Application of cellular automaton–finite element model to the grain refinement of directionally solidified Al–4.15 wt% Mg alloys

Vandyoussefi, M.; Greer, A.L.

doi:10.1016/s1359-6454(02)00015-0

Cited by 68 publications

(45 citation statements)

References 20 publications

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“…Rotation often occurs as grains become elongated because some dendrite arms extend preferentially in the direction where they are not obstructed by neighbors. Increasing the growth velocity gives finer and less elongated (or globular) grains, as shown by Vandyoussefi et al [19] in Al-Mg alloys by postmortem analysis. This can be expected, since for high pulling rates, secondary and tertiary branches of equiaxed grains do not have enough time to grow before interacting with neighboring grains.…”

Section: Equiaxed Microstructure As a Function Of Pulling Ratementioning

confidence: 69%

“…In most models and numerical simulations, N and also the nucleation undercooling are adjustable parameters in order to give a good agreement with experimental observations. For example, grain density is taken within the range 10 11 to 10 13 m À3 by Vandyoussefi et al, [19] 10 5 to 10 11 m À3 by Martorano et al, [6] and constant at 10 12 m À3 by Dong and Lee. [23] Experimentally, postmortem analysis by the anodization technique gives an estimate of the parameter N, but coarsening of dendrites could strongly affect the measurement.…”

Section: Equiaxed Microstructure As a Function Of Pulling Ratementioning

confidence: 99%

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In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy

Nguyen-Thi

Reinhart

Mangelinck‐Noël

et al. 2007

Metall Mater Trans A

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In this article, we present a review of observations during Al-3.5 wt pct Ni alloy solidification experiments performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble. These experiments provide direct access to dynamical phenomena during columnar growth (initial transient and breakdown of a planar solid-liquid interface), and for the first time to the transition from columnar-to-equiaxed microstructure (nucleation ahead of a columnar front and blocking of a columnar front by an equiaxed microstructure) and fully equiaxed growth (propagation of an effective front). Based on these experimental observations, critical parameters such as columnar growth velocity variation during the transition or equiaxed-grain diameter are measured and discussed.

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Section: Equiaxed Microstructure As a Function Of Pulling Ratementioning

confidence: 69%

Section: Equiaxed Microstructure As a Function Of Pulling Ratementioning

confidence: 99%

In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy

Nguyen-Thi

Reinhart

Mangelinck‐Noël

et al. 2007

Metall Mater Trans A

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“…[32] Within the MEBSP project, work of this kind has been extended to focus on the role of added grain refiner. [33] In the model, the parameter N max is the maximum possible density of grain nucleation events and scales with the addition level of refiner. Figure 11 shows the variations of grain structure revealed in two-dimensional CA-FE modelling.…”

Section: Reviewsmentioning

confidence: 99%

Grain Refinement of Aluminium Alloys by Inoculation

Greer¹,

Cooper²,

Meredith³

et al. 2003

Adv Eng Mater

269

147

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A review is given of the studies of aluminium inoculation undertaken within the EU Network “Microstructural Engineering by Solidification Processing” (MEBSP). A wide range of studies of industrial practice of grain refining and of the fundamental mechanisms of nucleation and growth have contributed to improved understanding. Particular advances have been made in understanding the relative performance of different grain refiners.

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“…Although the CET phenomena have been directly described by means of several simulation approaches such as the Phase-field method 12) and the Cellular Automaton (CA) model, 13,14) a simplified simulation is performed in this study, focusing on only the time-dependences of G and V during the columnar dendrite growth. Instead of directly describing the CET process, then, we analyze the occurrence of the CET by comparing the G-V relation with the Hunt's criterion.…”

Section: Calculation Detailsmentioning

confidence: 99%

“…Based on this picture, Hunt developed an analytical model to provide a criterion for the occurrence of CET. 8) While several improvements have been presented [9][10][11] and more detailed simulations have been performed to directly describe the CET, [12][13][14][15] it is considered that the Hunt's model should be successful to capture the essence of the CET phenomenon. According to the Hunt's model, the fully equiaxed growth occurs when the temperature gradient at the solidification front, G, satisfies the following condition, ............... (1) where N 0 is the number of the nucleation sites for the equiaxed dendrites, DT N is the undercooling for the nucleation of equiaxed dendrite and DT t is the undercooling for the columnar dendrite growth.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis on Columnar-to-equiaxed Transition of δ-Ferrite Dendrite in Carbon Steel Induced by Titanium Carbonitride Particles

Ohno

Matsuura

2009

ISIJ Int.

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Dendrite growth simulations have been performed to analyze Columnar-to-Equiaxed Transition (CET) of dferrite dendrite structure triggered by fine particles of a primary Ti(C, N) crystal. The CET position estimated by Hunt's criterion and the present simulation indicated that the existence of a large number of the Ti(C, N) particles gives rise to the CET of the dendrite structure even in the vicinity of the mold wall under the present casting condition. Furthermore, the capability of the Ti(C, N) leading to the CET was discussed in the light of the different number of Ti(C, N) particles and the different thickness of cast ingot. It was shown that a sufficient number of Ti(C, N) leads to the formation of fully equiaxed dendrite structure irrespective of the ingot thickness.KEY WORDS: columnar-to-equiaxed transition; hyperperitectic steel; titanium carbonitride; casting; solidification; simulation; dendrite structure.Ti(C, N) giving rise to the CET of d dendrite solidification. When the values of N 0 and DT N are given, one can predict the occurrence of the CET based on the relation between G and DT t (or the growth velocity of columnar dendrite described as a function of DT t , V(DT t )) within the Hunt's model. It should be pointed out that G and DT t (and V) are essentially time-dependent quantities during the casting process and the analysis of the CET requires such a time dependency to be addressed in detail.The main objective of this study is twofold; one is to substantiate the occurrence of the CET of d dendrite morphology induced by the primary Ti(C, N) in the light of the time-dependent behavior of G-V relation during the casting process and the other is to analyze the capability of Ti(C, N) giving rise to the CET under various casting conditions. To this end, we carry out a columnar dendrite growth simulation describing the time-dependent behavior of G-V relation. The input parameters for the simulation are obtained from the results of casting experiment. The relation between our calculated results and the Hunt's criterion suggests that the Ti(C, N) particles induce the CET of d dendrite morphology in the vicinity of the side surface of the ingot, which is fairly consistent with the metallographic observations. Finally, the capability of the Ti(C, N) giving rise to the CET is discussed in terms of several solidification conditions with the different number of Ti(C, N) particles and the different cooling conditions. In the conventional continuous casting process of the steel, the slab thickness is one of parameters to change the cooling rate of the cast. Therefore, we will discuss the occurrence of the CET in the different cast thickness. One will see that a sufficient number of the Ti(C, N) particles lead to the formation of the equiaxed dendrite over almost the entire cast ingot irrespective of the cast thickness. ExperimentalThe casting experiments were carried out for samples of S45C steel with and without titanium addition. The S45C steel employed in this study consists of 0.436 wt% C, 0.204 wt% Si, 0...

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Application of cellular automaton–finite element model to the grain refinement of directionally solidified Al–4.15 wt% Mg alloys

Cited by 68 publications

References 20 publications

In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy

In-Situ and Real-Time Investigation of Columnar-to-Equiaxed Transition in Metallic Alloy

Grain Refinement of Aluminium Alloys by Inoculation

Numerical Analysis on Columnar-to-equiaxed Transition of δ-Ferrite Dendrite in Carbon Steel Induced by Titanium Carbonitride Particles

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