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.     

重轨钢大方坯连铸二冷系统及轻压下工艺的优化

针对武钢生产重轨钢初期,连铸二冷系统和轻压下工艺参数不合理,铸坯存在部分内裂纹、中心疏松严重、重轨探伤合格率低等问题,开展了优化二冷配水和轻压下的试验。通过工艺优化使重轨钢铸坯质量得到明显改善,铸坯内裂纹消失、疏松I级率从之前的89.64%上升至99.51%,铸坯生产的重轨探伤合格率由85%左右上升至98.3%。     

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。     

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.     

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.     

动态轻压下工艺在重轨钢生产中的应用效果分析

5#铸机是国产的较先进连铸机,主要用于生产包括高速轨在内的重轨钢.第一台国产动态轻压下设备在包钢2006年底投产的5#铸机上成功安装.文章对重轨钢等典型钢种进行了轻压下试验研究,经过一年多的试验,结果表明:该轻压下设备在合理的工艺条件下可以显著改善重轨钢的质量,横断面中心碳偏析指数不大于1.04,铸坯纵向中心线的碳偏析指数波动明显减小,中心裂纹不大于1级,中间裂纹为不大于1级,钢轨的轨腰中心条纹明显减轻.     

动态轻压下模型对连铸坯内部质量改善的影响

针对南阳汉冶特钢有限公司250 mm×1 600 mm连铸坯内在质量差的情况,通过铸坯射钉试验建立了连铸动态轻压下控制模型.模型投入连铸生产使用后,可根据生产钢种工艺条件的不同实现动态二冷配水调整及轻压下参数调整,在减轻铸坯中心偏析,改善铸坯内在质量方面效果明显,极大的提高了轧后钢板探伤质量合格率.     

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。     

高速重轨钢连铸坯质量控制技术研究

高速铁路要求钢轨连铸坯具有良好的表面和内部质量。文章介绍了包钢大方坯连铸机应用结晶器电磁搅拌、动态二冷配水与动态轻压下等关键技术生产重轨钢U71Mn、U75V等代表性钢种的效果。     

GCr15轴承钢大方坯连铸生产中动态轻压下工艺的应用

介绍了动态轻压下技术(轻压下区域铸坯固相率40%～96%,总压下量8.3～12.5mm)在邢台钢铁公司285 mm×325 mm连铸机生产GCr15轴承钢连铸坯的应用。结果表明,当钢水过热度20～30℃,拉速0.65～0.75m/min,实施动态轻压下后,中心疏松评级≤1.5级和中心缩孔0～1.5级的比例分别由未压下的49.45%和63.74%增加到了85.0%和87.5%;碳偏析值范围由未压下的0.875～1.390变为0.872～1.086;中心偏析和V型偏析明显改善。     

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.     

轻压下改善重轨钢铸坯成分均匀性的生产试验

包钢在5~#280 mm×380 mm方坯连铸机上安装了一套国产动态轻压下设备、对重轨钢U71 Mn和U75V进行了一年多的生产试验。结果表明,在合理工艺条件下,采用轻压下可显著改善重轨钢的中心碳偏析,横断面中心碳偏析指数≤1.08,铸坯纵向中心线碳偏析指数波动明显减小,钢轨成分偏差也随之减小。     

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.     

方坯连铸动态轻压下的研究

利用三维弹塑性大变形的热机耦合模型,研究了在不同的中心固相率、不同的压下量条件下,液芯体积收缩率变化规律以及压下辊所需的压下力,同时分析了压下工艺参数对铸坯内裂纹的影响,并提出了动态轻压下的压下方案。     

Closure of Internal Porosity in Continuous Casting Bloom During Heavy Reduction Process

Metallurgical and Materials Transactions B - To investigate the closure behavior of internal porosity (also referred to as internal void) in continuous casting bloom during heavy reduction (HR) and...     

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.