连铸板坯全冶金长度凝固形貌  

Solidification morphology for full metallurgical length of continuous casting slab

作　　者：王鑫 孟祥宁 黄烁 朱苗勇 WANG Xin;MENG Xiangning;HUANG Shuo;ZHU Miaoyong(School of Metallurgy, Northeastern University, Shenyang 110819, China)

机构地区：[1]东北大学冶金学院,辽宁沈阳110819

出　　处：《中南大学学报（自然科学版）》2017年第12期3160-3169,共10页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51004031);中央高校基本科研业务费资助项目(N140205002)~~

摘　　要：采用移动边界法计算低碳钢连铸板坯全冶金长度温度场,利用CAFE耦合模型模拟其凝固行为,考察过热度和拉坯速度对板坯宽面中心温度、横断面微观组织形貌及二次枝晶臂间距等影响,并计算二次枝晶臂间距与冷却速度关系及碳元素中心偏析。研究结果表明:过热度和拉坯速度降低均能使宽面中心温度和中心二次枝晶臂间距下降,而拉坯速度的影响更为显著;拉坯速度越高中心等轴晶率越高,晶粒半径越小,利于提高连铸板坯质量,过热度对中心等轴晶率及晶粒半径影响较小;二次枝晶臂间距在固液两相区生成并增大,二次枝晶臂间距与冷却速度之间呈指数关系;连铸板坯中心偏析区域呈岛状分布在中心线上,最大偏析指数为1.14,中心部位负压抽吸临近枝晶间富积溶质钢液导致中心线附近形成负偏析。Steel solidification for continuously cast low carbon slab was calculated using a coupled model of CAFE in combination with the temperature distribution in the full metallurgical length,which was predicted by the moving boundary method.Further,the influences of steel superheat and casting speed on the central temperature of slab wide-surface,morphology of slab section and secondary dendritic arm spacing were investigated,and the relationship between arm spacing and cooling rate of steel as well as the central carbon segregation of slab were analyzed.The results show that the decreases of superheat and casting speed lead to the reductions of central temperature and arm spacing,and the impact from casting speed is more significant.Ratio of equiaxed zone increases with casting speed and the grain radius decreases,and it is conducive to improve the continuous casting slab quality,while the superheat does not have significant effect on casting speed and grain radius.Secondary dendritic arm spacing is formed and increased in mushy zone,and it presents an exponential trend with cooling rate.Central carbon segregation distributes in the central line of slab in the form of islands,and the maximum segregation index reaches1.14.Enriched solute elements around the dendrites are pumped into the steel by negative pressure and then generate the negative segregation.

关 键 词：连铸板坯 宽面中心温度 微观组织形貌 二次枝晶臂间距 碳偏析 

分 类 号：TF777[冶金工程—钢铁冶金]