攀钢大方坯连铸钢轨钢的生产工艺及质量控制

攀钢大方坯连铸机建成投产后,迅速实现了钢轨钢生产工艺由模铸向连铸的转变.采用连铸工艺生产钢轨钢,通过成分精度、钢质纯净度和连铸工艺参术的控制,获得了质量良好的铸坯和钢轨,完全满足200km/h客运专线钢轨的质量要求,部分指标达到350km/h高速轨的要求.     

高速轨用钢连铸坯内部质量控制的关键技术

简述了攀钢提高350 km/h高速轨用钢连铸坯内部质量的控制技术,包括大方坯连铸结晶器电磁搅拌技术、二冷控制技术和凝固末端动态轻压下技术及其在重轨钢连铸中的应用效果.近3年的生产实践表明,课题研究解决了重轨钢连铸大方坯中心疏松、中心偏析、中心裂纹等内部缺陷较严重的技术难题,重轨钢连铸坯内部质量优异,铸坯收得率达到98.55%,铸坯合格率达到99.97%,铸坯中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤1.0级,中心裂纹≤0.5级,中间裂纹≤0.5级,中心碳偏析指数≤1.05,为攀钢开发生产350 km/h高速铁路用钢轨提供了合格铸坯.     

重轨钢大方坯连铸二冷技术研究

针对攀钢大方坯连铸引进的二冷控制技术在连铸比水量和二冷区水量分配等方面存在的问题,通过测试研究重轨钢的高温延塑性能和二冷区的铸坯表面温度分布,制定了满足攀钢重轨钢连铸工艺要求的二冷控制制度.生产应用表明,重轨钢连铸坯内部质量明显提高,铸坯中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤1.0级,中心碳偏析指数≤1.05,中心区域等轴晶率≥30%,由连铸坯轧成重轨的内部质量和力学性能能够满足350 km/h高速铁路用钢轨的要求.     

重轨钢连铸结晶器电磁搅拌技术应用研究

针对大方坯连铸机投产初期重轨钢连铸电磁搅拌冶金效果不明显的问题,开展了优化重轨钢连铸结晶器电磁搅拌工艺参数的现场试验,对比研究了电磁搅拌电流强度对重轨钢铸坯中心疏松、中心偏析、等轴晶率等内部质量的影响,制定了满足攀钢重轨钢连铸工艺要求的电磁搅拌工艺制度.生产应用表明,重轨钢连铸坯内部质量明显提高,铸坯中心区等轴晶率由18.8%增至36.2%,中心疏松≤1.5级,中心偏析≤1.0级,中心缩孔≤1.0级,中心碳偏析指数≤1.05,连铸坯轧成重轨的内部质量和力学性能能够满足350 km/h高速铁路用钢轨的要求.     

连铸坯生产铁路钢轨

介绍了库兹涅茨克等几家钢铁公司用连铸坯生产钢轨的情况，分析了铸坯各种缺陷和分布，认为通过优化铸坯断面规格和面的比值，可保证缺陷在钢轨中有满意的颁上并根据缺陷对钢轨使用性能的影响，对钢轨中的缺陷作了等级、分布的限定，通过试车场实验和铁路的使用实验，考核和评定了连铸坯所扎钢轨的使用性能。     

结晶器电磁搅拌改善重轨钢连铸坯内部质量的试验研究

针对攀钢大方坯连铸机投产初期重轨钢连铸电磁搅拌冶金效果不明显的问题,开展了优化重轨钢连铸结晶器电磁搅拌工艺参数的现场试验,对比研究了电磁搅拌电流对重轨钢铸坯中心疏松、中心偏析、等轴晶率等内部质量的影响,制定了满足攀钢重轨钢连铸工艺要求的电磁搅拌工艺制度.生产应用表明,重轨钢连铸坯内部质量明显提高,铸坯中心区等轴晶率由18.8%增至36.2%,中心疏松≤1.5级,中心偏析≤1.0级,中心缩孔≤1.0级,连铸坯轧成重轨的内部质量和力学性能能够满足时速350 km高速铁路用钢轨的要求.     

重载铁路钢轨钢连铸重压下工艺研发及应用

与普通铁路相比，重载铁路的运输具有大轴重、高牵引质量、大运量的特点，对钢轨的质量要求更为严苛。大断面连铸坯作为重载铁路钢轨钢生产的重要母材，提升母材连铸坯的质量才是决定重载铁路钢轨钢质量的关键。为了解决大断面连铸坯的内部质量问题，首先采用数值计算方法，研究了重轨钢连铸大方坯重压下过程的变形行为，为重压下工艺及装备设计提供了理论依据。在此基础上，结合现场生产实践，系统对比并分析了轻压下与重压下工艺对重载铁路钢轨钢内部质量的影响，证明了实施重压下工艺可以大幅度提升重轨钢的内部质量。     

高洁净度钢轨钢的夹杂物控制技术

针对国内生产350 km/h高洁净度钢轨存在非金属夹杂物控制的核心问题,开展了相关研究.通过采用适宜的钢包底部吹氩模式和钢包渣组成,显著提高了钢中非金属夹杂物的去除率,T[O]去除率提高近40%;对硫化物夹杂的变性处理有效地控制了钢轨钢中夹杂组成和形态.这些技术在350 km/h高洁净度钢轨钢生产中的应用,不仅使钢轨的T[O]降到10.17×10-6,而且A类和B、C、D类非金属夹杂物评级分别≤2.0级和1.0级,实现了350km/h高洁净度钢轨钢的批量生产.     

用连铸坯生产铁路钢轨

乌克兰冶金工业科学研究所和库兹涅茨克钢铁公司及亚速钢厂共同制订出用连俦坯生产P65铁路钢轨的轧制工艺。电炉钢轨钢的冶炼和浇铸是在奥斯科尔电冶金公司和顿涅茨克钢铁厂的连铸机上进行的。冶炼和浇铸时采用了各种先进的炉外处理技术(吹氩、真空处理),连铸坯的冷却方式为缓冷。在亚速钢厂将第聂伯钢厂生产     

我国重轨生产的发展

随着铁路运输事业的飞速发展,铁路货运量日益增加,有的繁忙路线货运量已超过100Mt/km,轴重也不断加大,目前的重型钢轨已不能满足铁路事业的需要。为此,我们必须开发新钢种,研制75kg/m以上的重型钢轨和耐磨合金钢轨。在完善目前仅有的三条全长淬火线的同时,要加速耐磨合金轨的研制,鞍钢已经研制了SiMnVXt特级合金钢轨,其耐磨性能是中锰钢轨的4倍,并要积极吸收国外经验,采用连铸坯轧制钢轨,研究控制轧制和控制冷却技术。     

重轨钢连铸坯内部质量控制技术

针对攀钢大方坯连铸机投产初期重轨钢连铸坯中心疏松、中心偏析等内部缺陷较严重的问题,研究应用了提高重轨钢连铸坯内部质量的控制技术,包括凝固末端动态轻压下、结晶器电磁搅拌、二冷动态控制、连铸拉速与钢水温度优化控制等核心工艺技术.生产实践表明,重轨钢连铸坯综合合格率达到99.97%,铸坯中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤1.0级,中心裂纹≤0.5级,中间裂纹≤0.5级,角部内裂≤0.5级,中心碳偏析指数≤1.05,由连铸坯轧成重轨的内部质量和力学性能满足时速350 km高速铁路用钢轨的要求.     

Dynamic Soft Reduction for Continuously Cast Rail Bloom

  Center porosity and centerline segregation in continuously cast bloom can be minimized by the well known method of dynamic soft reduction. Metallurgical results of soft reduction previously employed in continuous bloom casting for heavy rail steel in Panzhihua Iron and Steel Group were not fully achieved because of the improper soft reduction process. Therefore, experiments for optimizing the process parameters of soft reduction for bloom were carried out. The results show that the proportion of the center porosity, which is less than 10, increases from 2841% to 9981%, while the proportion of the centerline segregation class increases from 4091% to 100%, and the proportion of the central cavity increases from 9205% to 100%, whereas the center carbon segregation index decreases from 117 to 105. The internal quality and the mechanical performance of the rails produced from continuously cast blooms meet the requirement of high speed tracks of 350 km/h.     

Research on Key Metallurgical Technology of 350Km/h High‐Speed Rail Steel

Requirements like higher cleanliness and better quality of casting blooms are proposed for 350km/h higher speed rail steel. Present paper focuses on technical measures on improving the steel cleanliness and strand quality of 350km/h high‐speed rail steel in Panzhihua Iron & Steel Group Company. By means of series of packaging technology like dephosphorization in BOF, ladle refining, mold electromagnetic stirring and dynamic soft reduction, dephosphorization rate cleanliness and morphology control are greatly improved, with [S]≤0.015%, [P]≤0.025%, [H]≤1.5 × 10^?6, Al_s ≤ 0.004%, T[O] ≤20 × 10^?6, the grade of central porosity and segregation ≤1.0, the grade of central crack and middle crack ≤0.5, index of central carbon segregation ≤1.05, severity level of type‐A and type‐B inclusions ≤2.0 and 1.0, respectively. The optimized process meets the technical requirements on producing 350 km/h high‐speed rail steel and stable production is realized.     

Effect of melting and casting parameters on the hot ductility behavior of Nb-bearing beams,billets and slabs

The production of defect free continuously cast microalloy Nb-bearing steel slabs, blooms and billets have increased in importance for both the producer and the end user. The minimization of surface and internal defects has a substantial impact on steel producing operating costs, internal and external cost of quality and delivery performance. A keen and thorough understanding of the hot ductility behavior of various steel grades is essential to successfully melt and cast high quality microalloy steels. This paper describes current steelmaking and casting considerations and recommendations to successfully cast high quality niobium-bearing slabs, billets and blooms. This study also integrates the process metallurgy and the physical metallurgy to better understand the hot ductility mechanisms and process metallurgy control practices in use today for the high quality production of Nb-bearing steels.     

高速铁路用钢轨生产技术

采用铌稀土(BNbRE)钢种,进行了钢的高纯净度、无缺陷连铸坯、高精度轧制、在线检验及相关技术研究,形成高级别钢轨生产工艺.结果表明:生产的钢轨能够满足<时速200公里客运专线60 kg/m钢轨暂行技术条件>的技术指标.     

连铸坯轧重轨的压缩比及帽形孔和切深孔的应力场分析

对某厂所使用的重轨孔型自切深孔以后的轧件压缩比进行了分析，对帽形孔和切深孔中沿轧件横断面上的应力场分布进行了弹塑性有限元计算机模拟。结果表明，用连铸坯取代初轧坯，如果坯形和孔形不进行相应的改变，轧件轨头和轨底的压缩比小，难以确保重轨的质量。现有的孔型，沿轧件的横断面上，局部位置存在着较大的拉应力。使用初轧坯，这种拉应力对产品质量的影响不大。但对于连铸坯，如果坯形和孔型均与初轧坯相同，轧件有产生内部缺陷的条件。     

帘线钢连铸坯中心偏析的控制技术

分析帘线钢连铸过程中中心偏析的形成原理及对铸坯质量的影响。研究帘线钢连铸坯中心偏析的控制措施,包括连铸拉速与钢水温度优化控制、结晶器电磁搅拌、凝固末端轻压下、二冷动态控制等核心工艺技术。通过应用这些技术,帘线钢WLX72A和WLX82A连铸坯平均中心碳偏析指数分别控制在1.042和1.027,综合合格率达到99.97%。     

Optimisation of flash welding parameters for wheel rim manufacture using continuously cast steels

Continuously cast steels are nowadays commonly employed for the manufacture of wheel rims, and the flash welding process is generally employed for that purpose. The current work addresses the flash welding of a continuously cast material (carbon steel with carbon segregation in it), in the wheel rim manufacturing process route, with emphasis on the control of process parameters on the quality of weld joints. It has been established in this research work that the controlled post weld heat cycles, during the flash welding process, Improve the quality of joints and also eliminate or at least drastically decrease the failure susceptibility of such flash welded joints during subsequent manufacturing operations.     

安钢炼铁厂1号高炉降低生铁成本的实践

安钢炼铁厂1号(350m3)高炉依靠科技进步,抓住高炉自身的特点,保持高炉炉况顺行,实现高煤比喷吹,加强企业管理等措施,使高炉各项技术指标不断改善,生铁成本不断降低.     

Nonmetallic Inclusion Control of 350 km/h High Speed Rail Steel

Inclusion has an important effect on quality of high speed rail steel. In consideration of the lower acceptance percentage of the inclusion and its constraint against the requirement for large scale production of 350 km/h high speed rail steel in Panzhihua Iron and Steel (Group) Co, the technology of nonmetallic inclusion control for 350 km/h high speed rail steel was studied. An optimized model of the argon-blowing in ladle furnace (LF), the control of the components of the ladle slag, and the technique of calcium treatment for the molten steel was brought forward. Using the researched technology, the removal ratio of the inclusion was increased and the components, distribution, and shape of the inclusion in the rail steel were changed, which resulted in a reduction in the average total oxygen content to 10. 17 × 10⁻⁶ and an increase in the comprehensive acceptance percentage of the nonmetallic inclusion from 48. 21% to 98. 1%. Test has shown that this metallurgical technology can meet the requirement for large scale production of 350 km/h high speed steel in Panzhihua Iron and Steel (Group) Co.