连铸坯质量预测系统及应用

为满足热装热送、薄板坯连铸连轧等紧凑型生产流程技术的需要,中冶连铸技术工程股份有限公司自主研发了连铸坯质量预测系统(QES)。该系统针对容易影响铸坯质量的各个铸机参数进行实时监视,并将监视结果以缺陷发生概率的形式反映到铸流和铸坯上,实现铸流质量的在线预测以及铸坯质量预测。该系统已在山东莱芜银山钢铁厂3#板坯连铸机上成功上线应用,针对Q235B和SPHC钢种建立了判定规则,QES的铸坯判定准确率高达90.6%。     

板坯质量判定与产品质量诊断系统

针对中冶连铸技术工程股份有限公司自主研发的铸坯质量判定与产品质量诊断系统,介绍了该系统的原理、功能和应用情况。系统主要包括4个核心模块：数据采集、质量事件触发、质量跟踪和铸坯质量判定。其主要功能是：铸坯质量参数全线跟踪、在线监视异常信息、判定铸坯质量等级、重放历史浇铸和积淀冶金专家经验等。莱芜钢铁股份有限公司铸机在线应...     

大型铸坯测温及工艺质量分析

铸坯的内部质量主要取决于钢液的纯净度及铸坯的冷却状况和其支撑系统的几何条件。铸坯的表面温度是体现冷却状况的一个重要参数,特别是矫直点的温度控制将直接影响到铸坯质量。本文在科学试验的基础上,报告武钢二炼钢厂1号2号4号铸机的测温结果,结合相应的工艺参数和铸坯质量进行综合分析和讨论,从工艺方面提出提高铸坯质量的措施和建议。     

宝钢1930板坯铸机二冷喷嘴布置方式对铸坯质量的影响

在对宝钢1930铸机铸坯质量缺陷类型和形成位置分析的基础上，通过喷嘴性能测试和数值模拟计算，重点研究了1930铸机六、七冷却区喷嘴布置方式对铸坯的冷却均匀性和铸坯质量的影响，从解决铸坯角部横裂纹和内部三角区裂纹角度出发，提出了宝钢1930铸机二冷系统进一步改造方案。     

浦项公司连铸技术的进步

浦项公司连铸技术的进步主要体现在铸坯质量好、生产效率高。概述了浦项典型连铸机采用的先进技术装备和生产现状。阐述了该公司在铸坯质量控制方面进行的研究:开发的"自适性模糊评价器"、在M-EMS上安装电磁屏蔽罩、凸辊压下技术以及铸坯质量预报系统和铸流自动检测系统,显著改善了铸坯内部质量,且降低了成本,保证了连铸生产过程的稳定运行。     

连铸坯质量分析专家系统的开发

本文用Turbo Prolog语言,研制开发了连铸坯质量分析专家系统(CCES),用于连铸生产中铸坯缺陷的分析、诊断和预测,以便有效地解决连铸生产中出现的问题,提高连铸生产率和铸坯质量。该系统包括一般咨询、缺陷命名、缺陷产生原因分析及改进建议、知识库和开发工具等五个模块。系统具有半自动方式的知识获取,以及知识库查询、修改和维护等功能,并具有良好的解释机制和人机界面,易于学习和使用。     

方圆坯连铸工艺及质量控制技术研究

针对方圆坯连铸钢水可浇性差,圆坯表面纵裂趋向严重以及因压缩比较小、铸坯内部缺陷难以在轧制工序消除等问题,结合攀钢钒公司新建六机六流方圆坯连铸机的装备特点,从改善连铸钢水可浇性、提高铸坯表面质量和内部质量三个方面,系统研究了方圆坯连铸工艺及相关技术,形成了一系列涵盖连铸工艺与设备的提高钢水质量和铸坯质量的综合控制技术.工业生产应用表明,单中包连浇炉数由原来的平均4～5炉提高到8～10炉;方坯和圆坯表面无缺陷率分别达到98.91％和97.81％;方坯、圆坯中心疏松、中心偏析、中心裂纹等内部缺陷均小于1.0级的综合比例分别达到98.9％和98.5％,铸坯碳偏析指数为0.93 ～1.09.研究结果为方圆坯连铸机顺利投产、稳定生产以及提高铸坯质量和扩大连铸品种提供了重要的技术支撑.     

结晶器电磁搅拌对铸坯质量影响的研究

研究了电磁搅拌对中高碳钢铸坯组织和质量的影响,通过对搅拌强度的控制,改善了铸坯的表面质量,得到了良好的铸坯组织,减少了偏析、缩孔,提高了连铸坯质量.     

二次冷却配水模型在石家庄钢厂中的应用

在连铸生产过程中,二次冷却配水的控制对铸坯质量和性能有直接的影响.本文介绍二冷水控制模型在石家庄钢厂大方坯自动化控制系统中的应用,实际生产表明该模型提高了系统的控制精度,进而大大提高了铸坯的表面和内部质量.     

基于“压力反馈”的动态轻压下技术的应用

河北钢铁集团开发的基于“压力反馈”轻压下系统包括:以压力为控制目标的扇形段设备和基于“压力反馈”探测铸坯液芯的控制系统.该系统在邯钢应用后,铸机实现了可视化浇钢操作,铸机生产和铸坯质量的稳定性得到了提高,铸机产量提高了17％,铸坯中心偏析可以100％控制在C类2.0以下,铸机辊耗降低了50％,采用该铸机生产的铸坯轧制中板的分层率由原来的2.92％下降至1.01％.     

超低碳IF钢头坯洁净度的研究

对比分析超低碳IF钢浇次头坯、过渡坯和尾坯的洁净度发现,非稳态头坯洁净度远差于其它铸坯,换钢包交接坯和尾坯洁净度满足质量要求。提出了改善头坯洁净度的措施,即浇铸前中间包吹氩以减少浇铸初期钢水的二次氧化、优化中间包堰坝结构以增加中间包堰坝吸附夹杂物的能力。采取措施后,浇次头坯洁净度得到了提高,钢种夹杂废品率降低。     

Technology innovations on high quality special steel products

Because special steels are the basic materials for industrialization,a national R&D program on special steel technology for high quality products have been granted to promote the special steel production and applications since 2008.Since then,great progresses have been achieved on ferritic stainless steel sheets,heat resistance steel pipes and tubes,microalloyed forging steel bars,and mould steel forgings for hot working. The ratio of ferritic stainless steel sheets produced by TISCO and Baosteel has been promoted through technology innovations and increased 42%and 48 in 2009 respectively.439M steel sheets have been used to exhaust system,and 444 steel sheets have been applied to kitchen and architecture.The production technologies for heat resistance steel pipes and tubes(T/P92,S3043,S31042 steels) have been developed in Baosteel and Pansteel to meet the market requirements.Meanwhile,the round bloom technology has been initiated in Xingcheng Steel.The new technologies for microalloyed forging steels,low cost steel bar,and tailored steel and components,were proposed by CISRI based on the understanding of precise chemical composition and segregation control.And the applications of microalloyed forging steel bars have been promoted remarkably.The researchers have developed high quality mould steel technologies,heavy section forgings of 718 steel,high premium H13 steel blocks and large diameter mandrels used for seamless pipe rolling.The technology innovations of the program could lead to the progress of production technology in special steel sheets,pipes,bars and forgings,and meet the demands from market.For the moment,it is actually believed that there still strong requirements for the technology innovations on special steels.     

超低碳钢中最大夹杂物尺寸预测方法

介绍了超低碳钢连铸坯中最大夹杂物尺寸的预测方法——极值法(SEV),利用该方法预测了不同生产线超低碳钢连铸坯内部最大夹杂物的尺寸,并与生产实际中的铸坯情况进行了对比,结果证明,该方法有效。     

Improving oxide cleanness on basis of MIDAS method

Abstract

The MIDAS method (Mannesmann inclusion detection by analysing surfboards) was established in 1987 and enabled steelmakers to detect less frequent macroscopic inclusion particles in large volumes of steel. The basic idea of MIDAS is the flat cross-rolling of a strand sample perpendicular to the casting direction. Improvements in secondary metallurgy and casting technology have been achieved, since it became possible to define macrocleanness in exact numbers. In this paper, MIDAS results are presented for various strand sections: billets, blooms, jumbo blooms, round strands, conventional slabs and thin slabs. The variation of cleanness during sequence casting, at the front portion and end portion of heats, at ladle change and during steady state casting is investigated. The effect of teeming disturbances and accidental casting events on macrocleanness is studied. Selection of clean material can be optimised by adjusting the cutting length and downgrading critical casting portions. Detected inclusion particles in ultrasonic tested 'surfboard' samples are subsequently identified by metallography and by SEM or EPMA. The exogenous sources of contaminations and the formation mechanisms of inclusion particles are elucidated. Fundamental aspects, such as flotation due to buoyancy forces, coagulation of liquid particles, agglomeration of solid particles due to turbulent fluid flow, and the emulsification of slag droplets from ladle, tundish or mould, are now more deeply understood and enable progressive steps towards clean steel practice. MIDAS results correlate with material behaviour and properties at manufacturing and end-use of long and flat steel products. Future objectives should stress the stabilisation of optimised steady state conditions to realise a higher consistency and reproducibility of properties. Revamping of older continuous casting machines with curved moulds and the introduction of vertical sections are most essential for clean steelmaking. To avoid subsurface inclusions at the midwidth of the strand, submerged entry nozzle design and fluid flow pattern in the mould and liquid pool of continuous cast slabs should be reconsidered.     

The production and practice of cold-rolled steel sheets for automobile

Shougang Group has carried out a strategic structure adjustment in order to realize the promise of Chinese people to the Olympic Games.Automotive sheets are chosen as a type of strategic product and an engine to upgrade enterprise management,technology and operation to reach the top international level during the transition from long products to steel sheets in Shougang Group.Since 2006,Shougang Group has made an elaborate preparation on steel sheet culture,production line construction,technology import,pilot plant and talent reserve.It lays the foundation for the development of automotive sheets.The developing history of cold rolled automotive sheets is reviewed and the research and development of cold rolled automotive sheets, tackling key problem of defect on surface and the latest progress of automotive sheets construction are described in this paper.The main contents were given as follows:①The products of automotive sheets realize zero breakthrough in Shougang Group.Monthly output was 300 ton in January,2009 and it increased to 48 000 ton in June,2010.The ratio of IF steel sheets increases to 70%from 40%.The proportion of outside panel in automotive sheets occupys more than 15%.②A high emulational pilot plant is used as a product developing platform to develop successfully automotive sheets with 1 000 MPa and below.It guarantees that the industrial development of DP and TRIP sheets gets success at a time.It covers continuous annealing sheets with tensile strength≤780 MPa and galvanizing sheets with tensile strength≤590 MPa.③Individual design is used to meet special requirement of customer.Shougang owns 23 inner brands of LCAK and IF steels.It insures that the grades of yield strength cover whole range from 120 to 270 MPa.It keeps the stabilization of steel performance by means of chemical composition control and high accuracy rolling technology.For example,the strength of soft steel fluctuates within±15 MPa.④The steel sheets with surface grade O5 are produced steadily by solving forming striation of IF steel,grain coarse on surface,edge curling skin and mountains - and - waters painting defects.⑤The safeguard mechanism on quality of products is improved steadily and the output of automotive sheets and outside panel increases greatly by building consistency quality management system、information - system and customer service system.     

Friction Forces between Mould and Strand Shell during Billet Casting

During continuous casting processes lubrication between mould and strand shell is very important for reaching and maintaining a good surface quality of both the as‐cast strand and the finished product. The lubrication is influenced by the properties of the mould powder but also by the friction forces caused by the periodic movements of mould and the descending strand shell. In the present research measurements were carried out to investigate the friction forces during 150 mm sq. billet casting of different steel grades using mould powder or granules and submerged entry nozzles. The friction forces reached values up to 6 kN. Since friction forces are depending on upward and downward movements within the mould‐strand‐system, the evaluation of a rheogram shows the typical change of pressure and tension. Maximum friction forces arise during the positive strip time of the rising mould, introducing tensions and cracks in the as‐cast strand. On the other hand lowest frictions forces are generated by the descending mould within the negative strip time leading to the healing of faults in the as‐cast strand. These industrial experiments indicate a correlation between friction forces and surface quality of as‐cast strands.     

特殊钢大方坯连铸中间包各流冶金效果一致性研究

摘要：多流中间包各流钢水流动与温度状态差异是造成高端特殊钢连铸坯质量一致性差的重要原因之一。针对国内某钢厂特殊钢大方坯连铸用4流T型中间包边部流和中部流实测温差较大问题（4~7℃）,基于实际工况特点,进行了中间包冶金行为的热流体动力学数值模拟研究,揭示了原型中间包边流水口响应慢及各流一致性差的原因;提出一种控制钢水流动和流间温差的内腔结构改进措施,可使包内钢液温度均匀性得到明显改善。其中,理论最小流间温差可降低到1℃以内,实测流间温差在0~3℃之间,较原型大大减小。同时指出,基于热流体动力学数值模拟优化中间包结构、提升多流中间包全铸流冶金效果一致性在特殊钢长材生产中具有重要意义。     

连铸多流中间包钢水导分流技术

通过设置湍流控制器、挡渣墙和导分流管,实施导分流技术,使注入流钢水同时到达内、外侧水口,从而解决多年来一直困扰炼钢界的连铸多流中间包由于注入流钢水到达内、外侧水口的时间差过大而引起的诸多生产问题和产品质量问题。此技术在各分流口设置特殊形式的气幕挡墙,使钢水全部经过气洗,中间包的冶金效果更为理想。本文还就连铸多流中间包导分流技术的可行性及发展前景作了进一步阐述。     

Physical modelling investigation of influence of strand blockage on RTD characteristics in a multistrand tundish

Abstract

In the continuous casting process, the tundish acts as a continuous molten steel distribution vessel. The importance of the tundish during the molten steel delivery becomes more significant when it supplies liquid steel to more than one mould. In the present work, a water model of a six strand billet caster tundish has been used to study the effect of strand blockage on the residence time distribution (RTD) characteristics at the strands. All the experiments were performed under steady state conditions. Potassium chloride was used as a tracer for the study. The effects of blockage on the strand dissimilarity among the open strands were also studied. Both single and dual strand blockage experiments were performed. Blockage of strands deteriorated the RTD characteristics at the open strands. The results reveal the most preferred options for strand blockage when the plant operation needs to do so.     

管线钢浇次头坯夹杂物控制

研究了管线钢浇次头坯夹杂物的主要来源及控制措施。采取将浇次头坯轧制成热轧板和在热轧板取样分析的试验方案,得出热轧板和铸坯夹杂物分布。结果表明开浇初期4 m以内的头坯存在2级以上的B类夹杂物和保护渣卷渣。开浇初期钢水注流的二次氧化是导致头坯夹杂物超标的主要因素。提出开浇初期增加吹氩量和适当延长吹氩时间能够较好的排除中包空气,对降低注流二次氧化起到很好作用。