大方坯连铸动态轻压下技术应用研究

简述了攀钢引进的奥钢联SMART/ASTC动态轻压下技术及其在重轨钢大方坯连铸生产中的应用效果.生产结果表明铸坯表面无清理率达到100%,中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤0.5级,中心碳偏析指数≤1.05,为攀钢生产合格的高速铁路用钢轨铸坯提供了条件.     

大方坯连铸动态轻压下技术应用研究

攀钢全连铸工程新建的大方坯连铸机采用了奥钢联SMART／ASTC动态轻压下技术。自大方坯连铸机投产以来,以重轨钢、硬线等典型钢种为代表开展了应用大方坯连铸轻压下技术的试验研究。通过不断优化调整轻压下工艺制度,取得了改善铸坯中心偏析、疏松和缩孔的显著效果。结果表明,铸坯表面无清理率达到100％,中心疏松≤1．0级,中心偏析≤1．0级,中心缩孔≤0．5级,中心碳偏析指数≤1．05,无其他内部质量缺陷,为攀钢生产高速铁路用钢轨提供了合格铸坯。     

连铸大方坯动态轻压下冶金效果分析

动态轻压下技术是减轻铸坯的中心偏析与疏松缺陷、提升铸坯内部质量的有效途径.包钢新建的5号大方坯铸机的动态轻压下控制系统由北京科技大学与包钢合作设计和开发,能够在非稳态的浇注条件下进行有效的动态轻压下和动态二冷配水实时控制.针对重轨钢U71Mn、U75V等代表性钢种,在5号连铸机上进行了动态轻压下冶金效果热负荷试验.经过合理地制定试验方案、取样设计以及冶金效果分析,结果表明,采用动态轻压下工艺后,铸坯中心疏松明显减轻,中心区域等轴晶率增加,连铸坯横断面上C成分分布更加均匀,中心C偏析指数波动范围明显变窄,有效减轻了铸坯的中心偏析缺陷,铸坯内质得到明显提升.     

重轨钢大方坯连铸动态轻压下技术研究

针对攀钢大方坯连铸机投产初期引进的轻压下装备技术冶金效果不明显、重轨钢铸坯中心疏松、中心偏析等内部缺陷较严重的问题,开展了优化重轨钢连铸轻压下工艺的现场试验,对比研究了轻压下工艺对重轨钢铸坯中心疏松、中心偏析等内部质量的影响,建立了适应重轨钢要求的动态轻压下工艺技术.生产实践表明,重轨钢铸坯内部质量明显提高,铸坯中心疏松评级≤1.0级的比例由28.41%增至99.91%,中心偏析评级≤1.0级的比例由40.91%增至100%,中心缩孔≤1.0级的比例由92.05%增至100%,铸坯中心碳偏析指数由1.17降至1.05,连铸坯轧制的重轨的内部质量和力学性能完全满足350 km/h高速轨要求.     

连铸大方坯轻压下过程的变形行为

首先从理论上描述了轻压下过程铸坯的三维变形行为,并采用有限元法定量分析了轻压下工艺对铸坯变形行为的影响规律.结果表明:铸坯宽展变形和延展变形达到平衡后,随着压下量增加,铸坯延展率随压下量呈直线关系变化.在相同轻压下条件下,随铸坯长宽比和中心未凝固率的增加,铸坯宽展效率和延展效率下降,压下效率增加.     

大方坯连铸轻压下压下过程有限元分析

基于某钢厂的铸机条件,建立了大方坯连铸轻压下的有限元模型,得到了不同压下量和固相率下铸坯表面变化量和压下辊作用范围的规律。结果表明：在一定的压下量范围内,压下后铸坯表面的反弹量约为压下量的19%;压下量每增加1mm,压下辊的作用范围增加16mm;固相率每增加0.2,反弹量增加压下量的1.7%;实施轻压下时应该考虑压下的反弹量。     

攀钢重轨钢大方坯成功应用“动态轻压下”技术

近日，攀钢于国内率先在重轨钢大方坯连铸生产中成功应用了动态轻压下技术，标志着攀钢重轨钢大方坯连铸工艺取得新的突破。     

板坯连铸动态轻压下控制模型的开发与应用

 为保证轻压下参数的有效、稳定实施,研究开发了板坯动态轻压下控制模型,给出了模型计算流程,详述了压下起始段和结束段的辊缝设定值计算方法,并分析了铸坯自然热收缩制度和轻压下作用方式切换条件。模型投产应用后,低碳钢、包晶钢、低合金钢的中心偏析均控制在C级0.5以内,中心疏松基本消除。     

国产动态轻压下设备的应用

包头钢铁集团公司在2006年底投产的5号连铸机上成功安装国产动态轻压下设备,并对重轨钢进行了轻压下试验研究.1年多的试验结果表明:该轻压下设备在合理的工艺条件下可以显著提高重轨钢的质量,改善了重轨钢铸坯的碳元素平均偏差指数,钢轨的内伤率减少,并使普通钢轨的成分偏差达到了高速轨的要求.     

大方坯连铸关键装备技术应用研究

简述了攀钢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在重轨钢连铸中的应用效果。生产统计表明,铸坯表面无清理率达到100％,中心疏松≤1．0级,中心偏析≤1．0级,中心缩孔≤0．5级,中心碳偏析指数≤1．05,等轴晶率≥38％,为攀钢生产高速铁路用钢轨提供了合格铸坯。     

Control Model of Bloom Dynamic Soft Reduction

There are significant effects of process parameters on internal qualities of bloom,and these process parameters are as follows:position and reduction amount,reduction distribution,reduction rate,and so on.Developing a control model is the key to apply soft reduction technology successfully.As the research object,360 mm×450 mm bloom caster in PISCO (Panzhihua Iron and Steel Co.) has been studied,and the research method for control model of dynamic soft reduction has been proposed.On the basis of solidification and heat transfer model,the position of soft reduction and reduction distribution of each frame are determined according to the bloom temperature distribution and solid fraction in bloom center calculated.Production practice shows that the ratio of center porosity which is less than or equal to 1.0,increased to 97.27%,ratio of central segregation which is less than or equal to 0.5,increased to 80.91%,and ratio of central carbon segregation index which is more than or equal to 1.10,decreased to 4% with the applying model of dynamic soft reduction.     

Dynamic Soft Reduction Technology for Bloom Casting

 The dynamic soft reduction technology for 360mm×450mm bloom casting and its application results at PISCO (Panzhihua Iron &; Steel Co.) were presented. In order to analyze the influence of the soft reduction on internal defects of bloom, such as center porosity and central segregation, experiment for contrasting process with or without soft reduction for bloom was investigated. The operation shows that after applying the soft reduction of bloom alloy steel, the ratio of center porosity whose defect level is below 1.0 increased from 66.67% to 85.71%, ratio of central segregation whose defect level is below 1.0 increased from 94.44% to 100%, ratio of central shrinkage cavity which is free increased from 88.89% to 96.42%, and central segregation index of carbon decreased from mean value of 1.15 to 1.05. These results have provided important technology supports for PISCO to optimize the steel product structure, and to improve the production of high quality, property, and value added products.     

连铸动态轻压下关键技术与自主开发应用进展

连铸机动态轻压下技术是解决铸坯中心偏析和中心疏松的有效手段。在总结国内外研究工作的基础上阐述了动态轻压下的关键技术,介绍了该技术的国内自主开发进展及应用效果。随着轻压下技术的广泛应用和推广,动态轻压下技术的自主研究、设计和应用已成为发展中国高端钢铁产品的必然趋势。     

连铸轻压下技术的发展和应用

介绍了轻压下技术的作用机理及发展过程，分析了轻压下工艺参数：压下区间、压下量及压下速率，研究了轻压下工艺对铸坯组织结构、性能、表面质量和内部裂纹的影响。     

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.