20CrMnTi钢160mm×160mm方坯内部质量控制  

Internal quality control of 160 mm×160 mm square billet of 20CrMnTi steel with EMS

作　　者：康吉柏 王卫领 罗腾飞 罗森 朱苗勇 KANG Ji-bai;WANG Wei-ling;LUO Teng-fei;LUO Sen;ZHU Miao-yong(School of Metallurgy,Northeastern University,Shenyang 110819,Liaoning,China;State Key Laboratory of Rolling and Automation.Northeastern University,Shenyang 110819,Liaoning,China)

机构地区：[1]东北大学冶金学院,辽宁沈阳110819 [2]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819

出　　处：《钢铁》2021年第2期82-92,共11页Iron and Steel

基　　金：国家自然科学基金资助项目(51804067,51674072);辽宁省“兴辽英才计划”资助项目(XLYC1802032);中央高校基本科研业务专项资金资助项目(N2025027,N182504014)。

摘　　要：针对20CrMnTi连铸160mm×160mm方坯严重的内部质量问题,开展结晶器电磁搅拌(M-EMS)与凝固末端电磁搅拌(F-EMS)参数协同优化试验,通过方坯凝固组织检测和碳偏析检测,详细分析电磁搅拌参数对方坯内部质量的影响规律。此外,借助红外热成像仪检测方坯表面温度,进而利用ANSYS软件预测方坯凝固传热过程,得到F-EMS作用区域内的液芯厚度。结果表明,方坯内弧侧与外弧侧柱状晶向等轴晶转变(CET)的起始位置分别距方坯表面约42和28mm,在M-EMS 240~260A条件下,受M-EMS电流强度的影响很小;碳元素在方坯皮下10mm内存在负偏析,然而在CET前沿富集,同时在凝固中心呈现为交替正、负偏析;凝固中心附近负偏析程度正相关于M-EMS和F-EMS强度。根据方坯低倍组织与碳偏析情况,最终确定20CrMnTi最佳的电磁搅拌参数为M-EMS 250A/4.0Hz、F-EMS 300A/7.0Hz。另外,F-EMS入口与出口处的液芯厚度分别为66.2和60.6mm,与之对应的固相率分别为86.6%和88.7%,F-EMS安装位置合理。In order to improve the severe internal quality problems in continuously cast 160 mm×160 mm billets of 20CrMnTi,industrial tests to optimize synergistically processing parameters of mold electromagnetic stirring(M-EMS)and final electromagnetic stirring(F-EMS)were carried out.The effects of technical parameters on the internal quality of 20CrMnTi billets were analyzed in detail through the chemical etching for the macrostructure and via measurements for the carbon contents.Besides,an infrared thermal image instrument was used to test the billet surface temperature,and ANSYS software was subsequently utilized to calculate the temperature variation during the solidification of the billet.Accordingly,the thickness of the liquid pool at F-EMS was obtained.The results show that the initial locations of columnar-to-equiaxed transition(CET)zone at the inner arc and outer arc sides are fixed around 42 and 28 mm,respectively,and they have only a little change within the range of M-EMS current intensity from 240 to 260 A.There exists negative segregation of carbon at 10 mm below the billet surface.However,carbon enriches in front of the CET zone and appears to be positive and negative segregation alternately in the solidification center.The negative segregation of carbon in the vicinity of the solidification center is positively correlated with the stirring intensity of M-EMS and F-EMS.According to the experimental results,the optimal parameters of M-EMS and F-EMS are 250 A/4.0 Hz and 300 A/7.0 Hz,respectively.Additionally,the liquid pool’s thicknesses vary from 66.2 mm at the entrance of F-EMS stirrer to 60.6 mm at the outlet of F-EMS stirrer and the corresponding solidification ratio ranges from 86.6% to 88.7%,which manifests that the current F-EMS implemented position is proposed.

关 键 词：20CrMnTi 碳宏观偏析 结晶器 电磁搅拌(M-EMS) 凝固末端电磁搅拌(F-EMS) 

分 类 号：TF777.2[冶金工程—钢铁冶金]