共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
《钢铁冶炼》2013,40(10):791-800
AbstractElectroslag remelting (ESR) hollow ingot process with T-shape current supplying mould is a new metallurgical technology. A mathematical model was developed to describe the interaction of multiple physical fields of this process for studying the process technology. Maxwell, Navier-Stokes and heat transfer equations have been adopted in the model to analyse the electromagnetic field, magnetic driven fluid flow, buoyancy driven flow and heat transfer using finite element software ANSYS. Moreover, the model has been verified through the metal pool depth measurements, which were obtained during remelting of 10 electrodes into Φ900/500 mm hollow ingots of P91 steel, with a slag composition of 50–60 wt-% CaF2, 10–20 wt-% CaO, 20–30 wt-% Al2O3, ≤8 wt-% SiO2. There was a good agreement between the calculated results and the measured results. The calculated results show that the distribution of current density, magnetic induction intensity, electromagnetic force, Joule heating, fluid flow and temperature are symmetric but not uniform due to the multi-electrode arrangement in two symmetric groups. Simulation of the ESR hollow ingot process will help to understand the new technology process and optimise operating parameters. 相似文献
3.
4.
利用有限元分析软件ANSYS求得稳定电渣重熔过程电极、渣池和钢锭系统电磁场和焦耳热场分布,并通过计算流体力学软件FLUENT模拟分析了耦合电磁场和焦耳热场的三维电渣重熔过程电极填充比0.3~0.7对电渣重熔系统温度场、速度场和电磁场的影响。结果表明,随着电极填充比的增加,速度最大值和湍动能最大值逐渐增加,但变化速率随填充比增加而下降;填充比0.3和0.5之间的最大湍动能差值约为填充比0.5和0.7之间湍动能的2倍;温度最大值随填充比不是单调变化的。 相似文献
5.
6.
The paper is devoted to comparison of electroslag remelting (ESR) with consumable electrode and electroslag refining with liquid metal (ESR LM) processes. The possibility of rearrangement of the heat contributions coming from the consumable electrode and current supplying mould (non-consumable electrode, CSM) makes the core of the ESR process organisation in the CSM. The usage of liquid metal instead of consumable electrodes allows to reduce liquid bath temperature and volume in order to provide low segregation ingot. The formal assessment of physico-chemical conditions and experimental measurements of desulphurisation have shown the same level of refining ability of both processes. Replacing the classic ESR by the ESR LM is a prospective way to produce high-quality ingots from sophisticated and hard-to-deform materials, whereas manufacturing of the consumable electrodes is technically problematic and costly. 相似文献
7.
8.
9.
V. Weber A. Jardy B. Dussoubs D. Ablitzer S. Rybéron V. Schmitt S. Hans H. Poisson 《Metallurgical and Materials Transactions B》2009,40(3):271-280
Electroslag remelting (ESR) is widely used for the production of high-value-added alloys such as special steels or nickel-based
superalloys. Because of high trial costs and the complexity of the mechanisms involved, trial-and-error-based approaches are
not well suited for fundamental studies or for optimization of the process. Consequently, a transient-state numerical model
has been developed that accounts for electromagnetic phenomena and coupled heat and momentum transfers in an axisymmetrical
geometry. The model simulates the continuous growth of the electroslag-remelted ingot through a mesh-splitting method. In
addition, solidification of the metal is modeled by an enthalpy-based technique. A turbulence model is implemented to compute
the motion of liquid phases (slag and metal), while the mushy zone is described as a porous medium the permeability of which
varies with the liquid fraction, thus enabling accurate calculation of solid/liquid interaction. The coupled partial differential
equations (PDEs) are solved using a finite-volume technique. The computed results are compared to the experimental observation
of an industrial remelted ingot; the melt pool depth and shape, in particular, are investigated, in order to validate the
model. These results provide valuable information about the process performance and the influence of the operating parameters.
In this way, we present an example of a model used as a support in analyzing the influence of the electrode fill ratio.
This article is based on a presentation given at the International Symposium on Liquid Metal Processing and Casting (LMPC
2007), which occurred in September 2007 in Nancy, France. 相似文献
10.
D. C. Prasso J. W. Evans I. J. Wilson 《Metallurgical and Materials Transactions B》1995,26(1):1281-1288
In this second article of a two-part series, a mathematical model for heat transport and solidification of aluminum in electromagnetic
casting is developed. The model is a three-dimensional one but involves a simplified treatment of convective heat transport
in the liquid metal pool. Heat conduction in the solid was thought to play a dominant role in heat transport, and the thermal
properties of the two alloys used in measurements reported in Part I (AA 5182 and 3104) were measured independently for input
to the model. Heat transfer into the water sprays impacting the sides of the ingot was approximated using a heat-transfer
coefficient from direct chill casting; because this heat-transfer step appears not to be rate determining for solidification
and cooling of most of the ingot, there is little inaccuracy involved in this approximation. Joule heating was incorporated
into some of the computations, which were carried out using the finite element software FIDAP. There was good agreement between
the computed results and extensive thermocouple measurements (reported in Part I) made on a pilot-scale caster at Reynolds
Metals Company (Richmond, VA). 相似文献
11.
Currently, the market demands for large-scale and high-quality slab ingots are increasing significantly.A novel electroslag remelting withdrawal (ESRW) process with two series-connected electrodes and a T-shaped mould was developed to produce large-scale and high-quality slab ingots.It is very difficult to ob-tain large slab ingots with good surface quality and high width-to-thickness ratio.And it is not efficient for improving the quality of slab ingots by using trial-and-error-based approaches because the ESRW mecha-nisms are very complex.Thus, a three-dimensional mathematical model was developed to determine the relationship between process parameters and physical phenomena during the ESRW process.The relation-ship between the temperature field of the ESRW process and the surface quality of slab ingots was estab-lished.A good agreement between the simulated and measured temperature fields of slab ingots was ob-tained.The results indicate that the maximum values of current density, electromagnetic force and Joule heat all occur at the electrode-slag interface between the two electrodes.It can be found that the flow is turbulent and the temperature distribution is uniform in the slag pool with the influences of buoyancy and electromagnetic force.The wrinkles in the narrow faces of slab ingots are caused by the relatively lower in-put power.Increasing the electrode width and reducing the curvature can significantly improve the surface quality of slab ingots. 相似文献
12.
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
13.
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
14.
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
15.
16.
《钢铁冶炼》2013,40(8):611-617
AbstractSteel solidification process control, especially in the solidification process of high alloy steel, and improvement of the solidification structure have been increasingly gaining interest among metallurgists, particularly the electroslag workers. To further develop the electroslag remelting (ESR) process and to improve the advantage of the ingot solidification structure, the effects of relative motion between the consumable electrodes and the mould (namely, mould rotation) on chemical element distribution were observed in this study, as well as the compact density changes in electroslag ingots. Experiment results show that applying relative motion between the mould and the consumable electrodes in ESR results in a more uniform chemical element distribution in the electroslag ingots. Compared with the electroslag ingot of conventional ESR, maximum segregation of carbon could decrease from 3·19 to 1·146, and statistical segregation decreased from 0·2636 to 0·0608. Maximum segregation of chromium could decrease from 1·316 to 1·253, and statistical segregation decreased from 0·2753 to 0·1201. The compact density for the stationary mould increased from 0·7693 to a compact density of 0·9501 for the rotating mould. The improvement in the solidification structure of the electroslag ingot can be attributed to mould motion, which led to the generation of a shallow pool and the improvement of the solidification structure. But the excessive rotation rate is harmful to solidification structure instead due to the molten metal pool motion caused by violent slag pool motion. 相似文献
17.
18.
Yehia Mohamed Shash Tarek El Gammal Mohamed Ahmed El Salamoni Friedrich Alexander Denkhaus 《国际钢铁研究》1988,59(6):269-274
Most of the metallurgical effects resulting from electroslag remelting of metal may be divided into two groups, namely, the effects due to the slag/metal reactions taking place and the effects due to the special solidification conditions characteristic of this process. Solidification of ESR ingots takes place progressively as heat is removed from the liquid metal pool via the mold walls. By careful matching of the melting rate with the freezing rate, the desired shallow metal pool is attained, leading to the well known directional solidification pattern with consequent improvement in properties of the steel. The choice of power parameters is limited by a compromise between the need for a high melting rate for economic reasons (costs) which may tend to give a rather deep metal pool and the need for a shallow metal pool to obtain optimum metallurgical properties. In this process only a relatively small amount of the total energy input is actually utilized to melt down the metal. The major part of the energy is lost from the slag and metal pool to the water cooled mold. In this paper the results of numerical and experimental investigations are presented, setting out a simple method of saving energy and controlling the solidification pattern of the ingot. This method involves the addition of solid particles to the melt to utilize the surplus energy evolved in the central area of the slag bath. 相似文献
19.
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
20.
为了改善M2高速钢中的碳化物分布,通过数值模拟详细分析了结晶器旋转对M2高速钢电渣重熔过程温度场、金属熔池形状的影响,并进一步通过实验室双极串联结晶器旋转电渣炉研究了旋转速率对M2高速钢电渣重熔过程的影响。采用扫描电镜观察并分析了结晶器旋转对电渣锭中碳化物形貌、分布的影响;采用小样电解萃取实验,分析了结晶器旋转速率对碳化物组成的影响。结果发现,随着结晶器旋转速率的增加,渣池的高温区从芯部向边部迁移,温度分布更加均匀;金属熔池的深度变浅,两相区的宽度收窄,从而导致局部凝固时间降低、二次枝晶间距减小。与此相对应,随着结晶器旋转速率的增加,M2电渣锭的渣皮更薄、更加均匀,结晶器对电渣锭的冷却强度更大,碳化物网格开始破碎、变薄,碳化物由片状改变为细小的棒状。X射线衍射分析表明,不论结晶器是否旋转,碳化物的类型始终不变,由M2C、MC和M6C组成,但是随旋转速率增加M2C含量增加,MC和M6C含量降低。碳化物组织得以改善的主要原因在于,结晶器旋转导致金属熔池深度降低、两相区宽度收窄,改善了凝固条件,减轻了元素偏析。 相似文献