薄板坯连铸工艺

1　薄板坯连铸工艺的特点八十年代以来 ,炉外精炼和保护浇注技术的开发 ,促进了薄板坯连铸技术的迅速发展 ,其铸机类型之多 ,发展速度之快 ,都达到前所未有的地步。目前应用于工业生产的薄板坯连铸尚属于固定式结晶器连铸法 ,作为近终形浇注 ,它与传统板坯连铸相比 ,具有下述特点 :1 )板坯厚度小　薄板坯坯厚一般小于或等于 2 0～ 80 mm,典型薄板坯厚度为 50 mm,而厚板坯厚为 2 50 mm;2 )拉坯速度大　目前几种典型薄板坯连铸设计拉速均在5m/ min左右 ,高于传统板坯连铸速度 ;3)凝固速度快　对于 50 mm厚的薄板坯 ,全凝固时间为 0 .9min,而 2…     

国外连铸—直轧技术的新进展和我国应采取的对策

本文介绍了国外薄板坯连铸——直轧、薄带浇铸和常规连铸——直轧技术的发展情况;比较了薄板坯连铸——直轧工艺和常规连铸——直轧工艺的特点;对我国发展薄板坯连铸——直轧技术提出了建议。     

关于薄板坯连铸工艺选型的几点看法

根据铸坯厚度将现有的连铸工艺分为三个大的类型，即：薄板坯，中板坯和厚板坯，并讨论了各类工艺的技术特点和适应的市场范围，以期对投资者作出正确选择有所帮助。     

薄板坯连铸新工艺

现有普通板坯连铸机都是浇铸厚板坯。浇铸薄板坯有许多优点,如减少加工道次、节约能耗、节省投资等。因此研究薄板坯连铸是连铸工艺发展的主要方向。日本住友金属工业公司鹿岛厂氧气转炉车间建成一台生产薄板坯的工业性试验连铸机。这台连铸机为带式,浇铸时温度和化学成分符合要求的钢水从30t盛钢桶经过大、小两个中间罐进入连铸机。大中间罐的容量为10t,用于控制钢水使用量;小中间罐为2t,带流钢槽,用于将钢水送入连铸机的两根带间隙内。铸流     

SM41A连铸板坯的解剖与轧制

本文通过对250mm厚连铸板坯SM41A的解剖,剖析了铸坯的冶金质量,在板坯厚度中心出现偏析峰值,且以S、P为最;轧板试验表明,用250mm厚连铸板坯可以生产出质量良好的60mm厚板。     

不锈钢薄板坯连铸

目前，高合金不锈钢宽薄板坯连铸已得以充分确认。通过改进技术，板坯表面质量得到了改善。相当于或好于常规厚板坯的表面质量，同时也改善了板坯内在质量，尤其是对超级奥氏体钢质量的改善更为明显。     

薄板坯连铸连轧及薄带钢连铸冷轧技术现状

介绍了世界各国薄板坯连铸轧技术的发展情况，并以美国纽柯公司的“ＣＳＰ”工艺和意大利阿尔维迪公司的“ＩＳＰ”工艺为例，介绍了薄板坯连铸轧生产线的设备组成，工艺布置及该生产线的优点，带钢直接浇铸技术，目前尚处于试验阶段，文中介绍了世界各国的试验研究现状及各国大多采用的双式薄；连铸机的技术特点，最后简述了我国的现状。     

鞍钢大板坯连铸的钢材质量

鞍钢第三炼钢厂大板坯连铸热试车以来,对百万余吨铸坯生产和对几百罐钢水浇铸板坯进行质量,性能的调查研究,结果表明,连铸坯产品质量优良,性能稳定,板坯质量合格率达到了99.5%以上。     

对薄板坯连铸连轧技术的分析

与传统连铸相比,薄板坯连铸在铸坯厚度、浇铸速度、铸态组织、在线连轧等方面都发生了很大变化,既具有冷却强度大、生产线短、能耗低等优点,也具有表面质量不高、产品适应范围较小等缺点.近年来我国薄板坯连铸连轧技术发展较快,已建成十几条生产线,但对其生产情况褒贬不一.通过对薄板坯连铸产品组织、化合物析出、产品的适应性等方面的优缺点进行分析比较,客观地评价了薄板坯连铸连轧生产技术.     

薄板坯连铸连轧新技术

介绍了意大利达涅利公司最新推出的薄板坯连铸轧新技术，其中重点介绍薄板坯连铸的主要技术特点和连轧的几项主要技术特点。     

DANIELI concepts and experiences in thin slab casting and rolling technology for HRC production—the evolution of a winning process route to face increasing market requirements

The direct rolling process for hot strip production,where the thin slab caster is connected directly to the mill,has gained market share rapidly because of its remarkable advantages in terms of energy savings and investment cost over the conventional hot strip mills. However,the unquestionable advantages of the first-generation applications of this plant concept also entail significant limitations both in productivity and steel grades that can be produced. Since his first pioneering applications,Danieli considered strategic the development of new technical solutions specifically conceived to overcome these limitations with the goal of increasing plant production volumes and enlarging steel grade product mix,in order to cover the gap between "Conventional mill" and "Thin slab casting and rolling" process routes. In order to reach this goal,Danieli has developed a complete portfolio of plant lay outs adopting Thin Slab Casting and Rolling technologies,each of them conceived to guarantee the optimal CAPEX and OPEX parameters in fitting with market requirements our Customer intend to target.in terms of productivity,steel grades and coil dimension product mix. Danieli TSR(Thin Slab Rolling) fTSR(flexible Thins Slab Rolling) QSP(Quality Strip Production) and ETR(Extra Thin Rolling) plant configurations are analyzed in this paper. With this diversified approach,Danieli solutions are most appropriate answers to thin slab casting and rolling to produce hot rolled coils with superior quality and an extremely diversified range of steel grades. Already,this approach has allowed Danieli plants to:①exceed the threshold production of 3.0 Mt/a with 2 casting strands in operation as done in Tangshan Iron and Steel plant in P.R.China since 2005;②expand the product mix to include virtually all the steel grades used for flat product applications,including the most demanding ones,such as peritectic(in Essar Algoma Canada and Benxi Iron and Steel,China),micro-alloyed,and silicon steels,for the most sophisticated applications,such as automotive and pipe manufacturing,including Arctic applications,(as done in OMK plant in Russia);③extend the range of final strip thicknesses to include ultra thin gauges,down to 0.8 mm(as in Ezz Flat Steel,in Egypt).     

采用薄板坯连铸生产高表面质量冷轧钢板的可行性分析

薄板坯连铸由于拉速高,结晶器容量小,结晶器钢水液面波动高度和表面流速显著高于传统连铸,因此容易造成保护渣卷渣,这是薄板坯连铸生产高表面质量冷轧钢板钢种的主要困难所在。NUCOR、蒂森一克鲁伯等企业采用薄板坯连铸连轧工艺生产冷轧钢板的实践也表明,在表面质量方面与传统工艺产品尚有较大的差距。采用薄板坯连铸工艺生产优质冷轧钢种,应适当增加铸坯厚度,以降低拉速和增加结晶器对钢水流的缓冲作用,可采用120mm厚铸坯(结晶器出口),3m／min左右拉速。为了减少结晶器保护渣卷渣,应对中等厚度薄板坯连铸结晶器内钢水流动控制(SEN结构参数、SEN浸入深度、拉速等)、电磁制动、保护渣等开展深入的试验研究。     

高品质冷轧薄板钢中非金属夹杂物控制技术

 能够造成冷轧薄板表面缺陷的钢中夹杂物主要是簇群状Al2O3、“Ar气泡+Al2O3”和结晶器保护渣卷入形成的大型夹杂物。在正常稳定连铸条件下,目前已能够做到对结晶器保护渣卷渣形成夹杂物加以有效控制。在各类非稳浇铸铸坯中,浇次开浇头坯的品质降低最严重,浇次尾坯中保护渣卷渣形成的夹杂物数量明显多于正常坯,炉-炉间交接坯和快换浸入式水口期间浇铸铸坯中,来源于保护渣卷入形成的夹杂物数量也多于正常坯试样。首钢京唐公司生产冷轧薄板钢类,在1.0～2.0m/min拉速范围,大型夹杂物随拉速增加呈减少趋势,对此应加以关注。研究发现,尺寸100μm以上的有害夹杂物主要存在于铸坯2mm表层内,生产“无表面缺陷”要求的汽车外板,应该采用铸坯表面清理。     

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。     

Theoretical modelling of an isokinetical steel feeding system for near-net-shape strip casting

During near-net-shape casting as considered here, liquid steel in thicknesses between 5 and 15 mm has to be put onto a cooled belt recirculating with speeds of 30 to 60 m/min. On the belt the liquid steel solidifies, before it can be subjected to one or two in-line hot deformation steps. The requirement that the surface and the shape of the strips should already have the best possible structure upon being cast means that high demands are placed above all on the liquid steel feeding system. Especially the liquid metal should ideally be cast with the lowest possible turbulence and at a casting speed which is equal to the speed of the conveyor belt or cooled conveyor belt. In other words, the relative speed between the cast liquid and the cooled conveyor should become “zero” in order that the cast liquid can be more or less “laid” onto the cooled conveyor (known as isokinetic feeding). Different kinds of feeding liquid metals onto a circulating belt are reported with main emphasis on the theoretical modelling of the so-called underpressure feeding systems. It is shown that, on the one hand, the casting speed can be regulated independently of the input mass flow rate into the tundish and, on the other hand, the liquid can be accumulated in the tundish or discharged from it at constant casting speed.     

板坯中间裂纹产生原因及防止措施

针对天铁热轧1#板坯连铸机生产的板坯中间裂纹严重的问题,通过低倍检验分析形成板坯中间裂纹的影响因素。结果表明:拉坯速度、Mn/S比、设备辊缝精度与铸坯中间裂纹密切相关,其中设备精度是影响铸坯中间裂纹的主要因素;将拉速控制在0.85m/min,可以防止Q235B钢铸坯中间裂纹产生;当钢中Mn/S>90,普碳钢铸坯无中间裂纹产生;将辊缝偏差调整至0.3mm以下,可有效防止铸坯中间裂纹的产生。     

Flow Control in the Thin Slab Mould at the Corus Direct Sheet Plant

Thin slab casting forms the most important development in continuous casting of the past two decades. Within a short period of time the technology developed into a serious alternative for conventional slab casting, both with respect to productivity and product quality. Corus implemented the technology in its Direct Sheet Plant (DSP) enabling the production of thin‐gauged coils. The development of thin slab casting technology has not come to an end yet. Further increase in productivity can be expected still respecting high quality standards. The control of the mould fluid flow is one of the key technologies for thin slab casting. Here not only the (complex) design of the submerged entry nozzle is important. A strong interaction exists with the shaping of the funnel mould and the layout of the electromagnetic brake (EMBR). Modern physical and numerical modelling techniques enable a detailed design study of all aspects of the process. This resulted in a new design of the EMBR for the DSP thin slab caster, based on a multi‐pole approach. One pole is controlling the symmetry of the flow, where another two poles control the speed of the liquid steel in the meniscus area. By using this technology the operational window can be enlarged significantly without deterioration of the situation in the mould.     

Modeling of steel grade transition in continuous slab casting processes

Mathematical models have been developed and applied to investigate the composition distributions that arise during steel grade changes in the continuous slab casting processes. Three-dimensional (3-D) turbulent flow and transient mixing phenomena in the mold and the strand were calculated under conditions corresponding to a sudden change in grade. The composition distribution in the final slab was then predicted. Reasonable agreement was obtained between predicted and experimental concentration profiles in the slab centerlines. Intermixing in the center extends many meters below the transition point, while intermixing at the surface extends above. Higher casting speed increases the extent of intermixing. Mold width, ramping of casting speed, and nozzle design have only small effects. Slab thickness, however, significantly influences the intermixing length of the slab. The axial transport of solute due to turbulent eddy motion was found to be many orders of magnitude greater than molecular diffusion and thus dominates the resulting composition distribution. Different elements, therefore, exhibited the same mixing behavior under the same casting conditions, despite having different molecular properties. Numerical diffusion caused by the finite difference schemes was investigated and confirmed to be much less important than turbulent diffusion. In the lower portion of the strand (lower than 3 m below the meniscus), the convection and diffusion can be reasonably approximated as one-dimensional (1-D) axial flow.     

薄板铸机开浇冷齿形成的分析与解决

本钢炼钢厂薄板坯连铸机在开浇初期,特别是在低碳钢的生产时,结晶器内几乎每个浇次开浇时都会产生冷齿,由于薄板坯铸机拉速高,冷齿现象极易产生漏钢的事故,并产生7m左右的废坯,增加了生产成本。因此主要对能够引起冷齿的生产和设备各种相关的因素进行分析,并通过生产实践的方法找出最佳的解决办法。     

IF钢连铸开浇工艺对头坯洁净度影响的研究

IF钢连铸开浇过程头坯洁净度水平较低,目前各企业一般将开浇坯作判废或降级处理,这导致了产品质量不稳定,成材率低等问题.为研究IF钢非稳态开浇阶段连铸坯的洁净度水平及优化措施,采用现场取样、检测分析及数值模拟计算相结合的方法,分析了IF钢开浇阶段不同拉速变化曲线条件下连铸坯沿拉坯方向的洁净度变化规律.通过实验检测发现沿拉坯方向头坯T[O]、[N]及显微夹杂物含量呈现明显下降趋势,距离头坯头部6 m处T[O]含量为13×10^-6,接近正常坯水平,距离头坯头部7 m处[N]含量约为19×10^-6,接近正常坯水平,开浇工艺对于连铸坯T[O]、[N]及显微夹杂物含量影响不大.匀速、前快后慢和前慢后快三种拉速工艺条件下,大型夹杂物在距离头坯头部2 m处的质量分数约为0.2 mg·kg^-1,但之后均存在不同程度的大型夹杂物数量波动现象,而前快后慢工艺影响范围最小,在5.5 m后均达到正常水平.通过数值计算同样发现,前快后慢的提拉速工艺条件下产生的头坯洁净度更快地接近正常坯洁净度水平(约开浇430 s后,对应拉坯5 m).基于本文研究,...