Solidified end characteristics and center quality control of bearing steel bloom
XIA Shuaikang1, WANG Pu1, TANG Qunwei2, LI Weitao2, HU Kai2, ZHANG Jiaquan1
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China;
2. Joint Research Center, Weifang Iron and Steel Group Co., Ltd.,Weifang 262400, Shandong, China
Abstract：It is presently a dominant process to produce quality bearing steel by continuous casting and rolling instead of traditional ingot casting and forging. To improve the frequently observed severe center shrinkage and center segregation in the bloom continuous casting process of GCr15 bearing steel, the numerical simulation has been carried out to predict the solidification process of the continuous casting, and the industrial trials of adjusting the casting speed have been made to explore the influence mechanism and effect of external-field control technology such as F-EMS and soft reduction. The center shrinkage and cracks of the cross-sectional and longitudinal sections of the casting bloom under different processes were observed by the thermal acid etching tests. The distribution of C segregation on the cross-section of the casting bloom was detected by drilling cuttings sampling The results showed that the solidification endpoint at a casting speed of 0.95 m/min was only 13.0 m. Accordingly, although the center shrinkage could be improved by increasing the F-EMS strength and using soft reduction. But F-EMS also stirred more high-concentration molten steel into the center of the bloom. Due to the small width of the molten pool in the billet center, the dilution effect on the high-concentration solute was small, and the molten pool was difficult to dilute these molten steel, so that the segregation of the bloom center was worsened. However, under the process of F-EMS current intensity of 540 A and 7 mm under soft reduction, when the casting speed increased to 1.2 and 1.4 m/min, internal cracks were generated on the inner arc side of the strand, and due to the wide mushy zone of the GCr15 bearing steel, when the casting speed was 1.4 m/min, the crack sensitive interval of the casting blooms was closer to the surface of the casting bloom than the white bright band at the press-down roller where the crack was generated, and finally the white bright band is closer to the center of the billet than the depressed crack. At a casting speed of 1.1 m/min, although the central shrinkage was controlled, the negative segregation occurred in the central area, resulting in the homogeneity of the strand could not be controlled to a high level. Under the casting speed of 1.0 m/min, the central solid-phase rate at F-EMS was around 0.1, the central solid-phase rate of the strand at the No. 2 and No. 3 reduction rollers were within 0.30-0.75, the center shrinkage rating of the cross-section for strand was below 0.5, the center segregation degree was 1.003, and the carbon range was 0.125%, which was the best quality.
夏帅康, 王璞, 汤群伟, 李伟涛, 扈凯, 张家泉. 轴承钢大方坯凝固末端特性与中心质量控制[J]. 钢铁, 2024, 59(2): 99-110.
XIA Shuaikang, WANG Pu, TANG Qunwei, LI Weitao, HU Kai, ZHANG Jiaquan. Solidified end characteristics and center quality control of bearing steel bloom[J]. Iron and Steel, 2024, 59(2): 99-110.
[1] 张朝磊,朱禹承,蒋波. 高碳铬轴承钢组织双超细化的研究现状与发展趋势[J]. 材料导报,2023,37(6):142.(ZHANG C L,ZHU Y C,JIANG B. Research status and development trend of microstructure double ultra refinement on high carbon chromium bearing steel[J]. Materials Reports,2023,37(6):142.)
[2] 王利, 韩杰, 刘成宝, 等. 稀土对GCr15轴承钢夹杂物和疲劳性能的影响[J]. 中国冶金, 2023, 33(9): 52.(WANG L, HAN J, LIU C B, et al. Effect of rare earth on inclusions and fatigue properties of GCr15 bearing steel[J]. China Metallurgy, 2023, 33(9): 52.)
[3] 马帅, 李阳, 姜周华, 等. Ce对440C不锈轴承钢夹杂物演变的影响[J]. 中国冶金, 2022, 32(6): 71.(MA S, LI Y, JIANG Z H, et al. Effect of Ce on inclusion evolution for 440C stainless bearing steel[J]. China Metallurgy, 2022, 32(6): 71.)
[4] 赵新凯, 田凤喜, 高文娟, 等. 轴承钢连铸过程中非金属夹杂物群迁移行为的分析[J]. 连铸, 2022(5): 50.(ZHAO X K, TIAN F X, GAO W J, et al. Behavior analysis of non-metallic inclusion groups in bearing steel during bloom casting[J]. Continuous Casting, 2022(5): 50.)
[5] 韩杰, 王毅, 刘成宝, 等. 稀土对GCr15轴承钢夹杂物的变质行为分析[J]. 连铸, 2023(2): 70.(HAN J, WANG Y, LIU C B, et al. Analysis on modification behavior of rare earth to inclusions in GCr15 bearing steel[J]. Continuous Casting, 2023(2): 70.)
[6] 沈腾飞, 张壮, 牛帅, 等. 连铸工艺对轴承钢大方坯凝固结构及其棒材碳化物带影响[J]. 中国冶金, 2023, 33(6): 54.(SHEN T F, ZHANG Z, NIU S, et al. Effect of casting process on bloom solidification structure of bearing steel and following as-rolled carbide bandings[J]. China Metallurgy, 2023, 33(6): 54.)
[7] 李浩, 李新, 陶承岗, 等. 特殊钢大方坯连铸机设计特点及生产实践[J]. 连铸, 2023(2): 99.(LI H, LI X, TAO C G, et al. Design characteristics and production practice of bloom caster for special steel[J]. Continuous Casting, 2023(2):99.)
[8] 王坤,胡锋,周雯,等. 轴承钢研究现状及发展趋势[J]. 中国冶金,2020,30(9):119.(WANG K,HU F,ZHOU W,et al. Research status and development trend of bearing steel[J]. Chinese Metallurgy,2020,30(9):119.)
[9] 潘鹏, 侯栋, 戈文英, 等. 连铸坯凝固末端电磁搅拌位置及连铸工艺优化[J]. 连铸, 2022(2): 66.(PAN P, HOU D, GE W Y, et al. Position of electromagnetic stirring at solidification end of continuous casting billet and optimization of continuous casting process[J]. Continuous Casting, 2022(2): 66.)
[10] 吴红健, 许长军, 雷冲,等. 凝固末端螺旋电磁搅拌对大圆坯裂纹形成的影响[J]. 中国冶金, 2023, 33(11): 72.(WU H J, XU C J, LEI C, et al. Effect of final helical electromagnetic stirring on crack formation in large bloom[J]. China Metallurgy, 2023, 33(11): 72.)
[11] 李大明, 林俊, 贺佳佳, 等. 低碳钢连铸轻压下工艺的技术研发和应用[J]. 连铸, 2023(2): 52.(LI D M, LIN J, HE J J, et al. Development practice of the soft reduction process in mild steel con-casting[J]. Continuous Casting, 2023(2):52.)
[12] 周素强,成旭东,姜东滨,等. 邯钢中碳微合金钢板坯轻压下位置优化[J]. 中国冶金,2018,28(8):17.(ZHOU S Q,CHENG X D,JANG D B,et al. Optimization of soft reduction location of medium-carbon micro-alloyed continuously cast slab in Hansteel[J].China Metallurgy,2018,28(8):17.)
[13] 王彪,谢植,贾光霖,等. 凝固末端电磁搅拌参数确定及其对中心偏析的影响[J]. 钢铁,2007,42(3):18.(WANG B,XIE Z,JIA G L,et al. Parameter determination and effects on center segregation of F-EMS[J]. Iron and Steel,2007,42(3):18.)
[14] 陈亮,宋波,陈天明,等. 320 mm×410 mm大方坯连铸重轨钢质量改进与应用[J]. 钢铁,2017,52(4):31.(CHENG L,SONG B,CHENG T M,et al. Improvement of quality of 320 mm×410 mm bloom in continuous casting of railway steel and its application[J]. Iron and Steel,2017,52(4):31.)
[15] WAN Y,LI M H,CHEN L J,et al. Effect of final electromagnetic stirring parameters on central cross-sectional carbon concentration distribution of high-carbon square billet[J]. Metals,2019,9(6):665.
[16] XU Y,XU R J,FAN Z J,et al. Analysis of cracking phenomena in continuous casting of 1Cr13 stainless steel billets with final electromagnetic stirring[J]. International Journal of Minerals,Metallurgy and Materials,2016,23(5):534.
[17] YIN S K,LUO S,ZHANG W J,et al. Numerical simulation of macrosegregation in continuously cast gear steel 20CrMnTi with final electromagnetic stirring[J]. Journal of Iron and Steel Research International,2021,28(4):424.
[18] WU H J,XU C J,JIN H Y,et al. Effect of different positions of final electromagnetic stirring for φ800 mm vertical round billet on fluid flow and heat transfer[J]. Applied Physics A,2022,128(2).
[19] JIANG D B,ZHU M Y. Center segregation with final electromagnetic stirring in billet continuous casting process[J]. Metallurgical and Materials Transactions B,2017,48(1):444.
[20] FANG Q,ZHANG H,WANG J H,et al. Effect of final electromagnetic stirring on flow, solidification, and solute transport in continuous casting bloom[J]. JOM,2021,73(9):2698.
[21] SASAKI K. The effect of fluid on the formation of the negative segregation zone steel ingots[J]. Tetsu to Hagane,1979,65(1):60.
[22] 纪振双,姚留枋,唐仲和,等. 连铸过程采用电磁搅拌时的负偏析带的形成机理[J]. 钢铁研究学报,1993(2):9.(JI Z S,YAO L F,TANG Z H,et al. Study on the mechanism of the negative segregation band formation during CC process with EMS[J]. Journal of Iron and Steel Research,1993(2):9.)
[23] 康吉柏,王卫领,罗腾飞,等. 20CrMnTi钢160 mm×160 mm方坯内部质量控制[J]. 钢铁,2021,56(2):82.(KANG J B,WANG W L,LUO T F,et al. Internal quality control of 160 mm×160 mm square billet of 20CrMnTi steel with EMS[J]. Iron and Steel,2021,56(2):82.)
[24] JIANG D B,ZHANG L F,ZHU M Y. Center segregation evolution in slab continuous casting with mechanical reduction:A 3D simulation[J]. Steel Research International,2022,93(5):2100569.
[25] JIANG M,YANG E J,HOU Z W,et al. Decreasing porosities in continuous casting thick slab by soft reduction technology[J]. Metallurgical and Materials Transactions B,2021,52(4):2753.
[26] LI L,ZHANG Z H,LUO M,et al. Control of shrinkage porosity and spot segregation in φ195 mm continuously cast round bloom of oil pipe steel by soft reduction[J]. Metals,2021,11(1):9.
[27] 李茂印,杨树峰,李京社,等. 轻压下调整对模具钢宽厚板坯中心质量的优化[J]. 钢铁,2017,52(12):36.(LI M Y,YANG S F,LI J S,et al. Optimization for internal quality in wide and heavy die billets by soft reduction[J]. Iron and Steel,2017,52(12):36.)
[28] ZONG N F,HUANG J,LIU Y,et al. Controlling centre segregation and shrinkage cavities without internal crack in as-cast bloom of steel GCr15 induced by soft reduction technologies[J]. Ironmaking and Steelmaking,2021,48(8):944.
[29] WANG B,ZHANG J M,XIAO C,et al. Analysis of internal cracks in continuous casting slabs with soft reduction[J]. High Temperature Materials and Processes,2016,35(3):269.
[30] SUN H B,LI L J,WANG J H,et al. Coordinating optimisation of F-EMS and soft reduction during bloom continuous casting process for special steel[J]. Ironmaking and Steelmaking,2018,45(8):708.
[31] AN H H,BAO Y P,WANG M,et al. High-efficiency continuous casting of GCr15 bearing steel bloom based on cooperative control technique of complex electromagnetic stirring and soft reduction[J]. Metallurgical Research and Technology,2019,116(6):621.
[32] 安航航,包燕平,王敏,等. 凝固末端电磁搅拌和轻压下复合技术对大方坯高碳钢偏析和中心缩孔的影响[J]. 工程科学学报,2017,39(7):996.(AN H H,BAO Y P,WANG M,et al. Effect of combining F-EMS and MSR on the segregation and shrinkage cavity in continuously cast high-carbon steel blooms[J]. Chinese Journal of Engineering,2017,39(7):996.)
[33] 刘少伟,韩延申,管敏,等. 基于过热度变化的82B钢连铸末端电搅位置研究[J]. 钢铁研究学报,2018,30(9):716.(LIU S W,HAN Y S,GUAN M,et al. Research on final-electromagnetic stirring position of 82B steel continuous casting based on superheat variation[J]. Journal of Iron and Steel Research,2018,30(9):716.)
[34] LI S X,HAN Z Q,ZHANG J Q. Numerical modeling of the macrosegregation improvement in continuous casting blooms by using F-EMS[J]. JOM,2020,72(11):4117.
[35] THOME R, HARSTE K. Principles of billet soft-reduction and consequences for continuous casting[J]. ISIJ International,2006,46(12):1839.
[36] 祁猛,李亮,铁占鹏,等. 轻压下对GCr15轴承钢大方坯内部质量的影响[J]. 中国冶金,2020,30(9):67.(QI M,LI L,TIE Z P,et al. Influence of soft reduction on internal quality of GCr15 bearing steel bloom castings[J]. China Metallurgy,2020,30(9):67.)
[37] 林启勇,朱苗勇. 连铸板坯轻压下过程中的压下效率分析[J]. 金属学报,2007(12):1301.(LIN Q Y,ZHU M Y. Analysis of reduction efficiency in soft reduction for continuous casting slab[J]. Acta Metallurgica Sinica,2007(12):1301.)
[38] TAKASHI T,HHSASA K,KATAYAMA N. Simulation for progress of solid-liquid coexisting zone in continuous casting of carbon steels[J]. Tetsu to Hagane,1990,76(5):728.
[39] ZONG N F,ZHANG H,LIU Y,et al. Analysis on morphology and stress concentration in continuous casting bloom to learn the formation and propagation of internal cracks induced by soft reduction technology[J]. Ironmaking and Steelmaking,2019,46(9):872.
[40] ZEZE M,MISUMI H,NAGATA S. Segregation behavior and deformation behavior during soft reduction of unsolidified steel ingot[J]. Tetsu To Hagane,2001,87(2):71.
[41] WU C H,JI C,ZHU M Y. Closure of internal porosity in continuous casting bloom during heavy reduction process[J]. Metallurgical and Materials Transactions B,2019,50(6):2867.
[42] 曹磊,祭程,杨吉林,等. 轻压下帘线钢大方坯成分偏析特征及形成机制[J]. 钢铁,2010,45(8):44.(CAO L,JI C,YANG J L,et al. Characteristics and Mechanism of segregation of tie cord steel bloom with soft reduction[J]. Iron and Steel,2010,45(8):44.
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