Local Criterion for Cleavage Fracture : Structural and Mechanical Approach

Марголин, Б. З.; Shvetsova, V. A.

doi:10.1051/jp4:1996622

Cited by 13 publications

(27 citation statements)

References 8 publications

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“…On the other hand, the microcracks arising near the grain boundaries can readily propagate at the boundaries for the strength of the boundaries, with sharp microcracks present there, is low. Fort instance, the critical stress in the case of intergranular brittle fracture can decrease to 500 MPa in the presence of sharp microcracks at the grain boundaries, even if there occurs no embrittlement of the boundaries due to phosphorus segregations [7].…”

Section: Variantmentioning

confidence: 99%

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Embrittlement and fracture toughness of highly irradiated austenitic steels for vessel internals of WWER type reactors. Part 2. Relation between irradiation swelling and irradiation embrittlement. Physical and mechanical behavior

et al. 2010

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The mechanical test results and fractographic observations reported in Part 1 are discussed from the standpoint of possible fracture mechanisms in austenitic steels subjected to intensive neutron irradiation. We put forward the mechanisms that relate the γ α → -transformation to the occurrence of a ductile-brittle transition in the irradiated austenitic steels and presents a criterion that defines the irradiation conditions whereby the γ α → -transformation leads to the ductile-brittle transition.Some possible reasons for the deterioration of the material ultimate strength at a very high (above 20%) level of swelling are discussed.Introduction. Part 1 [1] presented the results of experimental investigations of mechanical properties and irradiation swelling of austenitic steel 08Kh18N10T and its weld metal upon intensive neutron irradiation, which were performed in order to clarify the nature of the effect of the swelling on mechanical properties of austenitic steels.For this study some specimens were irradiated at a "low" temperature (T irr = 330-340°C) with a dose of 46 dpa (hereinafter referred to as the LTI material) and the other at a "high" temperature (T irr = 400-450°C) with a dose of 49 dpa (called the HTI material). These irradiation conditions were chosen for the purpose of producing different levels of swelling in the specimens. Specifically, the irradiation swelling is close to zero in the LTI material and ranges between 3 and 13% in the HTI material.The experimental investigations performed demonstrate that for the base metal the temperature functions σ 0 2 . ( ) T test and σ u test T ( ) are almost equidistant for the unirradiated and LTI material. For the HTI irradiated base metal which has a significant irradiation swelling, these functions are not equidistant to those for unirradiated and LTI specimens. However, for the weld metal they are equidistant for all three material states studied. We noted a significant increase in plasticity of the HTI material in comparison to that of the unirradiated material and the HTI material. At T test ≤°200 C the plasticity of the base metal upon HTI is close to zero.It was suggested in [1] that the base metal upon HTI undergoes an γ α → phase transformations.

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Section: Variantmentioning

confidence: 99%

“…The quasibrittle fracture is initiated in the ferrite phase or during the breakage of the carbide-matrix bond, subject to the following condition [6][7][8]:…”

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Embrittlement and fracture toughness of highly irradiated austenitic steels for vessel internals of WWER type reactors. Part 2. Relation between irradiation swelling and irradiation embrittlement. Physical and mechanical behavior

et al. 2010

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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].…”

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“…It was shown that for medium-and high-strength steels the use of these models causes some inconsistencies [18][19][20]23]. One of them pertains to testing specimens of various geometries, e.g., smooth cylindrical specimens and cylindrical specimens with a circular notch.…”

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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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On Issue of Comparison of the Unified Curve and Master Curve Methods and Application for RPV Structural Integrity Assessment

et al. 2016

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Ïðîàíàëèçèðîâàíû äâà èíaeåíåðíûõ ìåòîäà -Master Curve è Unified Curve ïðèìåíèòåëüíî ê îöåíêå ñîïðîòèâëåíèÿ õðóïêîìó ðàçðóøåíèþ êîðïóñîâ ðåàêòîðîâ. Äëÿ ñðàâíåíèÿ ýòèõ ìåòîäîâ ïðè îáðàáîòêå áàçû äàííûõ ïî âÿçêîñòè ðàçðóøåíèÿ äëÿ 44 ñòàëåé è èõ øâîâ ñ ðàçëè÷íîé ñòåïåíüþ îõðóï÷èâàíèÿ áûëî èñïîëüçîâàíî òðè ðàçíûõ ñòàòèñòè÷åñêèõ ïàðàìåòðà. Óñòàíîâëåíî, ÷òî ìåòîä Unified Curve èìååò ïðåèìóùåñòâà ïåðåä ìåòîäîì Master Curve. Ïðîàíàëèçèðîâàíû âîçìîaeíûå ïðè÷èíû êàaeóùåãîñÿ ïðåèìóùåñòâà ìåòîäà Master Curve, à òàêaeå ñôîðìóëèðîâàíû è îáîñíîâàíû òðåáîâàíèÿ äëÿ îáúåêòèâíîãî ñðàâíåíèÿ ìåòîäîâ. Îáîáùåíèå ýêñïåðèìåíòàëüíûõ äàííûõ ïî òåìïåðàòóðíîé çàâèñèìîñòè òåðìîàêòèâèðîâàííîé ÷àñòè ïðåäåëà òåêó÷åñòè è ìîäåëè Prometey (ìîäåëè õðóïêîãî ðàçðóøåíèÿ, îñíîâàííîé íà ëîêàëüíîì ïîäõîäå) ïîçâîëèëî îáúÿñíèòü, ïî÷åìó çàâèñèìîñòü K T JC ( ) äëÿ ðàçëè÷íûõ ñòàëåé, ïðè íåáîëüøîé ñòåïåíè îõðóï÷èâàíèÿ, ìîaeåò áûòü àïïðîêñèìèðîâàíà ýêñïîíåíöèàëüíîé ôóíêöèåé, â ÷àñòíîñòè çàâèñèìîñòüþ Master Curve. Ïîëó÷åíà êîððåëÿöèÿ ìåaeäó òåìïåðàòóðíîé çàâèñèìîñòüþ òåðìîàêòèâèðîâàííîé ÷àñòè ïðåäåëà òåêó÷åñòè è çàâèñèìîñòüþ Master Curve.

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Local Criterion for Cleavage Fracture : Structural and Mechanical Approach

Cited by 13 publications

References 8 publications

Embrittlement and fracture toughness of highly irradiated austenitic steels for vessel internals of WWER type reactors. Part 2. Relation between irradiation swelling and irradiation embrittlement. Physical and mechanical behavior

Embrittlement and fracture toughness of highly irradiated austenitic steels for vessel internals of WWER type reactors. Part 2. Relation between irradiation swelling and irradiation embrittlement. Physical and mechanical behavior

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

On Issue of Comparison of the Unified Curve and Master Curve Methods and Application for RPV Structural Integrity Assessment

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