溶质元素的微观偏析及其对连铸坯中间裂纹的影响  

Microsegregation of solute elements and its effect on intermediate crack of continuous casting slab

作　　者：李麦麦 肖超 颜昊 LI Maimai;XIAO Chao;YAN Hao(Qingdao Branch of CITIC Pacific Steel Research Institute,Qingdao Special Steel Co.,Ltd.,Qingdao 266000,Shandong,China;Automotive Research Institute,China National Heavy Duty Truck Group Co.,Ltd.,Jinan 250000,Shandong,China)

机构地区：[1]青岛特殊钢铁有限公司中特研究院青钢分院,山东青岛266000 [2]中国重型汽车集团有限公司汽车研究总院,山东济南250000

出　　处：《连铸》2023年第5期57-63,共7页Continuous Casting

摘　　要：以Ueshima等提出来的正六面体模型为基础,采用板坯凝固的实际冷却数据,建立了溶质元素的微观偏析模型,采用偏析模型分析了位于柱状晶区末端的裂纹起源处溶质元素的偏析情况;考虑传热、钢水静压力和相变等因素,采用有限元软件模拟分析了凝固坯壳承受的应变情况,分析中间裂纹的形成机理。结果表明,柱状晶区末端的裂纹起源处的P、S元素偏析严重,碳偏析相对较轻,枝晶间偏析使裂纹的形成温度区间即LIT和ZDT的差值显著增大,元素的偏析是形成中间裂纹的关键内在原因;坯壳厚度等于裂纹起源距内弧的距离即85 mm时,坯壳所承受的拉应变大大超过了铸坯凝固时所允许的临界应变值,具备了裂纹形成的外在受力因素。Based on the regular hexahedron model proposed by Ueshima et al.,and combined with the actual solidifi-cation and cooling conditions of continuous casting slab,the microscopic segregation model of solute elements was established.The segregation of solute elements at the crack origin at the end of the columnar crystal region was ana-lyzed by using the segregation model.Considering heat transfer,static pressure of molten steel and phase transfor-mation,the strain of solidified billet shell was simulated by finite element software to analyze the formation mecha-nism of intermediate crack.The results show that the segregation of phosphorus and sulfur elements at the end of the columnar crystal region is serious,and the segregation of carbon is relatively light.The difference between LIT and ZDT of the crack formation temperature increases significantly due to the segregation of elements.When the thickness of the billet is equal to the distance between the crack origin and the inner arc,that is,85 mm,the tensile strain of the billet greatly exceeds the critical strain value allowed during the solidification of the billet,which has the external force factor of crack formation.

关 键 词：溶质元素 显微偏析 中间裂纹 数值模型 坯壳应变 

分 类 号：TF777[冶金工程—钢铁冶金]