基于ANSYS的铸嘴熔体耦合场三维有限元仿真分析

本文用大型通用有限元分析软件ANSYS对铸嘴内稳态层流铝熔体进行仿真分析，实现了三维建模，解决了三维热-流耦合场耦合求解的问题，得到铝熔体的速度、压力及温度的分布图，分析了铸嘴出口速度和温度的分布规律及其对连续铸轧的影响。     

铝连续铸轧铸嘴型腔的数值模拟及其结构优化

采用低雷诺数k-ε湍流模型建立了一种铝合金连续铸轧使用的铸嘴型腔三维流动与传热数学模型,并对所建立的数学模型进行了计算机模拟,得出这种铸嘴型腔内铝熔体温度和速度的分布规律。通过现场温度测量实验验证,实测结果与模拟结果基本吻合。根据模拟结果,对原铸嘴边部尺寸进行改进,并对新改进的铸嘴进行模拟,结果显示与改进前相比,铸嘴型腔内部速度分布更加合理,出口处边部与中部的温度差减小了,并在实际生产中得到了验证。     

双辊铸轧铝合金中分流块对温度场影响的数值模拟研究

文章采用有限元方法,在大型通用有限元分析软件ANSYS中建立双辊轧制模拟的三维模型。重点研究铸嘴型腔中不同分流块的数目及分布对温度场、出口温度和出口速度的影响,以及对不同工艺条件下凝固行为的分析。研究结果表明,铝熔体在单个分流块的作用下分布更加均衡,避免了宽度方向上温差过大以及流动过程中出现较大的波动,其中板带表面和心部的出口温度、出口速度均匀性对于提高铸轧铝合金板带的质量有很大影响。实验结果为初步的,为提高铸轧板带质量提供理论和技术支撑。     

宽1500 mm的镁合金双辊连铸铸嘴结构的研究

铸嘴结构是形成镁合金熔体流场的决定因素,其出口处流体速度分布的均匀与否直接影响铸坯质量的优劣。以宽度1500 mm的镁合金水平双辊连铸铸嘴结构为研究对象,对不同型式铸嘴结构内镁合金熔体的流场进行数值模拟计算,分析铸嘴长度、侧壁形状、尾迹区长度对铸嘴出口处流体速度分布均匀性的影响。结果表明：长度越长,铸嘴出口处流体速度分布越均匀;采用渐扩式侧壁的铸嘴结构能获得更均匀的流体速度分布;尾迹区越长,流体速度分布越均匀。     

铝铸轧机常用铸嘴结构和材质应用性研究

铝铸轧机用铸嘴结构的种类较多，但常用铸嘴较为集中地分为两种典型类型，本文剖析了目前国内铸轧机使用厂家在这两种典型铸嘴的结构和与之配套的材质方面存在的差异以及形成各自不同的生产工艺过程和对铝铸轧板内在质量的影响。     

电工铝盘杆连铸连轧的质量控制

国产首台ＬＱＺ１０００－２５６／７Ｙ－９．５型铸轧机用于生产电工铝盘杆，本文分析了铝液成分、精炼净化、铸造温度、铸造速度、冷却强度对坯料的影响及轧制温度、速度、乳化液浓度对铝杆伸长率、抗拉强度和电阻率的影响。     

SS400铝镇静钢连铸板坯角横裂纹成因及对策

针对SS400铝镇静钢连铸板坯的角横裂纹缺陷问题,研究了铸坯的高温力学性能、铸坯在矫直区内的角部温度,同时对铸坯角横裂纹缺陷试样进行了金相分析并对裂纹表面进行了SEM观察.研究分析认为对于SS400铝镇静钢,在800 ℃左右,奥氏体向铁素体转变引起的晶间脆化以及在更高温度开始析出的AlN对晶界的脆化降低了钢的延塑性,使得铸坯在这一温度附近矫直时导致角部出现沿晶开裂.在对连铸机二冷喷嘴水量分布研究的基础上,通过更改二冷喷嘴的位置和排布方式,减弱了对铸坯角部的冷却,从而有效地避免了角横裂纹缺陷的发生.     

基于CFX的双辊铸轧304不锈钢流场和温度场数值模拟

建立了包括铸辊在内的三维整体模型,计算了熔池与铸辊的流场和温度场.流场模拟结果表明熔池内形成了大面积的环形流动区,有利于温度及池内钢液的均化.温度场模拟结果表明熔池内漩涡区由于回流作用温度比周围要低30 ～50℃.经试验验证,模拟结果与实际生产情况相吻合,证明了所建模型的有效性.分析了铸轧速度对熔池内流场和温度场的影响,并根据凝固终点的位置给出较合理的铸轧速度为0.5 m/s左右.     

连续铸挤Al-Mg-Sc合金线材工艺

采用连续铸挤工艺生产Al-Mg-Sc合金线材.对Al-Mg-Sc合金线材质量的影响因素:合金化工艺、铸挤轮转速、浇注温度、冷却水流量等进行了研究.结果表明:采用合理的熔炼工艺,在铸挤轮速度15 r/min,冷却水流量5L/min,熔体浇注温度720～730℃的情况下,线材表面质量好,气孔少.320℃人工时效3h,细小析出相Al3Sc粒子弥散分布在铝基体中.     

双辊铸轧机新型供料嘴的研制及供料嘴对铸轧坯表面质量的分析

双辊铸轧机能经济的生产出宽幅铝板坯,得到国内外加工工厂的重视。然而铸坯表面往往会出现气孔带(热缩孔带)导致产生次品及废品。作者认为,气孔带的形成与供料嘴布液不均有关。文中简要阐述了气孔带产生的原因。本文从水力模拟角度出发,提供了研究供料嘴合理结构的有关资料,供使用厂家和研究单位参考。     

攀钢板坯连铸机的铸坯温度测量与分析

在工业生产条件下测量了攀钢板坯连铸机的铸坯表面温度分布，建立了连铸板凝冷却过程的二维传热数学模型，全面探讨了连铸工艺参数对铸坯热状态的影响，深入分析，讨论了凝固终点的控制及铸坯保温输送的模拟计算效果。     

板坯连铸结晶器冷却铜板的温度场分析及结构优化

采用结构分析有限元软件ABAQUS对具有不同冷却系统的两种结晶器在工作过程中的稳态温度场进行了模拟。在所采用的热材料参数和边界条件尽町能符合实际条件下。证明了采用新的设计可获得较理想的温度场分布。其结果对连铸结晶器的设计及优化、提高结晶器寿命和改善板坯质量具有指导作用。     

Effects of melt temperature and casting speed on the structure and defect formation during direct-chill casting of an Al-Cu alloy

A thorough experimental investigation of the effects of melt temperature and casting speed on the structure and defect formation during the steady and nonsteady stages of direct-chill (DC) casting of an Al-2.8 pct Cu alloy is performed. In addition, the temperature and melt-flow distributions in the sump of billets cast at different melt temperatures are numerically simulated and used in the discussion on the experimental results. Apart from already known phenomena such as the coarsening of the structure, deepening of the sump, and increased probability of bleed-outs during DC casting with increased casting temperature, a few new observations are made. The increased melt temperature is shown to increase the severity of subsurface segregation, whereas the macrosegregation in the rest of the billet remains virtually unaffected. Hot-tearing susceptibility is strongly diminished by an increased melt superheat. The amount and distribution of “floating” grains is demonstrated to depend on both the melt temperature and the casting speed. The porosity was found to only slightly depend on the melt temperature. The amount of nonequilibrium eutectic in the center of the billet increases with increasing melt temperature. The effects of melt temperature on the dimensions of the sump, transition region, and mushy zone and on the melt-flow pattern in the sump are discussed and used in the interpretation of experimentally observed phenomena. An erratum to this article is available at .     

中间包连浇过程非稳态流场与温度场的数值模拟研究

通过计算得出在浇注过程中连铸中间包包壁瞬态热量损失作为边界条件的基础上,建立了连铸中间包内钢液流动与传热耦合数学模型,对连浇过程中中间包内非稳态的温度场和流场进行了数值模拟,考察了中间包连浇5个包次过程中钢液热量损失、温度分布以及流场情况,为现场操作和工艺优化提供依据和指导。     

Alloy shrinkage factors for the investment casting process

This study deals with the experimental measurements and numerical predictions of alloy shrinkage factors (SFs) related to the investment casting process. The dimensions of the A356 aluminum alloy casting were determined from the numerical simulation results of solidification, heat transfer, fluid dynamics, and deformation phenomena. The investment casting process was carried out using wax patterns of unfilled wax and shell molds that were made of fused silica with a zircon prime coat. The dimensions of the die tooling, wax pattern, and casting were measured, in order to determine the actual tooling allowances. Several numerical simulations were carried out, to assess the level of accuracy for the casting shrinkage. The solid fraction threshold, at which the transition from the fluid dynamics to the solid dynamics occurs, was found to be important in predicting shrinkage factors (SFs). It was found that accurate predictions were obtained for all measured dimensions when the shell mold was considered a deformable material.     

不锈钢薄带铸轧过程中的流动特性

采用有限元法模拟了双辊铸轧不锈钢过程的流热耦合问题,分析了铸轧速度对熔池内流场、温度场遥影响以及流场与温度场之间的相互关系,给出了大过程中熔池与铸轧辊之间的热流密度变化趋势及帮轧速度的变化规律,并比较了模拟与试验的结果;给出了薄带表面温度在铸轧过程中的变化及其随铸轧速度变化的趋势。     

基于PIV技术的板坯连铸结晶器内钢水流动行为研究

利用粒子图像测速技术,以200 mm×2040 mm板坯连铸结晶器为原型,建立1∶4水模型进行实验,对结晶器内钢液流动形态、流速及各流态所占比例、液面波动、以水口为中心结晶器两侧对称点速度随时间的变化、水口两侧液面水平流速、水口两侧对称位置液面至结晶器底部垂直方向速度和钢液对两侧窄面的冲击深度进行系统地研究和分析,并对比拉速的影响.研究表明,粒子图像测速技术不仅可以测量结晶器内流场流速,还可以对流场对称性进行全方位、多角度定量分析,为研究连铸参数变化,比如拉速、水口结构和水口浸入深度,对板坯连铸结晶器内钢液流动及对称性的影响提供一种较为精确的方法和思路.通过分析得出,在本实验条件下拉速0.5 m·min-1优于0.6 m·min-1.      

Numerical analysis of fluid flow and heat transfer in pool of twin roll strip caster

Abstract

Twin roll strip casting is regarded as a prospective technology offering many economic benefits. The control of fluid flow in the pool is, however, particularly difficult due to the high casting speed and small pool volume. In the present study, a three-dimensional mathematical model has been developed for the coupled analysis of fluid flow, heat transfer and solidification in the pool using the finite difference method. The characteristics of transport phenomena in the pool of a twin roll strip caster using a wedge type melt delivery system were analysed by numerical simulation. The results show that it is desirable for the wedge melt delivery system to provide the uniformity of flow and temperature in the pool to maintain the casting process and improve the strip quality.     

Numerical Simulation for Effect of Inlet Cooling Rate on Fluid Flow and Temperature Distribution in Tundish

 The fluid flow in tundish is a non-isothermal process and the temperature variation of stream from teeming ladle dominates the fluid flow and thermal distribution in tundish. A numerical model was established to investigate the effect of inlet cooling rate on fluid flow and temperature distribution in tundish based on a FTSC (Flexible Thin Slab Casting) tundish. The inlet cooling rate varies from 0.5 to 0.25 ℃/min. Under the present calculation conditions, the following conclusions were made. When the stream temperature from teeming ladle drops seriously (for inlet cooling rate of 0.5 ℃/min), there is a “backward flow” at the coming end of casting. The horizontal flow along the free surface turns to flow along the bottom of tundish. The bottom flow shortens the fluid flow route in tundish and deteriorates the removal effect of nonmetallic inclusions from molten steel. Nevertheless, when the inlet cooling rate decreases to 0.25 ℃/min, the horizontal flow is sustained during the whole casting period. The present research provides theoretical directions for temperature control in teeming ladle and continuous casting tundish during production of advanced steels.     

Influence of electromagnetic stirring on transport phenomena in round billet continuous casting mould and macrostructure of high carbon steel billet

Abstract

The characteristics of magnetic field, flow field, temperature profile and inclusion trajectories in a round billet continuous casting mould with electromagnetic stirring (M-EMS) were numerically simulated. An industrial plant trial was conducted to verify the magnetic field characteristics and investigate the influence of M-EMS on the solidification macrostructure of high carbon steel. The results indicate that the predicted magnetic field was in good agreement with the measured data, and the velocity patterns, temperature, inclusion trajectory distributions and macrostructure of steel are significantly modified using M-EMS during casting.