Three‐dimensional Simulation of Thermosolutal Convection and Macrosegregation in Steel Ingots

In present paper, a ladle-tundish-mold CFD model and a macrosegregation model were utilized to investigate the effects of the multiple pouring (MP) process on the macrosegregation in a 438-ton steel ingot. Firstly, the model was partially proved as compared to the measured carbon distributions along the transverse sections in the riser of ingot. Then, the comparison between the single pouring (SP) and MP process has been carried out to study their influences on the macrosegregation in ingot. Besides, the predicted macrosegregation results in MP process which introduced the improved riser fixed with an insulating sleeve were compared with that in traditional MP process. The traditional MP process leads to certain favorable initial carbon distribution in the mold, which has some favorable influence on suppressing the positive segregation in ingot. The holding time of the low carbon in the riser is the main factor to suppress the positive segregation in ingot. Improved insulating sleeve can prolong the holding time of the low carbon in the riser and release the positive segregation in the riser of ingot. Improvement of the insulating effect of the riser is an efficient method to control macrosegregation in large steel ingot.

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“…[21]. Generally, the numerical results of the present model are in good agreement with the measurements by Hebditch and Hunt [22].…”

Section: Macrosegregation With Multiple Pouring and Validationsupporting

confidence: 89%

A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot

Duan

Shen

Liu

2015

Acta Metall. Sin. (Engl. Lett.)

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“…Li et al (2013) and Wu and Ludwig (2006) suggested that the negative segregation is caused by the sedimentation of grains when grains solidified from liquid phase. However, Li et al (2010) found that the solutal buoyancy is also an important factor for the formation of both the top positive segregation and the lower conic negative segregation. In current model, both sedimentation of grains and solutal buoyancy are treated as key factors for the formation of above segregations.…”

Section: Characteristics Of Segregationmentioning

confidence: 95%

Dendritic model for macrosegregation prediction of large scale castings

Han

et al. 2016

Journal of Materials Processing Technology

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“…14. The total solidification time for this 3?3 t Fe-3?6 wt-%C steel ingot is y105 min, as calculated by Li and Shen, 28 whereas in the present model it is y90 min under the same solution conditions. However, different solid fractions are presented as show in Fig.…”

Section: Initial Conditions and Boundary Conditionsmentioning

confidence: 99%

Numerical analysis of macrosegregation and shrinkage porosity in large steel ingot

Peng

Zhang

2013

Ironmaking & Steelmaking

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A three-dimensional finite element model has been developed with heat, flow and solute transfer behaviour coupled calculation to predict shrinkage and macrosegregation defects in an as cast steel ingot. Solidification evolution and carbon segregation have been verified by previous investigations of a 3?3 t steel ingot. The heat transfer coefficient (HTC) at the ingot mould interface against temperature was researched by an inverse calculation method based on thermophysical parameters from microsegregation model and experimental temperatures. Good agreements were obtained both in range and variation trend of HTC compared with experimental results in references. Macrosegregation and shrinkage porosities were observed to accompany each other at the hot top of the rectangular ingot, which should be further investigated by numerical simulation. Applications of the model were extended to steel plants. The soundness and homogeneity of rolled blooms were both satisfied. IntroductionIngot casting remains a common process for metals and alloys, especially for automotive, hydroelectric, aeronautic and military applications, where continuously cast semis cannot meet the requirements of quality, postcast reduction ratios or product size. However, shrinkage and macrosegregation are the most common defects in large steel ingots, resulting in service property deterioration of the final products.It has been an important issue to analyse the formation mechanism of these defects and take effective measures to improve ingot quality. With the rapid development of numerical simulation technology numerous studies have been carried out in recent decades by numerical methods 1-4 to obtain a further understanding of the internal defects. Thomas and Samarasekera et al. 5,6 built a 2D FEM model with heat and stress coupled calculation where the thermophysical and thermomechanical parameters were treated as a function of temperature. Tashiro and Watanabe et al. 7 put forward a criterion for predicting central shrinkage and A type segregation based on a 100 and 135 t steel ingot solidification analysis. Kubo and Pehlke 8 developed a 2D FDM model including convection calculation to study the mechanism of shrinkage formation and the results were observed to be in line with those of Pellini. 9 Rappaz et al. 10,11 created a 3D FVM model based on Darcy's law and gas segregation calculation, and the pipe and porosity distribution for Al-Cu, Al-Si alloys are consistent with the observation. Beckermann et al. 12,13 predicted the macrosegregation under the hot top of a 3?3 t steel ingot by a 2D FDM model, but the negative segregation in the lower part was ignored. Založnik and Combeau et al. 14,15 expanded Beckermann's model to a 3D domain, and the equiaxed settling during the solidification of this 3?3 t ingot was also taken into consideration. Macrosegregation results matched well with the experiment. In addition, simulation and experimental analysis for optimising mould design, improving flow pattern and increasing yield rate have been heavily pres...

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Three‐dimensional Simulation of Thermosolutal Convection and Macrosegregation in Steel Ingots

Cited by 23 publications

References 18 publications

A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot

A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot

Dendritic model for macrosegregation prediction of large scale castings

Numerical analysis of macrosegregation and shrinkage porosity in large steel ingot

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