A Multiscale Approach to Measuring and Modeling Cleavage Fracture Toughness in Structural Steels

Odette, G.R.; Rathbun, H.J.; Hribernik, M.; Yamamoto, Takuya; He, Ming; Spätig, P.

doi:10.1007/978-1-4020-8422-5_10

Cited by 4 publications

(6 citation statements)

References 33 publications

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“…reason, the presented structures are regarded as typical pre-cleavage dislocation arrangements, possibly spreading across numerous bainitic laths (since (50) 3 2 × 10 × 10 µm 3 ). In section 1, accumulation of plastic deformation was regarded as a necessary condition for cleavage initiation, using evidence coming from macroscopic testing [17,18]. The present observation brings further confirmation of the same rule, from a microscopic perspective.…”

Section: Discussionsupporting

confidence: 75%

“…Examination of failed specimens made of structural steels shows that cleavage fracture systematically initiates and propagates after a significant amount of cumulated plastic deformation; while the strain at fracture steadily increases with temperature. Similar results are obtained in cleavage oriented Fe single crystals and appear to relate to the flow properties of the metal [17,18]. In iron and iron-based alloys, however, there is strong experimental evidence suggesting that cleavage initiation and propagation are closely related to plasticity mechanisms.…”

Section: Introductionsupporting

confidence: 72%

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Internal stress evolution in Fe laths deformed at low temperature analysed by dislocation dynamics simulations

Chaussidon¹,

Robertson²,

Fivel³

et al. 2010

Modelling Simul. Mater. Sci. Eng.

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Stress evolution in Fe laths undergoing plastic deformation is investigated using three-dimensional dislocation dynamics simulations adapted to body centred cubic crystals, in the ductile to brittle transition temperature range. The selected boundary conditions, applied stress tensor and initial dislocation structures account for the realistic microstructure observed in bainitic steels. The effective stress field projected in the three different {1 0 0} cleavage planes is calculated for two different temperatures (50 and 200 K) and presented quantitatively, in the form of stress/frequency diagrams. It is shown that plastic activity tends to relax the stress acting in certain cleavage planes (the (0 1 0) and (0 0 1) planes) while, at the same time, amplifying the stress acting in other cleavage planes (the (1 0 0) planes). The selective stress amplification in the latter planes depends on the applied load direction, in combination with the limited set of available slip systems and the lath geometry. In the examined configuration, this selection effect is more pronounced with decreasing temperature, emphasizing the role of thermally activated plasticity on deformation-induced stress concentrations.

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Section: Discussionsupporting

confidence: 75%

Section: Introductionsupporting

confidence: 72%

Internal stress evolution in Fe laths deformed at low temperature analysed by dislocation dynamics simulations

Chaussidon¹,

Robertson²,

Fivel³

et al. 2010

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

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“…11. Results to date indicate a temperature dependence of r Ã that rationalizes the constant shape of MC [68,69].…”

Section: Contributionsmentioning

confidence: 80%

An evolution of understanding of reactor pressure vessel steel embrittlement

Lucas

2010

Journal of Nuclear Materials

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“…Based on the elastic fracture stresses measured in tensile tests with loading in the short plate thickness direction, that will be reported elsewhere, the brittle {100}<110>cleavage system in NFA-1 has an estimated low-temperature toughness of only ≈ 2 MPa√m, assuming a 100 µm diameter penny-shaped triggering microcrack. Notably, the microcrack cleavage system BDTT is much higher for NFA-1 than the corresponding BDTT for single crystal ferrite due to the much higher alloy strength relative to almost pure Fe [41][42][43][44][45][46]. As discussed elsewhere, and in future publications, the alloy strengthmicrocrack cleavage toughness relation has a significant effect on the shape of the master toughness temperature curve [45][46].…”

Section: Microstructural Characterizationmentioning

confidence: 99%

“…Notably, the microcrack cleavage system BDTT is much higher for NFA-1 than the corresponding BDTT for single crystal ferrite due to the much higher alloy strength relative to almost pure Fe [41][42][43][44][45][46]. As discussed elsewhere, and in future publications, the alloy strengthmicrocrack cleavage toughness relation has a significant effect on the shape of the master toughness temperature curve [45][46]. This paper focuses on characterizing the microcracks and their subsequent propagation as delaminations, which has a major corresponding effect on fracture properties.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

On delamination toughening of a 14YWT nanostructured ferritic alloy

et al. 2017

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The FCRD NFA-1 is a high strength, irradiation tolerant nanostructured ferritic alloy (NFA) produced by ball milling argon atomized Fe-14Cr-3W-0.35Ti-0.25Y (wt.%) and FeO powders, followed by hot extrusion at 850ºC, and subsequent annealing and crossrolling at 1000ºC. The microstructure of the resulting ≈ 10 mm thick NFA-1 plate is dominated by ultrafine sub-micron pancake shaped grains, and a large population of microcracks lying on planes parallel to the plate faces. Pre-cracked fracture toughness tests in four different orientations (L-T, T-L, L-S and T-S) show stable crack growth by ductile tearing, with peak load KJc from ≈ 88 to 154 MPa√m at ambient temperature. Stable crack tearing persists down to ≈-175°C and is accompanied by extensive delamination due to the propagation of the microcracks. Depending on the specimen orientation, this unusual toughening mechanism is either due to reduction of crack tip stresses in thin ligaments formed by the delaminations (L-T and T-L), or 90° deflection of cracks initially running normal to the delaminations (L-S and T-S), thereby 2 suppressing cleavage in both cases. Understanding the fracture processes in NFA-1 is also important to its irradiation tolerance in nuclear service as well as its fabricability in making defect-free components such as thin-walled tubing.

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A Multiscale Approach to Measuring and Modeling Cleavage Fracture Toughness in Structural Steels

Cited by 4 publications

References 33 publications

Internal stress evolution in Fe laths deformed at low temperature analysed by dislocation dynamics simulations

Internal stress evolution in Fe laths deformed at low temperature analysed by dislocation dynamics simulations

An evolution of understanding of reactor pressure vessel steel embrittlement

On delamination toughening of a 14YWT nanostructured ferritic alloy

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