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BW Li,XY Tian,EG Wang,and JC He,

金属学报(英文版) , 2007,
Abstract: In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel type mold,a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based on structured body fitted coordinate grids. The CFD (computational fluid dynamics) package is validated first using one typical case described in previously published studies,and then it is developed to study the effect of operational parameters on fluid flow in thin slab caster.Two operational parameters, casting speed and SEN (submerged entry nozzle) depth, are mainly considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.
The interfacial behavior of molten steel and liquid slag in a slab continuous casting mold with electromagnetic brake and argon gas injection

YU Hai-Qi,

金属学报 , 2008,
Abstract: It described a numerical simulation study for the interfacial behaviour between molten steel and liquid slag layer with different flow-control technologies in the slab continuous casting mold, considering the effects of argon gas flow rate, casting speed and current intensity of coils on the interfacial behaviour of molten steel and liquid slag with the coupling action of electromagnetic brake (EMBr) and argon gas injection. The relationship between the level fluctuation index of F value and level fluctuation of free surface was also investigated. For a given casting speed with EMBr, increasing the argon gas flow rate can aggravate the local fluctuation of interface so much as lead to the breakup of the steel-slag interface, F value increases with the increasing argon gas flow rate and the thickness of liquid slag near the meniscus increases linearly with F value. For a given argon gas flow rate with EMBr, increasing the casting speed has helpful for restraining the interfacial fluctuation near the nozzle, and F value also increasing, the thickness of liquid slag near the meniscus reduces linearly with F value. On the contrary, for a certain casting speed and argon gas flow rate, increasing the current intensity of coils can aggravate the steel/slag interfacial fluctuation near the nozzle.

YU Haiqi,ZHU Miaoyong,

金属学报 , 2009,
Abstract: Mathematical model was developed to study the 3D temperature distribution and heat transfer from superheated liquid steel to the inside of the solidifying shell in the slab continuous casting mold. The effects of some factors, such as submergence depth and port angle of submerged entry nozzle (SEN), mold width, casting speed, superheat temperature, argon gas injection, electromagnetic brake (EMBr) and also including the argon gas flow rate and current intensity etc., on the temperature distribution and heat transfer of superheated liquid steel in the mold were analyzed. The results indicate that the maximum heat input to the solidifying shell forefront occurs near the impingement point of liquid steel on the narrow face of mold, and the most superheat of superheated liquid steel is dissipated near the impingement zone. Heat flux of superheated liquid steel delivered to the shell surface increases in direct proportion to the casting speed and superheat temperature, respectively. Argon gas injection leads to a substantial increase in superheat flux to the impingement zone of narrow face and the upper region of wide face. EMBr is beneficial in increasing the temperature of upper region of the mold, but has no obvious effect on the heat flux distribution. The double action of argon gas injection and EMBr also produces an increase in heat flux to the upper region of wide face, which has no visible influence for the hat flux distribution of impingement zone.
Numerical Simulation for the Interfacial Behavior of Steel and Slag in a Slab Continuous Casting Mold with High Casting Speed

CAO Na,ZHU Miaoyong,

金属学报 , 2007,
Abstract: The entrainment of steel and slag interface has a great effect on casting process and the product quality. The research described the interfacial behavior between fluid steel and molten slag layer in a slab continuous casting mold with high casting speed by numerical simulation method. Good agreement between the mathematical model and experimental observation was obtained. The influences of casting speed, mold width, port angle, submergence depth of SEN and molten slag viscosity on interfacial behavior were investigated. For a given casting speed, increasing the penetration depth and downward port degree can effectively restrain interfacial oscillations. Molten slag viscosity has hardly influence on interfacial profile of steel and slag. Steel-slag interface velocity decreases with increasing molten slag viscosity.
Influence of EMBr on Flow Field of Molten Steel in a Continuous Casting Slab Mold

JIA Hao,ZHANG Zhen-qiang,CHANG Tong-xu,DENG Kang,REN Zhong-ming,

过程工程学报 , 2012,
Abstract: A mercury model was developed to studied the effects of different types of electromagnetic brake(EMBr),electromagnetic mold brake ruler(EMBr-Ruler) and flow control mold(FC Mold) on molten steel flow with the practical casting speeds of 1.0,1.3 and 2.0 m/min in a slab continuous casting mold.The results show that the velocity and fluctuation of the liquid surface flow are depressed with FC Mold,the maximum values of the horizontal velocity and turbulent intensity near the surface are 1/5 and 1/6 respectively compared with those without EMBr,both types of EMBr compress the expanding space of the jet discharged from the outport,the maximum vertical velocity of downward flow near the narrow wall increases from 0.030 m/s without EMBr to 0.066(EMBr-Ruler) and 0.057 m/s(FC Mold),it inhibits the formation of plug flow.EMBr is conductive to the formation of plug flow when the port is placed in the EMBr region and the casting speed is suitable.The flow velocity distribution in mold with FC Mold is better than that without EMBr and with EMBr-Ruler with high practical casting speed(2 m/min).The flow field is better with EMBr-Ruler at 1.3 m/min,but when the casting speed is low(1 m/min),the effects of two types of EMBr are unsatisfactory,even deteriorate the original metal flow.

MENG Xiangning,ZHU Miaoyong School of Materials,Metallurgy,Northeastern University,Shenyang,

金属学报 , 2009,
Abstract: Liquid flux is an effective lubrication in the conventional continuous casting of steel, which can prevent the breakout effectively, and also the longitudinal cracks that occur on strand surface are decreased obviously. Previously, many studies have been reported on the flux infiltration, some empirical equations for calculating flux consumption have been reported based on the data accumulated through the commercial operation of casters, and the new tools and techniques for estimating the lubrication condition in mold have also been introduced. Especially, the lubrication mechanism of liquid flux has drawn general concerns recently, and some relevant simulation of flux infiltration behavior based on the cold model experiments and mathematical models of flux infiltration derived from theoretical calculations have been conducted. Most of these researches lay particular emphasis on the macroscopical detection and calculation to the infiltration behavior, and some researches related to micro–mechanism lack the discussion of the relevant influence factor yet. In the present work, on the basis of calculation of liquid flux channel pressure in meniscus for slab continuous casting mold, a new mechanism of the liquid flux consumption was proposed by analyzing the deformation behavior of initial solidifying shell during the mold oscillation cycle as high casting speed 2.0 m/min, and the concepts of infiltration time and infiltration intensity were defined for the first time, then the effect of non–sinusoidal oscillation parameters on the liquid flux consumption was discussed. The results show that the periodically continued liquid flux consumption is caused by variety of flux channel pressure which is induced by change of channel width, and the liquid flux will be infiltrated into flux channel from last stage of positive strip time until last stage of negative strip time by negative flux channel pressure. The infiltration time is lengthened and the infiltration intensity is weakened by reducing oscillation frequency. The infiltration intensity is strengthened by improving amplitude, and the infiltration time is slimly influenced. Non–sinusoidal oscillation factor has a little effect on the infiltration intensity, and the infiltration time is increased with the oscillation factor decreasing.
Numerical Simulation for the Interfacial Behavior of Steel and Slag in a Slab Continuous Casting Mold with Blowing Argon Gas

CAO Na,ZHU Miaoyong,

金属学报 , 2008,
Abstract: A mathematical model to describe the interfacial behavior between fluid steel and molten slag layer in a slab continuous casting mold with blowing argon gas was developed, and the prediction was validated by the water model. The influences of casting speed, argon gas volume flowrate, mold width, submergence depth of SEN (Submerged Entry Nozzle) and bubble size on interfacial behavior were numerically investigated. The results show that given a casting speed 1.8m/min, the upper circulating flow in the mold gradually disappears and the interfacial uneven disturbed by argon bubbles is gradually evident with the increasing argon gas flowrate. Raising the casting speed from 1.2m/min to 2.2m/min leads to the deeper penetration of bubbles and less influence of argon bubbles on the flow pattern and interfacial profile with a given argon gas flowrate. Increasing the submergence depth of SEN can effectively restrain interfacial oscillations in mold, while mold width has little effect on it. Bubble size has a remarkable influence on the interfacial behavior of molten steel and slag in mold.
Effect of continuous casting speed on mold surface flow and the related near-surface distribution of non-metallic inclusions  [PDF]
Peng Fei,Yi Min,Cheng-jun Liu,Mao-fa Jiang
- , 2019, DOI: https://doi.org/10.1007/s12613-019-1723-y
Abstract: For the control of surface defects in interstitial-free (IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. The results show that, at casting speeds of 0.8 and 1.0 m/min, a thin liquid mold flux layer forms and non-uniform floating of argon bubbles occurs, inducing the entrainment and subsequent entrapment of the liquid flux; fine inclusion particles of Al2O3 can also aggregate at the solidification front. At higher casting speeds of 1.4 and 1.6 m/min, the liquid mold flux can be entrained and carried deeper into the liquid steel pool because of strong level fluctuations of the liquid steel and the flux. The optimal casting speed is approximately 1.2 m/min, with the most favorable surface flow status and, correspondingly, the lowest number of inclusions near the slab surface.
CFD Model Study of a New Four-Port Submerged Entry Nozzle for Decreasing the Turbulence in Slab Casting Mold  [PDF]
Debasish Chatterjee
ISRN Metallurgy , 2013, DOI: 10.1155/2013/981597
Abstract: In recent years, the continuous casting process in which molten metal is constantly cast into semifinished shapes has been widely adopted in the steel and nonferrous metal producing industry, mainly due to its economic advantages associated with increased yields and the elimination of intermediate processing steps. Turbulent flow in submerged entrance nozzle and mold of continuous casting is associated with costly failure such as the entrainment of slag inclusions and the formation of surface defects. A number of previously studies have analyzed the flow. A CFD model study has done to decrease the turbulence within the mold by developing a 4-port submerged entry nozzle in comparison with conventional 2-port submerged entry nozzle. VOF (volume of fluid) simulation study has been done to find out the effect of turbulence within mold on slag metal interaction, level fluctuation, and risk of breakout. In all the cases the performance of new 4-port SEN over 2-port SEN has been compared by plotting graph. 1. Introduction Steel maker around the world is emphasized to increase the production rate to cope with the global demand of steel in coming decade. Simultaneously the supply of quality steel is demanding by customer. But to meet this stringent demand is very difficult as production machine has certain drawbacks and limitations. One of these drawbacks is creation of turbulence within mold during casting of steel at high casting speed. The submerged entry nozzle (SEN) with two bifurcated ports is commonly applied in slab continuous casting. As the source of the flow, the SEN decides on the steel flow pattern in the mold. For unreasonable nozzle design, impingement of hot liquid metal with high momentum against the solidifying shell can contribute to shell thinning and costly breakout as well as large surface fluctuation [1]. Scientists have been interested in the fluid flow that is observed in the mold during continuous casting because the flow pattern affects the inner and the surface quality of the steel slab to a great extent. Figure 1(a) shows the basic phenomenon produced in the mold during the continuous casting. The flow pattern depends on the structure of the submerged entry nozzle (SEN) and other relative parameters. On the one hand, a calm and smooth mold level assists the uniform formation of the strand shell in circumferential direction and reduces the thermomechanical stresses in the strand shell. It also allows the homogeneous intake of casting powder into the lubrication gap between the strand shell and the mold wall and this, in turn, is
Numerical Simulation of Inclusion Removal with Argon Blowing in a Slab Continuous Casting Mold

LUO Zhi-guo,NI Bing,DI Zhan-xia,ZOU Zong-shu,

过程工程学报 , 2010,
Abstract: Aiming at the removal of non-metallic inclusions in liquid steel in a slab continuous casting mold, the harmonious phase model (HPM) and discrete phase model (DPM) were used to describe the particle behavior and removal rate in water-air-inclusion simulation and steel-argon-inclusion systems. The results showed that the argon blowing promotes inclusion removal. In the study on the mold, inclusion removal efficiency is the lowest at 1.3 m/min casting speed with 6.0 L/min gas flow rate. The inclusion trapping...
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