Critical fracture stress and fracture strain models for the prediction of lower and upper shelf toughness in nuclear pressure vessel steels

Ritchie, Robert O.; Server, W.L.; Wullaert, R.A.

doi:10.1007/bf02812022

Cited by 251 publications

(57 citation statements)

References 24 publications

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“…Unstable crack propagation in metallic alloys begins when a critical stress is reached over a microstructurally significant distance. Some researchers have reported this distance to be in the order of 100 to 300 micrometers, depending on alloy chemistry, testing conditions and heat treatment [55]. If this interpretation is accepted, it may also be possible to say that a number of damage sites of length a 0 (sub-units of the critical length) join over the microstructurally significant distance, and thereby, lead to unstable crack propagation.…”

Section: Discussionmentioning

confidence: 99%

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Carney¹,

Mecholsky²

2013

MSA

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This study analyzes the relationship between fracture toughness and the fracture surface fractal dimension for a set of twenty-four CT-type AISI 4340 steel specimens heat treated to a variety of tensile strengths. Specimens were tested in accordance with ASTM E 399. Their respective fracture surfaces were plated, polished, photographed under an SEM in BSE mode and measured according to the Richardson method to obtain fractal dimensions. For brittle materials the limited results are consistent with previous literature: increasing fractal dimension with increasing toughness. For partially or fully ductile materials the results indicate a decrease in fractal dimension with an increase in fracture toughness. The data are modeled using a variation of the function applied to ceramics. Fracture in a ductile mode is characterized by the formation of dimples which exhibit fractal characteristics. The results are discussed in terms of the micromechanisms of fracture.

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Section: Discussionmentioning

confidence: 99%

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Carney¹,

Mecholsky²

2013

MSA

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“…Quantitatively, such failures are described by a criterion in which the continuum crack-tip strain exceeds a critical value, ε * , over a characteristic distance, l * , ahead of the crack tip [57,58]. This characteristic distance is generally the distance spanned by a microstructural crack emanating from the main crack.…”

Section: Fracture Mechanismsmentioning

confidence: 99%

“…This characteristic distance is generally the distance spanned by a microstructural crack emanating from the main crack. Based on the Hutchinson-Rice-Rosengren (HRR) crack-tip field solutions, the critical stress intensity factor for crack extension can be related to the critical strain and the characteristic distance as [57,58] …”

Section: Fracture Mechanismsmentioning

confidence: 99%

Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

Dadfarnia

Nibur²,

Marchi³

et al. 2010

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Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K THi * is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; 3 K THa is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K JH is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K THi *, and the crack arrest threshold, K THa , were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustainedload cracking tests under constant displacement. In contrast, K JH , which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which subcritical crack extension is driven by internal hydrogen gas pressure.4 ACKNOWLEDGMENTS

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“…Based on the model proposed by Richie, Knott, and Rice (RKR) [2,3], brittle fracture occurs when the stress state exceeds σ f at a characteristic distance (r c ) about twice the grain size away from the crack tip. Further investigation showed that, even the cleavage fracture mechanism during ductile-brittle transition may change with the specimen geometry, temperature, loading rate, prestrain, and material composition, it appears that σ f is a stable quantity and may be used as a material toughness parameter [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Prediction of Characteristic Length and Fracture Toughness in Ductile-Brittle Transition

Wang

Chao

et al. 2008

Volume 6: Materials and Fabrication, Parts a and B

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Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from -160 to -45 °C within the ductile-brittle transition regime. As many researchers have shown, the failure stress (σ f ) of the material could be approximated as a constant. The characteristic length, or the critical distance (r c ) from the crack tip, at which σ f is reached, is shown to be temperature dependent based on the crack tip stress field calculated by the finite element method. With the J-A 2 two-parameter constraint theory in fracture mechanics, the fracture toughness (J C or K JC ) can be expressed as a function of the constraint level (A 2 ) and the critical distance r c . This relationship is used to predict the fracture toughness of A533B-1 in the ductile-brittle transition regime with a constant σ f and a set of temperature-dependent r c . It can be shown that the prediction agrees well with the test data for wide range of constraint levels from shallow cracks (a/W= 0.075) to deep cracks (a/W= 0.5), where a is the crack length and W is the specimen width.

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Critical fracture stress and fracture strain models for the prediction of lower and upper shelf toughness in nuclear pressure vessel steels

Cited by 251 publications

References 24 publications

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Relationship between Fracture Toughness and Fracture Surface Fractal Dimension in AISI 4340 Steel

Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

Prediction of Characteristic Length and Fracture Toughness in Ductile-Brittle Transition

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