喂钢带碳浓度对连铸大圆坯宏观偏析的影响

Effect of Feeding Steel Strip Carbon Content on Macrosegregation Distribution in Large Continuous Casting Round Bloom

结晶器喂钢带工艺是提高大截面连铸坯中心质量的有效方法之一.本文发展了液相-柱状晶-等轴晶三相体积平均凝固模型,探究了喂入钢带的碳浓度对连铸大圆坯凝固组织结构及宏观偏析分布的影响规律.结果表明:喂入钢带的碳浓度会极大地影响等轴晶与柱状晶的生长,碳浓度过低或过高均会降低喂钢带对等轴晶体积分数提高的效果.通过调控钢带溶质浓度可以直接影响铸坯内溶质浓度及分布,喂入1.0倍钢液碳浓度(r_(C)=1.0)的钢带对连铸坯宏观偏析的改善效果最佳,其中铸坯径向碳极差和宏观偏析指数极值差分别为0.165 7%和38.36%.

Feeding a cold steel strip into continuous casting(CC)mold is an effective method to improve the center quality of large round bloom.A liquid‐columnar‐equiaxed solidification three‐phase volume averaged solidification model was developed to explore the effect of feeding strip carbon content on solidification structure and macrosegregation distribution of large CC round bloom in this paper.The results show that the carbon content of feeding steel strip has a significant effect on the growth of equiaxed crystals and columnar crystals.Under the condition of both low and high strip carbon contents,the effect of feeding steel strip on increasing equiaxed grain volume fraction will be reduced.The solute concentration and distribution in the casting bloom can be directly affected by regulating the solute concentration of steel strip.The steel strip with 1.0 times the carbon content of casting steel(r_(C)=1.0)has the best improvement effect on the large CC round bloom,with the radial extreme difference of carbon content and macrosegregation index of the bloom being 0.1657% and 38.36%,respectively.