Floating Properties of Agglomerated Inclusion in Liquid Steel

 The fractal properties and floating features of agglomerated inclusions are investigated by the analysis of fractal theory and water simulation experiment. The results show that there is an obvious quantitative relationship between the aggregate floating velocity, the number of tiny inclusion granules and fractal dimension. Namely, for the aggregates which contain the same number of micro granules, the greater the fractal dimension, the larger the floating velocity; for the aggregates which have the same fractal dimension, the more the number of tiny inclusion granules contained by an aggregate, the larger the floating velocity. The mathematical model obtained by regression analysis can better reflect the relationship between the aggregate floating velocity, the number of tiny inclusion granules and fractal dimension. So in order to increase the floating velocity of aggregated inclusion with small fractal dimension, some appropriate measures of making it reconstruct to increase its fractal dimension can be taken.     

基于格子Boltzmann方法的泊肃叶流数值研究

应用格子Boltzmann方法对泊肃叶流进行数值模拟,采用标准的D2Q9模型,边界采用非平衡外推格式和周期性边界条件,使得边界与整体的格子Boltzmann方法的二阶精度保持一致。通过格子Boltzmann方法得出平板间的速度矢量图、速度云图;通过速度矢量图和速度云图可以得出平板间的速度呈现类似抛物线分布。对同一截面分别应用格子Boltzmann方法和解析解,得出曲面上的速度随平板间距的变化曲线,得出格子Boltzmann的数值解与解析解的吻合很好,说明格子Boltzmann方法在处理压力驱动类层流问题的可行性。     

钢液中夹杂物行为数学模型的现状和展望

论述了夹杂物行为数学模型的研究现状,分析了钢中夹杂物的基本数学模型、多模式数学模型和多过程数学模型优点和不足,并提出了未来的发展趋势和需解决的夹杂物研究中的关键问题。     

Numerical Modeling of Inclusion Removal in Electromagnetic Stirred Steel Billets

To investigate the inclusion removal in billets cast under electromagnetic stirring (EMS) influence, a numerical model has been developed to compute the magnetic field, the Lorentz force, the steel flow velocities, and the particle transport within the liquid pool. The electromagnetic field was described by the Maxwell equations and the finite element method was applied using a commercial package. The turbulent fluid flow was described by the Navier‐Stokes equation and by the Reynolds Stress model and the finite volume method was applied using another numerical package. The time average of the Lorentz force was calculated in each element center and this value was applied as a body force in the Navier‐Stokes equation. The magnetic flux density profile was compared with the data obtained in the stirrer of the steel plant. The particle transport model includes the drag force, the buoyancy force and the random walk model, to include the turbulence effects on the particle trajectory. The inclusion removal was calculated and analysed in function of casting speed and stirring current for one size section of mold. The inclusions considered in the calculations have a fixed density and four values of diameter. The numerical results of the electromagnetic model are in agreement with the experimental measurements. A good relationship between the electromagnetic model and the fluid flow model could be shown. An interesting effect is the break of the rotation motion due to the EMS by the jet from the nozzle. The fraction of inclusions removed by the top surface of the mold was improved due to the EMS.     

Numerical Prediction on the Flow Field of Molten Steel and the Trajectory of Inclusion in Continuous Casting Mold Effected by Electromagnetic Field

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Influence of Inclusion on Corrosion Behavior of E36 Grade Low-alloy Steel in Cargo Oil Tank Bottom Plate Environment

Corrosion behavior of low-alloy steel was investigated in simulated cargo oil tank （COT） bottom plate service environment （10% NaCl solution, pH = 0.85）. The corrosion behavior of inclusion was studied by in-situ scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. It was found that pitting corrosion was inclined to occur around the place where inclusions exist. After initial corrosion, an area of 10-20μm in diameter was formed as a cireinate cathode around the edge of inclusion. MnS inclusion dissolved in the simulated COT corrosion solution before low-alloy steel matrix, and pitting was formed at the place where MnS dissolved. TiO2 inclusion dissolved in the simulated COT corrosion solution after low alloy steel matrix, and pitting was formed at the place where steel matrix dissolved. The corrosion tended to occur at the area where the curvature radius of inclusion is smaller. The size of round TiO2 inclusions had little influence on corrosion behavior in this certain environment.     

Simulation of Flow Field of Molten Salt in Neodymium Metal Electrolytic Cell Using Vortex-Flow Function Method

With the applications of Nd-Fe-B material extending in recent years, the materials of neodymium metal and other rare earth metal alloy confront the increased demand and the high quality request at the same time.These factors stimulated greatly to perfect the producing craft of RE metals and improve the equipments.The rare earth electrolysis cell is developing towards large-scale way.Notwithstanding the present electrolysis cell of Nd metal, include 6 kA and 10 kA cell, exists some insurmountable problems during operation and these problems lead to lower electric efficiency and higher operating costs.So it is significant to study the physical fields of rare earth electrolysis cell.In this paper,a numerical flow mode is established using vortex- flowing function method and the fluid flow field of 3000A Nd electrolysis cell is computed using MATLAB.The results of the study will be important reference in theory for improving and enlarging rare earth fluoride system cell.