Conservatism of ASME KIR-reference curve with respect to crack arrest

Kim Wallin (Corresponding Author), Rauno Rintamaa, G. Nagel

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)

Abstract

The conservatism of the RTNDT temperature indexing parameter and the ASME KIR-reference curve with respect to crack arrest toughness, has been evaluated. Based on an analysis of the original ASME KIa data, it was established that inherently, the ASME KIR-reference curve corresponds to an overall 5% lower bound curve with respect to crack arrest. It was shown that the scatter of crack arrest toughness is essentially material independent and has a standard deviation (S.D.) of 18% and the temperature dependence of KIa has the same form as predicted by the master curve for crack initiation toughness. The ‘built in’ offset between the mean 100 MPa√m crack arrest temperature, TKIa, and RTNDT is 38°C (TKIa=RTNDT+38°C) and the experimental relation between TKIa and NDT is, TKIa=NDT+28°C. The KIR-reference curve using NDT as reference temperature will be conservative with respect to the general 5% lower bound KIa(5%)-curve, with a 75% confidence. The use of RTNDT, instead of NDT, will generally increase the degree of conservatism, both for non-irradiated as well as irradiated materials, close to a 95% confidence level. This trend is pronounced for materials with Charpy-V upper shelf energies below 100 J. It is shown that the KIR-curve effectively constitutes a deterministic lower bound curve for crack arrest The findings are valid both for nuclear pressure vessel plates, forgings and welds.
Original languageEnglish
Pages (from-to)185-199
Number of pages15
JournalNuclear Engineering and Design
Volume206
Issue number2-3
DOIs
Publication statusPublished - 2001
MoE publication typeA1 Journal article-refereed

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crack arrest
crack
Nondestructive examination
Cracks
Toughness
curves
toughness
temperature
Forgings
Temperature
confidence
Pressure vessels
Crack initiation
Welds
pressure vessels
forging
crack initiation
vessel
shelves
standard deviation

Cite this

Wallin, Kim ; Rintamaa, Rauno ; Nagel, G. / Conservatism of ASME KIR-reference curve with respect to crack arrest. In: Nuclear Engineering and Design. 2001 ; Vol. 206, No. 2-3. pp. 185-199.
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abstract = "The conservatism of the RTNDT temperature indexing parameter and the ASME KIR-reference curve with respect to crack arrest toughness, has been evaluated. Based on an analysis of the original ASME KIa data, it was established that inherently, the ASME KIR-reference curve corresponds to an overall 5{\%} lower bound curve with respect to crack arrest. It was shown that the scatter of crack arrest toughness is essentially material independent and has a standard deviation (S.D.) of 18{\%} and the temperature dependence of KIa has the same form as predicted by the master curve for crack initiation toughness. The ‘built in’ offset between the mean 100 MPa√m crack arrest temperature, TKIa, and RTNDT is 38°C (TKIa=RTNDT+38°C) and the experimental relation between TKIa and NDT is, TKIa=NDT+28°C. The KIR-reference curve using NDT as reference temperature will be conservative with respect to the general 5{\%} lower bound KIa(5{\%})-curve, with a 75{\%} confidence. The use of RTNDT, instead of NDT, will generally increase the degree of conservatism, both for non-irradiated as well as irradiated materials, close to a 95{\%} confidence level. This trend is pronounced for materials with Charpy-V upper shelf energies below 100 J. It is shown that the KIR-curve effectively constitutes a deterministic lower bound curve for crack arrest The findings are valid both for nuclear pressure vessel plates, forgings and welds.",
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Conservatism of ASME KIR-reference curve with respect to crack arrest. / Wallin, Kim (Corresponding Author); Rintamaa, Rauno; Nagel, G.

In: Nuclear Engineering and Design, Vol. 206, No. 2-3, 2001, p. 185-199.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

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AU - Wallin, Kim

AU - Rintamaa, Rauno

AU - Nagel, G.

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N2 - The conservatism of the RTNDT temperature indexing parameter and the ASME KIR-reference curve with respect to crack arrest toughness, has been evaluated. Based on an analysis of the original ASME KIa data, it was established that inherently, the ASME KIR-reference curve corresponds to an overall 5% lower bound curve with respect to crack arrest. It was shown that the scatter of crack arrest toughness is essentially material independent and has a standard deviation (S.D.) of 18% and the temperature dependence of KIa has the same form as predicted by the master curve for crack initiation toughness. The ‘built in’ offset between the mean 100 MPa√m crack arrest temperature, TKIa, and RTNDT is 38°C (TKIa=RTNDT+38°C) and the experimental relation between TKIa and NDT is, TKIa=NDT+28°C. The KIR-reference curve using NDT as reference temperature will be conservative with respect to the general 5% lower bound KIa(5%)-curve, with a 75% confidence. The use of RTNDT, instead of NDT, will generally increase the degree of conservatism, both for non-irradiated as well as irradiated materials, close to a 95% confidence level. This trend is pronounced for materials with Charpy-V upper shelf energies below 100 J. It is shown that the KIR-curve effectively constitutes a deterministic lower bound curve for crack arrest The findings are valid both for nuclear pressure vessel plates, forgings and welds.

AB - The conservatism of the RTNDT temperature indexing parameter and the ASME KIR-reference curve with respect to crack arrest toughness, has been evaluated. Based on an analysis of the original ASME KIa data, it was established that inherently, the ASME KIR-reference curve corresponds to an overall 5% lower bound curve with respect to crack arrest. It was shown that the scatter of crack arrest toughness is essentially material independent and has a standard deviation (S.D.) of 18% and the temperature dependence of KIa has the same form as predicted by the master curve for crack initiation toughness. The ‘built in’ offset between the mean 100 MPa√m crack arrest temperature, TKIa, and RTNDT is 38°C (TKIa=RTNDT+38°C) and the experimental relation between TKIa and NDT is, TKIa=NDT+28°C. The KIR-reference curve using NDT as reference temperature will be conservative with respect to the general 5% lower bound KIa(5%)-curve, with a 75% confidence. The use of RTNDT, instead of NDT, will generally increase the degree of conservatism, both for non-irradiated as well as irradiated materials, close to a 95% confidence level. This trend is pronounced for materials with Charpy-V upper shelf energies below 100 J. It is shown that the KIR-curve effectively constitutes a deterministic lower bound curve for crack arrest The findings are valid both for nuclear pressure vessel plates, forgings and welds.

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