浸没在金属熔池中固体颗粒熔化过程的数学模型

建立了金属熔池中固体颗粒熔化过程的数学模型。该模型包括颗粒熔点高于、等于和低于熔池中金属熔点的情况。用冰块在水中及铝颗粒在铝熔池中熔化过程的实验数据检验了模型的可靠性，并分析了颗粒尺寸、熔池温度及颗粒相对金属熔体的滑移速度等因素对熔化过程的影响。     

Redistribution of Extraneous Solid Particles Suspended in Molten Metal during Passage of an Electric Current

Redistribution of nickel-base heat-resistant alloy suspended in molten tin under the action of a direct electric current is studied by experiment and analyzed. It is established that there is an increase in solid particle concentration over the height and in the radial direction under the action of a current passing along the container axis. This is explained by the simultaneous effect of thermal convection and Lorentz contraction electromagnetic forces directed radially.     

Stereological Analysis of Nonspherical Particles in Solid Metal

We review in this article the stereological theory of particles and perform stereological analysis of nonspherical TiB₂ particles dispersed in solid aluminum. The two-dimensional (2D) particle size distribution (PSD) obtained from a projected area (PSDP) of TiB₂ powder and the three-dimensional (3D) PSD based on the volume of particles were independently measured by optical microscopy and the electrical sensing zone method, respectively. The results obtained by the two methods were compared by transforming between them, using a fitted fractal dimension for the particles. The probability mass function of the cross-sectional areas (CSAs) of single nonspherical particles was measured by sectioning 3D reconstructions of particles obtained from a series of X-ray micro-CT images. The transformation from 3D PSD to 2D PSD according to the CSA (PSDC) was performed based on the stereological model. The inverse problem for the transformation from the 2D PSDC to 3D PSD is discussed.     

转炉使用低硫铁水冶炼时熔池硫含量变化规律

分析了某厂300t转炉使用低硫铁水冶炼时熔池硫含量的变化规律及影响因素,结果表明：废钢的熔化是熔池硫含量升高的主要原因,钢渣间的脱硫反应主要发生在吹炼的后期,降低废钢比,保持吹炼后期炉渣较高的碱度及较低的氧化铁量有利于得到较低的熔池终点硫含量。     

Heat Transfer Characteristic of Molten Pool for Twin-Roll Strip Casting

Body-fitted coordinate transformation equation was deduced and used to generate the body-fitted grids of molten pool for twin-roll strip casting. The orthogonality of the grids on the boundary was modified by adjusting source item. The energy equation and the boundary conditions were transformed from physical space to computational space. The velocity field model proposed by Hirohiko Takuda was used to calculate the temperature field of molten steel, and the influence of technical factors was also discussed.     

喷涂粒子在等离子体射流中的加热历程及熔化状态研究

本文通过对水中收集的等离子喷涂熔融粒子进行粒度分析及形貌观察,研究了喷涂粒子在普通大气等离子喷涂(APS)及超音速大气等离子喷涂(SAPS)射流中的加热历程及熔化状态。实验观察到氧化钇部分稳定的纳米颗粒团聚造粒的氧化锆(Y-PSZ)球形粉末颗粒在APS及SAPS射流中传热传质过程中的熔融与"细化"现象有明显不同:在SAPS射流中,尺寸较大(粒径在几十微米)的颗粒大部分形成了十分细小的(小于5μm)颗粒;相对而言,APS中的熔融粒子仍以十几微米以上较大粒径的半熔融粒子为主。进一步研究表明,大尺寸粒子在等离子射流中先从表层熔化,逐渐向颗粒内部扩展,形成柱晶熔区,属典型的梯度熔化模式,最终芯部存留大量细小未熔一次粒子,即所谓半熔融状态;相应的SAPS中大量粒径小于5μm的小颗粒在超音速等离子体射流中整体迅速熔化(即所谓等温熔化模式)。对熔融或半熔融粒子撞击基体后的扁平化过程进行分析表明:在APS射流中扁平粒子的直径一般在100μm以上,且周围飞溅较多,导致典型的层状多孔的粗大组织结构,层间出现较多平行横向裂纹;而SAPS大量细小熔滴撞击基体后,冷却更快,多呈无明显飞溅的直径约10～30μm圆盘状,形成大量细密柱晶交错堆垛而成的、无明显分层的特殊结构。对收集粒子进行X-射线衍射相分析表明,APS及SAPS两种工艺下的熔融粒子均未发生明显相变,相组成主要为室温下非转变四方氧化锆(t’-ZrO2),说明喷涂粒子在高温等离子射流的加热历程中,其晶体结构和化学成分未发生明显变化。     

Performance of Flow and Heat Transfer in a Hot-Dip Round Coreless Galvanizing Bath

Metallurgical and Materials Transactions B - Flow field in a coreless hot-dip galvanizing pot was investigated through a water modeling experiment. The corresponding velocity vector was measured...     

Liquid Metal Heat Transfer in an Inclined Tube Affected by a Longitudinal Magnetic Field

This paper presents results of hydrodynamic and heat transfer investigations in liquid metal flow affected by a longitudinal magnetic field in an inclined tube with respect to tokamak cooling problem.Experimental study has been conducted for the tube with slope 15 to the horizon which corresponds to the conditions oflTER project in case the LM flow faced longitudinal MF.The results obtained in the regimes without the MF,may be interesting for the design of nuclear reactors cooled by LM and metallurgical processes.     

Metastable Phases of Dross Particles Formed in a Molten Zinc Bath and Prediction of Soluble Aluminum During Galvannealing Processes

The morphology, chemistry, and crystallographic characteristics of metastable dross particles were identified. These particles are formed during the initial stage of precipitation. The particles had aluminum concentrations of 15 to 80 mass pct, with values that decreased gradually as particle size increased. These metastable dross particles were a mixture of the crystalline phase of FeZn₁₀, which is called the “delta phase,” and the high-aluminum amorphous phase, which covered the surface of the crystalline phase. The new “meta Q” concept was proposed to predict the amount of soluble aluminum in the zinc bath by considering nucleation kinetics and particle growth. The results calculated using the “meta Q” concept were compared with the values measured by the aluminum sensor, which were taken during the same period at the commercial galvanizing line. The mean of the absolute values of the differences between the calculated and measured values was 9.7 ppm.     

Wetting Transition in a Molten Metal and Solid Substrate System in High Magnetic Fields

Metallurgical and Materials Transactions A - Wetting transitions between molten metals and different solid substrates were investigated using the sessile drop method to evaluate the possibilities...     

铁水熔池中钛和硅的扩散能力

采用毛细管—熔池法测定及分析了铁水中钛、硅的扩散系数和铁水中钒对钛扩散系数的影响。结果表明，钛和硅的扩散活化能为ＥＤＴｉ＝４４２３０４Ｊ／ｍｏｌ，ＥＤＳｉ＝４９７６６Ｊ／ｍｏｌ；扩散系数与温度的关系为ＤＴｉ＝７．７６×１０８ｅｘｐ（－５３２２５．５／Ｔ）ｃｍ２／ｓ，ＤＳｉ＝１．８４×１０－３ｅｘｐ（－５９８８．７／Ｔ）ｃｍ２／ｓ。铁水中的钒会降低钛的扩散能力，这有利于抑制钒钛磁铁矿冶炼时钛的还原     

金属凝固前沿热传递系数变化规律的探讨

分析了金属凝固过程中界面热传递的4个阶段及在各阶段热传递的机理,推导出界面热传递系数在各个阶段的表达式。通过分析文献实验数据,得出了在整个凝固过程中热传递系数与空气隙成反比的半径经验耦合表达式。     

Computational Modelling of Heat/Mass Transfer Near the Liquid-Solid Interface During Rapid Solidification of Binary Metal Alloys Under Laser Treatment

Abstract

This paper presents the results of an investigation into the problem of planar solid-liquid interface stability during rapid solidification of binary metal alloys under laser treatment. A new quantitative model is proposed. This model describes the self-organized development of stable spatially-periodic vortices in the melt near the solid-liquid interface due to concentration- (or thermal) capillary effects) together with effects due to the influence of normal concentration or temperature gradients directed from the interface towards the melt. These vortices give rise to a cellular structure at the solid-liquid interface of rapidly frozen melts.

A computer code was developed to solve the set of second-order linear differential equations which describe heat and mass transfer at the liquid-solid interface. This model allows calculation of the liquid phase velocity field, the second component concentration field in the melt, as well as the temperature field in the liquid and solid phases near the solid-liquid interface at a given solidification rate. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.

Résumé

Ce document presenté les résultats de l'etude du problème de stabilité de l'interface solide-liquide plane lors de la solidification rapide d'alliages metalliques binaires par traitement au laser. On propose un nouveau modèle quantitatif. Ce modele decrit le développement auto-organisé de tourbillons stables,périodiques dans l'espace, dans le bain fondu près de l'interface solide-liquide. Ces tourbillons sont dus aux effets1 capillaires de concentration (ou thermiques) ainsi qu'à l'influence de la concentration normale ou des gradients de températures diriges de l'interface vers le bain fondu. Ces tourbillons donnent naissance à une structure cellulaire a l'interface solide-liquide des bains fondus rapidément solidifiés.

On a développé un code d'ordinateur pour resoudre l'ensemble d'equations differentielles lineaires de second ordre qui decrivent le transfert de chaleur et de masse à l'interface liquide-solide. Ce modèle permet le calcul du champ de vitesse de la phase liquide, du champ de concentration de la seconde composante dans le bain fondu, ainsi que du champ de temperature dans la phase liquide et la phase solide près de l'interface solide-liquide, à un taux donné de solidification. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.     

Agglomeration of Solid Inclusions in Molten Steel

Metallurgical and Materials Transactions B - Agglomeration of alumina inclusions in the molten steel is investigated through the free energy analysis of the cavitation between inclusions. The...     

Scrap Dissolution in Molten Iron Containing Carbon for the Case of Coupled Heat and Mass Transfer Control

The scrap dissolution in an actual process like the BOF is affected both by mass transfer and heat transfer. In this paper, the mass transfer of carbon in liquid melt is considered along with heat transfer. The approaches used in this paper to model the scrap dissolution phenomenon include the application of Green’s function, quasi-static, integral profile, and the finite difference approach for different Biot numbers. Mass transfer coefficients are calculated using the Chilton–Colburn’s analogy for the case of forced convection. Since the quasi-static approach requires the least computational time, it is used for a detailed parametric study, including the effect of other parameters like different scrap ratios and heating rates of liquid melt. The region of control of heat transfer vs mass transfer is also identified. The dissolution of mixed scrap (light and heavy scrap) is investigated for different scrap ratios and the autogenous heating rates of liquid melt, with the help of mathematical models. The heat transfer coefficient is estimated as a function of mixing energy and the mass transfer coefficient by invoking the Chilton–Colburn analogy. The permissible limits of light scrap, which can be charged into the BOF, are also suggested from the results of this model. The Artificial Neural Network (ANN) model is trained on the dataset (patterns) generated by the coupled heat and mass transfer model. The accuracy of the results obtained using different ANN topologies is discussed followed by a recommendation for selecting the best approach.     

六流中间包钢液流动及传热过程的耦合数值模拟

针对某厂六流特殊非对称型中间包温降严重的特点,采用耦合数值求解方法,计算并优化了中间包内的流场与温度场.结果表明:这种特殊中间包在未设控流装置时,入口与近端出口短路流严重,近端出口与远端出口的温差最大为8℃;优化后的中间包结构消除了短路流,均匀了各流钢液温度,最大温差降低到3.3℃,优化后的中间包能更好地满足生产的需求.     

Mathematical and Physical Modelling of Fluid Flow and Heat Transfer in Electric Smelting

Abstract

Heat and momentum transfer in a submerged electric smelting furnace were investigated in a physical model, using oil and an aqueous calcium chloride solution to simulate the slag and matte phases, respectively. Gas evolution at the electrode was simulated by the injection of gas through the electrode in the model. A mathematical model for fluid flow and heat transfer in the model was also developed. The measured temperature distributions near the oil/solution interface could only be reproduced in the mathematical model by the imposition of a no-slip boundary condition at the interface. This condition impedes the transfer of heat and momentum into the lower phase; the implications for smelting are discussed. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.

Résumé

On a étudié avec un modèle physique, le transfert de chaleur et de movement dans un four à fusion électrique submergé, en utilisant de l'huile et une solution aqueuse de chlorure de calcium pour simuler les phases de laitier et de matte, respectivement. Dans le modèle, l'évolution de gaz à l'électrode était simulée par l'injection de gaz à travers l'électrode. On a aussi développe un modèle mathematique de l'écoulement de fluide et de transfert de chaleur dans le modèle (physique). Dans le modele mathématique, on pouvait reproduire les distributions de temperature mesurée pres de l'interface huile/solution seulement si on imposait une condition limite de non-glissant à l'interface. Cette condition empeche le transfert de chaleur et de movement vers la phase inferieure; on discute des implications pour le traitement en fonderie. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.     

顶吹浸没铜熔炼技术述评

通过对顶吹熔池熔炼技术的发展过程和特点加以论述，特别是对顶吹熔炼技术中的澳斯麦特熔炼和艾萨熔炼两种技术加以对比，从而揭示其优缺点。另外本文还对两种技术在国内外的应用情况进行介绍，目的是为中小企业的改造提供一定的根据。该技术在国内的全面推广一定会对我国的炼铜业带来深远影响。