The rate of dislocation multiplication in polycrystalline iron

Roberts, W. T.; Karlsson, S; Bergström, Y.

doi:10.1016/0025-5416(73)90089-x

Cited by 32 publications

(3 citation statements)

References 15 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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“…Several values of α have been derived experimentally and collated by Baker. 255 The value 0.88, obtained by Roberts et al , 291 is recommended.…”

Section: Strength Toughness and Ductilitymentioning

confidence: 99%

Microalloyed steels

Baker

2016

Ironmaking & Steelmaking

166

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This review considers the compositions, the main process routes, microstructure, and structural properties of microalloyed steels. The background and brief history are followed by sections dealing with aspects of precipitation which control grain size and dispersion strengthening in ferrite- pearlite steels, the approaches to modelling thermomechanical processing and the influence of multiple additions of transition metals on properties. High strength acicular ferrite/bainite steels used for linepipe are included and lead to super bainite steels. Around 12% of the world strip production is processed by the thin slab direct charging route, which is considered in some detail. The weldability of microalloyed steels now embraces joining using friction stir welding, which is discussed. Over the years, many approaches have been developed to predict the structural properties of microalloyed steels. They comprise several quantifiable microstructural features including atom clusters, relatively recently identified through atom probe tomography. A comprehensive collection of references is provided

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“…The model can determine the flow stress based on a physical description of dislocation density evolution. A well-known dislocation density-dependent flow stress model which was proven to describe the flow stress for a wide range of crystalline materials and alloys [6,15,16] is used in this model and has the form of…”

Section: A Flow Stressmentioning

confidence: 99%

Modeling Microstructure Evolution in a Martensitic Stainless Steel Subjected to Hot Working Using a Physically Based Model

Safara

Engberg

Ågren

2018

Metall Mater Trans A

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The microstructure evolution of a martensitic Stainless steel subjected to hot compression is simulated with a physically based model. The model is based on coupled sets of evolution equations for dislocations, vacancies, recrystallization, and grain growth. The advantage of this model is that with only a few experiments, the material-dependent parameters of the model can be calibrated and used for a new alloy in any deformation condition. The experimental data of this work are obtained from a series of hot compression, and subsequent stress relaxation tests performed in a Gleeble thermo-mechanical simulator. These tests are carried out at various temperatures ranging from 900 to 1200°C, strains up to 0.7, and strain rates of 0.01, 1, and 10 s À1. The grain growth, flow stress, and stress relaxations are simulated by finding reasonable values for model parameters. The flow stress data obtained at the strain rate of 10 s À1 were used to calibrate the model parameters and the predictions of the model for the lower strain rates were quite satisfactory. An assumption in the model is that the structure of second phase particles does not change during the short time of deformation. The results show a satisfactory agreement between the experimental data and simulated flow stress, as well as less than 5 pct difference for grain growth simulations and predicting the dominant softening mechanisms during stress relaxation according to the strain rates and temperatures under deformation.

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The rate of dislocation multiplication in polycrystalline iron

Cited by 32 publications

References 15 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

Microalloyed steels

Modeling Microstructure Evolution in a Martensitic Stainless Steel Subjected to Hot Working Using a Physically Based Model

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