Numerical Simulation of the Solidification Process Under the Effect of Nature Convection

The process of solidification is numerically simulated with control volume method. The authors study the nature convection in the liquid phase and flow pattern of nature convection during the process of solidification. The result of simulation shows that there are the global flow cells inside the liquid phase, and the local circumfluence exists in the global cells. Especially, the authors analyze transformation of the interface between phases under the effect of free convection on the process of solidification.     

Current Research Status of Micro-Scale Solidification Models of Binary Alloys

According to determine the non-equilibrium solidification path and local liquid solute concentration in the macro transport model during solidification process of binary alloys, the two kinds of micro-scale solidification models are discussed detailedly, viz. solidification kinetics model and miceosegregation model. The current research status of deterministic solidification kinetics model and semi-analytical microsegregation model are reviewed comprehensively, respectively. The main influencing factors of the two models have also been discussed, viz. undercooling and nucleation rate & back-diffusion and coarsening. Further more, the practical value in the coupled numerical simulation of alloy solidification and the future developmental directions of the micro-scale solidification models are elaborated.     

Dealing with Thermal Exchange in Temperature Field Simulation in Low Pressure Die-casting Process

The main effort is to develop numerical simulation software of low pressure die casting on Windows platform in Personal Computer, based on the production of aluminum wheel in Die cast wheel manufacture Co. Ltd.. The heat conduction calculation is the basis of solidification simulation. A 3 dimentional model including the refrigeration medium block is set up based on the study of boundary heat exchange. Various calculation method is analyzed for different types of boundary element. A comprehensive calculation model is set up according to practically manipulable parameters in production.     

Micromodel of Computer Emulational Simulation on Twin-roll Casting Strip Solidification Structure

Based on the research on the solidifiation of twin-roll casting strip,the analytical model and emulational model of nucleation,the growth of dendrity tip and colunar dendrity transformation to equiaxis dendrity (CET)of twin-roll casting strip solidification are established by means of the principle of metal solidification and modern computer emulational technology.The foundation for the emulational simulation of twin-roll casting strip solidification structure is laid.     

Design of Simulation System for Logistics in Steel-making Process

A simulation system for logistics in steel-making process has been developed by analyzing the state of logistics in steel plant, integrating the approach of coloured Petri nets with time and queuing network and using object-oriented methodology. The software functions for building-up simulation model, executing simulation, managing simulations, playing demo, analyzing statistics and online help. The objectives and principles of the simulation software have schematically been introduced. At last, the software is visually validated with measured input data of primary logistics in Vanadium-extracting, Steel-making Plant of Panzhihua Iron and Steel Corporation. A Gantt diagram and statistics of simulation case are included in simulation results and can be used to assist decision-making for scheduling in steel-making process.     

Dynamical Solidification Characteristic of Metal Surface Alloying by Action of Continuous Laser

The solidification microstructures and their nucleation models are discussed,and the effect of the shape effect of moving melton pool on the solidification features is anslyzed on the basis of experiments. The experimental results show that its solidification behavior is complex,because the continuous laser alloying is a dynamical process. The reason for this complexity is that the dynamical solidification characteristic is significantly controlled by the laser alloying parameters and the molten pool shape. On the other hand,the solidification structures of laser alloying have a series of specialities,and their nucleation mechanisms are mainly heteroepitaxial growth and heterogeneous nucleation growth.     

Model Building and Simulation for Subcritical Pressure Boiler

In order to meet the demand of large scale boiler design and operating optimization, this paper establishes the dynamic mathematic model for domestic 600MW subcritical pressure boiler. MMS software is adopted in the whole process from modeling to simulation. This software make process simple and quick. This model is based on modulariza- tion and the comprehensive physical and chemical process in boiler is considered. Simulation result shows that the re- sponses of this model under different disturbance are coincident to mechanics analysis. The simulation result under ste Pdisturbance can be used to analyze unit changes and provide some guide and it also can supply performance reference data to boiler design.     

The Numerical Simulation of Casting Process for Making Metal Matrix Composites

In this paper,a numerical simulation of the casting process for making the MMC.using the PEM, is studied.The convection of liquid metal and the release of latent heat of solidification are taken into account.The algorithm and program for axisymmetric casting model are developed to the problem of coupling between flow and heat transfer,as well as phase change.The variational curves of temperature,the position of flow front and the distrsbutions of volume fraction of solid metal in matrix and their variation with time are obtained.The influences of technological paarmeters to casting are discussed.     

METAL MATRIX PARTICULATE COMPOSITES BY SPRAYING CODEPOSITION

The spraying codeposition process is used to produce metal matrix paniculate composites, whose technical procedure and main processing parameters are analyzed. The microstructure of the composites is examined and the properties are tested. The solidification characteristics in the spraying deposition and solidification process are discussed. The results indicate that several problems involved in conventional methods can be overcome with this technique to preduce metal matrix paniculate composites. The reinforce particles are dispersed in the matrix homogeneously without solidification segregation. Compared with the matrix alloy,the composite proves to be harder and has excellent wear resistance.     

含铈耐热钢凝固过程中的夹杂物行为

建立了稀土耐热钢凝固过程中夹杂物析出与溶质元素微观偏析的耦合热力学模型,并通过工业试验与高温模拟实验验证了模型的准确性。利用该模型,依次考察了铈添加量,初始氧含量,初始硫含量对253MA耐热钢凝固过程中夹杂物析出行为的影响作用规律。在本模型条件下,随着铈添加量的增加,钢中的SiO2与MnS消失,且凝固过程中开始析出CeN;随着初始氧含量的增加,钢中开始析出Ce2O3,SiO2及MnS,其中SiO2与MnS在凝固过程中析出;随着初始硫含量的增加,钢中的Ce2O3消失,钢中开始析出Ce3S4与MnS,在凝固过程中析出的Ce3S4逐渐在液相线温度以上析出。研究工作对于稀土耐热钢连铸水口结瘤问题的解决具有理论指导意义。     

The Numerical Simulation Commercial Software for Secondary Cooling Process in Billet Continuous Casting

A numerical simulation commercial software has been developed by the object-oriented Visual Basic programming language on the basis of the 2D mathematical model of secondary cooling Process in billet continuous casting. Thereby an effective experimenting tool for computer simulation of continuous casting process is gained. By simulation with the software, the caster structures and operating parameters in continuous casting can be designed and optimized. The simulating calculation examples on several casters and its production applications indicate that the commercial software developed has more accuracy, practicability and commonality, as also as simpler operating capability. The simulated results have been successfully applied to the design and production of the high-efficiency modification for several billet casters interiorly.     

Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

The Conversion Calculation and Graph Simulation about Engineering CAD of CNC Pipe Bender

Some conversion calculation formulas from the XYZ axises to PRB axises of CNC Pipe Bender are set up.The calculation model of graph simulation about moving process of Pipe Bender is set up.Finaly a CAD software is programmed.     

Numerical Simulation of Temperature Field during the Dissolution-Diffusion Bonding Process to Mending Iron Casting Defects

The common finite element method microcomputer software for simulation of the temperature field is developed by authors. It is used for calculating the temperature field duringthe mending process of iron casting defects by means of the dissolution-diffusion bonding technology. The correctness has been proved by testing results. This software has been used to analyse thecaused of hardness rising in heat effecting zone,and also find out the approach for solving the problem.     

Torsional Vibration Simulation Analysis of Drilling String and Rock Bit

In this paper,the method of establishing the torsional vibration model of drilling string and rock bit and the process of simulation analysis are introduced.The interaction between bit and rock and elastic deformation of drilling string in the process of petroleum drilling which caused the torsional vibration of the drilling string and rock bit is main considered in establishing the model.The torsional model is solved by difference method.Based on the models,the simulation analysis software of drilling string and rock bit is designed,and simulation calculation and analysis of the tortional vibration of drilling string and rock bit under different conditions are computed,and the dynamic behavior and kinetics regularity of drilling string and rock bit in drilling are obtained.     

The Research about Single-crystal Casts Made by the Technology of Directional Solidification

Single-crystal casts are obtained with the technology of directional solidification, The reasonable technique is discussed and the growing process of single crystal is analyzed.     

Advance in Spray Forming Technology and Its Prospect

Spray Forming technology gets involved with new materials preparation techniques in multiple domains such as powder metallurgy, fluent metal atomization, rapid cooling and non-equilibrium solidification. High performance alloy and metal matrix composite with high density, low oxygen content and microstructure featuring rapid solidification can be fabricated by spray forming. Spray forming, which is of short process flow, low cost, high deposition efficiency, flexible manufacture system, becomes a kind of near shape forming and rapid solidification technology with great prospect. Therefore the developing process history of spray forming technology is introduced and the current research and development status of spray forming technology in the fields of aluminum alloy, steel material, magnesium alloy, copper alloy and high temperature alloy and metal matrix composite is described. Multi-layer spray forming and in-situ reaction atomization spray forming are also discussed. In addition, evaluation and prospect for the technology are presented.     

An optimization method for the nozzle arrangement in secondary cooling zone of continuous casting

Based on the existing research on nozzle arrangement method in secondary cooling zone of continuous casting, the method of superposed water flow density is put forward to optimize the nozzle arrangement at casting direction and transverse section of slab according to the optimization principle. The two-dimension heat transfer model is established. The solidification morphology of cross-section at casting direction is simulated with consideration of the influence of water flow density inhomogeneity on solidification process at transversal section, and the temperature distribution of slab, solidification process, and quality of slab are compared between before and after optimization. The results indicate that the surface temperature of slab is dropped equably after optimization, and the casting blank is cooling uniformly in the water springing zone so as to ensure better quality of the casting blank.     

低温谷物干燥计算机模拟中的可视化

运用计算机图形技术进行了低温谷物干燥计算机模拟可视化研究，从计算机生成图象中可及时，直观地观察了到低温物干燥过程中的有关现象和规律，而无需冗繁的数据处理。     

板坯连铸结晶器内凝固坯壳的三维数值模拟

基于流场和温度场的计算,对断面为1 780 mm×225 mm的板坯结晶器进行数值模拟,考虑3种不同水口条件下,钢液流动对凝固壳的冲刷,计算出凝固壳厚度的三维分布特征,并与二维切片法的计算结果进行了对比。结果表明：有水口时结晶器角部位置凝固壳最大值为约45 mm,宽面和窄面中心凝固厚度壳最大值为24 mm,分别比无水口条件下凝固壳薄1~2 mm;钢液的扩散会使凝固壳在距离结晶器角部300 mm和顶部400 mm的位置形成约深度2.5 mm的凹陷;同时钢液会冲刷整个结晶器窄面的凝固壳,在窄面中心最严重;对比不同的水口,凸底水口冲刷最大,凹底最小。