Monolithic protective coatings for billet continuous casting machine tundishes

Conclusions Magnesia-spinellide refractory coatings for protection of tundish linings of brick refractory parts have been developed.The use of protective coatings makes it possible to increase the lining life by five heats, to decrease the refractory consumption by 1.6 kg per ton of steel, and to increase the productivity of billet continuous casting machines.Translated from Ogneupory, No. 7, pp. 49–52, July, 1984.     

拉坯速度对结晶器内钢液流动和温度分布的影响

针对板坯连铸过程,建立了钢液流动、传热、凝固的三维耦合数值计算程序,计算分析了拉坯速度对结晶器内钢液的流动、凝固特征的影响.计算结果表明,拉坯速度对流动的影响主要表现在宏观速度的大小上,不会影响流动的形态.但对传热和凝固过程有重要影响,直接影响到凝固终点的位置.凝固终点的长度与拉坯速度成正比关系.     

连铸凝固过程热模拟实验方法及应用案例

凝固是制约冶金产品质量的重要环节,但因高温、不透明、大规模和连续化的生产特点,连铸生产条件下的凝固问题研究极为困难。目前的研究方法主要包括数值模拟、物理模拟和热模拟,其中热模拟方法因可以直接获取接近生产条件的实验数据而备受关注。本工作系统介绍了连铸凝固热模拟研究方法,简述了热模拟技术原理,并对结晶器热模拟方法及特征单元热模拟方法的原理和应用进行总结。其中,基于特征单元热相似性提出的连铸坯枝晶生长热模拟及凝固裂纹热模拟等方法成功地将十几吨铸坯的凝固过程“浓缩”到实验室用百克钢研究,不仅可以揭示钢液成分、浇注和冷却条件等因素对凝固过程、组织和元素分布的影响规律,而且还可以获得铸坯固液界面形貌、界面前沿溶质扩散和夹杂物演变、凝固裂纹形成的可能性及条件等其他手段无法得到而冶金界非常关注的问题。要点：(1)概述了连铸凝固过程研究方法。(2)重点介绍了连铸凝固过程热模拟方法的分类、原理和应用。(3)总结展望了连铸热模拟研究方法的研究方向。     

结晶器角部气隙厚度对方坯温度场影响的数值模拟

使用有限单元法对小方坯温度场进行数值模拟，根据温度场计算不同时刻坯壳的收缩量．通过分析铸坯偏角部温度场和收缩的变化规律，确定了不合理的结晶器锥度是产生偏角部缺陷的主要原因，提出了结晶器角部锥度设计的新观点．     

Hydrostatic compaction of refractory articles for continuous billet casting machines

Development of technology and equipment for compaction of refractory articles for a continuous billet casting machine (CBCM) in the Soviet Union and in Russia from the 1960s up to the present day is considered. The main production schemes for compaction and design layouts for compaction equipment (hydrostats) used in the country are given and there is also comparative analysis of compaction processes for refractory components for CBCM used in Russia and abroad. __________ Translated from Novye Ogneupory, No. 11, pp. 31–38, November 2007.     

Service of refractories in continuous casting of stainless steel

Conclusions Work was done on studying the service of refractories in continuous casting of stainless steel.It was established that refractories produced by domestic industry are suitable for this process and make it possible to obtain continuously cast billets in accordance with the requirements of TU 14-105-469-83. Gas protection of the stream of metal causes additional refining of the metal of nonmetallic inclusions and makes it possible to increase the quality of the cast billet.Stream treatment of the metal with inert gas makes it possible to significantly reduce encrustation of the nozzle channel with products of interaction of the molten metal with the refractory material of the ladle nozzle.Translated from Ogneupory, No. 6, pp. 52–55, June, 1985.     

Effect of argon blow through a monoblock stopper in continuous casting of steel on the service of the stopper and nonmetallic inclusions in the cast steel

Kinetic equations of the dependence of the wear of corundum-graphite monoblock stoppers in the slag line and the head on the temperature of the steel in the intermediate ladle in continuous casting are derived as a result of a full-scale experiment. The equations make it possible to calculate the casting time at any possible temperature of casting with the use of corundum-graphite monoblock stoppers of a standard composition (TU 14-8-371-81). In addition to increasing substantially the number of casting cycles in a batch, argon blow through monoblock stoppers with porous inserts improves the quality parameters of cast steel ShKh-15 with respect to segregation bands, globules, central porosity, carbide segregation, content of sulfides and oxides, and subshrinkage segregation.     

Modeling and calculation of the temperature fields in two-layer articles

A mathematical model and algorithm for calculation of the temperature fields for two-layer articles are developed. Using the new algorithm a program is created and numerical calculations of the temperature fields that develop in a two-layer article (nonswirl nozzle) in the course of preparation of the pony ladle of a continuous-casting machine for service and in its operating regime are performed. With the use of the program and computer software (in light of experimental results) it becomes possible to perform calculations and predict the sintering mode of ceramic refractory materials as well as optimize the temperature and time heat-treatment diagrams of one-and two-layer articles.     

下引式连续定向凝固薄壁铜管中具有温度梯度的结晶器对固液界面位置影响的数值模拟与分析

根据凝固原理建立了下引式连续定向凝固薄壁铜管过程中具有温度梯度的结晶器下二维稳态温度场的物理、数学模型,并通过数值计算与绝热结晶器、恒温结晶器下工艺参数对固液界面位置的影响进行对比分析,结果表明在保证熔体温度稳定的条件下,使用具有温度梯度的结晶器能够获得相对较宽的适宜工艺参数范围以及较高的极限拉坯速度.     

Gradient-controlled freeze casting of preceramic polymers

Solidification is the foundation upon which freeze casting is built, and this work seeks to understand the solidification process in freeze casting, especially with respect to the growth of dendrites. To this end, two solidification parameters, freezing front velocity and temperature gradient, were independently controlled using a gradient-controlled freeze casting setup to investigate the effects of each parameter. Changes in dendritic pore size and morphology with solidification parameters were investigated by scanning electron microscopy and mercury intrusion porosimetry. The results agree with dendrite growth theory. The theory of constitutional supercooling is used to describe the morphological changes of dendritic pores to cellular pores by the control of freezing front velocity, temperature gradient, and preceramic polymer concentrations.     

水平轴离心铸造套筒凝固过程温度场数值计算

本文通过分析水平轴离心铸造长／径比小于5的圆筒型铸件的凝固过程，建立了表征铸件凝固过程和二维传热模型．并采用交替陷式差分的方法对离心铸造45#碳钢单材质套筒凝固过程温度场进行了数值计算。结果表明：套筒凝固过程表现为沿径向从靠近模具的铸件外表面层向内表面层、轴向从靠近端盖的铸件层向套筒长度中心部位顺序凝固的特点，模具初温对铸件的凝固速度也有重要的影响。提出减少套筒内表面形成的型腔对外界冷空气的卷吸作用。或在铸件金属浇注完毕后浇注一层低熔点保护渣对保持套筒的这种顺序凝固的特点、以加强最后凝固的内层金属液对外层的补缩作用有一定效果。     

基于FLUENT对水平连铸结晶器凝固过程数值模拟

对圆柱形钢坯的水平连铸问题,采用轴对称二维传热模型,基于FLUENT软件,通过简化边界条件的方法,对初期坯壳生长规律作了计算分析,与射钉结果相比较得到很好验证.通过分析过热度和拉速对出结晶器坯壳厚度,液芯长度的影响,发现40Cr拉速提高0.1 m/min,出结晶器坯壳减薄0.91 mm,过热度每增加10℃,出结晶器坯壳减薄1.4 mm等凝固特点,降低过热度有助于提高拉速.由凝固曲线看出,在刚开始的0～2 m内,曲线斜率大,说明冷却强度大,圆坯在凝固后期有个加速凝固阶段.     

State-of-the-art plants for drying and high-temperature heating of ladles

The Stal’proekt Institute has developed state-of-the-art plants for drying and high-temperature heating of steel-teeming ladles. Two new plants for drying tundish ladle lining have been designed for machine No. 6 for continuous billet casting at the Oskol’skii Electrometallurgical Works. Plants for drying and heating 30-ton teeming ladles to a temperature of 800°C and for high-temperature heating of ladle lining (1200°C) have been designed for a currently constructed metallurgical works. All these plants recover flue gas heat and use it for heating air supplied for combustion, thus decreasing the consumption of fuel. The process of drying and heating of lining is analyzed using a mathematical model developed at the institute. The plants are equipped with automatic control systems controlling the temperature schedule of drying and heating the lining. The specified plants ensure cost-effective operation in an automatic mode __________ Translated from Novye Ogneupory, No. 10, pp. 21–25, October, 2006.     

新型真空关风器的研制

为实现连续真空干燥,开发了一种真空关风器。这种关风器采用弹性密封技术和复合耐磨、自润滑材料来减少关风器的漏气量。漏气率试验证明,该新型真空关风器达到了颗粒物塔式连续真空干燥设备的性能要求。     

喷射成形沉积坯凝固过程和温度场的数值模拟

结合沉积坯的实际沉积过程,利用跟踪计算沉积坯表面轮廓线坐标而建立沉积坯形状的预测模型,模拟结果与实验基本吻合,表明该方法可以获得较合理外形的沉积坯;使用有限元分析方法,对沉积坯动态凝固过程做出了表征,并对其温度场做出数值模拟,结果表明,利用数值模拟方法可以理解喷射沉积动态凝固过程,有效优化沉积工艺,对获得优质沉积材料具有一定指导意义.     

表面改性技术在连铸结晶器上的应用进展

表面处理是提高结晶器耐磨性和高温耐腐蚀性的有效手段,通过对镀层的改进可以达到提高连铸坯质量、延长结晶器寿命、提高铸坯的表面质量和降低生产成本的目的。综述了国内外最新的涂、镀层在结晶器上的应用情况及其特点。主要有热喷涂Ni-Cr镀层、超厚Ni-Fe镀层、Ni-Co合金、Ni-Fe-W-Co镀层、Ni-P复合镀层、陶瓷涂层、Hipercoat和Hiper H3镀层、纳米复合镀层等。同时指出采用稀土和纳米复合镀层等一些新型复合镀层是今后结晶器镀层的发展方向。     

Selection of the structures of tunnel kiln suspended roof thermal insulation

Conclusions A method has been developed for thermal calculation of suspended roofs taking into consideration the three-dimensional geometric configuration of the roof, the temperature relationship of the thermal conductivity of the materials, and the mutual irradiance of the projecting elements of the structure. An engineering program for calculation of suspended, and, as a particular case, of nonsuspended roofs was developed for Fortran IV algorithm language.With use of the program for thermal calculation of the roof at temperatures in the working channel from 1100 to 1900°C variations were developed of structures of the thermal insulation of tunnel kiln suspended roofs making it possible to substantially (up to 30%) reduce heat losses in comparison with those observed in existing kilns.Translated from Ogneupory, No. 6, pp. 40–44, June, 1983.     

板坯连铸凝固过程动态耦合数值模拟

基于实际生产测得的数据,采用连续动态三维耦合模型对板坯连铸凝固过程的流场、温度场和凝固进行模拟. 结果表明,由浸入式水口进入的钢液在结晶器内冲击形成上下两股回流,凝固促进了流动速度的衰减,提高拉速扩大了回流区域;结晶器内铸坯宽面偏角部100~150 mm处存在局部过热,在结晶器出口,拉速由0.02 m/s增加到0.025 m/s,坯壳厚度减小约3 mm.     

The Solidification Process of Melt Casting Explosives in Shell

A solidification process of casting explosives in shell is studied in this paper. Heat enthalpy model and Darcy law are used to simulate the process of phase change and mushy zone. SIMPLER algorithm is used to solve the mass, momentum, and energy equations to obtain the temperature and velocity distribution of the field. Both the conduction and free convection effects on solidification are analyzed. Numerical results show that the solidification time is increased and the temperature distribution is more homogeneous if both the conduction and free convection effects are taken into account during solidification.     

离心渗铸充型过程中伴随有瞬态固化与再熔现象的流场变化规律

针对离心渗铸工艺中熔体浇注温度太高会带来铸件冶金质量下降问题,在充型过程中一般会发生金属熔液的瞬态固化与再熔现象,建立了旋转多孔介质内伴随有瞬态固化与再熔现象的渗流传热理论模型.通过理论分析获得了离心渗铸充型过程中瞬态压力分布计算公式,建立了不同区域界面的移动速率与温度间的耦合关系,分析了流场变化规律.结果表明：渗透前沿界面推移速度主要受离心渗透压力即渗透动力学因素的影响,而再熔界面推移速度主要受热导率和金属相变特性即材料热力学因素的影响,多孔预型体内发生的瞬态固化与再熔是决定充形过程中渗铸复合层能达到的最大厚度的重要因素.