GCr15轴承钢大方坯宏观碳偏析形成机理及二次冷却调控机制研究

以国内某钢厂GCr15轴承钢连铸坯实际生产为研究对象，建立了GCr15轴承钢连铸坯凝固传热-微观组织耦合模型，通过研究不同连铸二次冷却模式下大方坯凝固组织特征参数（二次枝晶间距(SDAS)、中心等轴晶率(ECR)）的变化规律，阐明了二次冷却模式对GCr15轴承钢连铸坯凝固组织的影响机理。在此基础上，结合工厂试验与数值模拟分析，阐述了凝固组织特征对宏观碳偏析的作用机理。综合以上研究，揭示了GCr15轴承钢连铸坯二次冷却模式-凝固组织特征参数-宏观碳偏析的作用关系，从“宏-微”观角度提出，通过改善二次冷却调控机制，优化铸坯凝固组织结构，进而减轻GCr15轴承钢的宏观碳偏析。

Research on carbon macro-segregation mechanism and secondary cooling control for bloom of GCr15 bearing steel

A coupling model of heat transfer and microstructure for GCr15 bearing steel from a domestic steel plant is established to study the influence mechanism of different secondary cooling patterns on the variation of characteristic parameters (secondary dendrite arming spacing, equiaxed crystal ratio). On this basis, the influence of microstructure evolution on carbon macro-segregation is researched via plant trials and numerical simulation. Based on above results, the relationship of secondary cooling pattern, characteristic parameters for solidification structure as well as carbon macro-segregation is revealed from the “macro-micro” perspective thus alleviating the carbon macro-segregation degree for GCr15 bearing steel by obtaining reasonable secondary cooling control pattern.