行波磁场铸流搅拌提升不锈钢板坯等轴晶率  

Stirring strands via traveling-wave magnetic fields to increase the equiaxed crystal ratio of stainless-steel slab castings

作　　者：肖红 王璞 兰芳 李伟红 唐海燕[1] 李爱武 张家泉[1] XIAO Hong;WANG Pu;LAN Fang;LI Wei-hong;TANG Hai-yan;LI Ai-wu;ZHANG Jia-quan(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;Magnetoelectric Research Institute,Hunan Zhongke Electric Co.,Ltd.,Yueyang 414000,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]湖南中科电气股份有限公司磁电研究院,岳阳414000

出　　处：《工程科学学报》2021年第6期797-807,共11页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(U1860111,51874033);国家重点研发计划资助项目(016YEB0601302);湖南省科技计划资助项目(2019RS2065)。

摘　　要：为揭示各种行波磁场铸流搅拌的电磁冶金效果,基于计算域分段法建立了断面1280 mm×200 mm板坯连铸电磁、流动、传热和凝固的耦合模型,利用电气参数和磁感应强度的实测值和预测值的对比验证了模型的可靠性.研究表明:行波磁场搅拌器因电磁推力的方向性特点在板坯二冷区搅拌过程中均表现有不同程度与特征的端部效应,辊后箱式搅拌器(Boxtyped electromagnetic stirrer,B-EMS)的单侧安装形式导致板坯内弧侧磁感应强度远大于外弧侧,辊式搅拌器(Roller-typed electromagnetic stirrer,R-EMS)的对辊安装形式则使磁感应强度呈现对称分布.在400 kW和7 Hz的相同电气参数下,REMS的电流强度比B-EMS高75 A;尽管箱式电磁搅拌的有效作用区域较辊式电磁搅拌大,铸坯中心钢液过热耗散区域大,但辊式搅拌推动钢液冲刷凝固前沿形核作用则明显大于箱式搅拌.两者均具有较好的抑制柱状晶生长、促进凝固前沿等轴晶形核与发展的能力,将不锈钢板坯等轴晶率提高至45%的门槛值以上,其中间隔型反向辊式搅拌器下的等轴晶率比箱式搅拌高约17%.综合表明,基于行波磁场铸流搅拌的间隔型反向辊式搅拌器有望更好地消除铁素体不锈钢板材表面皱折缺陷.Electromagnetic stirring of strands by a traveling-wave magnetic field is a cutting-edge continuous casting technology for eliminating the columnar crystal structure that tends to develop in stainless-and/or silicon-steel slab castings.The common ridging defect on the surface of ferritic stainless strip products has been found to be closely related to the well-developed as-cast columnar crystal structure.To explore the various electromagnetic properties of the traveling-wave magnetic fields applied to the secondary cooling zone of a slab casting strand,we used the segmented computational domain method to develop a coupled math model to analyze the electromagnetic,fluid flow,heat transfer,and solidification behaviors,which had been previously determined in an electromagnetic measurement experiment to be a valid approach.The modeling analysis results regarding the traveling-wave magnetic fields show that molten steel stirring has some effect on the end of the slab strand.We also found that the intensity of the magnetic induction when using a box-type electromagnetic stirrer(B-EMS)is much greater on the inside of the strand than on the outside,as compared with its symmetric behavior when applying a roller-type electromagnetic stirrer(R-EMS).At an electrical power of 400 kW and frequency of 7 Hz,the current intensity of the R-EMS is higher than that of the B-EMS by 75 A,achieving a more efficient stirring effect for promoting equiaxed crystal nucleation in front of the solidified shell.In casting experiments in a stainless-steel slab caster,both the BEMS and R-EMS are found to inhibit the growth of columnar crystals through nucleation of the heads of the dendrites,which realizes an equiaxed crystal ratio of the slab casting 45%higher than its threshold value.In addition,an R-MES with two pairs of rollers using inverse thrust EMS forces can produce an equiaxed crystal ratio 17%higher than that achieved by the B-EMS,and can thus be used in the casting production of ferritic stainless steels to obtain final strip produc

关 键 词：铁素体不锈钢 行波磁场 辊式电磁搅拌 箱式电磁搅拌 等轴晶率 

分 类 号：TF777.2[冶金工程—钢铁冶金]