Ductile to brittle transition of an A508 steel characterized by Charpy impact test

Tanguy, B.; Besson, Jacques; Piques, R.; Pineau, A.

doi:10.1016/j.engfracmech.2004.03.011

Cited by 146 publications

(108 citation statements)

References 51 publications

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“…Another threshold parameter ðr min w Þ is sometimes introduced to improve the experimental fitting results, so that Eq. (1) becomes: like found in [11,12] but the best results are obtained considering a temperature dependence of the Weibull parameters that has been widely observed and taken into account in recent work [13,11,14], and considering damage mechanisms [15]. But the precise description of the physical mechanisms leading to this temperature dependence is still to be understood.…”

Section: Introductionmentioning

confidence: 78%

A micromechanical interpretation of the temperature dependence of Beremin model parameters for french RPV steel

Mathieu

Inal

Berveiller

et al. 2010

Journal of Nuclear Materials

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International audienceLocal approach to brittle fracture for low-alloyed steels is discussed in this paper. A bibliographical introduction intends to highlight general trends and consensual points of the topic and evokes debatable aspects. French RPV steel 16MND5 (equ. ASTM A508 Cl.3), is then used as a model material to study the influence of temperature on brittle fracture. A micromechanical modelling of brittle fracture at the elementary volume scale already used in previous work is then recalled. It involves a multiscale modelling of microstructural plasticity which has been tuned on experimental inter-phase and inter-granular stresses heterogeneities measurements. Fracture probability of the elementary volume can then be computed using a randomly attributed defect size distribution based on realistic carbides repartition. This defect distribution is then deterministically correlated to stress heterogeneities simulated within the microstructure using a weakest-link hypothesis on the elementary volume, which results in a deterministic stress to fracture. Repeating the process allows to compute Weibull parameters on the elementary volume. This tool is then used to investigate the physical mechanisms that could explain the already experimentally observed temperature dependence of Beremin's parameter for 16MND5 steel. It is showed that, assuming that the hypothesis made in this work about cleavage micro-mechanisms are correct, effective equivalent surface energy (i.e. surface energy plus plastically dissipated energy when blunting the crack tip) for propagating a crack has to be temperature dependent to explain Beremin's parameters temperature evolution

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Section: Introductionmentioning

confidence: 78%

A micromechanical interpretation of the temperature dependence of Beremin model parameters for french RPV steel

Mathieu

Inal

Berveiller

et al. 2010

Journal of Nuclear Materials

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“…It should be mentioned that for this reason the current ASTM E1921 [3] invalidates the results having more than 0.2 mm crack growth prior cleavage. It should be noted that in case of Charpy impact test in the middle of the ductile to brittle transition, ductile tearing always precede cleavage, therefore an approach such the one proposed in [4] should be used. In [5], a methodology has been developed and validated with experimental data in order to predict the effect of ductile crack growth on cleavage.…”

Section: Introductionmentioning

confidence: 99%

Effect of prior crack growth on cleavage fracture of low toughness precracked Charpy specimens

Scibetta

2010

Journal of Nuclear Materials

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“…To account for the environment dependence of the activation barrier, we used the Final-Initial-System-Energy (FISE) method [45] to update the activation barrier for each KMC event based on the local atomic configurations. In the FISE method, the effective activation barrier is given by (18) In the equation E 0 is a constant, usually the activation barrier in the pure metallic matrix. E f and E i represent the final and initial system energies calculated by the broken bond mode: (19) Here means the bond energy between elements X and Y in the phase ϕ, e.g, fcc or bcc phases.…”

Section: Atomic Kinetic Monte Carlo Model (Akmc)mentioning

confidence: 99%

“…In the FISE method, the effective activation barrier is given by (18) In the equation E 0 is a constant, usually the activation barrier in the pure metallic matrix. E f and E i represent the final and initial system energies calculated by the broken bond mode: (19) Here means the bond energy between elements X and Y in the phase ϕ, e.g, fcc or bcc phases. The bond interactions are defined on nearest-neighbor (NN) atoms of different orders, depending on the complexity of the system.…”

Section: Atomic Kinetic Monte Carlo Model (Akmc)mentioning

confidence: 99%

“…By incorporating ductile damage models proposed by Rousselier [16] or Gurson [17] to simulate stable crack growth prior to unstable failure, improved predictions can be made. In [18,19] DBT using Charpy specimens have been performed using the Rousselier model [16] in conjunction with the Beremin model [14] to predict onset of cleavage failure. Modifications have been made to the Beremin model by introducing the effect of plastic strain and history of maximum principal stress to evaluate the critical Weibull stress.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Light Water Reactor Sustainability Program Grizzly Year-End Progress Report

Spencer¹,

Zhang²,

Chakraborty³

et al. 2013

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The Grizzly software application is being developed under the Light Water Reactor Sustainability (LWRS) program to address aging and material degradation issues that could potentially become an obstacle to life extension of nuclear power plants beyond 60 years of operation. Grizzly is based on INL's MOOSE multiphysics simulation environment, and can simultaneously solve a variety of tightly coupled physics equations, and is thus a very powerful and flexible tool with a wide range of potential applications. Grizzly, the development of which was begun during fiscal year (FY) 2012, is intended to address degradation in a variety of critical structures.The reactor pressure vessel (RPV) was chosen for an initial application of this software. Because it fulfills the critical roles of housing the reactor core and providing a barrier to the release of coolant, the RPV is clearly one of the most safety-critical components of a nuclear power plant. In addition, because of its cost, size and location in the plant, replacement of this component would be prohibitively expensive, so failure of the RPV to meet acceptance criteria would likely result in the shutting down of a nuclear power plant.During service, the RPV is subjected to intense neutron flux. This flux, combined with thermal aging affects, has an embrittling effect on the RPV steel, which is manifested as an increase in the brittle/ductile transition temperature of that material. This means that at a given temperature, aging effects cause the steel to have a lower toughness and tend to fracture in a more brittle manner.The current practice used to perform engineering evaluations of the susceptibility of RPVs to fracture is to use the ASME Master Fracture Toughness Curve (ASME Code Case N-631 Section III), which provides the fracture toughness as a function of temperature. This is used in conjunction with empirically based models that describe the evolution of this curve due to embrittlement in terms of a transition temperature shift. These models are based on an extensive database of surveillance coupons that have been irradiated in operating nuclear power plants, but this data is limited to the lifetime of the current reactor fleet. This is an important limitation when considering life extension beyond 60 years. The currently available data cannot be extrapolated with confidence further out in time because there is a potential for additional damage mechanisms (i.e. late blooming phases) to become active later in life beyond the current operational experience.To improve our understanding of the degradation of RPV steels under the conditions that would be seen under extended service life, science-based predictive modeling at the atomistic scale is needed. This modeling, combined with the limited applicable experimental data in the regime of interest, can provide understanding of the fundamental degradation mechanisms, with the goal of eventually informing models that can be useful for engineering-scale evaluations of RPVs.

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Ductile to brittle transition of an A508 steel characterized by Charpy impact test

Cited by 146 publications

References 51 publications

A micromechanical interpretation of the temperature dependence of Beremin model parameters for french RPV steel

A micromechanical interpretation of the temperature dependence of Beremin model parameters for french RPV steel

Effect of prior crack growth on cleavage fracture of low toughness precracked Charpy specimens

Light Water Reactor Sustainability Program Grizzly Year-End Progress Report

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