新钢第二炼钢厂提高连铸恒拉速的生产实践

新余钢铁集团有限公司（简称新钢）第二炼钢厂贯彻以“连铸恒拉速”为主线的生产思路。板坯恒拉速是铸机顺行及铸坯高质量生产的重要保证。影响连铸恒拉速的因素有高温钢水、水口蓄瘤、结晶器液面波动和生产节奏。通过采取引进新的浇注系统、改进操作工艺、更新系统软件及合理控制碳添加量为0.14%～0.16%等措施,恒拉速达标率达到85%以上,产品质量得到稳步提升。     

基于钢水过热度的连铸机拉速自适应指导与控制

连铸机生产过程中频繁调整拉速不利于铸坯质量的改善,工艺要求尽可能的保持恒拉速生产,但由于生产节奏、设备工艺及操作人员等各种因素导致钢水过热度的变化,必须对拉速进行适当和必要的调整,这是一对矛盾难以解决。为此,对连铸生产阶段的各种情况下拉速调整进行试验、研究,分析大量数据并通过工艺、设备及操作结合实践,以自动控制为基础采用先进的控制方法,解决了上述实际生产中的问题,很好地指导生产,保障连铸生产工艺的顺利进行。     

迁钢板坯恒拉速技术应用与实践

炼钢系统是离散-连续的过程,整个系统的设备较多且操作变数大,实现常规板坯恒定拉速连续铸钢的关键是铁水预处理、转炉炼钢、钢水二次精炼、板坯连铸等环节间的钢水物质流、温度变化的能量流、生产节奏的时间流的传递,恒拉速实施过程中要求设备平稳运行、生产工艺科学合理、生产节奏平稳有序等一系列稳定条件,同时还要做到“时时、班班”相同。迁钢炼钢厂在实行板坯恒拉速技术开发与应用过程中,以优化各工序生产工艺,加强过程控制能力,科学、稳定、高效组织生产为手段,恒拉速率已经连续49个月稳定在97%以上,创造了1 000万t 连续不漏钢的记录。     

连铸坯在线定重切割技术工艺实践

连铸坯重量由连铸坯断面尺寸、钢坯长度及其密度三个因素决定。这三个因素又与结晶器铜管服役期内磨损程度、浇注温度、拉速、定尺切割精度和钢水成分有关。因此通过连铸坯在线称重结合定尺微调,可以控制连铸坯定重精度,达到最大程度提高轧钢钢材成材率、定尺率的目的。我厂通过自主设计研发的连铸坯在线吊钩式提升称重法获取连铸坯单支重量,及时调整定尺,配合连铸"恒温度、恒拉速"操作模式,稳定连铸坯定重,连铸坯定重准确率明显提高。     

连铸坯内部裂纹产生的主要原因及解决措施

以莱钢50 t电炉生产线及新二区转炉炼钢生产线生产的两种规格的连铸坯作为研究对象,分析了内部裂纹形成的原因,并采用扫描电镜和能谱分析了内部裂纹的类型。通过采取恒拉速浇注、拉坯速度与水量合理匹配、实行中间包窄温度波动控制、提高钢水纯净度等措施,连铸坯的质量得到了明显改善,低倍和热顶锻合格率也有了显著提高。     

IF钢浇铸过程浸入式水口结瘤的治理研究

IF钢连铸生产过程浸入式水口结瘤是一个长期存在的难题,某钢厂从钢水洁净度、恒拉速、连铸用耐材选择等多个方面提出治理办法,并将之投入到实际生产中用,取得了良好的结果,IF钢浇铸过程浸入式水口结瘤率降低到1%以内。     

40Cr合金结构钢连铸工艺研究与应用

莱钢特钢厂在1#连铸系统中采用EBT—LF—连铸工艺生产40Cr合金结构钢,通过合理控制用氧、调整炉渣碱度、采用Si—Ca线处理钢水、控制钢水过热度、调整拉速、合理控制二冷配水,确定了最佳工艺方案,提高了钢水收得率,解决了水口锈眼问题,保证了连铸生产顺行和质量稳定。     

小方坯连铸拉速问题初探

连铸拉速的调整,一般都以中间包钢水温度为依据。通过分析结晶器内钢水凝固的不均匀性以及钢水放热和结晶器散热的热量平衡情况,可计算出基准状况下的最大工作拉速以及非基准状态下拉速调整量与结晶器冷却水量、进出水温差、中包钢水温度之间的定量关系,计算结果表明,上述三因素对拉速的影响系数以BY_2为例,分别为0.018、0.59、-0.0062,在连铸操作中,拉速调整应该以结晶器冷却水进出温差的变化为主要依据。     

20#管坯钢连铸生产工艺实践

特殊钢厂在1#连铸系统中采用20tEAF-LF-连铸工艺生产20#管坯钢，通过合理控制吹氩工艺、调整炉渣碱度、采用Si—Ca线处理钢水、控制钢水过热度、调整拉速、合理控制二次配水，确定了最佳工艺方案，提高了钢水收得率，解决了铸坯裂纹问题，保证了连铸生产工艺顺行和质量稳定。     

连铸板坯表面纵裂分析

对生产数据进行分析，认为钢水成分、拉速和结晶器液面波动等是造成连铸坯表面纵裂的主要原因。为此，根据结晶器专家系统进行町视化的生产指导，从钢种成分控制、生产操作等方面提出了改进措施，减少了连铸板坯表面纵裂的产生。     

Numerical Simulation of Influence of Casting Speed Variation on Surface Fluctuation of Molten Steel in Mold

The influences of casting speed variation on surface fluctuation of the molten steel in mold during continuous casting were investigated with numerical simulation method.It was found that when the casting speed was evenly decreased from 1.4 m·min-1 to 0.6 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only on time that was at the start of casting speed change.While,in experiment of increasing casting speed evenly from 0.6 m·min-1 to 1.4 m·min-1,the increase of the surface fluctuation of the molten steel in mold was observed only at the time when the casting speed was stopped to increase after it had been increased to 1.4 m·min-1.For surface fluctuation of the molten steel in mold which was produced during the casting speed evenly increasing or decreasing period and at the time when increasing or decreasing the casting speed at low casting speed level(0.6 m·min-1),the influence of casting speed change is very small.In addition,it is found that,at high casting speed level(1.4 m·min-1),even a little change of casting speed could result in remarkable increase of the surface fluctuation.Thus,at high casting speed,changing casting speed should be avoided or much slower speed changing rate should be used.     

宝钢圆坯连铸提高拉速生产实践

介绍了圆坯连铸提速的生产实践和取得的效果.对于包晶钢,尝试通过提高拉速来改善结晶器壁与坯壳间换热的均匀性,从而降低这类钢种的漏钢率.对于石油套管、钻杆类钢种,经过3个阶段的工作,成功将平均拉速提高到2.6 m/min,而且产品的内部质量有所提高.连铸拉速提高后,有了降低中间包过热度的可能,平均过热度下降达5 K.随着拉速的提高,VD成为产线生产的瓶颈.经试验,即使VD高真空时间缩短5 min,VD后的[H]仍可达到1.5×10-4%,同时发现,VD脱氮率与高真空保持时间无相关关系.于是VD处理时间成功缩短5 min,满足产线的节奏要求.     

拉速变化对IF钢铸坯非金属夹杂物含量的影响

采用原位统计分布分析仪（OPA）对IF钢连铸过程拉速变动对铸坯表层试样非金属夹杂物含量的影响进行了研究,发现在由较高拉速（1．4m／min）向低拉速（0．6m／min）变动时,对结晶器保护渣卷入的影响主要发生在降速初期,而随后的降速和低拉速下停止降速对铸坯表层试样夹杂物含量影响不大。当由较低拉速（0．6m／min）向高拉速（1．4m／min）变动时,对保护渣卷渣的影响主要发生在提升到高拉速后停止升速阶段,而低拉速时启动升速和随后均匀升速对铸坯夹杂物含量的影响不大。研究中还发现在较高拉速下（1．4m／min）即使较少量地变速,也会造成铸坯表层夹杂物含量的显著增加,因此在较高拉速时应避免对拉速进行变动或尽量采用低的拉速改变速率。采用数值模拟方法对拉速变化影响进行的研究结果同样表明,在较高拉速下发生的拉速变化,对结晶器内钢水流动有更显著的影响。     

加速山东省连铸机的高效化改造

为提高山东省内各钢铁企业的连铸效率,实现合理的炉机匹配,并促进热装热送工艺的发展,应加速山东省连铸机的高效化改造。采用高效连铸技术应结合企业实际,以炉机匹配和少投入为原则,加强设备及工艺改进以优化结构,降低成本,增加产量。     

电铅直线铸锭机爬行运动问题的处理

本文对电铅直线铸锭机爬行的原因进行了探讨，介绍了电铅直线铸锭机爬行问题的处理实践，并提出了局部结构改进方案。     

小方坯恒拉速浇注工艺实践

介绍了安钢第二炼钢厂以连铸为中心,通过设定典型拉速和标准浇注温度规范过程控制参数,严格执行一炉对一机匹配模式,从工艺优化和生产组织上双向保证,实现连铸机恒拉速浇注的工艺实践.使炉机生产运行水平和铸坯质量得到同步改善,促进了精益生产水平的进一步提高.     

Numerical study of an application of a divergent reverse TurboSwirl nozzle in the billet continuous casting process

The swirling flow has widely been investigated for liquid steel flowing in the continuous casting process. In this paper, a new design of the submerged entry nozzle (SEN) is applied by using a reverse TurboSwirl device with a divergent nozzle. This divergent reverse TurboSwirl nozzle (DRTSN) is shown to gain a more beneficial flow pattern compared to the straight nozzle. A stronger swirling flow can be obtained at the SEN outlet, which leads to a calmer flow field and an appropriately active meniscus flow that could improve the heat and mass transfer near the meniscus. The swirl number in the SEN is independent of the casting speed, while a lower casting speed yields a lower maximum wall shear stress. The DRTSN is connected to the tundish by an elbow and a horizontal runner. A longer horizontal runner supplies a more uniform velocity profile and a more symmetrical flow pattern.     

Effect of Casting Speed on Slab Broadening in Continuous Casting

A three‐dimensional viscoelastic‐plastic thermal‐mechanical coupled finite element model was based on the basis of the secondary development of commercial software (MSC, Marc software, USA) to simulation the effect of casting speed on slab broadening in the secondary cooling zone. The results show that the ratio of ultimate broadening increased with increasing casting speed for various steel grades, but the change in broadening lagged that in casting speed. When the casting speeds were 1.0 m/min, 1.1 m/min, and 1.2 m/min for Q235 steel, the maximum ratios of ultimate broadening were 1.52%, 1.59%, and 1.81%, respectively, and the average ratios of ultimate broadening at the exit of the caster were 1.00%, 1.27%, and 1.48%, respectively; for SPHC steel, the maximum ratios of ultimate broadening were 1.34%, 1.44%, and 1.69%, respectively, and the average ratios of ultimate broadening at the exit of the caster were 0.64%, 0.76%, and 0.95%, respectively. The simulation results were verified by measurements on an SMS‐Demag continuous caster of Maanshan Iron and Steel Co. Ltd.; the measurement results agree with the simulation results. The mechanism of the effect of casting speed on slab broadening was also analyzed.     

济钢炼钢厂超低头板坯铸机恒速拉钢的实践

为实现板坯铸机恒速拉钢的目标,济钢炼钢厂通过统计各个阶段的过程温降控制合理的钢水过热度,严格冶炼操作制度确保钢水的可浇性同时保证钢水的衔接等措施,恒速拉钢的比例由53.2%提高到了82.7%,板坯纵裂比例由19%降至14%以下,铸坯质量明显改善。     

拉速对结晶器平均热流的影响

通过计算8088块板坯的平均热汉研究了拉速对板坯结晶器平均热流的影响结果表明：拉速对结晶器宽边的平均热流有显的影响,拉速在0．6－1．2m/min范围内,结晶器宽边平均热流随拉速提高而增加,当拉速超过1．2m/min后,结晶器宽边平均热流随拉速增加而提高的幅度变得很小;结晶器窄边的平均热流较宽边的热流约低0．2MW／m^2,当拉速超过1．2m/min后,结晶器窄边的平均热流仍可随拉速的进一步提高而增加。