Development of Single‐Belt Strip Casting Simulator

Near‐net‐shape casting is one of the key technologies to improve process efficiency of steel production. Single‐belt strip casting is recognized as a promising technology for thin strip production because of the advantages like well‐controlled heat transfer rate, flexibility in production rate, compactness of equipment, and so on. In this study a newly designed simulator of the single‐belt strip casting process was developed. The simulator solidifies molten metal on the running solid metal bar with a groove for molten metal deposition pushed by a pneumatic cylinder. Capability of this simulator design was discussed by one‐dimensional numerical heat transfer analysis. It showed that a steel casting bar thicker than 40 mm was capable of casting test of 10 mm thick steel strip even if interfacial thermal resistance existed. Finally, the simulator was applied to the casting test of aluminum strip, and successfully estimated the variation of the interfacial heat flux from the solidifying strip to the casting bar.     

薄带钢直接连铸技术的发展现状和应用前景

薄带钢直接连铸技术较之传统连铸工艺具有投资和生产成本低，占地面积小，节能等优势，是未来10年连铸工艺发展的先进技术。     

钢的薄带铸轧技术的最新进展及产业化方向

对国内外钢的薄带铸轧技术发展情况进行了总结,结合实验室对耐侯钢、铁素体不锈钢和高锰TWIP／TRIP钢薄带铸轧的研究结论,对钢的薄带铸轧过程中的亚快速凝固和近终型成形引起的新的冶金学现象如表面负偏析、全等轴晶铸态组织以及消除带材边裂等进行了阐述,指出薄带铸轧有利于进一步提高材料性能。初步明确了钢的薄带铸轧技术的产业化发展方向。     

唐钢FTSC工艺薄板坯连铸生产实践

唐钢建设的FTSC工艺的薄板坯连铸机与日本三菱提供的热带钢轧机相结合,组成世界最先进的超薄带钢生产线。经过一年多的生产实践,已经基本掌握了薄板坯连铸的技术特点,铸坯产量和质量不断提高。本文简要叙述了唐钢薄板坯连铸机的设备技术和生产工艺的特点,以及人员培训和试生产运行情况。     

双辊薄带铸轧技术的进展及热点问题评述

美国纽柯公司双辊薄带铸轧生产线2002年投产以来,已经累计生产了近50万t薄带,最薄钢带厚度0.7mm,产品可部分替代冷轧钢板.介绍了纽柯公司双辊薄带铸轧生产线的最新进展,并对一些技术特点和热点问题进行了分析和评述.     

Slow Hot Rolling in Direct Linkage with Thin Slab and Strip Continuous Casting: Effect on the Evolution of Austenite Grain

This work was carried out in context with the development of strip casting with the single‐belt process. In this new process the hot rolling is performed in‐line with considerably lower velocity than in conventional hot rolling. It is of interest to study the effect of low rolling speed on the material properties. Based on a finite element model used to predict the thermomechanical behaviour of the strip in tandem mills, the microstructural evolution of austenite was computed. In order to take account of the non‐isothermal conditions in industrial hot rolling, the material equations for recrystallization and grain growth are modified. The parameter studies were carried out over a wide range of volumetric flow rate extending from that in thin slab casting to that in conventional finishing rolling. They demonstrate that the “slow hot rolling” can produce a fine grain of austenite. Austenite grain evolution was computed for conventional rolling with a seven stand mill and for in‐line hot rolling of strip produced by the single‐belt process. It is found that the final grain size of austenite is about the same for the two processes under the condition that strip thickness behind the last stand is the same.     

高锰板带钢及其制造技术

 总结了高锰板带钢的典型成分体系与性能特点,阐述了高锰板带钢在冶炼、铸造、热轧、冷轧等制造流程中存在的关键技术问题与瓶颈、以及国内外钢铁公司在以上领域的新进展,特别分析了薄板坯连铸连轧、薄带连铸连轧技术制造高锰板带钢的发展现状及其关键技术。从成分体系开发、制造技术等角度浅析了国内高锰板带钢的研发方向。     

Development of Continuous Electrical Steel and Casting Technology of New Products

 The development of continuous casting technology of electrical steel was analyzed. The technologies and products characteristics of conventional continuous casting, thin slab continuous casting and rolling, middle thin slab continuous casting and rolling and twin-roll thin strip were compared. Conventional continuous casting technology was widely adopted in producing electrical steel; thin slab continuous casting and rolling and middle thin slab continuous casting and rolling technology industrialized electrical steel; and study of twin-roll thin strip casting technology was focused on fundamental experiments.     

薄带铸轧技术现状与展望

薄带铸轧技术取得了令人瞩目的进展,世界上已有多条薄带铸轧生产线接近工业化水平。重点介绍了美国纽柯Castrip、欧洲Eurostrip、韩国浦项Postrip、日本新日铁Hikari和我国宝钢Baostrip等薄带铸轧试验设备参数、试验钢种、主要技术和产能指标,分析了双辊薄带铸轧技术的工艺特点和存在的问题,展望了薄带铸轧技术的发展前景;比较冷轧、热轧和薄带铸轧工艺生产的薄带成本可知,用薄带铸轧产品替代冷轧产品,每吨钢可降低成本60～70美元。     

机械侧封对双辊薄带钢连铸稳定性及铸带质量的影响

分析了影响双辊薄带连铸稳定性和铸带质量的因素，对机械侧封技术在薄带连铸中的侧封效果进行了分析和研究，在薄带连铸试验中，对侧封的压紧方式，侧封板的材质以及侧封板的预热温度对薄带连铸稳定性和铸带质量的影响进行了试验研究。     

世界薄带连铸技术的最新进展

阐述了钢的薄带连铸技术的发展现状,重点介绍了美国纽柯公司Castrip和宝钢薄带工业试验的最新进展,总结了双辊薄带连铸技术的工艺特点、存在的问题及其关键技术.     

双辊铸轧薄带钢裂纹形成原因分析

裂纹是影响双辊铸轧薄带钢质量的主要因素之一。分析了铸轧薄带钢裂纹的形成机理，并对形成裂纹的主要影响因素作了探讨与归纳。     

薄带连铸生产低碳钢的专利技术分析

介绍了国外几家公司接近产业化的薄带连铸技术的发展概况.根据国内外薄带连铸和薄板坯连铸的专利和生产实践,认为目前适合应用薄带连铸技术生产的碳钢为低碳硅锰镇静钢.也介绍了国外公司生产硅锰镇静钢的成分和性能.通过控制钢中的总氧含量,钢中可形成低熔点的夹杂物,并均匀地分布在铸带的厚度方向,从而有利于快速凝固过程中的高速传热.同时,还应该控制好钢中的碳、氮、氢含量,以获得表面质量良好的产品.     

半连续铸造机采用闭环控制提高铸锭质量

半连续铸造机在铸造过程中,如果铸造速度发生较大波动,会影响铸锭的质量,在轧制过程中可能出现断带、损坏设备并且降低带材的成品率.通过改造电控系统,采用比例阀及脉冲流量计,进行闭环控制来稳定铸造速度,可以提高铸锭的质量.     

薄带连铸侧封板材料及技术的研制现状

侧封技术是薄带连铸工艺中的关键问题，直接影响薄带质量和工序流程。主要介绍薄带连铸的现状，并从固体侧封技术、电磁侧封技术、气体侧封技术3个方面进行阐述，着重介绍交变磁场电磁侧封技术和固体侧封板的材质。结果表明，虽然电磁侧封和气体侧封技术具有明显优势，但是当前技术还不够成熟，存在能耗大、不稳定、设备复杂等缺陷；对固体侧封技术而言，传统耐火材料不能满足薄带连铸工艺的要求，而BN为基的复合陶瓷材料结合气体侧封是当前最适合的侧封技术。     

窄带钢BZ400打包带专用钢开发实践

为满足用户对窄带钢打包带原料需求,在现有方坯连铸和窄带钢轧机装备基础上,采用了LF精炼、钢水深脱氧、Nb微合金化、加大方坯连铸机中间包定径水口尺寸等工艺措施,成功开发了满足用户质量要求的中高强度窄带钢产品.     

Spray casting of steel strip: Process analysis

Near-net shape manufacturing (NNSM) of thin steel sections by spray casting eliminates casting as a separate step with attendant improved microstructures and properties and significant energy savings. The process involves atomization of a stream of liquid metal and deposition of droplets in the generated spray on a moving substrate at mass flow rates of 0.25 to 2.5 kg/s. In this paper, NNSM of steel strip by the Osprey spray casting process is investigated by combining numerical simulation and experiments. Critical input parameters for the computation are quantified utilizing existing state-of-the-art mathematical models and specific experiments. Numerical computation of the consolidation of the spray at the substrate during manufacture of thin sections is conducted using bothcontinuum anddiscrete event (“splat solidification”) approaches to predict: (1) variation of strip thickness in the transverse dimension and (2) isotherms and cooling rates across the strip thickness. Predicted geometries of the strip simulated by the continuum model are in good agreement with measurements. Predicted isotherms in narrow strip by the continuum approach are in reasonable agreement with thermocouple measurements for intermediate thicknesses (2 to 5 mm), and the observed microstructure is consistent with predicted cooling rates. The discrete event model predicts significantly higher cooling rates than the continuum model in the basal portion of the strip. This is consistent with the observed grain size in thin strip (<l-mm thick) and in the basal portion of thick strip. Beyond a threshold thickness, however, the discrete event model confirms the formation and persistence of a partially liquid layer at the growing surface of the deposit with an attendant decrease in the cooling rate. The influence of critical parameters on “splat solidification” is analyzed and assessed. DIRAN APELIAN, formerly Howmet Professor of Materials Engineering at Drexel University     

双辊薄带凝固组织的数值模拟(Ⅰ)--数学模型的建立及验证

以流线为边界划分网格,建立了双辊薄带凝固过程的宏观传热模型、溶质传输模型和凝固组织形成的微观模型,并以固相分数为媒介,采用宏观和微观两个不同的时间步长,实现了宏观模型与微观模型的耦合,模拟结果与实际情况吻合较好。     

Optimization of mold oscillation for high speed casting—new criteria for mold oscillation

Consistent and uniform lubrication in the mold during casting is an issue especially with high speed casting. However, criteria of mold oscillation related to lubrication, has not been clarified for critical conditions such as thin slab casting. This paper discusses the mechanism of powder penetration into the meniscus, in terms of negative strip area ratio and positive strip time, including the case of non-sinusoidal oscillation which is effective for better mold lubrication. In this context, a lubrication index is proposed as a new criteria which can be used to estimate mold powder consumption rate.