过热度对帘线钢连铸方坯碳偏析的影响

Effect of superheat on carbon segregation in continuous casting billet of cord steel

针对帘线钢生产过程中出现的质量波动问题,采用钻屑成分分析和低倍组织分析方法,研究了不同过热度对帘线钢连铸方坯横纵向碳偏析的影响。研究结果得出:(1)偏高过热度(34℃)比偏低过热度(29℃),其对应的中心碳偏析程度更低,中心线位置碳元素质量分数的波动程度更小;(2)V形偏析带是造成铸坯中心线位置偏析指数纵向发生波动的直接原因,这也表明仅通过横断面来判定铸坯偏析情况的好坏存在局限性;(3)过热度越低,等轴晶比例越高,但同时由于能够抽吸到中心位置附近的高溶质液相量更大,中心位置的偏析程度及波动程度可能更大。因此,对于本厂所生产的帘线钢而言,采用偏高的过热度铸坯碳元素分布更为均匀,质量更为稳定。

The influence of different superheat on the transverse and vertical carbon segregation of cord steel continuous casting billet was studied by means of drilling cutting composition analysis and solidification microstructure analysis for the quality fluctuation in cord steel production. The results show that the center carbon segregation degree of the higher degree of superheat （34 ℃） is lower than the lower superheat （29℃）, and the carbon element content fluctuation of center line position smaller than the lower superheat. The V-shaped segregation zone is the direct cause of longitudinal fluctuation of the carbon segregation index. It also shows that there are some limitations in revealing the segregation situation of the billet only by cross section. The lower the superheat degree, the higher the equiaxed ratio is, but at the same time due to the greater amount of solute liquid phase can be draw to the center of the vicinity, the central location of the degree of segregation and the degree of volatility may be greater. Therefore, the use of higher superheat in our plant, the carbon distribution of cord steel billet is more uniform, more stable quality.