重轨钢大方坯连铸动态轻压下技术研究

Research on Dynamic Soft Reduction Technologies for Bloom Continuous Casting of Heavy Rail

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。

With the aim of reducing the center looseness and central segregation of heavy rail steel bloom by enhancing the metallurgical results of soft reduction （SR） employed in continuous bloom caster, a series of experiments for optimizing the process parameters of soft reduction is carried out. The influence of the soft reduction parameters on the internal quality of heavy rail steel bloom is analyzed, which include center looseness and central segregation etc. On the basis, the dynamic soft reduction scheme most suitable for heavy rail steel is devel- oped, which improves the internal quality of heavy rail steel bloom obviously. The practical operation shows that the ratio of center looseness ≤ 1.0 is increased from 28% to 99.91 %, central segregation and central shrinkage cavity are all ≤ 1.0 whose ratio are 40.91% and 92.05% respectively before optimization, and central segregation index of carbon is decreased from 1.17 to 1.05. Internal quality and mechanical performance of the rails produced from continuously cast blooms have met the requirement of 350 km/h highspeed tracks.