Computational modeling of NbC/laves formation in INCONEL 718 equiaxed castings

Nastac, Laurentiu; Stefanescu, Doru M.

doi:10.1007/s11661-997-0220-5

Cited by 47 publications

(41 citation statements)

References 11 publications

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“…Based on these two equations and the boundary conditions, models for solute redistribution for equiaxed solidification 3,5 and the microsegregation for dendritic growth 2,4 have been developed. It is of interest to note that the solute and coupling equations do not account for moving boundary problems, although in the real solidification process, the solid/liquid interface moves.…”

Section: Imentioning

confidence: 99%

“…Therefore, the solute diffusion has been extensively studied both theoretically and experimentally. [1][2][3][4][5][6][7][8][9][10] Many solute diffusion models were developed and some of them are widely accepted as the fundamentals to establish the solidification theory, such as for dealing with the interface instability and the microstructure selection. 4 Currently, the time-dependent solute redistribution profile, C, can be determined by solving Fick's second law 4 …”

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confidence: 99%

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On the solute coupling at the moving solid/liquid interface during equiaxed solidification

Yao

2006

Applied Physics Letters

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Integral mass conservation was widely accepted for the solute coupling to solve solute redistribution during equiaxed solidification so far. The present study revealed that the integral form was invalid for moving boundary problems as it could not represent the mass balance at the moving interface. Accordingly, differential mass conservation at the solid/liquid interface was used to solve solute diffusion for spherical geometry. The model was applied for hydrogen diffusion in solidification to validate that the hydrogen enrichment was significant and depended on the growth rate.

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Section: Imentioning

confidence: 99%

mentioning

confidence: 99%

On the solute coupling at the moving solid/liquid interface during equiaxed solidification

Yao

2006

Applied Physics Letters

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“…T Metastable (°C)ϭ1 148Ϫ15͗Si%͘ϩ3͗Mn%͘Ϫ37͗P%͘.. (4) where ͗Si%͘, ͗Mn%͘, and ͗P%͘ are weight percents of silicon, manganese, and phosphorus of liquid.…”

Section: Nucleationmentioning

confidence: 99%

“…The modeling of gray-to-white transition of iron castings has been studied by a number of researchers, [1][2][3][4][5][6] and the following factors should be taken into account, such as: nucleation and competitive growth of stable and metastable eutectics, microsegregation of various elements during solidification. Therefore, the mathematical models should be further improved and be verified with quantitative experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of Stable and Metastable Eutectic Transformation of Spheroidal Graphite Iron Casting.

Zhao

Liu

2001

ISIJ International

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In this work, a mathematical model for stable and metastable transformation of SG cast iron, coupling with microsegregation of some elements and latent heat resulted from different phase formation, was presented. The quantitative experimental results of specimens obtained from a step-shape sample casting were compared with the simulation, and two results of nodular counts and sizes agreed quite well. For white eutectic growth in mottled SG iron, the frequent impingement of white eutectic with austenitegraphite bulks might suppress its growth remarkably and result in quite lower growth rate than that from the melt exclusively. Meanwhile, the relationship of morphology of carbides and solidification was discussed, and it was indicated that the growth of white eutectic and carbide morphology could also be predicted by solidification simulation. It was found that neglecting silicon microsegregation, if metastable transformation was advantageous to stable, the simulated carbide fraction was higher, and vice versa.KEY WORDS: spheroidal graphite cast iron; stable and metastable microstructure; eutectic transformation; modeling and simulation.ously, and may grow first freely and then surrounded by austenite shells. Considering the carbon diffusion and limited convection of liquid in front of liquid and graphite interface of Fig. 1, the growth rate of graphite spheres without austenite shell can be computed as follows:.... (5) where R t G is radii of graphite spheres (m) (superscript t and tϪdt are the calculation time) r l , and r G are densities of liquid and graphite (kg/m 3 ), D l C is diffusion coefficient of carbon in liquid (m 2 /s), C ළ l and C G are carbon content of initial liquid and graphite (%), C l * is carbon content of liquid in equilibrium with graphite and equals to C l/G approximately (Fig. 1), and d is thickness of carbon diffusion boundary layer in front of liquid-graphite interface (m).After the nodule was encapsulated by the austenite shell, its growth is dominated by the diffusion. 9) On the basis of carbon diffusion through the shell, the growth rates of bulks and graphite spheres were given as follows 10) :........... (6) ....... (7) where R g is radii of austenite shell of eutectic bulk, D C g is diffusion coefficient of carbon in austenite, r g is density of austenite, C g/l and C l/ g are carbon concentration of austenite and liquid in liquid-austenite interface respectively, and C g/G is carbon concentration of austenite in equilibrium with graphite.The growth of graphite spheres during eutectoid transformation could be determined by calculating the growth of ferrite shells with the model in the former research. 11)The growth of lamellar eutectic structure, such as ledeburite eutectic, was characterized by the well-known relationship 12,13) : where KЈ and KЉ are constants related materials properties, V is solidification rate (m/s). Because of crystal defects, the white eutectic grain often grows bending, and eventually becomes spherical. Therefore, the white eutectic was usually simplified ...

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Multiscale Modeling of the Solidification Structure Evolution of VAR‐Processed Alloy 718 Ingots

Nastac

2014

8th International Symposium on Superalloy 718 and Derivatives

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Computational modeling of NbC/laves formation in INCONEL 718 equiaxed castings

Cited by 47 publications

References 11 publications

On the solute coupling at the moving solid/liquid interface during equiaxed solidification

On the solute coupling at the moving solid/liquid interface during equiaxed solidification

Modeling of Stable and Metastable Eutectic Transformation of Spheroidal Graphite Iron Casting.

Multiscale Modeling of the Solidification Structure Evolution of VAR‐Processed Alloy 718 Ingots

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