微孔MgO耐火材料对钢液洁净度的影响

通过浸泡实验研究了3种镁质(致密镁质、微孔MgO质、镁碳质)耐火材料与超低碳钢液(1 560℃)的相互作用,考察了不同浸泡时间(0～35 min)钢中O、N、C和Al、Si、Mn含量及钢中夹杂物的成分、数量、分布等特征的变化,并对耐火材料与钢的界面层进行了观测和分析。结果表明,随着浸泡时间的延长,3组钢中氧含量均先升高再降低,均对钢液有一定的污染,钢中夹杂物的数量增加,夹杂物种类由Al₂O₃-MnO夹杂逐渐转变为Al-Mg-Si-Mn-O复合夹杂。与致密镁质耐火材料相比,微孔MgO质和镁碳质耐火材料与钢的界面处分别能形成连续的镁铝尖晶石层和致密的MgO层,有助于降低耐火材料的侵蚀以及对钢液的污染。此外,与不含碳的镁质耐火材料相比,镁碳质耐火材料对钢液增碳严重。因此,微孔MgO质耐火材料不仅对钢液的二次污染小、不会向钢液增碳,而且还可以吸附钢中氧化铝夹杂,更有利于超低碳洁净钢的生产。     

连铸中间包耐火材料使用实绩分析

本文介绍了中间包耐火材料在连铸投产以来的生产实绩。从耐材质量、耐材施工、耐材使用三方面及其相互关系,对中间包内衬耐材、浸入式水口、塞棒、包盖浇泣料等进行了分析,井指出了实现多炉连浇应采取的措施。     

连铸中间包内衬用耐火材料

本文结合炼钢工艺的发展及耐火材料的技术进步，阐述了中间包永久衬、中间包工作衬及中间包陶瓷过渡器的发展和应用情况，指出了中间包内衬用耐火材料对提高浇注速度和质量的重要性。     

中间包简介及酒钢不锈钢生产中间包用耐火材料调查

中间包是钢水包和结晶器之间用于钢水过度装置。中间包承受连铸钢包流人的钢水后起承上启下的作用，无论对于连铸操作的顺利进行，还是对于保证钢液品质符合需要，中间包的作用都非常重要，本文对酒钢不锈钢生产中间包的耐火材料做了一些调查，以供同仁共刷学习与参考。     

净化钢液的中间包耐火材料技术

用于多流扁坯连铸的、现代中间包的设计选型,包括了采用自动喷涂 MgO 工作层,用导流板代替隔板/堰堤系统,改善了钢液成分和温度的均匀性,并提高了非金属夹杂物的去除效果。     

攀钢1350板坯连铸中间包耐火材料的应用

根据攀钢连铸实践，介绍了连铸中间包耐火材料的使用现状，结合使用中存在的问题、耐材料消耗和成本分析，提出了改进措施。     

连铸中间包覆盖剂对钢液含碳量的影响

通过对异常钢材力学性能的分析研究 ,发现连铸中间包低碳覆盖剂对钢液含碳量的影响。明确这一问题 ,对于规范连铸工序的中间包操作 ,确保钢材质量的稳定性是极其重要的     

钢包耐火材料与钢液反应的研究现状

随着国家工业的快速发展,对高品质钢的需求增大,侵蚀的耐火材料作为钢中外来夹杂物的主要来源受到广泛关注.基于此,阐述了耐火材料与钢液的反应机制、不同耐火材料与钢液的相互作用以及对钢液质量造成的影响.耐火材料会向钢中溶解并与钢中成分发生反应,之后形成界面层,当界面层是高熔点物质时,会阻碍耐火材料的溶解扩散,当界面层是低熔点...     

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.     

MgO与低密度钢液相互作用及其对夹杂物的影响

 为了研究高锰高铝低密度钢液与耐火材料间的相互作用规律,以Fe-20Mn-10Al-C(20%Mn、10%Al)低密度钢液与MgO耐火材料棒在1 600 ℃时界面反应为研究对象,分别反应30和60 min后对MgO耐火材料的微观结构以及钢中非金属夹杂物特征进行了观察。结果表明,反应后MgO耐火材料转变为3层结构,分别为致密的MgO·Al₂O₃尖晶石界面层,尖晶石颗粒、钙铝酸盐和MgO颗粒组成的过渡层以及MgO颗粒组成的原始层,且随着反应时间的增加,尖晶石界面层厚度增加;在高锰高铝低密度钢液与MgO耐火材料的相互作用下,钢中非金属夹杂物主要包括单一MgO·Al₂O₃夹杂、AlN夹杂、MgS夹杂和MgO·Al₂O₃-AlN、MgO·Al₂O₃-MgS等复合夹杂物。     

不同湍流模型在中间包钢液流动数值模拟中的适用性研究

摘要：连铸中间包内部结构复杂,钢液流动状态多样,详尽准确的钢液流场信息是中间包控制和优化的前提。数值模拟方法已广泛应用于中间包内钢液流场研究,钢液流场的精确数值模拟离不开合适的湍流模型及相应的边界条件。基于CFD开源代码包OpenFOAM v8,分别应用标准k-ε模型、RNG k-ε模型、SST k-ω模型3种湍流模型,对称面边界、自由滑移边界2种液面边界条件,对中间包流场进行了数值模拟。通过与文献中实验结果比较,发现采用SST k-ω模型可以成功预测RTD曲线的“双峰”,且响应时间、峰值时间与实验结果较为接近;应用SST k-ω模型时,将液面边界类型由自由滑移改为对称面,获得的示踪剂响应时间的误差由93.89%降低至8.35%以下,峰值时间的误差由100.78%降低至12.32%左右。因此,SST k-ω模型、对称面液面边界可以较好地描述中间包内钢液流动过程。     

Study on applicability of different turbulence models in simulation of molten steel flow in tundish

The internal structure of continuous casting tundish is complex, and the flow state of molten steel is diverse. Detailed and accurate information of molten steel flow field is the premise of tundish control and optimization. Numerical simulation method has been widely used in the study of molten steel flow field in tundish. The accurate numerical simulation of molten steel flow field is inseparable from the appropriate turbulence model and the corresponding boundary conditions. Based on the CFD open source code OpenFOAM v8, three different types of turbulence models (standard k-ε model, RNG k-ε model, and SST k-ω model) were applied to simulate the molten steel flow in the tundish. Additionally, two boundary conditions of symmetry plane and the free slip were also applied. Comparing the simulation results to the experimental data, it shows the RTD curve obtained by the simulation with the SST k-ω model can successfully predict the "double peaks" that appeared in the experiment. Besides, the response time and peak value time are closest to that of experimental results. For SST k-ω, when changing the type of liquid surface boundary from free slip to symmetrical plane, the error of tracer response time obtained is reduced from 93.89% to less than 8.35%, and the error of peak time is reduced from 100.78% to about 12.32%. It can be concluded that the SST k-ω model and the symmetry boundary are applicable for the simulation of molten steel flow in the tundish.     

特殊钢大方坯连铸中间包各流冶金效果一致性研究

摘要：多流中间包各流钢水流动与温度状态差异是造成高端特殊钢连铸坯质量一致性差的重要原因之一。针对国内某钢厂特殊钢大方坯连铸用4流T型中间包边部流和中部流实测温差较大问题（4~7℃）,基于实际工况特点,进行了中间包冶金行为的热流体动力学数值模拟研究,揭示了原型中间包边流水口响应慢及各流一致性差的原因;提出一种控制钢水流动和流间温差的内腔结构改进措施,可使包内钢液温度均匀性得到明显改善。其中,理论最小流间温差可降低到1℃以内,实测流间温差在0~3℃之间,较原型大大减小。同时指出,基于热流体动力学数值模拟优化中间包结构、提升多流中间包全铸流冶金效果一致性在特殊钢长材生产中具有重要意义。     

Study on dimension and migration behavior of bubble under annular argon blowing at tundish upper nozzle

The water model experiments were carried out to study the bubble morphology in the tundish and mold with the process of annular argon blowing at tundish upper nozzle. The effects of the position of gas permeable brick, the casting speed and the argon flow rate on the bubble size distribution, the bubble migration behavior and the flow behavior of liquid steel near the liquid level in tundish were further investigated, coupled with the numerical simulation. The results show that with the process of annular argon blowing at tundish upper nozzle, a frustum cone shaped bubble plume can be formed around the stopper rod. The concentration of argon bubbles gradually decreases outward along the radial direction of the stopper rod. Owing to the wall attached effect, the bubble plumes float upward along the stopper rod, which can increase the collision probability between bubbles and the velocity of bubble plumes, causing a larger impact strength on the liquid level in tundish. In addition, a part of small bubbles are wrapped into the nozzle and the mold due to the drag force of liquid steel. With increasing argon flow rate, the number of bubbles in annular bubble plumes and the vertical velocity of liquid steel near the liquid level in tundish increase significantly. With increasing casting speed, the width and the bubble number of annular bubble plumes gradually decrease, leading to a decrease of the vertical velocity of liquid steel near the liquid level in tundish. Increasing the distance between the annular gas permeable brick and the center of tundish upper nozzle, the dispersion of bubbles and the width of bubble plumes increase, and the impact strength of bubbles acting on the liquid level in tundish becomes weaker. As the argon flow rate and the casting speed increase, and the distance between the gas permeable brick and the center of tundish upper nozzle decreases, the gas volume and bubble size in the mold increase. Under the experimental conditions, when the inner and outer diameters of the annular gas permeable brick are 110mm and 140mm, respectively, and the casting speed is 1.2m/min, the appropriate argon flow rate is 4L/min.     

中间包上水口环形吹氩下气泡大小和迁移行为研究

摘要：通过水模型实验研究了上水口环形吹氩工艺下中间包和结晶器内气泡形貌,并结合数值模拟分析了透气砖位置、拉坯速度和吹氩量对中间包和结晶器内气泡尺寸、气泡迁移和中间包近液面钢液流动的影响。结果表明：上水口环形吹氩形成以塞棒为中心的圆台状气泡羽流,气泡浓度沿径向向外逐渐减少;附壁效应使得气泡羽流偏向塞棒壁面流动,增大气泡的碰撞聚并概率和近塞棒壁面的羽流上升速度,对中间包液面产生较大冲击作用;同时,部分细小气泡会随钢液进入水口及结晶器内部;增大吹氩量,中间包内环形气泡羽流中气泡数目明显增多,中间包近液面钢液上升速度增大;增大拉坯速度,环形气泡羽流的宽度和气泡数量逐渐减小,近液面速度减小;增大透气环距水口中心距离,中间包内气泡弥散度增大,环形气泡羽流宽度也随之增大,气泡羽流对中间包液面冲击作用减弱;增大吹氩量和拉坯速度、减小透气环距水口中心距离,进入结晶器的气量和气泡尺寸逐渐增大。实验条件下,透气环内外径为110mm/140mm、拉坯速度为1.2m/min时,吹氩量为4L/min较为合适。