连铸轴承钢的保护浇注

介绍连铸轴承钢降低钢中氧含量采取的一些保护浇注措施。工业试验结果表明,在连铸生产过程中,开浇阶段钢水的二次氧化是钢中氧含量增加的主要原因。采取保护浇注措施可使轴承钢连铸坯的增氧量减少,氧含量可降低到10×10~(-6)以下。     

Simulation of continuous casting of steel by a meshless technique

Abstract

A recently developed local radial basis function collocation method is used for the solution of the transient convective–diffusive heat transport in continuous casting of steel. The solution of the thermal field with moving boundaries due to phase-change and the growing computational domain is based on the mixture continuum formulation. The growth of the domain and the movement of the starting block are described by activation of additional nodes and by the movement of the boundary nodes through the computational domain, respectively. Time-stepping is performed in an explicit way by a simple characteristic procedure. A two-dimensional transient test case solution is shown at different times and its accuracy is verified by comparison with the reference finite volume method results. The method is very attractive in the present context due to its trivial implementation of curved geometry for two and three dimensions, accuracy and stability of the results.     

重轨钢连铸工艺的生产实践

介绍连铸生产重轨钢U71Mn的工艺过程，包括结晶器液面自动控制、伺服液压振动、M—EMS、F—EMS、低过热度恒速保护浇铸、弱的二冷制度、铸坯表面精整等措施，确保铸坯表面和内部质量能满足重轨钢在性能和质量上的要求。     

连铸中间罐内钢水的混合状态

通过连铸过程中钢液过渡状态成分的数学公式,分析了钢液成分变化的规律,同时计算出某台铸机钢液混合参数.分析了连铸中间罐试样的代表性和准确性,提出控制质量稳定性的建议.     

拉速对包晶钢镀锡板连铸坯中夹杂物的影响

为了研究提高拉速对包晶类镀锡板连铸坯中夹杂物的影响,采用自动扫描电镜研究了不同拉速下包晶类镀锡板连铸坯中夹杂物的分布规律。结果表明,将包晶类镀锡板连铸拉速从1.3 m/min依次提高到1.4和1.5 m/min时,结晶器液面波动大于3 mm的比例都小于0.40%。拉速为1.4和1.5 m/min下连铸坯厚度四分之一处大于3μm的夹杂物数密度平均值分别为1.15和1.36个/mm²,面积百分数平均值分别为0.001 9%和0.002 4%,均低于拉速为1.3 m/min时的测量值。将拉速从1.3 m/min提高到1.5 m/min过程中,结晶器液面控制平稳,连铸坯表层大于10μm夹杂物数密度和面积百分数均呈减小趋势,最终实现了包晶类镀锡板高拉速稳定的工业化生产。     

连铸小方坯试制轴承钢工艺研究

重点探讨了连铸小方坯试制轴承钢的冶炼生产关键技术措施及对产品质量的影响,在150一3小方坯连铸机上成功地生产了轴承钢并形成批量.     

淮钢生产20号管坯钢的实践

介绍淮钢生产无缝钢管用的20号管坯钢的冶炼及连铸工艺，对钢水质量、钢水温度、拉坯速度、冷却配水制度等对铸坯质量的影响进行了分析和讨论，提出20号管坯钢的生产技术路线和措施，为下一步生产奠定基础。     

Dissolution behavior of zirconia-refractories during continuous casting of steel

Dissolution behavior of ZrO₂-graphite refractories used in a submerged entry nozzle (SEN) during continuous casting of steel was investigated using the rotating cylinder method. In the present work, the dissolution rate of the zirconia-graphite rod was determined by measuring the corrosion depth of the rod after a given immersion time. It was found that the dissolution rate was slow at the surface where molten flux alone is contacted, but much higher at the region that contacts the interface of the molten flux and liquid metal. The dissolution rate was influenced by the rotation speed of the rod, ZrO₂ content in the refractories, and the presence of Na₂O and fluoride (F⁻) in the mold flux. It is speculated that a cyclic process wherein zirconia dissolves into the molten flux and graphite dissolves into the liquid metal accelerates the dissolution at the flux-metal interface.     

Inverse problem-coupled heat transfer model for steel continuous casting

An integrated approach was proposed for determining the heat transfer coefficient, which combined inverse heat transfer calculation model with temperature measurement and pin-shooting experiment. Based on the roller-layout and spray nozzle distribution, the IHTP (inverse heat transfer problem) model was developed to calculate the secondary cooling heat transfer by means of non-linear estimate method. The method transformed the inverse problem of parameter identification into solution of optimization problem using evolutionary algorithm. With the help of temperature measurement and pin-shooting experiment, the whole procedure of the model solution for identification and application in continuous casting process was given. Simulation and experiment results in plant trial confirmed the efficiency of the method used.     

Microstructure and solidification thermal parameters in thin strip continuous casting of a stainless steel

The present work focuses on the relationships between solidification thermal parameters and the dendritic microstructure of an AISI 304 stainless steel solidified both in a strip casting pilot equipment (twin-roll) and in a directional solidification simulator. Experimental studies were conducted with a stainless steel strip casting obtained in a twin-roll continuous caster pilot equipment and in samples solidified in a directional solidification simulator with two different melt superheats. In both cases, the surface of the substrates was similar, with mean surface roughness of about 0.3 μm. After solidification, the specimens were cut at different positions from the metal/mold interface and etched for metallographic examination. An empirical equation from the literature relating secondary dendrite arm spacing and cooling rates was used to demonstrate the similarity of the cooling efficiency. The results have shown that the simulator can be used in the determination of transient metal/mold interface coefficients (h_i) and in the preprogramming of the strip casting operational conditions as a function of roll materials and surface roughness.     

430铁素体不锈钢连铸板坯振痕

利用光学显微镜对430铁素体不锈钢板坯表面振痕深度和形貌进行观察。结果表明:利用金相法测量振痕深度,测量的结果可以达到很高的精度。430连铸坯表面边部振痕深且紊乱,中部振痕浅、分布比较均匀。上表面边部和中部振痕深度平均值分别为320.847 6μm和247.886μm;下表面边部和中部振痕深度平均值为301.753μm和221.753 6μm。430不锈钢深振痕谷底有微裂纹和偏析带存在。通过优化结晶器的振频、振幅及保护渣黏度等工艺参数可以显著减小430板坯的振痕深度。     

辊式电磁搅拌器在包钢电工钢上的应用

通过辊式电磁搅拌器的实际应用,以及硫印、酸洗等方法研究了辊式电磁搅器对电工钢铸坯质量的影响。通过理论分析和试验结果表明,电工钢施加辊式电磁搅拌器后,铸坯的等轴晶率有明显的提高,可以达50%以上,夹杂物的分布有所改善,电工钢的成品质量得到很大的提高。     

连铸生产过程中钢液的二次氧化

本文通过钢包到中间罐钢液中[N]和[Al]s含量的变化，研究连铸生产过程中钢液的二次氧化。结果表明钢液与空气的二次氧化是一个不容忽视的问题，采用钢包注流保护既可以基本消除二次氧化又可以消除钢包注流冲击造成的卷渣。     

Dissolution behavior of alumina in mold fluxes for steel continuous casting

Dissolution of alumina in various mold fluxes for steel continuous casting has been investigated by employing the rotating cylinder method. The weight loss of the rod, the dipping area and the immersed time were measured to determine dissolution rate of Al₂O₃. The dissolution rate increased with temperature of molten fluxes, the rotating speed of the rod and the addition of MgO, CaF₂ and Na₂O components in the mold flux. When the Na₂O content exceeded 5%mass, the dissolution rate was found to decrease. Intermediate compounds such as CaO·6Al₂O₃, CaO·2Al₂O₃ and 2CaO·Al₂O·SiO₂ formed at the Al₂O₃/flux interface and formation of three compounds was found to play important roles in the dissolution rate. In conclusion, the dissolution of Al₂O₃ was controlled not only by the mass transfer in the molten flux also by the formation of intermediate compounds on the interface.     

关于21世纪发展连续铸钢的若干认识

1 连铸技术—20世纪钢铁工业技术进步的关键 21世纪已经来临,钢铁仍然是重要的基础材料。在不少情况下,特别是发展中国家,钢铁甚至是“必选”材料。然而,钢铁作为材料,钢厂作为产业,都面临着市场竞争力和可持续发展的挑战。回顾20世纪,钢铁工业在技术进步支撑下,得到了巨     

Applying MHD technology to the continuous casting of steel slab

The application of magnetohydrodynamics (MHD) in the continuous casting process started with the electromagnetic stirring of the stand pool with a traveling magnetic field. It has now advanced to the electromagnetic stirring of molten steel in the mold and the control of molten steel flow by an in-mold direct current magnetic field brake. These applied MHD techniques are designed to further improve the continuous casting process capability. They improve the surface quality of cast steel by homogenizing the meniscus temperature, stabilizing initial solidification, and cleaning the surface layer. They also improve the internal quality of cast steel by preventing inclusions from penetrating deep into the pool and promoting the flotation of argon bubbles. Applied MHD technology is still advancing in scope and methods in addition to the improvement of conventional continuously cast slab qualities. The continuous casting of bimetallic slab by suppressing mixing in the pool is one example of this progress.     

承钢连铸物料跟踪系统的应用

连铸物料跟踪系统是连铸工段信息管理系统的重要组成部分,同时也是实现连铸过程控制工艺模型的基础部分。其主要包括生产计划接收、钢种信息管理、炉次跟踪、铸流跟踪和板坯跟踪五部分,它使连铸与其上下工段的物料流程得以无缝对接,保证了整个炼钢环节信息的顺畅运行。     

铁素体不锈钢连铸板坯宽度尺寸的控制

铁素体不锈钢由于高温强度低,直弧型连铸机生产的板坯宽度尺寸难以满足公差要求.本文对铁素体不锈钢板坯宽度不合公差要求的原因进行了分析,并提出相应的工艺措施.     

高碳工具钢板坯连铸生产工艺优化

以某钢厂板坯连铸机生产高碳钢BJS55C为研究对象，结合钢种高温力学实验，优化了高碳钢BJS55C连铸生产工艺。其中对铸机弯曲段二次冷却强度减弱，调整各区冷却水分配，使板坯通过矫直区避开了脆性温度区间，板坯角部裂纹发生率降低41%；优化动态轻压下压下区间，压下量在原有基础上增加15%，板坯低倍指数由2.6改善到2.0；高碳钢保护渣熔点由1 100 ℃降低到980 ℃，保护渣黏度（Pa·s，1 300 ℃）由0.14降低到0.08，保护渣熔化效果与透气性得到明显改善。解决了板坯连铸生产高碳钢的一些关键难题，实现了高碳钢连铸的批量稳定生产。