冷轧无取向电工钢连铸生产实践

通过对连铸过程生产实践的总结以及现场数据分析,研究了太钢在生产冷轧无取向电工钢时连铸过程中间包钢水增碳、二次氧化、钢水吸氮以及在冷轧过程中钢板表面重皮、夹杂缺陷等的原因以及解决措施。结果表明,通过采用专用冷轧无取向电工钢中间包覆盖剂和结晶器保护渣、加强钢水从大包至中间包保护浇注、稳定连铸过程拉速和液面自动检测控制等措施解决上述存在的问题。     

CAS OB精炼和连铸过程钢中夹杂物来源示踪研究

通过添加示踪剂研究CAS OB的精炼过程和连铸过程以及板坯钢样夹杂物来源。结果表明,精炼过程和钙处理后的钢中显微夹杂物均含有钢包渣示踪元素镧;中间包钢样中的显微夹杂物同时含有镧和中间包示踪元素铈;板坯中的显微夹杂物含有镧、铈、钾、钠中的几种,说明钢液脱氧产物与钢包渣、中间包覆盖剂、结晶器保护渣均产生了反应。板坯中大型夹杂物主要源于结晶器保护渣,其次源于钢包渣,少部分源于中间包覆盖剂;大型夹杂物同时含有钾、钠、镧、铈中的几种元素,说明大型夹杂物是脱氧产物与卷入钢液中的钢包渣、中间包覆盖剂、保护渣或中间包内衬蚀损产物相互反应的复杂夹杂物。     

CAS OB精炼和连铸过程钢中夹杂物来源示踪研究

通过添加示踪剂研究CAS OB的精炼过程和连铸过程以及板坯钢样夹杂物来源。结果表明,精炼过程和钙处理后的钢中显微夹杂物均含有钢包渣示踪元素镧;中间包钢样中的显微夹杂物同时含有镧和中间包示踪元素铈;板坯中的显微夹杂物含有镧、铈、钾、钠中的几种,说明钢液脱氧产物与钢包渣、中间包覆盖剂、结晶器保护渣均产生了反应。板坯中大型夹杂物主要源于结晶器保护渣,其次源于钢包渣,少部分源于中间包覆盖剂;大型夹杂物同时含有钾、钠、镧、铈中的几种元素,说明大型夹杂物是脱氧产物与卷入钢液中的钢包渣、中间包覆盖剂、保护渣或中间包内衬蚀损产物相互反应的复杂夹杂物。     

圆坯连铸机浇铸20钢铸坯的生产实践

通过对20钢的冶炼、浇铸工艺的改进优化,解决了圆坯连铸机浇铸20钢铸坯时出现内裂纹、中包水口蓄流和粘结漏钢等问题,成功生产出了质量较高的圆坯.     

湘钢提高连铸方坯质量的措施

湘钢二炼钢厂应用了钢包和中间包称量系统、中间包连续测温装置、结晶器电磁搅拌技术和钢水液面自动控制系统、红外线自动定尺切割装置以及大方坯连铸机高效化技术,减少了连铸方坯内部和表面质量缺陷,提高了产品质量.     

Liquid steel flow in continuous casting machine: modelling and measurement

Abstract

Single phase (liquid steel) and two-phase (liquid steel and argon bubbles) three-dimensional computational fluid dynamic and heat transfer models were developed for the continuous casting machines of ArcelorMittal. The computational domains include tundishes, slide gates, submerged entry nozzles and moulds. The effects of buoyancy, tundish design, tundish practices, nozzle design and caster practices on flow structure were investigated. Mathematical modelling is discussed in detail. In addition, submeniscus velocity measurements in the slab caster mould are performed with the method of torque measurement. A consumable probe is inserted into the liquid steel meniscus from the top of the mould through mould powder and slag layer. The liquid steel flow applies a drag force to the probe, which then generates a torque. This torque value is measured and then converted back to velocity. The concept and challenges of the technique are discussed, and the effects of casting parameters on mould flow structure are investigated. Product quality in relation to real time meniscus velocity measurements is also discussed.     

薄板坯连铸中间包浸入式水口安装工艺攻关

文章分析了薄板坯连铸中间包浸入式水口原安装方法存在的问题,通过进和安装工艺的攻关,在水口处加装了碳质水口护圈,并且在工作层上增加了一定厚度的涂层,解决了塞棒波动和结晶器小动导致的系统自动停浇和漏钢问题.     

减少小方坯连铸漏钢的实践

针对抚顺新钢铁有限责任公司炼钢厂小方坯连铸漏钢事故频发的情况,从钢水浇铸条件、工艺操作和环境因素等方面,分析了造成钢水溢漏率高的原因,通过完善结晶器水冷制度,降低中间包钢水过热度,严格规范保护渣操作,进行射钉试验测定坯壳厚度等,使方坯溢漏率明显下降,平均溢漏率降至0.03%。     

水平连铸过程热平衡实测与分析

本文通过水平连铸全过程钢水和铸坯温度变化及相关参数的实测，研究了水平连铸过程中钢的热平衡规律，并建立了铸坯凝固传热，中间包钢水温度，钢包钢水温度，包衬温度与吸热等数学模型。实测和分析表明，在该铸机上，钢水在钢包和中间包中分别损失了其热量的７％和１．２％，在结晶器和空冷段所传出的热量分别占１８％和２０％，切割时仍有５４％的热量保留在铸坯中。     

不同喂入位置条件下稀土在连铸板坯中分布及其对性能影响

通过化学分析、金相观察及冲击试验,分析了结晶器喂稀土及中间包喂稀土的连铸坯中夹杂物形态、分布,并测试了横断面上的冲击韧性.研究表明与结晶器喂稀土相比,中间包喂稀土的连铸坯中,稀土及夹杂物分布更均匀,夹杂物球化效果更好、尺寸更小、总数更少;冲击韧性明显高于未喂稀土,尤其是克服了连铸坯内弧侧四分之一范围冲击韧性的大幅降低的缺陷.因此,中间包喂稀土比结晶器喂稀土具有更大的优越性.     

转炉-精炼-连铸过程钢中氧的控制

结合近年来的文献和笔者的研究工作,概要论述了转炉—精炼—连铸过程中钢洁净度(以总氧含量T[O]表示)的控制及夹杂物对产品质量的影响。提高钢的洁净度应从产生夹杂物的源头抓起,尽可能降低转炉终点氧含量。根据生产统计数据,建立了转炉终点氧预报模型。介绍了硅镇静钢、硅铝镇静钢、铝镇静钢三种脱氧模式及脱氧产物的控制方法。采用钢包精炼方法把夹杂物消灭在钢水进入结晶器之前是获得“干净”钢水的关键。介绍了RH、LF、中间包钢水总氧预报模型。介绍了在连铸过程中防止钢水再污染和进一步去除夹杂物的措施。     

连铸矩形坯漏钢原因及其对策

连铸矩形坯漏钢的原因是设备管理不到位,结晶器冷却水和二冷水控制不当、钢水过热度高、操作不当等。通过采取加强设备管理、严格操作规程、改进一冷和二冷系统、加强结晶器管理、实行低过热度浇注等措施后,漏钢事故大幅度减少,铸坯合格率达到99．9％,铸机生产率提高,单包连拉炉数达130炉。     

连铸铝镇静钢时中间包钢水氧含量预测模型

针对国内某厂６０ｔ中间包浇注低碳铝镇静钢的多次试验数据，从理论上建立了浇注过程中中间包钢水氧含量的预测模型，模型中综合考虑了钢包渣中ＦｅＯ及ＭｎＯ含量，耐火材料ＳｉＯ２含量，钢包到中间包钢水吸氮量，浇注时间，拉速，铸坯断面积等因素的影响，并对改进中间包操作进行了讨论。     

衡管水平连铸中间包流场分析

根据衡阳钢管水平连铸中间包的实际情况,采用1：1．5的相似比例建立水模拟系统,对水平连铸中间包内钢液流场进行研究．得出水平连铸中间包内钢水流场与弧形连铸中间包内钢水流场的主要区别,提出了优化水平连铸中间包钢水流动的方向。     

中间包钢水温度控制研究及优化

为了提高中间包温度合格率,减少连铸机拉速波动,根据首秦现有工装设备条件,分析了中间包温度合格率较低的原因,研究了精炼周期、浇铸断面、工艺路线以及钢包状况对钢水温降的影响,同时总结出连铸中间包烘烤、开浇钢水温度变化以及浇钢过程钢水温度变化规律。通过提高优质钢包的周转数量、规范操作并精确控制精炼吊包温度、保持连铸中间包钢水温降稳定,使钢水中间包温度合格率达到92%以上,铸坯内部质量也得到一定改善。     

Simulation of coagulation of non-metallic inclusions in tundish and their trapping into solidified shell in continuous casting mould

Abstract

A mathematical model simulating the coagulation and flotation of non-metallic inclusions in the tundish and continuous casting mould was developed based on turbulence coagulation and Stokes coagulation. From the simulation in the tundish, it was found that Stokes coagulation is dominant in the tundish. In the mould, the simulation result was that argon bubbles become the desirable sites where alumina inclusions are gathered and form large alumina clusters. The influence of the liquid steel flow in the mould applied by an in-mould electromagnetic stirring technique on the trapping rate of non-metallic inclusions into the solidified shell was examined. The horizontal flow in front of the shell was found to be effective for disturbing the trapping and decreasing the population of large non-metallic inclusions in the shallow surface layer of cast slabs. This effect was interpreted by the lift force applied to non-metallic inclusions in the velocity boundary layer formulated.     

降低超低碳钢结晶器液位波动及降级坯实践

针对鞍钢股份有限公司鲅鱼圈钢铁分公司生产超低碳钢时出现的结晶器液位波动和铸坯降级原因进行了分析,通过采取钢水顶渣改质、拉速调整、优化保护浇铸氩气流量、合理选择更换浸入式水口的时机及增加中间包钢水装入量等措施后,结晶器液位波动由14.38%降低到了7.44%,O5板比例由45.68%提高到58.23%。     

提高中间包钢水温度合格率的措施

针对韶钢第三炼钢厂钢水中间包温度波动大、中间包温度合格率偏低等的情况,在钢包精炼、连铸、生产组织等影响温度的各个控制环节进行了优化,钢水中间包温度控制合格率由80%左右提高到95%以上.     

Inclusion behaviour in aluminium-killed steel during continuous casting

The inclusion behaviour during continuous casting were investigated in ultra low carbon (ULC) and high strength low alloy (HSLA) steels. From tundish to cast slabs, the total oxygen (T.O) content decreased from 19 to 12?ppm, 12 to 11?ppm in ULC steel and HSLA steel, respectively. The number density of inclusions in ULC decreased by about 40%, while it kept almost constant in HSLA steel during casting. A simple calculation on the T.O removal agreed well with the measured value, which showed that T.O removal was much larger through mould flux absorption than nozzle attachment. The T.O removal in ULC steel is substantially higher than that of HSLA steel due to the fact that alumina particles in ULC steel tend to agglomerate easier than calcium aluminates in HSLA steel, which facilitates inclusion removal to the mould powder.     

Evolution or revolution?—a new era in billet casting

The billet industry was born in the mid-1960s as a series of scrap recycling plants, at a time when environmental awareness was not even in vogue. Out of the determination and vision of the individuals who forged this industry, a new philosophy of steelmaking emerged. A philosophy based on low man-hours per tonne, and profit sharing gave birth to the highly profitable minimill concept that has now gripped steel production in the flat-rolled area. The billet industry has evolved from being primary suppliers of reinforcing bar to being competitive in high quality products while retaining the original production philosophy. A quiet revolution is now underway in this industry with casting speeds approaching those of thin slab continuous casting. Mould powder lubrication and other practices common to slab casting, such as controlled feeding of liquid steel from tundish to mould in place of metering nozzles are becoming common place. This paper delineates some of the challenges facing the industry which is in the throes of a revolution. Professor Alexander McLean’s early work on the importance of controlling fluid flow in the tundish and its impact on turbulence in the mould is emerging as being critical to the challenge of producing high quality billets at high casting speeds.