Simulation of channel segregation using a two-phase columnar solidification model – Part I: Model description and verification

Li, J.; Wu, Menghuai; Hao, Jing; Ludwig, Andreas

doi:10.1016/j.commatsci.2011.12.037

Cited by 61 publications

(26 citation statements)

References 19 publications

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“…Despite the long calculation time, the grid resolution (average grid size of 2.2 cm) is still not sufficient to obtain the A‐segregates or quasi A‐segregates. A grid size of ≈1 mm is normally required to get the pipe/laminar channel structure of A‐segregates . This is not feasible for an industrial ingot with the today's computer hardware.…”

Section: Capabilities and Limitationsmentioning

confidence: 99%

“…It means that an experimental determination or calibration of the critical values is mostly required for each special case. Additionally, a recent study shows that the onset criterion is not sufficient to predict the A‐segregates, as the stabilization of the channel by the growth of the channel is governed by the flow‐solidification interaction near the solidification front . The base segregation − like the concentrated positive segregation in the hot top and the sedimentation induced bottom negative segregation − cannot be calculated with the criterion functions.…”

Section: Capabilities and Limitationsmentioning

confidence: 99%

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Simulation of As‐Cast Steel Ingots

Ludwig²,

Kharicha

2017

steel research int.

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Some of the most recent examples of simulations of as‐cast steel ingots are presented in this paper, focusing on discussions concerning available simulation/modeling tools and their capacities and limitations. Although, there has been some success from implementing criterion functions into commercial codes to predict shrinkage porosity and hot tearing, large‐scale ingot sectioning experiments, similar to what is done a century ago, are still needed to investigate other issues, such as macrosegregation, since models are currently unable to predict such issues well. Models with more sophisticated features for macrosegregation prediction that incorporate multiphase transport phenomena are already under development. A limiting factor in application of these models for simulating steel ingots is the demand on large computation resources. Following the recent development trend and the projection of Moore's law (computer hardware), in the foreseeable future, it is predicted that multiphase models will to a great extent reduce the need for the experimental pouring‐sectioning trials.

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Section: Capabilities and Limitationsmentioning

confidence: 99%

Section: Capabilities and Limitationsmentioning

confidence: 99%

Simulation of As‐Cast Steel Ingots

Ludwig²,

Kharicha

2017

steel research int.

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“…For instance, Ni and Beckermann [16] suggested a volume-averaged two-phase model which described the transport phenomena during solidification. Based on this pioneering numerical model, other studies ensued by applying the concept to equiaxed, [17] columnar, [18][19][20] and the most general columnar/equiaxed [21] solidification.…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Analysis of Macrosegregation Formation During Twin-Roll Casting

Rodrigues

Ludwig

et al. 2019

Metall Mater Trans B

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A two-phase Eulerian-Eulerian volume-averaged model is used to predict the formation of macrosegregation during the twin-roll casting of inoculated Al-4 wt pct Cu alloys. For low solid fractions, the equiaxed crystals are modeled according to the submerged object approach. However, above a given transition limit, they are assumed to behave like a viscoplastic material. This means that the solid phase behaves as a coherent structure that can influence the motion of the liquid. Such approach allows one to take into account the flow dynamics arising from the occurrence of both solidification and hot rolling simultaneously, which usually occurs in twin-roll casting. Therefore, it is possible to explain the origin of the macrosegregation patterns obtained in the simulations based on the relative motion between the phases. Compression-induced expulsion of segregated melt is observed as a result of the deformation of the solidifying shells. Such occurrence leads to a negative macrosegregation region in the outer part of the as-cast strip. Then, because the solute-enriched melt is squeezed out toward adjacent regions, two positively segregated bands can be found near the center of the domain. Furthermore, it is shown how solidification-induced feeding weakens the absolute value of the negative and positive segregation bands.

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“…This is also an important topic in the annual solidification course in Swiss Federal Institute of Technology of Lausanne (EPFL) [4,6]. There are lots of works carried out on lateral solidification benchmark [7][8][9][10][11] while the investigation on the vertical-directional solidification is not sufficient. In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during vertical-unidirectional solidification, a series of simulations with a liquid-columnar two phase model were carried out on 2D rectangular benchmark of Sn-10%Pb alloy.…”

mentioning

confidence: 99%

Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

Zheng

Kharicha

et al. 2016

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

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Abstract:In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during columnar solidification, simulations with a liquid-columnar two phase model were carried out on a 2D rectangular benchmark of Sn-10%Pb alloy. The solidification direction in the benchmark is unidirectional: (1) downwards from top to bottom or (2) upwards from bottom to top. Thermal expansion coefficient, solutal expansion coefficient and liquid diffusion coefficient of the melt are found to be key factors influencing the final macrosegregation. The segregation range and distribution are also strongly influenced by the benchmark configurations, e.g. the solidifying direction (upwards or downwards) and boundary conditions, et al. The global macrosegregation range increases with the velocity magnitude of the melt during the process of solidification. IntroductionMacrosegregation is the inhomogeneous solute distribution at the scale of a casting and it is very sensitive to thermal-solutal convection [1]. It is important to understand the macrosegregation, and be able to model and control it because macrosegregation is usually detrimental for castings. Macrosegregation is mainly due to a combination of microsegregation and relative motion between liquid phase and solid phase [2][3][4][5]. The relative motion during the solidification is induced by different flow phenomena, for example, equiaxed sedimentation, thermo-solutal convection or feeding flow. In this study it is dedicated to illustrate the delicate mechanism of macrosegregation during solidification with the presence of thermal-solutal convection. This is also an important topic in the annual solidification course in Swiss Federal Institute of Technology of Lausanne (EPFL) [4,6]. There are lots of works carried out on lateral solidification benchmark [7][8][9][10][11] while the investigation on the vertical-directional solidification is not sufficient. In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during vertical-unidirectional solidification, a series of simulations with a liquid-columnar two phase model were carried out on 2D rectangular benchmark of Sn-10%Pb alloy. The aim of this paper is to explore the effect of thermo-solutal convection on macrosegregation in detail.

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Simulation of channel segregation using a two-phase columnar solidification model – Part I: Model description and verification

Cited by 61 publications

References 19 publications

Simulation of As‐Cast Steel Ingots

Simulation of As‐Cast Steel Ingots

A Comprehensive Analysis of Macrosegregation Formation During Twin-Roll Casting

Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

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