辊式电磁搅拌线圈位置对板坯凝固行为的影响  

Effect of roller-typed electromagnetic stirring and its coils location on solidification behavior of a slab casting

作　　者：肖红 王璞 郑晴[3] 刘顺 陈希青 张家泉[2] XIAO Hong;WANG Pu;ZHENG Qing;LIU Shun;CHEN Xi-qing;ZHANG Jia-quan(Electromagnetic Center,Hunan Zhongke Electric Co.,Ltd.,Yueyang 414000,Hunan,China;School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;4th Steelmaking and Rolling General Works,Maanshan Iron and Steel Co.,Ltd.,Maanshan 243000,Anhui,China)

机构地区：[1]湖南中科电气股份有限公司磁电研究院,湖南岳阳414000 [2]北京科技大学冶金与生态工程学院,北京100083 [3]马鞍山钢铁股份有限公司第四钢轧总厂,安徽马鞍山243000

出　　处：《钢铁》2023年第3期79-88,共10页Iron and Steel

基　　金：湖南省科技计划资助项目(2019RS2065)。

摘　　要：铸流辊式电磁搅拌是当前调控板坯凝固组织与抑制中间裂纹的有效技术。为了揭示其作用机理以及使用过程伴生的铸态组织不对称与白亮带现象,通过建立连铸过程电磁-流动-传热-凝固耦合模型,并采用分段模拟法,研究了辊式电磁搅拌及其线圈不同偏置位置对1 600 mm×230 mm断面低合金高强钢板坯连铸凝固行为的影响。结果表明,电磁辊在坯壳凝固前沿所产生的行波磁场的切向力效应及其对浓化钢水流动与温度场的影响促使了柱状晶向等轴晶生长的转变,从而在铸态组织上消除了常见中间裂纹缺陷的发生条件。同时发现,在电磁辊线圈与板坯断面对中安装工况下,其行波磁场存在突出的端部效应,即起始侧的磁感应强度与电磁力明显小于推向侧,这是导致板坯断面两端铸态组织不对称的主要原因。通过将线圈向搅拌辊行波磁场起始侧偏置安装可以有效减轻这种不对称的作用行为。当前板坯断面条件下,偏置量为150 mm时,板坯两端的磁感应强度可接近一致,铸态组织实现基本对称。结合生产试验指出,搅拌辊在坯壳凝固前沿产生横向电磁推力的冲刷作用是造成其在铸态组织中发生负偏析白亮带的诱因,这种白亮带不影响当前产品的成材率,但在后续板带产品中的演变与危害性尚不清楚。Roller-typed electromagnetic stirring(R-EMS)is one of effective measures to control the as-cast macro-structure and prevent the occurrence of mid-way cracks for slab casting.To reveal the mechanism and the frequently attendant asymmetrical solidification along with white band,the solidification behavior of a slab casting with section of 1600mm×230mm has been numerically studied upon the applications a roller-typed electromagnetic stirrer,for which a coupled electro-magnetic,fluid flow,heat transfer and solidification model has been adopted by segment to segment consecutive calculation.It has been shown that it is the tangential forces produced by R-EMS ahead of the solidification frontier and its effect on the local enriched fluid flow and temperature which promote the columnar to e-quiaxed crystal transformation,and eliminate the occurrence condition of mid-way cracks from as-cast structure.It is found,there exists an obvious end effect for travelling wave magnetic field in the cross section while the EMS roll-er being in alignment with the slab geometrically.To be exact,the magnetic induction intensity and its induced force are much larger in the other side of the slab as compared with the initial side,which should be the reason of its final asymmetrical solidification structure.However,the asymmetrical behavior can be partly alleviated by an offset loca-tion of the roller coils toward the initial side.For the present format of slab casting,the magnetic induction intensity and the final as-cast structure shows a nearly symmetrical ones with a coil offset value around 150mm.Finally,it has been addressed that the white band of negative segregation,a scour marks left by the intensified fluid flow due to electromagnetic force,shows no unacceptable effect on the finished products presently,but should be given attention in the future for its change in the following hot rolling products and any possible other disadvantage.

关 键 词：辊式电磁磁拌 行波磁场 端部效应 线圈位置 凝固行为 

分 类 号：TF777[冶金工程—钢铁冶金]