Abstract：The large size non-metallic inclusions are mainly responsible for slivers defects in ultra low carbon steels. Taking IF steel for example,macro inclusions are caused by entrapped and captured mold flux in the continuous casting mold,remained re-oxidation products of molten steels,dropping of nozzle clogs due to accumulated small size non-metallic inclusions. As for the deoxidation products,it is easy to be removed during RH treatment for the size high than 100 μm. While,the flow of molten steel has great influence on the float up of the non-metallic inclusions less than 100 μm,especially for those less than 20 μm. RH is not only the most important facility for mass production of ultra low carbon steel,but also the most important place for inclusion removal. The influence of different vacuum degrees on the removal of inclusions during the production of IF steel was studied and new technology using low vacuum degree cycling for removing ≤20 μm inclusions were proposed. The results show that the inclusion density during RH process decreased faster under the treatment of lower vacuum degree (5 kPa) than that under conventional process. The average T.O content of molten steel in the tundish was decreased by 0.000 2% and [N] pickup under these two processes is nearly the same. In addition,the downgrade rate of cold-rolled sheet due to metallurgical defects was reduced approximately 29% when applying the new technology. The following index between inclusions and steel was proposed to explain the experimental results. The calculated results indicated the reduction of the RH vacuum degree decreased the cycling velocity of the steel and reduced the following tendency of inclusions,therefore enhance the removal efficiency of inclusions less than 20 μm,relieve the nozzle clogging and improve the surface quality of cold rolled steel sheets.
朱国森, 邓小旋, 季晨曦. RH精炼真空度对超低碳钢夹杂物去除的影响[J]. 钢铁, 2022, 57(11): 99-105.
ZHU Guo-sen, DENG Xiao-xuan, JI Chen-xi. Effect of vacuum degree on inclusion removal in ultra low carbon steel during RH refining process[J]. Iron and Steel, 2022, 57(11): 99-105.
[1] Sengo S, Romano Triguero P, Zinngrebe E, et al. Tracing the origin of non-ferrous oxides in lamination defects on hot-rolled coils: mold slag entrainment vs submerged entry nozzle reaction products[J]. Metallurgical and Materials Transactions B, 2017, 48(3): 1690. [2] JI Y, LIU C, LU Y, et al. Effects of FeO and CaO/Al2O3 ratio in slag on the cleanliness of Al-killed steel[J]. Metallurgical and Materials Transactions B, 2018, 49(6): 3127. [3] 徐国军, 胡华东, 田川, 等. Al2O3夹杂在DC06钢中的分布及对深冲性能的影响[J]. 中国冶金, 2021, 31(5): 111.(XU Guo-jun, HU Hua-dong, TIAN Chuan, et al.Distribution of Al2O3 inclusions in DC06 steel and its effect on deep drawing properties[J].China Metallurgy,2021,31(5): 111. ) [4] 邓小旋, 李海波, 季晨曦, 等. IF钢板坯表层大尺寸夹杂物的三维分布[J]. 连铸, 2022(2): 35.(DENG Xiao-xuan, LI Hai-bo, JI Chen-xi, et al. Three-dimensional distribution on macro inclusions in surface layer of IF steel slabs[J].Continuous Casting,2022 (2): 35 ) [5] 王林, 于洋, 倪有金, 等. 表检系统在冷轧板表面线性缺陷检测中的应用[J]. 中国冶金, 2022, 32(9): 105.(WANG Lin, YU Yang, NI You-jin, et al. Applicaiton of surface inspection system in detection of linear defects on cold-rolled sheets[J].China Metallurgy,2022,32(9): 105.) [6] 朱国森, 于会香, 王万军, 等. IF钢冷轧板表面缺陷研究[J]. 钢铁, 2004, 39(4): 54. (ZHU Guo-sen, YU Hui-xiang, WANG Wan-jun, et al. Study of surface defects of cold-rolled IF steel sheet[J]. Iron and Steel, 2004, 39(4): 54.) [7] 邓小旋, 王新华, 李林平, 等. 交换钢包过程对IF钢连铸板坯表层洁净度的影响[J]. 北京科技大学学报, 2014, 36(7): 880. (DENG Xiao-xuan, WANG Xin-hua, LI Lin-ping, et al. Effect of ladle change process on the surface cleanliness of IF steel continuous casting slabs[J]. Journal of University of Science and Technology Beijing, 2014, 36(7): 880.) [8] DENG X, JI C, ZHU G, et al. Quantitative evaluations of surface cleanliness in IF steel slabs at unsteady casting[J]. Metallurgical and Materials Transactions B, 2019, 50(4): 1974. [9] DENG X, WANG Q, JI C, et al. Three-dimensional distributions of large-sized inclusions in the surface layer of IF steel slabs[J]. Metallurgical and Materials Transactions B, 2020, 51(1): 318. [10] 朱国森,季晨曦,刘洋,等. 首钢板坯连铸技术进步[J]. 中国冶金,2019,29(8):1.(ZHU Guo-sen,JI Chen-xi,LIU Yang,et al. Progress of continuous casting technology development at Shougang Group[J]. China Metallurgy,2019,29(8):1.) [11] 邓小旋, 潘宏伟, 季晨曦, 等. 常规低碳钢板坯的高速连铸工艺技术[J].钢铁,2019, 54 (8): 70.(DENG Xiao-xuan, PAN Hong-wei, JI Chen-xi, et al.Review on high speed conventional slab continuous casting low carbon steels[J].Iron and Steel, 2019,54 (8): 70.). [12] TANG F, LI D, LIAO X, et al. Reviews and prospects of clean steel production practices in Ansteel[J]. Journal of Iron and Steel Research, International, 2011, 18(s2): 9. [13] Miki Y, Denissov B, Shimada Y. Model of inclusion removal during RH degassing of steel[C]//Steelmaking Conference Proceedings. Chicago,USA:Iron and Steel Society,1997:37. [14] 邓勇, 杨利彬, 汪成义. 马钢低碳钢板坯高拉速连铸技术的应用[J]. 连铸, 2022(1): 72.(DENG Yong, YANG Li-bin, WANG Cheng-yi. Application of high-speed continuous casting technology for low carbon steel slab in Masteel[J]. Continuous Casting,2022(1): 72.) [15] Murai T, Matsuno H, Sakurai E, et al. Separation mechanism of inclusion from molten steel during RH treatment[J]. Tetsu-to-Hagane, 1998, 84(1): 13. [16] Treadgold C. Behaviour of inclusions in RH vacuum degasser[J]. Ironmaking and Steelmaking, 2003, 30(2): 120. [17] 李宝宽,栾叶君,齐凤升,等. 带有旋流的RH精炼系统循环流动的实验研究[J]. 东北大学学报, 2005, 26(8): 759. (LI Bao-kuan, LUAN Ye-jun, QI Feng-sheng, et al. Experimental investigation on circulation flow in RH refining system with swirling flow[J]. Journal of Northeastern University, 2005, 26(8): 759.) [18] 郑淑国,朱苗勇,潘时松, 等. RH精炼装置内夹杂物行为的水模实验研究[C]//2005中国钢铁年会论文集(第3卷). 北京:中国金属学会,2005:258. (ZHENG Shu-guo, ZHU Miao-yong, PAN Shi-song, et al. Water modeling study on removal of non-metallic inclusions in RH degasser[C]//CSM 2005 Annual Meeting Proceedings(Vol.3). Beijing:Chinese Society for Metals,2005:258.) [19] 陈立峰. RH去除Al2O3夹杂物的数值模拟及工艺分析[J]. 钢铁, 2017, 52(7): 42. (CHEN Li-feng. Numerical simulation and process analysis of Al2O3 inclusion removal in RH refining process[J]. Iron and steel, 2017, 52(7): 42.) [20] 金大中,蔡开科. RH处理对低碳铝镇静钢洁净度影响的研究[J]. 钢铁, 1996, 31(1): 26. (JIN Da-zhong, CAI Kai-ke. Effect of RH treament on flow carbon Al-killed steel cleanliness[J]. Iron and Steel, 1996, 31(1): 26.) [21] 吴松杰,杨文,张立峰. 钙处理时机对LF-RH精炼过程 Al2O3基夹杂物的影响[J]. 中国冶金, 2022,32(1):36. (WU Song-jie,YANG Wen,ZHANG Li-feng,et al. Effect of calcium treatment time on Al2O3 based inclusions during LF-RH refining process[J]. China Metallurgy,2022,32(1):36.) [22] 吕国成, 包丽明, 朱金禄. IF钢210 t RH精炼过程中调钛时机对洁净度的影响[J]. 特殊钢, 2021, 42(6): 25. (LÜ Guo-cheng, BAO Li-ming, ZHU Jin-lu, et al. Effect of timing of titanium adjustment in 210 t RH refining process on cleanliness of IF steel[J]. Special Steel, 2021, 42(6): 25.) [23] Yin H, Shibata H, Emi T, et al. "In-situ" observation of collision, agglomeration and cluster formation of alumina inclusion particles on steel melts[J]. ISIJ International, 1997, 37 (10): 936. [24] 于会香,潘明,杨德新. 超低碳IF钢脱氧合金化过程中夹杂物的行为[J]. 钢铁,2020, 55(6):46. (YU Hui-xiang, PAN Ming, YANG De-xin. Behavior of inclusions in ultra-low carbon IF steel during deoxidation and alloying process[J]. Iron and Steel, 2020, 55(6): 46.) [25] 于会香,邵肖静,张静,等. 采用ASPEX扫描电镜研究钢中总氧和非金属夹杂物的定量关系[J]. 工程科学学报,2015, 37(s1): 35. (YU Hui-xiang, SHAO Xiao-jing, ZHANG Jing, et al. Study on the quantitative relationship between total oxygen content and non-metallic inclusion in steel with ASPEX SEM[J]. Chinese Journal of Engineering, 2015, 37(s1):35.) [26] 潘宏伟. 钢包中间包联合条件下流动与传热及夹杂物运动规律研究[D]. 北京:北京科技大学, 2012. (PAN Hong-wei. Study on Flow Field and Temperature Field and Inclusions Movement Behavior in Combined Ladle Furnace and Tundish System[D]. Beijing:University of Science and Technology Beijing, 2012.) [27] Tanaka H, Tsujino R, Imamura A, et al. Effect of length of vertical section on inclusion removal in vertical bending-type continuous casting machine[J]. ISIJ International, 1994, 34(6): 498. [28] 赵新宇. 超低碳铝镇静钢 RH 冶炼传输过程的数值模拟研究[D].北京:北京科技大学, 2011.(ZHAO Xin-yu.Numerical Simulation on Transport Process on RH for Ultra Low-carbon Aluminum Killed Steel[D]. Beijing:University of Science and Technology Beijing, 2011.) [29] Tsujino R, Nakashima J, Hirai M, et al. Numerical analysis of molten steel flow in ladle of RH process[J]. ISIJ International, 1989, 29(7): 589.
2022, Vol. 57 
