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3 pages, 151 KiB

Open AccessEditorial

Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting

by Zhongqiu Liu

Metals 2022, 12(5), 746; https://doi.org/10.3390/met12050746 - 27 Apr 2022

Cited by 1 | Viewed by 1248

Abstract

The multiscale transport phenomena (multiscale turbulence, multiphase flow, multiscale solidification, non-metallic inclusion, etc [...] Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

Research

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13 pages, 6605 KiB

Open AccessArticle

Distribution of Nonmetallic Inclusions in Slab for Tinplate

by Zhiying Mo, Zhendong Wang, Rudong Wang, Zhengzhi Zhao, Yuan Fang, Haixu Li, Yanzhao Luo, Shaojun Wang and Heng Cui

Metals 2022, 12(4), 679; https://doi.org/10.3390/met12040679 - 15 Apr 2022

Cited by 1 | Viewed by 1505

Abstract

Tinplate is widely used in food packaging and chemical packaging. Industrial production continues to reduce the thickness of tinplate steel, which puts higher requirements on the control of inclusions. In this study, compared with traditional detection methods, the Ultrasonic Detection method can analyze [...] Read more.

Tinplate is widely used in food packaging and chemical packaging. Industrial production continues to reduce the thickness of tinplate steel, which puts higher requirements on the control of inclusions. In this study, compared with traditional detection methods, the Ultrasonic Detection method can analyze the distribution of nonmetallic inclusions in larger size samples, which is closer to the actual production process. The numerical simulation model is established to analyze the flow, heat transfer and solidification behavior of molten steel. The results show: There are two nonmetallic inclusion bands in the sample at the edge of the slab, one is the inner and outer arc side of the sample, and the other is the 1/8 to 1/4 slab thickness region of the inner arc side in the sample. The inclusions in the thickness direction of the slab edge within the range of 1/8 to 1/4 are captured in areas 800 mm to 1400 mm below the meniscus. The solidification of the inner and outer arcs is not symmetrical, which leads to the asymmetrical distribution of inclusions in the inner and outer arcs. This study can provide a reference for improving the tinplate production process. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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11 pages, 3487 KiB

Open AccessArticle

A Study of Physical Modeling and Mathematical Modeling on Inclusion Behavior in a Planar Flow Casting Process

by Yu Liu, Hao Qiu, Zixu He, Yue Yu and Heping Liu

Metals 2022, 12(4), 606; https://doi.org/10.3390/met12040606 - 31 Mar 2022

Cited by 3 | Viewed by 1924

Abstract

Flow pattern and inclusion removal in a novel-designed crucible in the planar flow casting process were studied in the present paper. A color dye water experiment was used to show the flow field and validate the mathematical modeling. It was shown that the [...] Read more.

Flow pattern and inclusion removal in a novel-designed crucible in the planar flow casting process were studied in the present paper. A color dye water experiment was used to show the flow field and validate the mathematical modeling. It was shown that the flow pattern predicted by the Large Eddy Simulation model is maximally consistent with that in the physical modeling. The validated mathematical model was used to predict the flow pattern and inclusion behavior in the crucible with various prototypes using combinations of multiple facilities. The results show that the flow field, by using the stopper, enhances compared to that using none of the facilities, which causes the inclusion removal to become even worse when the stopper is individually used. Furthermore, as the magnetic field is added, the electromagnetic brake weakens the flow field in the magnetic zone. The function of the electromagnetic brake to weaken the flow pattern is most efficient for inclusion removal. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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14 pages, 7607 KiB

Open AccessArticle

Inclusion Removements in a Bottom-Stirring Ladle with Novel Slot-Porous Matched Dual Plugs

by Xianglong Li, Shaoyan Hu, Deyong Wang, Tianpeng Qu, Guangjun Wu, Pei Zhang, Qi Quan, Xingzhi Zhou and Zhixiao Zhang

Metals 2022, 12(1), 162; https://doi.org/10.3390/met12010162 - 17 Jan 2022

Cited by 6 | Viewed by 2211

Abstract

The cleanness of steel has always been a big problem for secondary refining. In this work, a new method, which is coupled with slot and porous plugs, is proposed to improve the cleanness in steel. Water experiments and numerical simulations were performed to [...] Read more.

The cleanness of steel has always been a big problem for secondary refining. In this work, a new method, which is coupled with slot and porous plugs, is proposed to improve the cleanness in steel. Water experiments and numerical simulations were performed to study this effect. Results revealed that when using slot-porous plugs, the flow field was obviously asymmetrical, and the circulation flow was pushed towards the porous side. Then, the removement of inclusions was increased to about 22.7% percent, comparing with traditional two-slot bottom stirring and reducing the dead zone area near the bottom of the ladle; however, the mixing time delay was 16%, comparing with traditional plugs. Then, in order to explain the reason for these phenomena, we established a mathematical model through large eddy simulation and discrete particle modeling (DPM). Results shows that the asymmetry flow field awoke the recirculation flow downwards after using slot-porous plugs, which would homogenize the flow at the bottom, promoting floating in steel. What is more, the velocity near the free surface was lowered; therefore, it could also stabilize the surface velocity as well, which is also beneficial for removing inclusions as well. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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21 pages, 9171 KiB

Open AccessArticle

Numerical Investigation of Segregation Evolution during the Vacuum Arc Remelting Process of Ni-Based Superalloy Ingots

by Jiajun Cui, Baokuan Li, Zhongqiu Liu, Fengsheng Qi, Beijiang Zhang and Ji Zhang

Metals 2021, 11(12), 2046; https://doi.org/10.3390/met11122046 - 17 Dec 2021

Cited by 12 | Viewed by 2918

Abstract

Segregation defects greatly affect the service performance and working life of castings during the vacuum arc remelting (VAR) process. However, the corresponding research on the prediction of segregation defects is still not comprehensive. Through considering the influence of water-cooled crucible on the electromagnetic [...] Read more.

Segregation defects greatly affect the service performance and working life of castings during the vacuum arc remelting (VAR) process. However, the corresponding research on the prediction of segregation defects is still not comprehensive. Through considering the influence of water-cooled crucible on the electromagnetic field inside an ingot, a full-scale model for the comprehensive prediction of freckles and macrosegregation defects during the VAR process is developed in this paper. The macroscopic solute transport phenomenon and the segregation behavior of Ni-5.8 wt% Al-15.2 wt% Ta alloy are predicted. The results indicate that the freckles are mainly concentrated in the lower region of the ingot. With the growth of the ingot, the solute enrichment channels gradually develop into solute enrichment regions, and the channel segregation evolves into macrosegregation. The Lorentz force mainly affects the flow pattern at the top of the molten pool, while the complex flow of multiple vortices is dominated by thermosolutal buoyancy. The maximum and minimum relative segregation ratio inside the ingot can reach 290% and −90%, respectively, and the positive segregation region accounts for about 79% of the total volume. This paper provides a new perspective for understanding the segregation behavior inside the ingot by studying the segregation evolution during the VAR process. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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15 pages, 5516 KiB

Open AccessArticle

Effect of Electromagnetic Frequency on the Flow Behavior in Mold during Bloom Casting

by Xianglong Li, Shaoyan Hu, Deyong Wang, Tianpeng Qu, Qi Quan and Xingzhi Zhou

Metals 2021, 11(11), 1828; https://doi.org/10.3390/met11111828 - 13 Nov 2021

Cited by 3 | Viewed by 1811

Abstract

Considering solidification, a large eddy simulation (LES) model of two-phase flow was established to simulate the thermal–magnetic flow coupled fields inside a jumbo bloom. The magnetic field was calculated based on Maxwell’s equations, constitutive equations, and Ohm’s law. An enthalpy–porosity technique was used [...] Read more.

Considering solidification, a large eddy simulation (LES) model of two-phase flow was established to simulate the thermal–magnetic flow coupled fields inside a jumbo bloom. The magnetic field was calculated based on Maxwell’s equations, constitutive equations, and Ohm’s law. An enthalpy–porosity technique was used to model the solidification of the steel. The movement of the free surface was described by the volume of fluid (VOF) approach. With the effect of electromagnetic stirring (MEMS), the vortices in the bloom tended to be strip-like; large vortices mostly appeared in the injection zone, while small ones were found near the surface of the bloom. It is newly found that even though the submerged entry nozzle (SEN) is asymmetrical about the bloom, a biased flow can also be found under the effect of MEMS. The reason for this phenomenon is because the magnetic force is asymmetrical and transient. A high frequency will reduce the period of biased flow; however, the frequency should not be too high because it could also intensify meniscus fluctuations and thus entrap slag droplets in the mold. The velocity near the solidification front can also be increased with a higher frequency. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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25 pages, 9467 KiB

Open AccessEditor’s ChoiceArticle

Numerical Simulation on Motion Behavior of Inclusions in the Lab-Scale Electroslag Remelting Process with a Vibrating Electrode

by Fang Wang, Boyang Sun, Zhongqiu Liu, Baokuan Li, Shuo Huang and Beijiang Zhang

Metals 2021, 11(11), 1784; https://doi.org/10.3390/met11111784 - 05 Nov 2021

Cited by 4 | Viewed by 1526

Abstract

In order to meet the requirement of high-quality ingots, the vibrating electrode technique in the electroslag remelting (ESR) process has been proposed. Non-metallic inclusions in ingots may cause serious defects and deteriorate mechanical properties of final products. Moreover, the dimension, number and distribution [...] Read more.

In order to meet the requirement of high-quality ingots, the vibrating electrode technique in the electroslag remelting (ESR) process has been proposed. Non-metallic inclusions in ingots may cause serious defects and deteriorate mechanical properties of final products. Moreover, the dimension, number and distribution of non-metallic inclusions should be strictly controlled during the ESR process in order to produce high-quality ingots. A transient 2-D coupled model is established to analyze the motion behavior of inclusions in the lab-scale ESR process with a vibrating electrode, especially under the influence of the vibration frequency, current, slag layer thickness, and filling ratio, as well as type and diameter of inclusions. Simulation model of inclusions motion behavior is established based on the Euler-Lagrange approach. The continuous phase including metal and slag, is calculated based on the volume of fluid (VOF) method, and the trajectory of inclusions is tracked with the discrete phase model (DPM). The vibrating electrode is simulated by the user-defined function and dynamic mesh. The results show that when the electrode vibration frequency is 0.25 Hz or 1 Hz, the inclusions will gather on one side of the slag layer. When it increases from 0.25 Hz to 1 Hz, the removal ratio of 10 μm and 50 μm inclusions increases by 5% and 4.1%, respectively. When the current increases from 1200 A to 1800 A, the flow following property of inclusions in the slag layer becomes worse. The removal ratio of inclusions reaches the maximum value of 92% with the current of 1500 A. The thickness of slag layer mainly affects the position of inclusions entering the liquid-metal pool. As the slag layer thickens, the inclusions removal ratio increases gradually from 82.73% to 85.91%. As the filling ratio increases, the flow following property of inclusions in the slag layer is enhanced. The removal ratio of 10 μm inclusions increases from 94.82% to 97%. However, for inclusions with a diameter of 50 μm, the maximum removal ratio is 96.04% with a filling ratio of 0.46. The distribution of 50 μm inclusions is significantly different, while the distribution of 10 μm inclusions is almost similar. Because of the influence of a vibrating electrode, 10 μm

{Al}_{2} O_{3}

and

MnO

have a similar removal ratios of 81.33% and 82.81%, respectively. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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14 pages, 4548 KiB

Open AccessArticle

Role of Electrode Rotation on Improvement of Metal Pool Profile in Electroslag Remelting Process

by Xuechi Huang, Yiru Duan, Zhongqiu Liu, Baokuan Li and Fang Wang

Metals 2021, 11(11), 1675; https://doi.org/10.3390/met11111675 - 20 Oct 2021

Cited by 8 | Viewed by 1688

Abstract

A comprehensive transient model is developed to study the effect of electrode rotation on the evolution of metal pool profiles and the solidification quality of ESR ingots. Magnetohydrodynamic flow, heat transfer, solidification, and electrode melting are considered simultaneously in the model. The growth [...] Read more.

A comprehensive transient model is developed to study the effect of electrode rotation on the evolution of metal pool profiles and the solidification quality of ESR ingots. Magnetohydrodynamic flow, heat transfer, solidification, and electrode melting are considered simultaneously in the model. The growth of the ESR ingot is predicted using the dynamic layering method. The numerical results show that the productivity reaches a maximum of 15.97% at the rotating speed of 40 rpm without increasing power. With the increasing rotating speed, the maximum temperature of the melt decreases, and the temperature distribution becomes more uniform. Compared with the static one, the pool profiles are flattened by −1.19%, −8.52%, and 12.44% at the rotating speeds of 20, 40, and 60 rpm, respectively. The metal pool profile was improved remarkably, but only at the higher speed (i.e., 60 rpm). The effect of rotating speed on the metal pool profile depends on the competition between the melting rate and slag temperature. Meanwhile, the local solidification time and the secondary dendrite arm spacing are slightly improved at lower rotating speeds but are significantly worse at higher rotating speeds. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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20 pages, 6300 KiB

Open AccessArticle

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

by Alexander Vakhrushev, Abdellah Kharicha, Menghuai Wu, Andreas Ludwig, Yong Tang, Gernot Hackl, Gerald Nitzl, Josef Watzinger and Jan Bohacek

Metals 2021, 11(9), 1375; https://doi.org/10.3390/met11091375 - 31 Aug 2021

Cited by 12 | Viewed by 3036

Abstract

Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining [...] Read more.

Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining issues of this goal is the stability of the casting process. The clogging of submerged entry nozzles (SENs) typically results in asymmetric mold flow, uneven solidification, meniscus fluctuations, and possible slag entrapment. Analyses of retained SENs have evidenced the solidification of entrapped melt inside clog material. The experimental study of these phenomena has significant difficulties that make numerical simulation a perfect investigation tool. In the present study, verified 2D simulations were performed with an advanced multi-material model based on a newly presented single mesh approach for the liquid and solid regions. Implemented as an in-house code using the OpenFOAM finite volume method libraries, it aggregated the liquid melt flow, solidification of the steel, and heat transfer through the refractory SENs, copper mold plates, and the slag layer, including its convection. The introduced novel technique dynamically couples the momentum at the steel/slag interface without complex multi-phase interface tracking. The following scenarios were studied: (i) SEN with proper fiber insulation, (ii) partial damage of SEN insulation, and (iii) complete damage of SEN insulation. A uniform 12 mm clog layer with 45% entrapped liquid steel was additionally considered. The simulations showed that parasitic solidification occurred inside an SEN bore with partially or completely absent insulation. SEN clogging was found to promote the solidification of the entrapped melt; without SEN insulation, it could overgrow the clogged region. The jet flow was shown to be accelerated due to the combined effect of the clogging and parasitic solidification; simultaneously, the superheat transport was impaired inside the mold cavity. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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20 pages, 7083 KiB

Open AccessArticle

Combined Effects of EMBr and SEMS on Melt Flow and Solidification in a Thin Slab Continuous Caster

by Changjun Wang, Zhongqiu Liu and Baokuan Li

Metals 2021, 11(6), 948; https://doi.org/10.3390/met11060948 - 11 Jun 2021

Cited by 16 | Viewed by 3308

Abstract

Electromagnetic fields have emerged as powerful tools for addressing current problems in thin slab continuous casting processes in the iron and steel industry. Substantial studies have been undertaken on the fundamental effects of electromagnetic brakes (EMBr) and strand electromagnetic stirring (SEMS). However, little [...] Read more.

Electromagnetic fields have emerged as powerful tools for addressing current problems in thin slab continuous casting processes in the iron and steel industry. Substantial studies have been undertaken on the fundamental effects of electromagnetic brakes (EMBr) and strand electromagnetic stirring (SEMS). However, little attention has been focused on melt flow and solidification in a thin slab continuous caster with the simultaneous application of an EMBr and SEMS. The present study aimed to predict transient fields in the caster using a large eddy simulation and an enthalpy-porosity method. The electric potential method was applied in the braking process, and the conductivity change with solidification was considered. The suppressive effect on the intensity of the nozzle jet, the balance effect on the mold flow, and a dispersion effect could be observed. The dispersion effect was a novel finding and was beneficial to a flatter nozzle jet. In contrast, SEMS caused a highly turbulent flow in the strand. A large vortex could be observed in the casting direction. The solidified shell became more uniform, and the solidification rate became obviously slower. These findings supported the view that a high-quality thin slab can be produced by the application of an EMBr and SEMS. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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11 pages, 6737 KiB

Open AccessArticle

Flow Field and Temperature Field in a Four-Strand Tundish Heated by Plasma

by Mengjing Zhao, Yong Wang, Shufeng Yang, Maolin Ye, Jingshe Li and Yuhang Liu

Metals 2021, 11(5), 722; https://doi.org/10.3390/met11050722 - 28 Apr 2021

Cited by 5 | Viewed by 1678

Abstract

Tundish plasma heating is an effective method for achieving steady casting with low superheat and constant temperature. In order to study the flow field, temperature field in tundish heated by plasma, a three-dimensional transient mathematical model was established in the present work. A [...] Read more.

Tundish plasma heating is an effective method for achieving steady casting with low superheat and constant temperature. In order to study the flow field, temperature field in tundish heated by plasma, a three-dimensional transient mathematical model was established in the present work. A four-strand T-type tundish in a steelmaking plant was used to explore the changes in the flow field and temperature field of molten steel in the tundish under different plasma heating powers. The results showed that plasma heating affected the flow state of molten steel. It could eliminate the short-circuit flow at outlet. When the plasma heating was 500 kW, the molten steel had an obvious upward flow. The turbulence intensity was improved and distributed evenly with an increase in plasma heating power. In the prototype tundish, the temperature of the outlet was dropped by nearly 2–3 K within 300 s. With the increase of plasma heating power, the low temperature area in the tundish gradually was decreased. When the heating power was 1000 kW, the temperature difference of two outlets was 0.5 K and the overall temperature distribution was more uniform. The research results have a certain guiding significance for the selection of the actual plasma heating power on site. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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16 pages, 7556 KiB

Open AccessArticle

Cone Clogging of Submerged Entry Nozzle in Rare Earth Treated Ultra-Low Carbon Al-Killed Steel and Its Effect on the Flow Field and Vortex in the Mold

by Chengjian Hua, Min Wang, Dieter Senk, Hao Wang, Qi Zhang, Jianguo Zhi and Yanping Bao

Metals 2021, 11(4), 662; https://doi.org/10.3390/met11040662 - 19 Apr 2021

Cited by 13 | Viewed by 2939

Abstract

Two submerged entry nozzles (SENs) used for casting 1300 tons and 260 tons of Al-killed steel were dissected. Several parameters including block rate, nozzle clog angle, port width, and port height of the clogged nozzle were introduced to describe the geometry of clogs [...] Read more.

Two submerged entry nozzles (SENs) used for casting 1300 tons and 260 tons of Al-killed steel were dissected. Several parameters including block rate, nozzle clog angle, port width, and port height of the clogged nozzle were introduced to describe the geometry of clogs in the SENs based on the dissection; furthermore, a geometry model was established to describe the characteristics of the nozzle clogging of the SENs. A large-eddy simulation (LES) coupled with the volume of fraction (VOF) method was adopted to simulate the steel–slag interface’s interaction behavior. The vortex visualization and rotation magnitude were characterized by the Liutex method. Quantitatively, the influence of nozzle clogging resulted in block rates of 0% to 45.9% on the flow and vortex distribution in the mold, and the characteristics of the steel–slag interface fluctuation were well verified in the industrial experiment. Full article

(This article belongs to the Special Issue Numerical Modeling of Metallurgical Processes: Continuous Casting and Electroslag Remelting)

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