Evaluation of the effect of metallurgical variables on materials behaviour and reference curves

Kari Törrönen, Timo Saario, Kim Wallin, Jarl Forsten

    Research output: Contribution to journalArticleScientificpeer-review

    4 Citations (Scopus)

    Abstract

    An integral part of the safety assessment of nuclear pressure vessels and piping is the quantitative estimation of defect growth in both a stable and an unstable manner during service. This estimation is essential for determining whether any defect detected during inspection should be repaired or whether the size of the defect even after its expected growth is small enough to leave the integrity of the vessel unaffected.

    The most important stable defect growth mechanism is that of environmentally assisted cyclic crack growth. Recent results indicate that it is markedly affected by sulphur content and/or manganese sulphide morphology and distribution. This implies that an essential improvement in component safety has been gained by currently applied steelmaking practices, which result in extra low sulphur content, generally below 0·010 wt.%, and in the round shape and small size of inclusions through, e.g. calcium treatment, hence considerably reducing the effect of the environment on crack growth rate. This further implies that the ASME Section XI reference curves for environmentally accelerated cyclic crack growth are conservative for steels produced by current steelmaking practices.

    The ASME Section XI applies predominantly linear elastic fracture mechanics to assess the effects of cracks on the integrity of nuclear power plant components. Unstable linear elastic fracture often propagates by a cleavage mechanism. The cleavage fracture process has recently been shown to be of a statistical nature in both ferritic and bainitic steels. The carbide size distribution plays a dominant role in controlling the fracture toughness of these steels. A cleavage fracture model has been developed, by which both the expectance value and the probability limits of the fracture toughness,

    , can be predicted. The probability limits given by the model are shown to be consistent with the experimental observations. The application of the model to the data on which the ASME Section XI reference fracture toughness curve is based indicates that the reference curve is slightly unconservative.
    Original languageEnglish
    Pages (from-to)251 - 269
    Number of pages19
    JournalInternational Journal of Pressure Vessels and Piping
    Volume15
    Issue number4
    DOIs
    Publication statusPublished - 1984
    MoE publication typeNot Eligible

    Fingerprint

    Steel
    Fracture toughness
    Crack propagation
    Defects
    Steelmaking
    Sulfur
    Pressure vessels
    Fracture mechanics
    Nuclear power plants
    Manganese
    Carbides
    Calcium
    Inspection
    Cracks

    Cite this

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    title = "Evaluation of the effect of metallurgical variables on materials behaviour and reference curves",
    abstract = "An integral part of the safety assessment of nuclear pressure vessels and piping is the quantitative estimation of defect growth in both a stable and an unstable manner during service. This estimation is essential for determining whether any defect detected during inspection should be repaired or whether the size of the defect even after its expected growth is small enough to leave the integrity of the vessel unaffected.The most important stable defect growth mechanism is that of environmentally assisted cyclic crack growth. Recent results indicate that it is markedly affected by sulphur content and/or manganese sulphide morphology and distribution. This implies that an essential improvement in component safety has been gained by currently applied steelmaking practices, which result in extra low sulphur content, generally below 0·010 wt.{\%}, and in the round shape and small size of inclusions through, e.g. calcium treatment, hence considerably reducing the effect of the environment on crack growth rate. This further implies that the ASME Section XI reference curves for environmentally accelerated cyclic crack growth are conservative for steels produced by current steelmaking practices.The ASME Section XI applies predominantly linear elastic fracture mechanics to assess the effects of cracks on the integrity of nuclear power plant components. Unstable linear elastic fracture often propagates by a cleavage mechanism. The cleavage fracture process has recently been shown to be of a statistical nature in both ferritic and bainitic steels. The carbide size distribution plays a dominant role in controlling the fracture toughness of these steels. A cleavage fracture model has been developed, by which both the expectance value and the probability limits of the fracture toughness, , can be predicted. The probability limits given by the model are shown to be consistent with the experimental observations. The application of the model to the data on which the ASME Section XI reference fracture toughness curve is based indicates that the reference curve is slightly unconservative.",
    author = "Kari T{\"o}rr{\"o}nen and Timo Saario and Kim Wallin and Jarl Forsten",
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    language = "English",
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    pages = "251 -- 269",
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    Evaluation of the effect of metallurgical variables on materials behaviour and reference curves. / Törrönen, Kari; Saario, Timo; Wallin, Kim; Forsten, Jarl.

    In: International Journal of Pressure Vessels and Piping, Vol. 15, No. 4, 1984, p. 251 - 269.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Evaluation of the effect of metallurgical variables on materials behaviour and reference curves

    AU - Törrönen, Kari

    AU - Saario, Timo

    AU - Wallin, Kim

    AU - Forsten, Jarl

    PY - 1984

    Y1 - 1984

    N2 - An integral part of the safety assessment of nuclear pressure vessels and piping is the quantitative estimation of defect growth in both a stable and an unstable manner during service. This estimation is essential for determining whether any defect detected during inspection should be repaired or whether the size of the defect even after its expected growth is small enough to leave the integrity of the vessel unaffected.The most important stable defect growth mechanism is that of environmentally assisted cyclic crack growth. Recent results indicate that it is markedly affected by sulphur content and/or manganese sulphide morphology and distribution. This implies that an essential improvement in component safety has been gained by currently applied steelmaking practices, which result in extra low sulphur content, generally below 0·010 wt.%, and in the round shape and small size of inclusions through, e.g. calcium treatment, hence considerably reducing the effect of the environment on crack growth rate. This further implies that the ASME Section XI reference curves for environmentally accelerated cyclic crack growth are conservative for steels produced by current steelmaking practices.The ASME Section XI applies predominantly linear elastic fracture mechanics to assess the effects of cracks on the integrity of nuclear power plant components. Unstable linear elastic fracture often propagates by a cleavage mechanism. The cleavage fracture process has recently been shown to be of a statistical nature in both ferritic and bainitic steels. The carbide size distribution plays a dominant role in controlling the fracture toughness of these steels. A cleavage fracture model has been developed, by which both the expectance value and the probability limits of the fracture toughness, , can be predicted. The probability limits given by the model are shown to be consistent with the experimental observations. The application of the model to the data on which the ASME Section XI reference fracture toughness curve is based indicates that the reference curve is slightly unconservative.

    AB - An integral part of the safety assessment of nuclear pressure vessels and piping is the quantitative estimation of defect growth in both a stable and an unstable manner during service. This estimation is essential for determining whether any defect detected during inspection should be repaired or whether the size of the defect even after its expected growth is small enough to leave the integrity of the vessel unaffected.The most important stable defect growth mechanism is that of environmentally assisted cyclic crack growth. Recent results indicate that it is markedly affected by sulphur content and/or manganese sulphide morphology and distribution. This implies that an essential improvement in component safety has been gained by currently applied steelmaking practices, which result in extra low sulphur content, generally below 0·010 wt.%, and in the round shape and small size of inclusions through, e.g. calcium treatment, hence considerably reducing the effect of the environment on crack growth rate. This further implies that the ASME Section XI reference curves for environmentally accelerated cyclic crack growth are conservative for steels produced by current steelmaking practices.The ASME Section XI applies predominantly linear elastic fracture mechanics to assess the effects of cracks on the integrity of nuclear power plant components. Unstable linear elastic fracture often propagates by a cleavage mechanism. The cleavage fracture process has recently been shown to be of a statistical nature in both ferritic and bainitic steels. The carbide size distribution plays a dominant role in controlling the fracture toughness of these steels. A cleavage fracture model has been developed, by which both the expectance value and the probability limits of the fracture toughness, , can be predicted. The probability limits given by the model are shown to be consistent with the experimental observations. The application of the model to the data on which the ASME Section XI reference fracture toughness curve is based indicates that the reference curve is slightly unconservative.

    U2 - 10.1016/0308-0161(84)90011-5

    DO - 10.1016/0308-0161(84)90011-5

    M3 - Article

    VL - 15

    SP - 251

    EP - 269

    JO - International Journal of Pressure Vessels and Piping

    JF - International Journal of Pressure Vessels and Piping

    SN - 0308-0161

    IS - 4

    ER -