3D phase-field computations of microsegregation in nodular cast iron compared to experimental data and Calphad-based Scheil-prediction

Eiken, Janin; Subasic, Emir; Lacaze, Jacques

doi:10.1016/j.mtla.2019.100538

Cited by 15 publications

(8 citation statements)

References 23 publications

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“…An important feature of the eutectoid transformation is microsegregation that develops during solidification. While microsegregation is relatively easy to describe (Eiken et al, 2020), mastering it is key for controlling the eutectoid transformation and has yet to be successfully achieved. Microsegregation is also an issue for the austempering of ADI parts as well as for so-called dual-phase microstructures.…”

Section: Globalmentioning

confidence: 99%

Cast Iron: A Historical and Green Material Worthy of Continuous Research

Jacques¹,

Dawson²,

Alain³

2021

IJTech

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Throughout history, cast iron has been unique amongst metallic materials. No other metal can boast such a long history, together with such a wide diversity of variants, properties, and applications. Arguably, no other material can claim to have such complexity. While the cast iron foundry produces myriad components, researchers and engineers have humbly ensured the continued development of this sophisticated material. We control this process not with furnaces and wirefeeders, but with knowledge. This knowledge enables the creation of a material with a unique combination of design flexibility, mechanical properties, wear resistance, recyclability, low life cycle energy consumption, and low cost. And it will be with the continued pursuit of understanding and knowledge that tomorrow's researchers and engineers will ensure the continued growth of new material variants, with improved material properties and new applications that make the world a better place. Cast iron: thousands of years of development and progress behind us; thousands of fascinating mysteries and opportunities ahead of us.

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Section: Globalmentioning

confidence: 99%

Cast Iron: A Historical and Green Material Worthy of Continuous Research

Jacques¹,

Dawson²,

Alain³

2021

IJTech

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“…In cast irons, the silicon concentration is typically higher early compared to late crystallized c. [26][27][28][29][30] This is due to the tendency of Si to partition at higher concentrations in c than liquid during solidification, as well as its low diffusivity in c making it resistant to back-diffusion. 31 Since silicon is known to strongly affect the equilibrium concentrations of carbon in c, 23 its microsegregation in c is important to consider when evaluating local carbon contents. Figure 6 shows the measured map of Si concentrations corresponding to the region shown in Figure 4b).…”

Section: Consideration Of Substitutional Elementsmentioning

confidence: 99%

The Distribution of Carbon in Austenite Studied on a Water-Quenched Compacted Graphite Iron Using Electron Probe Microanalysis

Domeij

Diószegi

2020

Inter Metalcast

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Spheroidal graphite is the defining microstructural feature of ductile iron and also plays an important role in compacted graphite iron. It is widely accepted that graphite spheroids are engulfed by austenite at an early stage of solidification after which their growth is impeded by the slow diffusion of carbon through a layer of austenite. In this work, a compacted graphite iron-containing spheroidal graphite was studied after interruption of its solidification by water quenching. Selected areas of a cross section of the castings were investigated using quantitative electron probe microanalysis, with emphasis on the distribution of carbon in austenite. The measured carbon concentration near graphite was generally below the theoretical carbon concentration in austenite at equilibrium with graphite at 1140°C. Numerical simulations of diffusion of carbon in austenite around spheroidal graphite suggest that a zone of austenite around graphite was likely depleted of carbon during quenching, possibly explaining the low measured concentrations. The measured carbon concentration near graphite varied by as much as 0.3 wt%, with the lowest concentrations consistently found in the central region of compacted graphite-austenite eutectic cells. Regardless of whether these differences were present prior to quenching or are consequences thereof, they seem to reflect either departures from, or displacements of, the carbon concentration in austenite at equilibrium with graphite. This indicates that there is something about growth of graphite embedded in austenite which is not well understood. Concentrations of Si, Mn and Cu are near equal in the compared regions and do not explain the observed differences in carbon content near graphite.

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“…Calphadcoupled MMPF simulations have become state of the art for steel grades, e.g. [4][5][6][7][8][9][10][11][12][13][14][15][16] and recently also for solidification of cast irons [17][18][19]. A general complexity of iron-based alloys is that the primary solidification structure does not remain stable, but austenite decomposes into ferrite and cementite during further cooling.…”

Section: Introductionmentioning

confidence: 99%

Diffuse modelling of pearlite growth in Calphad-coupled multicomponent multi-phase-field simulations

Eiken

Böttger

Apel

2023

IOP Conf. Ser.: Mater. Sci. Eng.

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During cooling of steels and cast irons, austenite can decompose by a eutectoid transformation into pearlite, a two-phased mixture of ferrite and cementite. Since the internal lamellar structure is commonly too fine to be distinguished on the scale of the austenite grain structure, pearlite is often modelled as an effective, pseudo-single phase. Such a pragmatic treatment would also be desirable to reduce the computational effort of large-scale multi-phase-field simulations, but a fundamental hindrance is that no consistent thermodynamic description exists for effective pearlite in multicomponent databases. Alternatively, we here propose to model pearlite as diffuse mixture of two phases with individual local fractions and concentrations, such that solute partitioning and thermodynamic driving forces can be consistently derived from standard Calphad databases. The essential computational advantage is that only the outer interfaces of the pearlite nodules have to be numerically resolved, which allows for increased grid spacing and time-steps. The impact of the unresolved lamellar structure on the curvature undercooling is modelled analytically based on a characteristic spacing, which may be calibrated either experimentally or by small-scale simulations. The potential and the limitations of the new approach, implemented in the frame of the Micress® software, shall be discussed.

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3D phase-field computations of microsegregation in nodular cast iron compared to experimental data and Calphad-based Scheil-prediction

Cited by 15 publications

References 23 publications

Cast Iron: A Historical and Green Material Worthy of Continuous Research

Cast Iron: A Historical and Green Material Worthy of Continuous Research

The Distribution of Carbon in Austenite Studied on a Water-Quenched Compacted Graphite Iron Using Electron Probe Microanalysis

Diffuse modelling of pearlite growth in Calphad-coupled multicomponent multi-phase-field simulations

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