宽板坯结晶器保护渣的开发

宽板坯连铸与常规板坯连铸相比有着较大的差异.通过对保护渣理化性能、绝热保温性能的研究,确定了适合于宽板坯中碳钢连铸用保护渣的理化指标,并开发出XCN-Z型保护渣.工业应用表明:研制的XCN-Z型宽板坯连铸用保护渣使用效果好,能满足拉速为1.3～1.5 m/min的中碳钢中厚板坯连铸连轧的要求.     

中厚板高速连铸技术的开发

通过用一台实验连铸机模拟生产高质量板坯的连铸机的基本设计原理，开发了高速连铸技术。在改进浇注系统、新型粉渣－－结晶保护渣的润滑性能、板坯冷却法和减少内部裂纹后，达到了以５．０ｍ／ｍｉｎ生产低碳钢的高速连铸技术水平。     

板坯连铸结晶器保护渣的选择和应用

连铸结晶器保护渣对铸坯表面质量具有显著影响。自从韶钢炼钢厂板坯连铸机投产以来,使用的保护渣品种较单一,且一渣多用。特别是在1998年铸坯表面质量问题较为严重,后来采用新型武钢保护渣以后,废品量明显减少。通过对保护渣的作用,物理、化学性能及影响因素的分析,提出了适合韶钢炼钢厂板坯连铸机结晶器保护渣的各种性能指标。     

南阳汉冶特钢连铸板坯表面横裂纹的控制实践

针对南阳汉冶特钢宽板坯连铸机生产的板坯出现表面横裂纹情况,分析认为钢水成分、中间包过热度、结晶器液面波动、结晶器振动、结晶器冷却水量、保护渣、扇形段二次冷却及连铸机检查等是主要影响因素。对以上影响因素采取针对性措施后,连铸板坯表面横裂纹得到了有效控制。     

韶钢板坯连铸结晶器保护渣的选择和应用

连铸结晶器保护渣对铸坯表达质量具有显著影响。通过对保护渣的作用，物理、化学性能及影响因素的分析，提出了适合我厂板坯连铸机的保护渣的各种性能指标。     

性能良好的大板坯连铸用保护渣研制成功

保护渣浇铸是防止连铸板坯表面纵裂和表面夹渣等缺陷产生的重要工艺措施。武钢第二炼钢厂引进了三台R10.3米全弧形大型板坯连铸机。开工期间,还进口了大量连铸保护渣。为了使保护渣自给,根据北京钢铁研究总院提供的配方和制渣要求,武钢第二炼钢厂生产了三种连铸保护渣(BZW-1号、BZW-2号、BZW-3号)。经过试用,证明其性能良好,已经于1979年8月初投入生产。迄至12月初,用自产保护渣浇铸出七万五千多吨表     

天钢4~#板坯连铸机结晶器保护渣的优化选择

天钢4#板坯连铸机生产的板坯,存在贯穿表面中心部位裂纹等缺陷。针对此问题,对天钢4#板坯连铸机所使用的A、B型保护渣的物理、化学性能及相关数据进行了采集和分析,确定了A型、B型保护渣所匹配的钢种;通过裂纹缺陷的统计分析,确定了所使用的A型、B型保护渣不是造成铸坯壳中心裂纹缺陷的主要原因;还指出A型、B型保护渣与目前各连铸工艺相匹配,基本能够满足生产要求。     

保护渣的成分对连铸渣和连铸生产的影响

保护渣的成分对所形成的连铸渣的性能的影响的知识是选择合适的连铸保护渣的基础。西德赫施钢铁公司利用生产中使用的标准保护渣实验研究了不同的保护渣成分对熔炼温度和渣的粘度的影响。实验目的在于发展板坯连铸机所使用的连铸保护渣。重点研究了助熔剂 Na_2O 和 CaF_2、碱度 CaO/SiO_2以及较高的 Al_2O_3含量的影响。利用模拟连     

结晶器保护渣对连铸板坯质量影响的研究

鞍钢三炼钢板坯连铸机采用日本ＭＯＰ－ＡＨＰ－８Ｆ和国产ＡＧＬ－２渣的使用效果，以及结晶器保护渣对连铸板坯质量和对铸坯轧制产品质量性能的影响。     

浅谈结晶器保护渣的性能与使用

结合板卷厂3250mm宽板坯连铸机保护渣的实际使用情况，对结晶器保护渣的性能与工艺条件、钢种的优化匹配等进行了探讨。     

F-free mould powders for low carbon steel slab casting – technological parameters and industrial trials

The choice of the mould powder for slab casting is a difficult task because mould powders have many important functions during the continuous casting of steel. CaF₂ is a key ingredient in conventional mould slags since it reduces the viscosity, the liquidus temperature and the break temperature. Fluorine in mould powders is undesirable from the environmental and health points of view due to the following reasons: (i) evolves easily from slags, producing health-injurious gaseous substances, such as hydrofluoric acid; (ii) creates problems for storage and utilisation of solid waste and (iii) causes machinery corrosion. Aim of the present work is to describe the development of a new F-free mould powder for low carbon steel slab casting replacing CaF₂ with B₂O₃. Laboratory tests and industrial trials were performed considering the technological parameters viscosity, break temperature and crystallisation tendency. From laboratory tests it was concluded that important technological parameters are similar when comparing the F-bearing mould powder (reference) and the new F-free B-bearing mould powder for low carbon steel slab casting: viscosity at 1300°C, break temperature, and crystallisation tendency. It was observed during industrial trials that a significant decrease of the submerged entry nozzle erosion was observed. The results were similar when comparing the F-bearing and the F-free performance: slag pool thickness measurements, melting behaviour, Al₂O₃ absorption, mould powder consumption and slabs superficial quality.     

Mould Powder Development for Continuous Casting of Steel

Mould powders significantly determine the stability of the continuous casting process of steel at all casting speeds. The main functions of mould powders are to provide strand lubrication and to control the mould heat transfer in the horizontal direction between the steel shell and the copper mould. The composition, properties and operational performance of mould powders were investigated in detail with a focus on high-speed thin slab casting and conventional slab casting. Various advanced characterisation methods were applied, completed with experiments at laboratory scale and full-scale plant trials. It was found that melting of mould powder at the meniscus and crystallisation of the slag film are key processes during continuous casting. Both powder melting and slag crystallisation are primarily based on the composition of the mould powder and the mould slag. Additionally, the operational parameters during continuous casting will affect these processes as well. Results of the work are used for a further and more fundamental understanding of the mould powder functions and to guide mould powder design for various steel grades.     

外加液态保护渣连铸生产实践与前景展望

 外加液态保护渣可以提高铸坯质量和可浇性。在某厂板坯连铸机上,分别采用液态保护渣和固态保护渣进行多钢种浇注试验,对比液态保护渣和固态保护渣消耗量、结晶器温度分布、拉坯摩擦力及铸坯质量,并对液态保护渣的应用前景进行展望。结果显示,液态保护渣比固态保护渣消耗量增加60%左右,结晶器温度分布更均匀,连铸拉坯摩擦力降低约15%,铸坯质量有所提高。这说明在连铸过程中,液态保护渣使结晶器和铸坯间传热更均匀;液态保护渣润滑效果更好,可以提高铸坯质量。同时,有望不添加F-、Na+等有害离子,改善环保问题。     

萤石含量对结晶器保护渣物理性质和渣膜矿相结构的影响

针对亚包晶钢连铸板坯易发生表面纵裂现象,研究和分析了萤石配加量对保护渣（/%:2937水泥熟料,8硼砂,20石英砂,15硅灰石,12纯碱,816萤石）熔化温度、黏度和平均热流密度以及渣膜矿相结构的影响。结果表明,随着萤石含量的增加,渣膜结晶率和枪晶石含量升高,硅灰石含量降低,同时保护渣熔化温度、黏度、平均热流密度降低;提出萤石配加量为12%时,能满足亚包晶连铸板坯对渣膜矿相结构的要求,并改善了铸坯质量。     

连铸板坯中碳钢开浇用发热保护渣

连铸板坯开浇时的浇铸状况恶劣,开浇炉的铸坯表面缺陷发生率较高。使铸坯在结晶器内缓冷是防止铸坯纵裂的有效措施。针对通常使用的低碱度、低结晶温度的发热型开浇渣不能使铸坯在开浇阶段得到缓冷的缺点,开发了连铸板坯中碳钢开浇用发热保护渣,除进一步改善发热性能外,高碱度、高结晶率的开浇渣所形成的渣膜增大了结晶器与铸坯问的热阻,改善了铸坯在结晶器内的缓冷条件,开浇炉的第1、2块板坯的纵裂发生率明显下降。     

Development of Mould Flux for High Speed Thin Slab Casting

Mould powders impact the stability of the continuous casting process for steel at all casting speeds. The main functions of mould powder are to provide sufficient lubrication and to control the mould heat transfer between the solidifying steel shell and the copper mould. At higher casting speeds associated with thin slab casting, the role of the mould powder is even more important. Actual casting speeds for the thin slab caster at Corus IJmuiden are between 5.4 and 6 m/min; the production level is around 1.3 Mt/year (coils). It has been decided to increase the production of this caster to a level of 1.8 Mt/year (coils). In order to meet this demand, the steel in mould time has to be increased to approximately 85% and the maximum casting speed will be increased to 8 m/min. A collaborative project between Sumitomo Metal Industries (SMI) and Corus IJmuiden was initiated to develop mould powders which facilitate casting speeds up to 8 m/min at the thin slab caster. Main subjects of this project are: mould powder design, characterisation of mould powder and mould slag, trials at the pilot caster of Sumitomo and finally plant trials at the thin slab caster of Corus. A special point of attention is the condition to use mould powder as a granulated material at the thin slab caster. As a consequence, the characterisation work focussed on the choice of raw materials and on the corresponding phase relations at elevated temperatures. Typical of the developed mould powders are so‐called mild cooling properties which will result in a controlled mould heat transfer during casting. In this paper, several aspects of this joint project between Sumitomo and Corus will be described.     

马氏体不锈钢板坯连铸保护渣研制与应用

 由于钢种特点,连铸马氏体不锈钢板坯容易产生裂纹缺陷,影响生产节奏和修磨效率;同时,由于采用通用型保护渣,也无法针对马氏体不锈钢板坯质量问题做出进一步改进。因此,尝试马氏体不锈钢板坯连铸保护渣的国产化研制和使用,通过保护渣碱度、CaF等的不同范围与保护渣结晶、黏度性能的关系研究,确定采用高碱度、低黏度、高结晶性的保护渣设计原则,并由此得出了适应马氏体不锈钢板坯连铸的保护渣设计方案。实际使用过程中,板坯纵裂率下降幅度达到30%,证明了马氏体不锈钢连铸板坯保护渣设计和研制的合理性和可行性。     

Mould Powder Requirements for High‐speed Casting

Mould powders play an important role in the stability of the continuous casting process of steel. The main functions of mould slag (i.e. molten powder) are to provide sufficient lubrication and to control the heat transfer between the developing steel shell and the mould. Sufficient lubrication requires an undisturbed melting of mould powders and uniform infiltration of mould slag. Based on the casting practice in IJmuiden, it is found that these demands become even more important for the applied high casting speeds in thin slab casting at 5 to 6 m/min. At Corus RD&T, mould powders were characterised by X‐ray diffraction and subsequent fully quantitative Rietveld analysis. Additionally, the melting of mould powders has been studied in‐situ using high‐temperature X‐ray diffraction, to gain crucial knowledge about melting relations. Slag rims obtained from the thin slab caster mould were characterised using extended microscopic techniques in order to describe the mechanisms of rim formation and growth. Finally, slag films obtained after casting were characterised. As a result, not only the melting process of mould powder, but also the mechanism of formation and growth of slag rims is much better understood. This knowledge will be applied to define the demands on the composition and properties of mould powder for even higher casting speeds.     

45#钢板坯粘结漏钢原因探讨及解决措施

通过研究板坯45^#钢液相线温度低、固液两相区宽、初生坯壳收缩量小等凝固特征，系统分析了45^#钢粘结漏钢的原因，从保护渣、结晶器、冷却水以及工艺操作等方面针对性地制定了措施，杜绝了粘结漏钢事故，稳定了生产。     

Understanding mould powders for high-speed casting

The development and application of mould powder for high-speed continuous casting of steel is described. For thin slab casting, the main requirements are proper powder melting, undisturbed slag infiltration, adequate strand lubrication and the control of mould heat transfer. For increased casting speeds i.e. up to 8?m/min, slag infiltration and in particular the control of mould heat transfer via crystallisation of the slag film becomes even more important. It was found that a low powder consumption and hence a thin slag film is no restriction for an undisturbed thin slab casting process. Given a stable casting process and machine condition, the mould powder properties are not as critical as widely assumed.