连铸异钢种连浇过渡坯模型的研究

以舞钢炼钢厂连铸坯异钢种连浇过渡坯为研究对象,通过数学模型和试验模型的验证,以两炉异钢种成分相差最大的化学元素为依据,来精确控制过渡坯长度,减少金属损耗,提高钢水收得率,实现降本增效。     

Improvement of Melt Mixing and Cleanness in Ladle,Tundish and Mould by Application of Advanced Simulation Techniques

Increasing the productivity and improving the product quality are permanent requirements in steelmaking. For this purpose also detailed information on flow conditions of the melt is required. Therefore, beside operational trials, mainly physical and mathematical modelling approaches play an important role to obtain relevant information. The present state of selected simulation approaches used at the BFI are described and their application is exemplarily shown for the alloying process in a ladle, inclusion separation in a tundish and the electromagnetic stirring in a billet mould. Detailed information on these processes was obtained and improved process engineering measures could be elaborated.     

Influence of Deformation Degree on the Evaluation of Macroscopic Oxide Cleanness

The demand for cleaner steels requires reducing the number of macroscopic non‐metallic oxide inclusions. A major problem of “clean steel” is the measurement and evaluation of the rare large inclusions which exceed a critical size harmful to the product. To this end, volumetric methods of evaluating macro‐inclusions in the three‐dimensional steel matrix are necessary to qualify steel heats or continuous cast slabs and to check if the refining and casting processes are stable and have been improved. Ultrasonic scans are a powerful tool to assess the quality of the volume. In order to activate macroscopic oxide inclusions for the reflexion of the ultrasound, as‐cast material is deformed by hot rolling. The aim of the present research work was to find out the most effective hot rolling practice with respect to ultrasonic detection of the rare large oxide inclusions. For this purpose, heavily contaminated neighbouring slab samples, corresponding to a severe incidence of ladle slag carryover, were hot rolled in a different manner. The 23‐kg‐samples were either elongated by a ratio λ = 2, 3, 10 or 15, or alternatively cross‐rolled, e.g. spread and stretched by ratios 2 × 5 or 3.2 × 3.2. The best compromise to quantify macroscopic steel cleanliness under consideration of cost and time requirements is based on the pure 10fold elongation or the cross‐rolling by 2fold x 5fold. It likewise became clear that rare large oxides can be detected with good sensitivity, as long as the hot rolling reduction ratio is large enough.     

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。     

帘线钢连铸坯氧化物夹杂分布规律研究

为了探索帘线钢中氧化物夹杂在连铸坯内的分布规律,对铸坯中氧化物夹杂的尺寸和成分进行了取样分析。结果表明,随着凝固时间的延长,帘线钢连铸坯中氧化物夹杂的尺寸由连铸坯表面到心部不断增大。采取连铸快冷及增强凝固末端电磁搅拌的措施后,夹杂物最大尺寸控制在20μm以下。     

提高含铅铜合金半连铸圆锭质量的方法

通过对含铅铜合金半连续铸造工艺的研究，提出了半连续铸造的基本原理，分析探讨了影响半连续铸锭质量的主要因素，并提出了改进措施，效果理想。     

板坯连铸机高连拉炉数的生产实践

简介了安钢板坯连铸生产组织的特点和连铸机的主要技术参数;找出了影响铸机提高连拉炉数的主要因素;阐明了所采取的快速更换中间包、防止浸入式水口堵塞、设备快速维修等技术措施。上述技术措施实施后取得明显实效     

板坯连铸机高连拉炉数的生产实践

简介了安钢板坯连铸生产组织的特点和连铸机的主要技术参数;找出了影响铸机提高连拉炉数的主要因素;阐明了所采取的快速更换中间包、防止浸入式水口堵塞、设备快速维修等技术措施。上述技术措施实施后取得明显实效     

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。     

连铸二冷传热系数测定仪的研制

本文说明了测定传热系数对连铸的重要性,给出了计算传热系数的方法。所研制的传热系数测定仪包括加热控温系统、温度信号放大与采集系统、数字计算与打印系统等。测定仪装有8位单板计算机和24行微型点阵式打印机。从加热温度传感器到打印测定结果,整个测试过程可连续自动进行。在同样条件下的测定结果稳定可靠。     

汽车用钢大方坯连铸二冷配水数学模型

应用开发的连铸传热数学模型对石家庄钢铁有限责任公司炼钢厂电炉车间所生产的5个钢种及2种规格铸坯的二次冷却配水进行了模拟计算；根据铸坯凝固冷却过程冶金准则的要求，经反复模拟及优化，得出了二次冷却区各段水量与拉速的二次关系式；综合考虑了过热度对铸坯凝固过程的影响，建立了新的二次冷却水控制模型，并应用于实际生产。     

板坯连铸涡流检测钢水液位系统的应用

介绍了新一代RAM型涡流传感钢水液位控制仪在莱钢板坯连铸机上的应用及其效果。     

Twin Roll Casting of Steel Strip ‐ Experiments and Model Considerations on Strip Spottiness

Thin strip casting of steel through a twin‐roll caster demands the production of a perfectly homogeneous strip. This requirement is often not fulfilled due to non‐uniform heat contact between the solidifying strip and the rolls in the pool, which leads to temperature inhomogeneities visible at the strip behind the rolls (spottiness). The effect of spottiness is described from experimental observations in terms of contrast between dark and hot spots and of the mean diameter of the hot spots. The contrast is found to depend on roll material, surface roughness and roll velocity. A general dependence on the temperature difference between melt and rolls is observed. Calculations of heat transfer in the liquid and solid pool explain the hot‐dark‐temperature differences. The spottiness visible on the strip after leaving the rolls is initiated in the liquid pool, but it is enlarged by rolling contact differences in the solid pool. A model consideration based on thermally caused bending of the solidified material layers leads to a good coincidence with experimental data of the heat transfer coefficient at hot spots.     

连铸拉速和中包过热度的耦合作用分析及二冷配水控制实现

应用三维凝固传热模型分析了拉速突变和中包钢水温度对铸坯凝固过程的影响,引入"有效拉速"和中包过热度作为二冷配水的前馈控制变量,动态模型仿真结果表明可以消除拉速引起的表面温度"尖峰"和钢水温度变化的影响,提出了建立基于有效拉速和中包过热度的二元动态配水模式,实际应用结果验证了此方法对提高铸坯质量的有效性.     

略钢铸坯脱方成因分析和实践

对略钢小方坯连铸机铸坯脱方的原因进行了分析,并采取了相应的对策后,取得了较好的效果.     

板坯连铸结晶器内坯壳厚度及枝晶间距

通过向结晶器内添加FeS测定了正常工况下结晶器内坯壳的厚度分布.由测得的坯壳厚度分布,分析了结晶器内弯月面参数、凝固系数以及坯壳的凝固速度、温度梯度和冷却速度.结果表明,用结晶器内钢水添加硫方法确定的坯壳厚度分布较为合理.     

轴承钢连铸坯偏析和致密度的分析

采用原位分析方法对轴承钢连铸大方坯不同部位的偏析和疏松进行了分析;将原位分析与低倍组织分析结合起来,完整地体现铸坯试样的成分分布和组织特征。轴承钢同一铸坯断面中部的C、Si、Mn元素偏析程度大于边部。轴承钢铸坯边缘部位致密度和均匀性都好于中心部位,即相应的柱状晶区致密度高于等轴晶区。     

不锈钢(304HC)浇铸过程保护渣成分变化及其对渣性能影响

通过不锈钢(304HC)连铸过程中对结晶器内液渣现场取样、分析,探索了结晶器内渣-钢界面化学反应及钢中杂夹的吸收造成渣成分的变化,及其对熔渣性能的影响.研究表明,渣中Al2O3、Cr2O3含量有所增长,F减少,碱度下降,并造成保护渣使用性能发生变化,粘度有波动、凝固温度升高及结晶率下降.研究结果为更合理地设计不锈钢连铸保护渣配方,进一步降低不锈钢铸坯表面缺陷提供了依据.     

略钢铸坯夹杂缺陷成因分析和实践

对略钢生产的钢筋和圆钢出现冷弯断裂和延伸率下降情况的成因进行分析,确定主要是由于铸坯中夹杂物过多。通过采取一系列技术措施,取得了较好的效果,产品合格率明显提高。