The application of a dislocation model to dynamical strain ageing in α-iron containing interstitial atoms

Bergström, Y.; Roberts, W. T.

doi:10.1016/0001-6160(71)90138-6

Cited by 50 publications

(28 citation statements)

References 7 publications

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“…Taylor's constant, s is the mean free path of dislocation motion which is the average travel distance of dislocations before it was immobilized by interaction with microstructure, and Ω is the strain-independent dynamic recovery coefficient which represents the remobilization of immobile dislocations. This model has been successfully applied to many Fe-based materials [60][61][62][63][64]. Assuming the mean free path of dislocation motion (s) is independent of true strain (ε), the solution of Eq.…”

Section: Modeling Of Dislocation Density Development During Deformationmentioning

confidence: 99%

In situ synchrotron tensile investigations on 14YWT, MA957, and 9-Cr ODS alloys

Lin

Yun

et al. 2016

Journal of Nuclear Materials

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Advanced ODS alloys provide exceptional radiation tolerance and high-temperature mechanical properties when compared to traditional ferritic and ferritic/martensitic (F/M) steels. Their remarkable properties result from ultrahigh density and ultrafine size of Y-Ti-O nanoclusters within the ferritic matrix. In this work, we applied a high-energy synchrotron radiation X-ray to study the deformation process of three advanced ODS materials including 14YWT, MA957, and 9-Cr ODS steel. Only the relatively large nanoparticles in the 9-Cr ODS were observed in the synchrotron X-ray diffraction. The nanoclusters in both 14 YWT and MA957 were invisible in the measurement due to their non-stoichiometric nature. Due to the different sizes of nanoparticles and nanoclusters in the materials, the Orowan looping was considered to be the major strengthening mechanism in the 9-Cr ODS, while the dispersed-barrier-hardening is dominant strengthening mechanism in both 14YWT and MA957, This analysis was inferred from the different build-up rates of dislocation density when plastic deformation was initiated. Finally, the dislocation densities interpreted from the X-ray measurements were successfully modeled using the Bergström's dislocation models.

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Section: Modeling Of Dislocation Density Development During Deformationmentioning

confidence: 99%

In situ synchrotron tensile investigations on 14YWT, MA957, and 9-Cr ODS alloys

Lin

Yun

et al. 2016

Journal of Nuclear Materials

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“…grain size, dislocation density, etc.). The Kocks and Mecking model (Kocks, 1976) and the Bergström et al model (Bergstrom and Roberts, 1971) can be cited as examples of this class of models, describing the evolution of the density of mobile (or all) dislocations to account for the hardening and restoration of the material. Semi-empirical models can be defined as having a simple formulation while incorporating the minimum physical phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Modelling, identification and application of phenomenological constitutive laws over a large strain rate and temperature range

Hor

Morel

Lebrun

et al. 2013

Mechanics of Materials

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. a b s t r a c t A review of the different phenomenological thermo-viscoplastic constitutive models often applied to forging and machining processes is presented. Several of the most common models have been identified using a large experimental database (Hor et al., 2013). The latter consists of the tests were done in compression on cylindrical shaped specimens and in shear using hat-shaped specimens. The comparison between these different models is shown that the group of decoupled empirical constitutive models (e.g. the Johnson and Cook (1983) model), despite their simple identification procedures, are relatively limited, especially over a large range of strain rates and temperatures. Recent studies have led to the proposal of coupled empirical models. Three models in this class have also been studied. The Lurdos (2008) model shows the best accuracy but requires a large experimental database to identify its high number of parameters. After this comparison, a constitutive equation is proposed by modifying the TANH model (Calamaz et al., 2010). Coupling between the effects of strain rate and temperature is introduced. This model is easier to identify and does not require knowledge of the saturation stress. Compared to other models, it better reproduces the experimental results especially in the semi-hot and hot domains. In order to study real machining conditions, an orthogonal cutting tests is considered. The comparison between experimental test results and numerical simulations conducted using the previously identified constitutive models shows that the decoupled empirical models are not capable of reproducing the experimental observations. However, the coupled constitutive models, that take into account softening, improve the accuracy of these simulations.

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“…In general, dislocation density tends to decrease with increase of temperature. However, the opposite of this was observed in the experiments by [13] as well as the model predictions by [14] as shown in Figure 3. The change in the dislocation density with respect to the equivalent plastic strain is given by Eq.…”

Section: Dynamic Strain Aging In Inconel 718mentioning

confidence: 58%

A physically based constitutive model for dynamic strain aging in Inconel 718 alloy at a wide range of temperatures and strain rates

Voyiadjis

Song

2019

Acta Mech

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Dynamic strain aging has a huge effect on the microstructural mechanical behavior of Inconel 718 high performance alloy when activated. In a number of experimental researches, the significant additional hardening due to the dynamic strain aging phenomenon was reported. A constitutive model without considering dynamic strain aging is insufficient to accurately predict the material behavior. In this paper, a new constitutive model for Inconel 718 high performance alloy is proposed to capture the additional hardening, which is caused by dynamic strain aging, by means of the Weibull distribution probability density function. The derivation of the proposed constitutive relation for the dynamic strain aging-induced flow stress, the athermal flow stress and the thermal flow stress is physically motivated. The developed model is applied to Inconel 718 high performance alloy to demonstrate its ability to capture the dynamic strain aging behavior, which was observed in the literature across a wide range of temperatures (300 − 1200) and strain rates from quasi-static loading (0.001/) to dynamic loading (1100/).

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The application of a dislocation model to dynamical strain ageing in α-iron containing interstitial atoms

Cited by 50 publications

References 7 publications

In situ synchrotron tensile investigations on 14YWT, MA957, and 9-Cr ODS alloys

In situ synchrotron tensile investigations on 14YWT, MA957, and 9-Cr ODS alloys

Modelling, identification and application of phenomenological constitutive laws over a large strain rate and temperature range

A physically based constitutive model for dynamic strain aging in Inconel 718 alloy at a wide range of temperatures and strain rates

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