共查询到20条相似文献,搜索用时 15 毫秒
1.
S. D. Ridder F. C. Reyes S. Chakravorty R. Mehrabian J. D. Nauman J. H. Chen H. J. Klein 《Metallurgical and Materials Transactions B》1978,9(4):415-425
A combined theoretical and experimental study of steady-state heat flow and segregation in ESR is presented. The segregation
model permits prediction of pressure gradients, hence, interdendritic flow velocities responsible for macrosegregation in
the “mushy≓ zone of axisymmetric ESR ingots. The heat flow model considers the solidus isotherm as a moving boundary. The
relationships between power and slag temperature as well as power and heat transfer coefficient are experimentally measured
and included in the heat balance equation for the slag. Experiments on both a low-temperature simulated ESR apparatus and
on a 200 mm diam ESR ingot mold verify both models.
S. CHAKRAVORTY formerly Research Associate, Department of Metallurgy and Mining Engineering, University of Illinois.
J. D. NAUMAN formerly Engineering Associate, Cabot. Corporation 相似文献
2.
J. Mendrykowski J. J. Poveromo J. Szekely A. Mitchell 《Metallurgical and Materials Transactions B》1972,3(7):1761-1768
On the assumption of one dimensional axial heat flow a mathematical model is developed for describing the temperature profile
in small ESR units. The model considers the regions both above and below the slag level and allowance is made for the development
of a slag crust on the electrode near the top slag level. The governing equations are solved numerically and the computed
results appear to be in agreement with experimental data reported on a laboratory scale ESR unit, employing 1 in. electrodes. 相似文献
3.
In the electroslag remelting (ESR) process, low-frequency power supply can significantly reduce power consumption and achieve three-phase balance of power supply. Therefore, a transient coupling model of fluid flow, heat transfer, and component transport in the ESR process, which is coupled to the electromagnetic field calculated using Maxwell 3D software, is established to study the influence of low-frequency power supply on desulfurization. When a 50 Hz power supply is used, a skin effect is observed in the metal, and the direction of the Lorentz force at the slag/metal interface changes. However, this effect becomes less pronounced with decreasing current frequency. Sulfur is mainly transferred at the electrode tip, and the desulfurization rate is approximately 50%. Electrochemical reactions mainly occur at the electrode tip/slag interface and the metal pool/slag interface. The removal rate of sulfur using direct current (DC) power supply is less than that using an alternating current power supply. The DC reverse polarity power supply leads to higher desulfurization rate than DC straight polarity, which is 74% and 31%, respectively. The sulfur removal rate increases from 81.37% to 84.59% as the frequency decreases from 50 to 2 Hz because of the longer electrochemical reaction time at this lower frequency. 相似文献
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Heat transfer and fluid flow phenomena in electroslag refining 总被引:4,自引:0,他引:4
A mathematical formulation has been developed to represent the electromagnetic force field, fluid flow and heat transfer in
ESR units. In the formulation, allowance has been made for both electromagnetically driven flows and natural convection; furthermore,
in considering heat transfer the effect of the moving droplets has been taken into account. The computed results have shown
that the electromagnetic force field appears to be the more important driving force for fluid motion, although natural convection
does affect the circulation pattern. The movement of the liquid droplets through the slag plays an important role in transporting
thermal energy from the slag to the molten metal pool, although the droplets are unlikely to contribute appreciably to slag-metal
mass transfer The for-formulation presented here enables the prediction of thermal and fluid flow phenomena in ESR units and
may be used to calculate the electrode melting rates from first principles. While a detailed comparison has not yet been made
between the predictions based on the model and actual plant scale measurements, it is thought that the theoretical predictions
are consistent with the plant-scale data that are available. 相似文献
6.
The paper is based on the development and use of a mathematical model that simulates the electroslag remelting (ESR) operation.
The model assumes axisymmetrical geometry and steady state. Maxwell equations are first solved to determine the electromagnetic
forces and Joule heating. Next, coupled fluid flow and heat transfer equations are written for the two liquids (slag and liquid
metal). Thek-ε model is used to represent turbulence. The system of coupled partial differential equations is then solved, using a control
volume method. Using the operating parameters as inputs, the model calculates the current density, velocity, and temperature
throughout the fluids. This paper is concerned with fluid flow and heat transfer in the slag phase. After being validated
by comparing its results with experimental observation, the model is used to evaluate the influence of operating variables,
such as the fill ratio, and the thermophysical properties of the slag. 相似文献
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Baokuan Li Bo Wang Fumitaka Tsukihashi 《Metallurgical and Materials Transactions B》2014,45(3):1122-1132
A three-dimensional finite-element model has been developed to understand the electromagnetic field and liquid metal pool shape in an electroslag remelting (ESR) process with two series-connected electrodes. The magnetic vector potential is introduced into the Maxwell’s equations, and the nodal-based method is used to solve a three-dimensional harmonic electromagnetic field. The heat transfer of the solidifying processes of ingot is modeled by a source-based enthalpy method, and the Joule heating is included in an inner source. The results show the main part of the current flows through the slag cap and a little enters into ingot in a two-series-connected electrode ESR system. As the interaction of self-induced and mutual-induced of two electrodes occurs, the skin effect is significantly suppressed by the neighbor effect. A symmetrical pattern of magnetic flux density in a two-series-connected electrode ESR system is displayed. The magnetic flux density between two electrodes is reinforced and reduced at the outside of two electrodes. The maximum Joule heat power density is located at the interface of slag and electrodes, and it decreases with an increase of the electrode immersion depth. The averaged Joule heat power density increases when slag cap thickness is reduced. With the increase of ingot height, the liquid metal pool shape changes from arc shaped to “V” shaped. When the ingot height is more than the diameter in the ESR processes, the liquid metal pool shape is constant. 相似文献
9.
A mathematical formulation has been developed to represent the electromagnetic force field, fluid flow and heat transfer in
ESR units. In the formulation, allowance has been made for both electromagnetically driven flows and natural convection; furthermore,
in considering heat transfer, the effect of the moving droplets has been taken into account. The computed results have shown
that the electromagnetic force field appears to be the more important driving force for fluid motion, although natural convection
does affect the circulation pattern. The movement of the liquid droplets through the slag plays an import-ant role in transporting
thermal energy from the slag to the molten metal pool, although the droplets are unlikely to contribute appreciably to slag-metal
mass transfer. The for-formulation presented here enables the prediction of thermal and fluid flow phenomena in ESR units
and may be used to calculate the electrode melting rates from first principles. While a detailed comparison has not yet been
made between the predictions based on the model and actual plant scale measurements, it is thought that the theoretical predictions
are consistent with the plant-scale data that are available.
Presently on leave from Institute of Chemical Engineering and Technology, Punjab University, Lahore-1, Pakistan. 相似文献
10.
Electroslag remelting (ESR) furnace with triple-electrode is always used to produce large ingots and the process complexity makes the application not widely spread. Thus, a transient three-dimensional coupled model in industrial scale has been developed to investigate the coupled magneto-hydrodynamics two-phase flow and heat transfer in system. Different from the previous studies with multi-electrode, the current work reveals the triple-electrode ESR with the formation of metal droplets and the solidification of liquid metal. Compared with single-electrode system with the same fill ratio, the heat source in the slag pool with triple-electrode is much more dispersive, and the U-shape metal pool in the ESR furnace with triple-electrode is much shallower and flatter than the V-shaped one in the single-electrode system. A shorter distance from each electrode to the center of system brings a higher heat efficiency, as well as a deeper and narrower metal pool. 相似文献
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A combined theoretical and experimental study of steady-state fluid flow, heat flow and segregation in axi-symmetric ingot
production is presented, with specific applications in continuous casting and ESR. The fluid flow-segregation model involves
the coupling of convective heat and fluid flow in the fully liquid metal pool ahead of the liquidus isotherm to the interdendritic
fluid flow responsible for macrosegregation in the “mushy” zone of ingots solidifying under axi-symmetric conditions. Experiments
on low-temperature Sn-Pb alloys verify the solidification model.
S. D. RIDDER AND MEHRABIAN, formerly Graduate Student and Professor at the University of Illinois at Urbana-Champaign, IL
S. KOU, formerly Research Associate at the University of Illinois in Urbana-Champaign, IL 相似文献
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摘要:旋转电极电渣重熔通过改变结晶器内熔体的流动和传热规律,增强了渣池与电极间的对流换热,在提高电极熔化速率和生产效率方面具有巨大潜力。提出了电渣重熔过程电极熔化速率的求解方法,并考虑了电极旋转时的强制对流,基于多物理场耦合模型预测了电极直径、转速对电极熔化速率的影响规律。结果表明,随着转速提高,金属液滴由从电极中心滴落向电极边缘滴落转变,高温区由渣池外侧向渣池中心移动。当转速从0增大至90r/min,55mm直径电极的熔化速率从7.90g/s增大至9.68g/s,对比固定电极,转速为90r/min时,生产效率最多提高了22.5%;进一步增大转速,电极熔化速率反而减小。存在一个最佳转速可使熔化速率达到最大,且该最佳转速随着电极直径的增大而减小。 相似文献
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模具钢是模具最重要的组成部分,其品种、规格、质量对模具的性能、使用寿命和制造周期起着决定性作用。因为模具钢苛刻的质量要求,对模具钢生产技术及制备过程提出了更高要求。电渣重熔(ESR,electroslag remelting)工艺冶炼出的钢锭具有高均匀度、高洁净度、低偏析度等优势,逐渐成为冶炼优质模具钢的主要技术手段。在电渣重熔生产过程中,电渣渣系起着熔化电极、钢水精炼、凝固结晶等主要作用,是熔炼稳定的基础,因此,选择合适的渣系成分及性能是电渣重熔工艺的关键。结合4Cr5MoSiV1热作模具钢特性,以某钢厂现行5种H13热作模具钢ESR渣系为研究对象,通过渣系物化性能分析和微观结构模拟研究,提出了渣系优化方向,确定了适合电渣重熔H13热作模具钢的渣系。结果表明,L4渣系的熔点、黏度、密度、光学碱度、电导率等物理化学性能较好。该熔渣铝的平均配位数最大,为2.39,且三配位和四配位的铝所占比例较高,网络结构较为复杂;复杂结构单元Q3和Q4含量最多,具有高聚合度的网络结构;Al—O键长较短且存在键长更短的Si—O、Si—F键,电渣重熔过程的稳定性最... 相似文献
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核电站压力容器用特厚钢板的生产技术 总被引:2,自引:0,他引:2
核电站压力容器用特厚钢板,因其使用条件特殊、质量要求高,需要采用特殊的生产技术才能达到要求。综述了核电用特厚钢板生产工艺中的冶炼、锭(坯)制造、轧制和热处理等关键技术,重点介绍和比较了模铸锭、电渣重熔锭和锻造坯三种不同锭(坯)的制造技术及特点。列举了国外先进钢铁企业利用这三种锭(坯)的制造技术生产核电用特厚钢板的实例及其典型产品的实物性能。结果表明,这些钢板具有良好的综合力学性能,尤其是具有高的低温冲击韧性。 相似文献
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电渣重熔(ESR)钢能显著改善冷轧辊质量,提高轧辊使用性能。通过对电渣重熔工艺的系统研究,在国产10t大型电渣重熔炉上开发了以递减功率模型为核心的钢锭结晶质量控制,渣皮厚度控制和防止增氢等先进工艺技术。采用该技术的重熔电耗为1 400(kW·h)/t,所生产的产品质量稳定,各项性能指标达到比国家标准更为严格的企业内控标准,得到用户好评。 相似文献