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建立小方坯喷淋结晶器凝固传热数学模型,模拟计算了铸坯温度场、坯壳厚度、热流场,坯壳与铜壁间气隙厚度。计算坯壳厚度与实测坯壳厚度基本吻合;与普通水缝式结晶器相比,铸坯温度场均匀,坯壳厚度均匀,冷却强度有所提高。 相似文献
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S. V. Lukin N. I. Shestakov T. I. Strashko A. V. Zverev 《Russian Metallurgy (Metally)》2007,(3):184-188
A mathematical model is proposed for cooling a metal solidifying in a continuous-casting mold. In this model, heat exchange is related to solidification; therefore, the thermal resistance of the gap between the ingot and the work mold surface, which is the main component of the total thermal resistance to heat transfer from the ingot to cooling water, can be calculated. This mathematical model is applied to the cooling and solidification of an ingot in a continuous-casting mold, and some numerical-calculation results for the case of a medium-carbon steel are presented. 相似文献
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Asaneffectivetechnique ,soft contactelectro magneticcontinuouscastingtechnologyisrecentlyintroducedinthecontinuouscastingprocesstocon troltheinitialsolidificationandimprovethequalityofbillet[1,2 ] .Thehighfrequencyelectromagneticfieldisusedmainlytoconfinet… 相似文献
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小方坯连铸机结晶器的研究 总被引:5,自引:1,他引:4
本文建立了铸坯凝固传热数学模型,模拟计算了铸坯温度场、坯壳厚度、热流场、坯壳热收缩应力场、坯壳与铜壁间气隙厚度;计算出的坯壳厚度与实测的坯壳厚度基本吻合,计算结果可为连铸机生产和连铸机设计提供参考。 相似文献
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Herein, a 3D mathematical model is established to elucidate the meniscus solidification and heat transfer in the chamfered mold. The fluid flow, heat transfer, the solidification of steel, the oscillation of the mold, and the steel–slag interfacial tension are considered, and the meniscus behavior on different longitudinal sections and cross sections is discussed. Under the influence of the upper roll flow, the height of the steel level increases from submerged entry nozzle to narrow face, which affects the distribution of the oscillation mark on the surface of the shell. With the mold chamfer and two new corners, the thickness of the slag film at the corner 1 with angle of 123.7° is the largest, and the shell thickness is the smallest, which is related to the 3D profile of the meniscus near the corner. The largest heat flux is located at 10–14 mm below the initial level of liquid steel and is below 3.0 MW m−2. The heat flux at the corner 1 with small obtuse angle is the smallest on the same cross section, indicating that small obtuse angle near the corner resulted in the low heat transfer. 相似文献
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从分析高拉速包晶钢板坯连铸结晶器内凝固传热行为特征入手,首先阐明拉速对结晶器内的界面热阻、凝固坯壳的温度与应力分布的影响规律,研究发现拉速超过1.6 m·min?1时,界面热阻明显增加,拉速由1.4 m·min?1提升至1.6 m·min?1和1.8m·min?1时,出结晶器坯壳厚度相应减少约10%,其发生漏钢的危险不断增加;在此基础上,阐述了结晶器的内腔结构、保护渣、振动与液面控制等控制结晶器内坯壳凝固均匀性的相关技术。要实现高速连铸,首要应考虑结晶器内腔结构的优化设计,使其能更好地迎合凝固坯壳的生长,研制适合包晶钢等凝固特点的专用连铸保护渣至关重要,铸坯鼓肚控制也是保障高拉速液面稳定的关键。 相似文献
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A simple, but comprehensive model of heat transfer and solidification of the continuous casting of steel slabs is described,
including phenomena in the mold and spray regions. The model includes a one-dimensional (1-D) transient finite-difference
calculation of heat conduction within the solidifying steel shell coupled with two-dimensional (2-D) steady-state heat conduction
within the mold wall. The model features a detailed treatment of the interfacial gap between the shell and mold, including
mass and momentum balances on the solid and liquid interfacial slag layers, and the effect of oscillation marks. The model
predicts the shell thickness, temperature distributions in the mold and shell, thickness of the resolidified and liquid powder
layers, heat-flux profiles down the wide and narrow faces, mold water temperature rise, ideal taper of the mold walls, and
other related phenomena. The important effect of the nonuniform distribution of superheat is incorporated using the results
from previous three-dimensional (3-D) turbulent fluid-flow calculations within the liquid pool. The FORTRAN program CONID
has a user-friendly interface and executes in less than 1 minute on a personal computer. Calibration of the model with several
different experimental measurements on operating slab casters is presented along with several example applications. In particular,
the model demonstrates that the increase in heat flux throughout the mold at higher casting speeds is caused by two combined
effects: a thinner interfacial gap near the top of the mold and a thinner shell toward the bottom. This modeling tool can
be applied to a wide range of practical problems in continuous casters. 相似文献
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M. Bellet F. Decultieux M. Ménaï F. Bay C. Levaillant J. -L. Chenot P. Schmidt I. L. Svensson 《Metallurgical and Materials Transactions B》1996,27(1):81-99
A thermomechanical three-dimensional (3-D) finite element analysis of solidification is presented. The heat transfer model is based on a multidomain analysis accounting for noncoincident meshes for the cast part and the different mold components. In each subdomain, a preconditioned conjugate gradient solver is used. The mechanical analysis assumes the mold is rigid. A thermoelastic-viscoplastic rheological model is used to compute the constrained shrinkage of the part, resulting in an effective local air gap width computation. At each time increment, a weak coupling of the heat transfer and mechanical analyses is performed. Comparisons of experimental measurements and model predictions are given in the case of a hollow cylindrical aluminum alloy part, showing a good quantitative agreement. An application to an industrial aluminum casting is presented, illustrating the practical interest of thermomechanical computations in solidification analysis. 相似文献
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In this paper, mold simulator trials were firstly carried out to study the phenomena of the initial shell solidification of molten steel and the heat transfer across the initial shell to the infiltrated mold/shell slag film and mold. Second, a one-dimensional inverse heat transfer problem for solidification (1DITPS) was built to determine the temperature distribution and the heat transfer behavior through the solidifying shell from the measured shell thickness. Third, the mold wall temperature field was recovered by a 2DIHCP mathematical model from the measured in-mold wall temperatures. Finally, coupled with the measured slag film thickness and the calculations of 1DITPS and 2DIHCP, the thermal resistance and the thickness of liquid slag film in the vicinity of the meniscus were evaluated. The experiment results show that: the total mold/shell thermal resistance, the mold/slag interfacial thermal resistance, the liquid film thermal resistance, and the solid film thermal resistance is 8.0 to 14.9 × 10?4, 2.7 to 4.8 × 10?4, 1.5 to 4.6 × 10?4, and 3.9 to 6.8 × 10?4 m2 K/W, respectively. The percentage of mold/slag interfacial thermal resistance, liquid film thermal resistance, and solid film thermal resistance over the total mold/shell thermal resistance is 27.5 to 34.4, 17.2 to 34.0, and 38.5 to 48.8 pct, respectively. The ratio of radiation heat flux is around 14.1 to 51.9 pct in the liquid slag film. 相似文献
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A coupled finite-element model, CON2D, has been developed to simulate temperature, stress, and shape development during the
continuous casting of steel, both in and below the mold. The model simulates a transverse section of the strand in generalized
plane strain as it moves down at the casting speed. It includes the effects of heat conduction, solidification, nonuniform
superheat dissipation due to turbulent fluid flow, mutual dependence of the heat transfer and shrinkage on the size of the
interfacial gap, the taper of the mold wall, and the thermal distortion of the mold. The stress model features an elastic-viscoplastic
creep constitutive equation that accounts for the different responses of the liquid, semisolid, delta-ferrite, and austenite
phases. Functions depending on temperature and composition are employed for properties such as thermal linear expansion. A
contact algorithm is used to prevent penetration of the shell into the mold wall due to the internal liquid pressure. An efficient
two-step algorithm is used to integrate these highly nonlinear equations. The model is validated with an analytical solution
for both temperature and stress in a solidifying slab. It is applied to simulate continuous casting of a 120 mm billet and
compares favorably with plant measurements of mold wall temperature, total heat removal, and shell thickness, including thinning
of the corner. The model is ready to investigate issues in continuous casting such as mold taper optimization, minimum shell
thickness to avoid breakouts, and maximum casting speed to avoid hot-tear crack formation due to submold bulging. 相似文献
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E. Lacoste M. Aboulfatah Ph.D. Student M. Danis F. Girot 《Metallurgical and Materials Transactions A》1993,24(12):2667-2678
The numerical simulation of the metal-matrix composites (MMCs) elaboration by an injection process is presented. The equations
governing the heat and mass transfers through a porous medium are applied to the metal injection process. The bidimensional
numerical model is described based on a finite volume formulation. It is shown that two types of metal solidification appear
during the injection: (1) a frontal solidification related to the heat balance between the fibrous preform and the metal and
(2) a lateral solidification related to the heat losses toward the mold walls. Numerical tests validate the numerical model
in the case of theoretical mono-dimensional geometries when analytical solutions exist. The model is then applied to bidimensional
geometries. The preform is progressively closed until the channel is obstructed so that injection is achieved to the “impregnation
depth.≓ A systematic study determines the influence on the impregnation depth of different parameters, such as thermal properties
of fibers and mold walls, injection flow rate, and preform geometry. Finally, the results of the experimental injection of
biphenyl resin through the SAFFIL* preform are discussed and compared with the numerical results. 相似文献
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E. Lacoste M. Aboulfatah M. Danis F. Girot 《Metallurgical and Materials Transactions A》1993,24(1):2667-2678
The numerical simulation of the metal-matrix composites (MMCs) elaboration by an injection process is presented. The equations
governing the heat and mass transfers through a porous medium are applied to the metal injection process. The bidimensional
numerical model is described based on a finite volume formulation. It is shown that two types of metal solidification appear
during the injection: (1) a frontal solidification related to the heat balance between the fibrous preform and the metal and
(2) a lateral solidification related to the heat losses toward the mold walls. Numerical tests validate the numerical model
in the case of theoretical mono-dimensional geometries when analytical solutions exist. The model is then applied to bidimensional
geometries. The preform is progressively closed until the channel is obstructed so that injection is achieved to the “impregnation
depth.” A systematic study determines the influence on the impregnation depth of different parameters, such as thermal properties
of fibers and mold walls, injection flow rate, and preform geometry. Finally, the results of the experimental injection of
biphenyl resin through the SAFFIL* preform are discussed and compared with the numerical results. 相似文献
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ZHU Miaoyong CAI Zhaozhen School of Materials Metallurgy Northeastern University Shenyang China 《Baosteel Technical Research》2010,(Z1):26
Thermal behavior of the solidifying shell in continuous casting mold is very important to final steel products.In the present work,one two-dimension transient thermal-mechanical finite element model was developed to simulate the thermal behavior of peritectic steel solidifying in slab continuous casting mold by using the sequential coupling method.In this model,the steel physical properties at high temperature was gotten from the micro-segregation model withδ/γtransformation in mushy zone,and the heat flux was obtained according to the displacement between the surface of solidifying shell and the hot face of mold as solidification contraction,the liquid-solid structure and distribution of mold flux,and the temperature distribution of slab surface and mold hot face,in addition,the rate-dependent elastic-viscoplastic constitutive equation was applied to account for the evolution of shell stress in the mold.With this model,the variation characteristics of surface temperature,heat flux, and growth of the solidifying shell corner,as well as the thickness distribution of the liquid flux,solidified flux,air gap and the corresponding thermal resistance were described. 相似文献
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以鞍山钢铁集团公司中薄板坯连铸机为研究对象,利用商业软件CFX44对结晶器内钢水流场和传热凝固进行了数值模拟,主要研究了三孔浸入式水口的冶金特征及其对结晶器内钢水流场和温度场的影响。结果表明,采用三孔浸入式水口可以优化结晶器内钢水流场和温度场,稳定坯壳发育和成形,防止拉漏。 相似文献
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The air-gap formation process at the casting-mold interface and the heat transfer mechanism through the gap 总被引:2,自引:0,他引:2
The formation process of the air gap at the casting-mold interface and the heat transfer mechanism through the gap were investigated
by measuring the displacement of, and the temperature in casting and mold for cylindrical and flat castings of aluminum alloys.
The thickness of the air gap was measured as the difference between the location of the casting surface and that of the mold
inner surface. For cylindrical castings, the mold began to move outward immediately after pouring, while the casting stayed
until solidification progressed to a great extent. For flat castings, the mold began to move greatly toward the casting pushing
the casting immediately after pouring and moved reversely after a maximum appeared. It was possible to calculate the displacement
of the mold by thermal expansion. It was found that when the thickness of the air gap was not large, the heat through the
gap was transferred mainly by heat conduction. 相似文献