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金属学报  2019, Vol. 55 Issue (7): 875-884    DOI: 10.11900/0412.1961.2018.00487
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电磁旋流水口连铸技术对小方坯凝固组织形貌和宏观偏析的影响
吴春雷,李德伟,朱晓伟,王强()
1. 东北大学材料电磁过程研究教育部重点实验室 沈阳 110819
2. 东北大学冶金学院 沈阳 110819
3. 东北大学秦皇岛分校资源与材料学院 秦皇岛 066004
Influence of Electromagnetic Swirling Flow in Nozzle on Solidification Structure and Macrosegregation of Continuous Casting Square Billet
Chunlei WU,Dewei LI,Xiaowei ZHU,Qiang WANG()
1. Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China
2. School of Metallurgy, Northeastern University, Shenyang 110819, China
3. School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004, China
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摘要: 

在不同工业实验条件下,研究了电磁旋流水口技术对小方坯的凝固组织和C、S元素宏观偏析特征的影响规律,并与结晶器电磁搅拌所得结果相比较。结果表明,仅用电磁旋流水口技术,在电流频率为50 Hz时,随着电流强度由200 A升至600 A,等轴晶逐渐增多,而中心偏析严重程度先减轻后加重,在凝固组织以细小柱状晶为主时出现最优值。研究还表明,可以通过调整电磁旋流装置的电流参数来改变浸入式水口内钢水的旋流强度,进而获得不同凝固组织形貌和宏观偏析严重程度的铸坯。在本实验条件下,当装置的电流参数达到一定值后,电磁旋流水口技术在提高铸坯质量方面可以达到与结晶器电磁搅拌相同甚至更优的效果。

关键词 连铸凝固组织宏观偏析电磁旋流浸入式水口    
Abstract

During continuous casting production of square billet, the quality of steel billet is determined by equiaxed grain rate and defect grade of centerline segregation. The application of mold electromagnetic stirrer (M-EMS) can improve the quality, but it also brings some negative effects. Some researchers have attempted to make a swirling flow generated in submerged entry nozzle keep rotating in the mold to replace M-EMS. In this work, the influence of electromagnetic swirling flow in nozzle (EMSFN) on morphology of solidification structure and macrosegregation characteristics of carbon and sulfur was studied under different industrial test conditions, and the results were compared with those obtained by M-EMS. The results show that when the current frequency of EMSFN device is 50 Hz, with the current intensity increasing from 200 A to 600 A, the quantity of equiaxed grains increases gradually, while the severity of centerline segregation decreases first and then increases. The optimum value of centerline segregation was obtained when solidification structure was dominated by fine columnar crystals. Therefore, the swirling flow intensity of molten steel in submerged entry nozzle can be changed by adjusting the current parameters of EMSFN device, and thus the billets with different morphology of solidification structure and severity of macrosegregation can be obtained. Under the experimental condition, when the current parameters of EMSFN device reach certain values, EMSFN can achieve the same or even better effect as M-EMS in improving the quality of billet.

Key wordscontinuous casting    solidification structure    macrosegregation    electromagnetic swirling flow    submerged entry nozzle
收稿日期: 2018-10-30      出版日期: 2019-04-23
ZTFLH:  TF777.1  
基金资助:国家重点研发计划项目(No.2017YFB0304400);国家自然科学基金委员会-宝钢集团有限公司钢铁联合研究基金项目(No.U1560207);辽宁省高等学校创新团队支持计划项目(No.LT2017011)
通讯作者: 王强     E-mail: wangq@epm.neu.edu.cn
Corresponding author: Qiang WANG     E-mail: wangq@epm.neu.edu.cn
作者简介: 吴春雷,男,1978年生,博士生

引用本文:

吴春雷,李德伟,朱晓伟,王强. 电磁旋流水口连铸技术对小方坯凝固组织形貌和宏观偏析的影响[J]. 金属学报, 2019, 55(7): 875-884.
Chunlei WU,Dewei LI,Xiaowei ZHU,Qiang WANG. Influence of Electromagnetic Swirling Flow in Nozzle on Solidification Structure and Macrosegregation of Continuous Casting Square Billet. Acta Metall Sin, 2019, 55(7): 875-884.

链接本文:

http://www.ams.org.cn/CN/10.11900/0412.1961.2018.00487      或      http://www.ams.org.cn/CN/Y2019/V55/I7/875

图1  工业实验中EMSFN设备、M-EMS、SEN与结晶器的结构与尺寸示意图
ItemValueUnit
Steel grade70#
Cross section140×140mm2
Pouring rate0.74m·s-1
Pouring temperature1773K
Casting rate2.56m·min-1
M-EMSON/OFF
M-EMS current intensity500A
M-EMS current frequency4Hz
F-EMSON
F-EMS current intensity500A
F-EMS current frequency12Hz
EMSFNON/OFF
Current frequency50Hz
Current intensity200, 400, 600A
表1  连铸工艺参数

Sample No.

EMSFN

M-EMS[border:border-top:solid;border-left:solid;border-right:solid;]

F-EMS

Current frequency / HzCurrent intensity / A
150200OFFON
250400OFFON
350600OFFON
4OFFONON
表2  实验条件与试样编号
图2  试样的图像选取位置示意图及凝固组织形貌
图3  EMSFN不同电流强度条件下的等轴晶率
图4  不同实验条件下二次枝晶间距(SDAS)结果
图5  不同实验条件下从铸坯中心到边缘C元素和S元素的偏析系数
图6  不同实验条件下硫印检验结果
图7  硫印偏析斑点尺寸和分布位置
图8  硫印偏析斑点的分布比例区域划分方法示意图及不同实验条件下的分布比例结果
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