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为研究在动态轻压下条件下等轴晶和柱状晶组织与管线钢板坯中心偏析的关系,试验通过改变中包钢水过热度来获得铸坯中心不同凝固组织,并分析不同凝固组织内的中心偏析情况。试验铸坯分别采用热酸腐蚀、化学分析的方法,定性、定量分析过热度在11～32℃之间,铸坯厚度方向上元素含量分布和不同凝固组织中的偏析形貌。结果显示:过热度在14℃以下的坯样中心为等轴晶组织,过热度在20℃以上的坯样中心完全为柱状晶组织;在现有轻压下条件下,中心为等轴晶和过热度为32℃时中心柱状晶组织的坯样中心偏析度均较低,但因铸坯中心整个等轴晶区内会分布着偏析点,因而较之中心柱状晶组织,中心为等轴晶组织中点状偏析分布范围较宽;当中心为柱状晶组织时,适当提高过热度、优化压下量,可降低中心偏析度,提高中心偏析评级。
In order to study the relationship between the equiaxed grains and columnar grain structure and centerline segregation of pipeline slab under the condition of dynamic soft reduction, different solidified structures in slab center were obtained by changing overheating degree of tundish, Center segregation situation. The test cast slabs were respectively treated by hot acid etching and chemical analysis. The superheat of the cast slabs was qualitatively and quantitatively analyzed at 11 ~ 32 ℃, the element content distribution in the slab thickness direction and the segregation morphology in different solidified structures. The results show that the center of the billet with the superheat below 14 ℃ is equiaxed and the center of the billet with superheat above 20 ℃ is completely columnar crystal structure. Under the existing soft reduction conditions, the center is equiaxed and When the degree of superheat is 32 ℃, the center segregation degree of the center columnar crystal structure is low, but because the segregation point is distributed in the entire equiaxed zone of the center of the slab, the center is equiaxed crystal When the center is columnar crystal structure, proper increase of superheat and optimization of the reduction can reduce the center segregation and improve the center segregation rating.