Brittle fracture of nuclear pressure vessel steels—II. Prediction of fracture toughness

Марголин, Б. З.; Karzov, G. P.; Shvetsova, V. A.

doi:10.1016/s0308-0161(97)00013-6

Cited by 23 publications

(13 citation statements)

References 11 publications

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“…Thus, two critical parameters S C and σ d may control cleavage fracture and this depends on loading conditions, mainly, on stress triaxiality and temperature. For example, the brittle fracture of smooth specimens is controlled by condition and, by contrast, the brittle fracture of notched or cracked specimens from RPV steels by condition 10–13 …”

Section: A New Local Criterion Of Cleavage Fracturementioning

confidence: 99%

“…Another model for fracture toughness prediction based on a new local cleavage fracture criterion 10–12 was proposed in both a deterministic 10,13 and a probabilistic 14–17 manner. The probabilistic model (known now as Prometey model) was verified by application to various RPV steels in the initial (as‐produced), irradiated and highly embrittled conditions 14–18 …”

Section: Introductionmentioning

confidence: 99%

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Application of a new cleavage fracture criterion for fracture toughness prediction for RPV steels

Марголин

Shvetsova

Gulenko

et al. 2006

Fatigue Fract Eng Mat Struct

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A B S T R A C T In the present paper, approaches for prediction of cleavage fracture proposed by authors over recent years are briefly reviewed. A new local criterion of cleavage fracture and its application are considered. Local criterion of cleavage fracture formulated in a probabilistic manner consists of cleavage microcrack nucleation condition and condition for their start and propagation through various barriers such as microstresses, grain and dislocation substructure boundaries. As distinct from universally accepted criterion in which microcrack nucleation occurs on the plastic deformation beginning (σ eq = σ Y ), cleavage microcrack nucleation according to the formulated condition depends on the maximum principal stress, plastic strain and temperature.On the basis of the proposed criterion, a probabilistic model for fracture toughness prediction (known now as Prometey model) was developed and verified by application to reactor pressure vessels (RPV) materials in the initial, moderately irradiated and highly embrittled states. The Prometey model and other applications of the proposed criterion are briefly considered. The predicted results are compared with test results and the Master Curve.Intensive development of local approach models over the past 30 years was stimulated, to a great extent, by the needs of assessing the structural integrity of reactor pressure vessels (RPV). A key input to calculation of the structural integrity of the RPV is known to be the fracture toughness of a material. It is important to determine how fracture toughness varies as a function of temperature, and how the fracture toughness versus temperature response changes with in-service material degradation due to irradiation.The neutron irradiation damage effect on RPV materials is estimated using data which are obtained from surveillance programs. These surveillance programs include irradiation and testing of small-sized specimens only. On the other hand, as it is well known, adequate determination of fracture toughness over wide temperature range requires full-sized specimen testing. Thus, the major problem arises how to predict the fracture toughness versus temperature curve, K IC (T) or K JC (T), for an irradiated steel on the basis of small-sized specimen testing.The application of a local approach for fracture toughness prediction in irradiated RPV materials appears to be the most promising way to solve this problem. This explains the reason why local approach models are now intensively developed.Currently, there are several brittle fracture models under development. These include the RKR model 1,2 and the Beremin model. 3 However, it was shown in 4,5 that fracture toughness prediction for irradiated RPV steels on the basis of the RKR and Beremin models is not correct. According to these models, the temperature dependence of fracture toughness K JC (T) is mainly determined by the temperature dependence of the yield stress σ Y (T). For RPV steels over the service temperature range 20 • C ≤ T ≤ 300 • C, the yield stress vari...

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Section: A New Local Criterion Of Cleavage Fracturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of a new cleavage fracture criterion for fracture toughness prediction for RPV steels

Марголин

Shvetsova

Gulenko

et al. 2006

Fatigue Fract Eng Mat Struct

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“…The applicability of the RKR and Beremin models has been much investigated for various materials [17][18][19][20][21][22][23]. It was shown that for medium-and high-strength steels the use of these models causes some inconsistencies [18][19][20]23].…”

mentioning

confidence: 99%

“…The inappropriateness of the RKR and Beremin models for medium-and high-strength steels has a different reason behind it. As shown in [18][19][20][21][22][23], it is associated with the definition of the local criterion for brittle fracture in the form (1).…”

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Brittle fracture local criterion and radiation embrittlement of reactor pressure vessel steels

et al. 2010

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The application of local criteria for predicting brittle fracture of reactor pressure vessel steels is discussed with an emphasis on radiation embrittlement. An association of the radiation-induced damages and the processes of initiation and propagation of cleavage microcracks is analyzed from the standpoint of the local criterion for fracture. Physical-mechanical models are put forward to describe the influence of radiation damages on the cleavage microcrack initiation. The influence of the material hardening caused by neutron irradiation and plastic deformation on the fracture toughness is studied.Introduction. The intensive development of the local criterion over the last three decades has been caused mostly by the need for adequate prediction of fracture toughness of irradiated materials of nuclear reactor pressure vessels. It is common knowledge that embrittlement of reactor pressure vessel (RPV) materials is assessed by the test results for surveillance specimens. The surveillance specimen programs usually involve irradiation and testing of small-sized specimens only. It has been also known that to determine the temperature dependence of fracture toughness K T Jc ( ) one should perform tests on sufficiently large specimens (full-size specimens) over a wide temperature range. Thus, there arises a problem in principle: how to determine K T Jc ( ) for an irradiated steels from the test results for small-size specimens.The most promising solution to this problem is to use a so-called local approach to predicting fracture toughness of irradiated RPV materials. The local approach can be defined as a method of predicting fracture characteristics on the macrolevel in terms of mechanical parameters using a local criterion for fracture. Clearly, the local approach is based on the local criterion for brittle fracture. The critical parameters involved in the criterion can be related, in principle, to the physical mechanisms of initiation and propagation of microdamages, in this case the cleavage microcracks.At present, there are several available definitions of the local criterion for brittle fracture. The conventional one is written as [1][2][3][4][5][6] σ σ

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Probabilistic prediction of the crack resistance of nuclear pressure vessel steels on the basis of a local approach. Part 1

Марголин¹,

Gulenko²,

Shvetsova³

1999

Strength Mater

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Brittle fracture of nuclear pressure vessel steels—II. Prediction of fracture toughness

Cited by 23 publications

References 11 publications

Application of a new cleavage fracture criterion for fracture toughness prediction for RPV steels

Application of a new cleavage fracture criterion for fracture toughness prediction for RPV steels

Brittle fracture local criterion and radiation embrittlement of reactor pressure vessel steels

Probabilistic prediction of the crack resistance of nuclear pressure vessel steels on the basis of a local approach. Part 1

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