Abstract：In order to improve the quality of cast-rolled strip products and reduce the risk of strip breakage caused by intrinsic cracks in the cast-rolling process. The oblique crack at the edge of the cast-rolled strip was studied to derive the formation mechanism of oblique crack in the edge:the heat exchange between the side seal and the molten pool makes the Kiss point height on the side of the pool locally elevated,leading to the local increase of the initial thickness of the thin strip in the plastic deformation stage of casting-rolling. Therefore,the oblique shear stress induced in the plastic deformation zone of the thin strip becomes the main reason for the formation of the oblique crack on the edge. A thermal-flow coupling numerical simulation model was established to analyze the distribution law of Kiss height along the width of the rollers in the molten pool. The results show that the Kiss point height on the edge of the pool is higher than that near the center of the pool. A thermally-mechanical coupling numerical simulation model was established to analyze the stress distribution in the plastic deformation zone of a thin strip with variable thickness during hot rolling. The shear stress analysis shows that the oblique shear stress is concentrated on the side of the backward slip zone in the plastic deformation zone,and its direction is consistent with the flow direction of the metal in the backsliding zone. A thermal-mechanical coupling numerical simulation model was established to analyze the stress distribution in the plastic deformation zone of the thin strip with a varying thickness during hot rolling. The analysis shows that the oblique shear stress is concentrated on the edge of the backward slip zone,and its direction is consistent with the flow direction of the metal there. The above simulation results verify the rationality of the formation mechanism.
[1] 孙明翰,杨玉青,朱志旺,等. 20CrMn钢双辊薄带振动铸轧细晶机理试验[J]. 机械工程学报,2019,55(4):54.(SUN Ming-han,YANG Yu-qing,ZHU Zhi-wang,et al. Experimental study on twin-roller strip cast-rolling under vibration of 20CrMn steel[J]. Journal of Mechanical Engineering,2019,55(4):54.) [2] 康永林,丁波,陈其安. 我国轧制学科发展现状与趋势分析及展望[J]. 轧钢,2017,34(6):1.(KANG Yong-lin,DING Bo,CHEN Qi-an. Analysis and prospect of developing status and trends of rolling discipline in China[J]. Steel Rolling,2017,34(6):1.) [3] 杨竣,袁章福,于湘涛,等. 薄带连铸侧封板材料及技术的研制现状[J]. 中国冶金,2018,28(12):1.(YANG Jun,YUAN Zhang-fu,YU Xiang-tao,et al. Research status of material and technology of side sealing plate for thin strip continuous casting[J]. China Metallurgy,2018,28(12):1.) [4] 高英,张健,方园. 双辊薄带铸轧后工序机组的选型探讨[J]. 宝钢技术,2018,200(4):79. (GAO Ying,ZHANG Jian,FANG Yuan. Exploration of several post process types for the twin roll strip casting[J]. Baosteel Technology,2018,200(4):79.) [5] 刘振宇,赵岩,刘鑫,等. 节约型高强韧不锈钢及其薄带连铸制备技术[J]. 轧钢,2017,34(1):53.(LIU Zhen-yu,ZHAO Yan,LIU Xin,et al. Development of cost saving high strength stainless steels by twin-roll strip casting technology[J]. Steel Rolling,2017,34(1):53.) [6] 黎先浩,孟小涛,赵鹏飞,等. 高磁感取向硅钢研发现状与展望[J]. 中国冶金,2019,29(1):1. (LI Xian-hao,MENG Xiao-tao,ZHAO Peng-fei,et al. Present status and future prospect of high permeability grain-oriented silicon steel[J]. China Metallurgy,2019,29(1):1.) [7] 方园,张健. 双辊薄带连铸连轧技术的发展现状及未来[J]. 宝钢技术,2018,200(4):6.(FANG Yuan,ZHANG Jian. Development status and future of twin roll strip casting and rolling[J]. Baosteel Technology,2018,200(4):6.) [8] 张凤泉. 双辊薄带铸轧技术最新进展及产业化问题探讨[J]. 世界金属导报,2017-11-14(B04). (ZHANG Feng-quan. Discussion on the latest progress of twin-roll thin strip casting technology and its industrialization[J]. World Metals,2017-11-14(B04).) [9] 杜凤山. 双辊薄带振动铸轧技术的研究与应用[J]. 世界金属导报,2017-10-31(B03). (DU Feng-shan. Research and application of twin roll thin strip vibration casting technology[J]. World Metals,2017-10-31(B03).) [10] 魏洁平,许志强,孙明翰,等. 20CrMn钢双辊振动铸轧薄带性能的试验[J]. 钢铁,2018,53(12):118.(WEI Jie-ping,XU Zhi-qiang,SUN Ming-han,et al. Experimental research of vibratory cast-rolling strips for 20CrMn alloy steel[J]. Iron and Steel,2018,53(12):118.) [11] 李龙,张薇,宋则进. 轧制润滑系统在薄带铸轧生产中的应用[J]. 轧钢,2019,36(4):69. (LI Long,ZHANG Wei,SONG Ze-jin. Application of roll gap lubrication in thin gauge strip casting and rolling production[J]. Steel Rolling,2019,36(4):69.) [12] ZHANG P,HU H,LIU Y,et al. Investigation on cracking mechanism of austenite stainless steel during in situ tension in transmission electron microscope[J]. Materials Science and Engineering A,2011,528(3):1201. [13] HU W L,ZHANG Y X,YUAN G,et al. Crack formation mechanism of high silicon steel during twin-roll strip casting[J]. Materials Science Forum,2017(898):7. [14] 康向东,邸洪双,张晓明. 双辊铸轧薄带钢裂纹形成原因分析[J]. 材料与冶金学报,2002,1(2):106.(KANG Xiang-dong,DI Hong-shuang,ZHANG Xiao-ming. Analysis of crack forming causes on twin-roll casting thin strip[J]. Journal of Materials and Metallurgy,2002,1(2):106.) [15] JU D Y,ZHAO H Y,HU X D,et al. Thermal flow simulation on twin roll casting process for thin strip production of magnesium alloy[J]. Materials Science Forum,2005(488/489):439. [16] 李永全,方园,施红家,等. 熔融石英质侧封板的研制与使用[J]. 耐火材料,2005,39(3):229. (LI Yong-quan,FANG Yuan,SHI Hong-jia,et al. Development and application of fused silica side sealing plate[J]. Refractories,2005,39(3):229.) [17] 李朝锋,邸洪双,张晓明,等. 双辊铸轧薄带钢侧封板材料评价及热应力有限元模拟[J]. 机械工程学报,2002,38(11):96.(LI Chao-feng,DI Hong-shuang,ZHANG Xiao-ming,et al. Material evaluation and thermal stress finite element simulation of side dam for twin roll strip casting[J]. Journal of Mechanical Engineering,2002,38(11):96.) [18] 李朝锋,邸洪双,张晓明,等. 侧封对双辊铸轧薄带钢工艺稳定性及铸带质量的影响[J]. 钢铁研究学报,2002,14(2):68.(LI Chao-feng,DI Hong-shuang,ZHANG Xiao-ming,et al. Effect of side dam on process stability and strip quality for twin-roll strip casting process[J]. Journal of Iron and Steel Research,2002,14(2):68.) [19] Aboutalebi M R,Hasan M,Guthrie R I L. Coupled turbulent flow,heat,and solute transport in continuous casting processes[J]. Metallurgical and Materials Transactions B,1995,26(4):731. [20] Lam C K G,Bremhorst K. A Modified form of the k-ε model for predicting wall turbulence[J]. Journal of Fluids Engineering,1981,103(3):456. [21] 李润昌. 980 MPa级双相钢边裂致断带原因分析[J]. 中国冶金,2018,28(9):37.(LI Run-chang. Reasons analysis of edge cracks on 980 MPa level dual-phase steel strip leading to strip-break[J]. China Metallurgy,2018,28(9):37.)
2020, Vol. 55 
