration: 15 Sept 199719 Sept 1997


    ConferenceIAEA Specialists' Meeting on Irradiation Effects and Mitigation
    Country/TerritoryRussian Federation


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