气体增氮法冶炼钒氮微合金钢

从理论上分析了钢液增氮的热力学、动力学影响因素,进行了BOF＋RH双联吹氮冶炼钒氮钢试验。结果表明,转炉底吹、RH喷吹均能有效增加钢液氮含量。RH真空度两段式控制既能满足控氢要求又能实现钢液搬出时较高的氮含量。BOF＋RH双联吹氮气工艺可以不加含氮合金冶炼钒氮微合金钢。     

八钢70t电弧炉冶炼弹簧钢钢液中氮含量的控制

针对EAF-LF-CCM（电炉一精炼炉一连铸）冶炼弹簧钢过程中钢液氮的控制进行了工业试验.试验表明：电炉冶炼过程中主要是电弧区增氮及出钢过程的增氮,精炼炉及连铸过程增氮主要是钢液与大气接触,通过试验对电炉短流程生产优钢过程中的氮含量的控制起到指导作用.     

氧气瓶钢冶炼过程氮含量控制

针对气瓶钢氮含量偏高,波动大,控制困难的问题,对炼钢工序全流程钢水中氮含量展开了调查.调查结果表明,转炉终点钢液氮含量偏高,增氮主要环节为转炉出钢过程和RH精炼结束到中包开浇.针对调查结果,提出了转炉低氮钢冶炼技术、出钢过程脱氧工艺优化及连铸保护浇注等技术措施,有效的降低了转炉终点氮含量,出钢增氮和浇注过程增氮也得到了有效的控制,使成品钢水中氮含量稳定控制在50×10-6以内,减小了氮对成品钢材性能的影响.     

炼钢生产过程中增氮分析与控制

控制钢种氮含量,对提高铸坯质量很关键。中厚板卷厂炼钢过程各环节钢水氮含量检测统计显示,连铸机浇注过程是钢水增氮的主要环节,而且氮含量高的炉次铸坯的横裂纹、碎裂纹检出率较高。通过分析钢液中氮的行为,加强连铸保护浇铸的控制手段,将终点氮含量控制在50 ppm以内。     

70t UHP DC EAF-LF-CC工艺生产ER50-6焊丝钢的实践

通过合理配加热装铁水及DRI,使得冶炼的ER 50-6焊丝钢残余Cu控制在0.10%以下,通过采取严格控制电炉、LF精炼和连铸控氮措施后,显著降低了ER 50-6焊丝钢中的氮含量,使得成品的氮达到70×10-6以下。改善了钢种的拉拔性能,基本满足了用户使用该钢种不经热处理直接拉拔成0.8~1.2mm的细焊丝的要求。     

LF/VD过程钢液氮含量控制试验研究

结合现场试验分析了LF/VD过程影响钢液氮含量的因素。结果表明:低氧、低硫钢液,在LF精炼钢液容易吸氮,而在VD有利于脱氮;LF过程喂线可使钢液增氮;真空度小于53.3Pa,保持时间大于10min,可生产出w(N)低于40×10~(-6)的钢液。     

铁路轮轴钢生产过程控氮工艺与实践

分析了太钢生产铁路轮轴钢炼钢过程影响氮含量控制的因素,基于炼钢过程脱氮的热力学和动力学理论,制定相应生产工序的控制措施。对实施控氮措施后各工序钢水氮含量的跟踪调查,实现产品控制要求。     

钢液中氮含量控制的工艺研究

从炼钢、精炼和连铸工艺方面入手,对影响钢液中氮含量的各个工序进行工艺研究,结果表明：随着出钢口次数的增加,氮含量增加量降低;弱吹氩时,对于降低氮含量的作用并不明显,控制不当时还会增加氮含量,且从大部分炉次来看,用钢包炉精炼时钢中的氮含量增加;生产过程中最终钢液的氮由其各工序的增（脱）氮量来决定。     

LF-VD钢包精炼炉脱氮工艺

氮对于大多数钢种来讲,是一种有害元素,它会使钢锭的宏观组织变坏,降低钢材的韧性和塑性。鉴于对钢质量的日益重视,钢中氮含量的控制已成为冶金工作者关注的重点之一。如在生产高强度ＰＣ钢和帘线钢中,为了使其产品获得良好的拉拔性能,常要求氮含量低于50×10-6。因此,深入研究冶炼过程中钢中氮含量的变化情况,探讨其规律性,以求获得控制钢水氮含量较为理想的方法。马钢ＳＫＦ(ＬＦＶＤ)钢包精炼炉脱氮工艺试验,是从工艺角度对其脱氮过程进行了理论分析和讨论,提出了ＬＦＶＤ钢包精炼炉脱氮的具体措施。1　试验条件及其工艺方案1.1　试验条…     

梅钢连铸生产中的增氮控制

氮在钢中通常是一种有害元素,钢中氮含量高会严重影响钢的高温强度和高温塑性,降低钢的深冲性能。在连铸环节,保护浇铸不当会导致钢水增氮。基于连铸生产的实绩,介绍了梅钢连铸生产中对钢水增氮的控制,通过分析钢水连铸过程中的增氮机理,调查梅钢连铸当前的增氮现状,查找出了连铸增氮的主要影响因素,并对连铸工序的生产工艺、设备、耐材等方面实施了改进,有效减少了连铸的增氮保留,减少了改钢损失,为高质量要求钢种的生产创造了条件。     

Influence of bottom-blowing gas species on the nitrogen content in molten steel during the EAF steelmaking process

In modern EAF steelmaking process, control of the nitrogen content of molten steel has become more and more important and bottom-blowing technique has been widely applied to promote the molten bath fluid flow, accelerate the metallurgical reaction and improve the quality of molten steel. In this study, the influence of bottom-blowing gas species on the nitrogen content in molten steel during EAF steelmaking was systematically investigated and analysed. Combining the induction furnace experiments and theoretical analysis, the kinetic models of nitrogen change in molten steel with bottom blowing N₂, Ar and CO₂ were established theoretically and validated experimentally. Meanwhile, the thermodynamic laws and agitation capacity of different bottom-blowing gases were also clarified. Then, based on the industrial application research, the metallurgical effects, especially nitrogen removal, with different bottom-blowing gases were also studied and finally, a new concept was proposed for cyclic utilisation of CO₂ in the EAF steelmaking process.     

Low-Cost and Large-Scale Clean Steel Production Technology

As the market demand for clean steel increased,a number of new technologies for clean steel production have been developed in some domestic and foreign steelmaking plants.Based on the existing equipments and technical conditions in the No.1 steelmaking plant of Ansteel,a series of clean steel technologies have been integrated including single bay duplex-dephosphorization in steelmaking control technology,high efficiency desulfurization technology,the control technology for nitrogen content during the whole process,the control technology for hydrogen content in VD,and the systematic control technology for oxygen content.A series of process for all kinds of ultra-low phosphorus,ultra-low sulfur and relative low level of inclusions have been designed in clean steel production.This process include hot metal desulfurization and slag-off,single bay duplex-dephosphorization in BOF,molten steel slag-off,LF processing,VD processing,and continuous casting with protection,then a stable,low-cost and large-scale production process has been formed.Applying this integrative technology,the sum of 5 major elements including phosphorus,sulfur,oxygen,nitrogen,hydrogen is less than 80×10-6 in high alloy steel scale production,and the industrial applications for clean steel technology have been achieved.     

A Kinetic Study on the Control of Nitrogen in Molten Slag and Metal

Nitrogen can easily contaminate molten steel during the steelmaking process and due to the low nitrogen capacity in slag, it is difficult to remove entrapped nitrogen from liquid steel. Degassing is often done to the steel at secondary steelmaking to lower the nitrogen content, but the control can often be kinetically limited by the steel grade and also the slag composition. Thus, a fundamental understanding of nitrogen dissolution into molten slag and metal including the rate of nitrogen dissolution can help in controlling nitrogen content in the final product.The kinetics of nitrogen dissolution in the molten calcium aluminate based slags and in molten steel with various element additions was investigated by measuring the 14N-15N isotope exchange reaction using a mass spectrometer at 1873 K.Results show that effect of elements on the rate constant of nitrogen dissolution such as Ni in Fe is relatively minimal similar to molybdenum. The surface rate constant of nitrogen dissolution in liquid Fe-10%Ni alloy was found to be 3.77×10-5 (mol/cm2·s·atm).The rate constant of nitrogen dissolution in the CaO-Al2O3-CaF2 slag was found to be wedge shaped, which decreased with increasing CaF2 to about 20 mol% followed by an increase through the rest of the CaF2 composition range. This was related to the effect of CaF2 on the structure of Al-O bonds for this slag.     

铝镇静钢氮含量控制分析

在炼钢过程中,将成品氮质量分数稳定控制在0.003%以下存在一定难度。对铝镇静钢而言,常规生产流程为BOF-RH-CC,增氮和脱氮在每个工艺环节都可能会发生。本研究进行了9炉工业试验以研究冶炼全过程中氮含量的变化。结果表明,转炉冶炼终点钢中氮含量随碳氧积的增加而增加,而碳氧积反映了转炉底吹搅拌效果。出钢过程发生了增氮现象,合金化时间越长,转炉终点碳含量越低,出钢口的使用炉数越多,增氮量越大。对于RH过程中脱氮行为,RH浸渍管越新,脱氮越多。根据所得结论,提出了控制钢中氮含量的可行措施。     

钢水过程增氮分析与控制

济钢炼钢过程各环节钢水氮含量检测统计结果显示,连铸机浇注过程是钢水增氮的主要环节,而且氮含量高的炉次,铸坯的横裂纹检出率较高。对大包保护浇注装置进行优化改造,在引进大包免烘烤套管的同时,改造大包水口与套管结构,采用台式双密封、环形槽式吹氩,增强了密封效果。改进后,浇注过程增氮由20.0×10-6降为6.1×10-6,横裂纹检出率由3.61%降为1.08%。     

超低温LNG储罐用钢的炼钢生产实践

介绍了超低温LNG储罐用钢的炼钢生产实践。采用转炉双渣、双联低温冶炼脱磷技术实现了转炉终点磷含量≤0.002 0%;钢水扒渣与LF脱硫实现了硫含量≤0.001 0%;RH真空度≤200 Pa,循环时间30 min,使钢中氮、氢含量分别控制在0.003 0%和0.000 1%以下;采用连铸全程保护浇铸工艺、铸坯高温矫直工艺以及铸坯缓冷工艺,抑制了铸坯表面和皮下裂纹的产生。     

260t转炉高磷铁水冶炼低磷钢生产实践

针对鞍钢铁水中ω([P])≥0.085%的高磷铁水冶炼低磷钢的难题,鞍钢炼钢总厂四工区通过调整铁水硅含量、优化供氧制度及温度控制度,采用高碱度单渣法、双渣法、复吹、出钢后炉外脱磷等冶炼工艺进行了低磷钢生产,实践结果表明,不同冶炼工艺对高磷铁水生产低磷钢均起到了有益的作用。     

鞍钢生产IF钢的进展与实践

为提高IF钢钢水成分控制水平和提高钢水洁净度,鞍钢股份有限公司炼钢总厂在降低碳、氮含量,减少钢中夹杂方面做了很多探索和实践,通过对炼钢、精炼和连铸工艺的改进,采取了降低钢板表面缺陷的措施,钢水洁净度得到提高,进一步改善了IF钢性能和质量。