连铸凝固过程宏观偏析的形成机理及预防措施

Formation Mechanism and Prevention Measurements of Macro-segregation during Continuous Casting Solidification

连铸坯的宏观偏析是影响钢材质量的重要原因之一,宏观偏析形成的本质原因是凝固过程固、液两相发生对流。对连铸凝固过程引起钢液流动的原因如外力强制对流、鼓肚、凝固收缩等进行了总结,并对这些原因造成宏观偏析的机理进行了分析。低过热度浇注、电磁搅拌、凝固末端液芯压下等技术是解决连铸坯宏观偏析的有效措施,然而单一的方法无法完全消除连铸坯宏观偏析,要完全解决铸坯宏观偏析应针对不同类型的偏析,采取相应的方法提高铸坯成分均匀性。

The macro-segregation of alloying elements during continuous casting steel has adverse effect on the quality of steel product. The nature of macro-segregation in casting is physical movement of liquid phase or solid phase during solidification. The causes of molten steel flow in continuous casting process were summarized,such as forced convection by external force, bulging and solidification shrinkage. Accordingly, the mechanisms of macro-segregation caused by these factors were analyzed. To solve macro-segregation, the technologies such as low superheat pouring ,electromagnetic stirring and liquid core reduction at the end of solidification were applied. However,practice result shows that this problem could not be solved by using every individual technology alone . In order to improve the composition uniformity of continuous casting product, it is advised that the corresponding measurements should be adopted for each type of segregation.