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20 August 2025, Volume 44 Issue 4
    

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    Comprehensive Summarization
  • Research development on clogging of submerged nozzle in continuous casting of high titanium steel
    LAN Peng, ZHANG Lirui, TAN Ming, ZHANG Jiaquan, TAN Qingfeng, HAN Bin, AN Jie, JIA Hongshuai
    Continuous Casting. 2025, 44(4): 1-14. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250014
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    With the increasing improvement of the performance requirements for steel in high-end equipment, high titanium steel has drawn wide attention due to its high strength, toughness, wear resistance and corrosion resistance. However, new challenge has encountered in smelting and casting of high Ti steel, due to the fact that Ti shows high activity and strong affinity to react with oxygen and nitrogen to form high melting point inclusions. The general characteristic of the submerged nozzle clogging in continuous casting of high Ti steel was reviewed, and the multilayer structure and chemical composition of the clog were revealed. The submerged nozzle clogging process and mechanism during continuous casting by Ti addition was summarized, and the chemical reaction type, sequence and clog component at the interface of the continuous casting nozzle were compared between Ti containing steel (w(Ti)≤0.01%) and high Ti steel (w(Ti)>0.1%). The inner wall erosion, temperature drop and physical adhesion were regarded as the key influencing mechanisms. Finally, the effective control strategy to solve the nozzle clogging problem in high Ti steel continuous casting has been proposed, and the new achievements on Ca treatment, nozzle material design and external field implementation has been outlined particularly.
  • Practice and application of tundish plasma heating technology in slabs production
    SONG Jingxin, ZHAN Qimei, SUN Ye, LIU Wei, YANG Shufeng, WANG Cun, LI Jingshe
    Continuous Casting. 2025, 44(4): 15-24. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240244
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Tundish plasma heating technology could reduce the tapping temperature and superheat fluctuation range, as well as improve the quality of casting billets, whose equipment has the advantages of easy installation, high heating efficiency, and low energy consumption. Focusing on the hot issues related to tundish plasma heating technology, the equipment characteristics were systematically described, the application progress of plasma heating technology in slab production was introduced, and the metallurgical effects of plasma heating technology in practical applications were analyzed. The effect of the device on the temperature, chemical composition, and inclusion removal in molten steel was revealed. It is demonstrated that the first domestically developed new hollow graphite electrode heating device has achieved a breakthrough in tundish heating technology. It effectively meets the production requirements of low-, medium-, and high-carbon steels, offering an effective solution to the problem of temperature heat loss in the tundish, and achieving the goal of energy-saving and consumption reduction.
    • Monographic Study
  • Finite element method simulation of loose healing in reduction process of solidification end of continuous casting round billet
    ZHENG Yan, ZHAO Yinghui, LI Chong, PENG Yang, KANG Jian, JIA Guanglin, YUAN Guo
    Continuous Casting. 2025, 44(4): 25-33. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240255
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Center porosity is one of the main defects of continuous casting round billet. In order to reduce the center defect of the continuous casting round billet, the mechanical reduction is performed at the solidification end of the continuous casting round billet. According to the actual production situation of a factory, a three-dimensional finite heat transfer model of the continuous casting round billet was first established to simulate solidification, and according to the results of the heat transfer model, different reduction positions were determined. Then, the mechanical reduction processes of the continuous casting round billet with a diameter of 350 mm were simulated using a thermodynamic coupling model. At the same time, the relative change of the shrinkage cavity volume was used as the standard to evaluate the influence of the reduction position on the shrinkage cavity healing. Finally, the experiment of continuous casting round billet pressing was carried out. The results show that during the reduction process of continuous casting of round billet, the central shrinkage cavity became closed under the combined effects of metal filling and compression deformation. The reduction position corresponds to the solid fraction in the center of the continuous casting billet, and the metal flow condition is different at various reduction positions. Under the same reduction amount, when the central solid fraction of the continuous casting round billet increases, the flow range of the central metal of the continuous casting round billet will gradually decrease, and the relative flow distance of the metal will first increase, then remain unchanged, and finally decrease, and the central shrinkage cavity of the casting round billet will gradually decrease and finally become close. When the reduction is 15 mm, the optimal reduction interval of the continuous casting round billet is fs=0.6-1.0. The experimental results show that the inner porosity of continuous casting round billet decreases after reduction.
  • Numerical simulation on solidification of extra-thick slab with non-uniform spray flux in secondary cooling zone
    QIU Haoyue, XU Longyun, YANG Jianhua, SHEN Houfa
    Continuous Casting. 2025, 44(4): 34-40. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250025
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Both the pre and prost processing modules for the calculation of heat transfer and solidification in continuous casting were compiled to integrate with ProCAST simulation software by the treatment of bow geometry of the caster machine and the non-uniform water spray flux in the secondary cooling zone. The temperature distribution and solid fraction in both the longitudinal and transverse sections of the extra-thick slab were obtained by the numerical simulation of the practical continuous casting process. The results show that the liquid pool in the shape of “W” would form in the central broad section of the slab with the less water flux in the edge compared to that in the central broad face. The solidification homogeneity in the slab cross section could be improved by adjusting the spray flux in the secondary cooling zone.
  • Simulation research on soft reduction of fine-blanking steel slab based on flow-solidification coupling
    YUAN Jing, XU Lijun, ZHANG Li, YIN Shubiao, REN Zixiang, YU Kezai
    Continuous Casting. 2025, 44(4): 41-50. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240261
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    By Comsol finite element software, the flow-solidification coupling model and the reduction model were used for the fine blanking steel with a cross-section of 230 mm×1 255 mm. Meanwhile, the model was verified based on the results of product experiments. The research results show that the cross-section of the fine blanking steel slab exhibits a “dumbbell”-shaped non-uniform temperature distribution at the position relatively close to the meniscus, and the temperature difference at the solidification end is 4 ℃. The solidification end is 21.81 m away from the meniscus. The solid fractions at the center of the reduction sections No.9 and No.10 are 0.44, 0.684 and 1, 1 respectively. When a reduction of 3 mm is applied at reduction section No.9, the plastic strain at the solidification front approaches the critical value of 0.4%, making it prone to crack defects. However, applying a reduction of 6 mm at reduction section No.10 cannot solve the quality problem at the center of the slab. Instead, the strain in the solidification front and the 1/4 corner area exceeds the critical values (0.4%, 13.7%), making it easy to generate cracks. The strain at each position of the cross-section increases significantly, exacerbating the development and expansion of existing defects. Through a study on the influence of various reduction amounts on the plastic strain in the temperature field at the entrance of reduction section No.9, the results show that when the reduction amount exceeds 3 mm, the strain at the solidification front exceeds the critical value, and cracks are more likely to occur inside the slab.
  • Repair technology and bonding mechanism of coating on Cu plate in crystallizer by laser cladding
    LI Xiaohan, LI Huirong, LI Jianping, WANG Bo, SUN Ligen, PENG Fei, ZHU Liguang
    Continuous Casting. 2025, 44(4): 51-60. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240263
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Compared with the traditional repair of electroplating coating in the mould, laser cladding has obvious advantages, but the high temperature effect of laser, especially the influence of process parameters, is not clear, which limits its use and application. Therefore, numerical simulation and laser cladding experiments under different technological parameters were carried out to determine the optimal range of laser cladding technological parameters for the mould coating. The results show that, theoretically, with the increase in laser power, the decrease in laser radius and the decrease in scanning speed, the highest temperature of the simulation system increases obviously, the depth of the melt transition layer and the heat affected zone gradually increases, and the equivalent stress and strain of the binding zone increase. When the laser power reaches more than 2 500 W, the laser radius does not exceed 1.5 mm, and the scanning speed does not exceed 4 mm/s, a full metallurgical bond can be formed between the coating and the copper. In the actual cladding process, when the laser power increases from 1 500 to 2 500 W, the depth of the melt transition layer increases from 196 to 306 μm, and the depth of the heat affected zone increases from 763 to 1 080 μm. When the laser radius increases from 1.0 to 2.0 mm, the depth of the heat affected zone decreases from 1 330 to 884 μm, but the depth of the melt transition layer shows a certain fluctuation. Therefore, for the laser cladding process of the mould coating, the relatively low laser power, reasonable scanning speed and laser radius should be adopted on the premise of ensuring the complete melting of the coating metal, which is conducive to reducing the width of the heat affected zone, reducing the amount of grinding during the mould repair, increasing the repair times, and reducing the cost of use.
  • Research and application of intelligent detection and precise grinding technology for surface defects of square billets
    YAN Junhua, YANG Songpu, WANG Xiangtao, DUAN Zhifeng, HUANG Zhijing, ZHOU Peng
    Continuous Casting. 2025, 44(4): 61-68. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250002
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Surface defects of square billets not only significantly compromise the mechanical properties of steel (e.g., strength and toughness) but also severely degrade product surface quality. Traditional manual grinding methods, plagued by inefficiency and inconsistency, often fail to achieve complete defect elimination. To address these challenges, an online intelligent detection and precision grinding technology for square billet surface defects based on machine vision has emerged, which holds critical significance for enhancing product quality and advancing intelligent and automated production processes. This study elaborates on the developmental background, research significance, and future trends of surface defect detection and grinding technologies for square billets. A successfully implemented intelligent detection and grinding solution is systematically introduced, with its core innovation lying in the proposed improved YOLOv11 algorithm. By replacing traditional convolution with the GhostConv module in the network backbone, the model performance is notably enhanced. Experimental results demonstrate that the optimized algorithm achieves accelerated inference speed, reducing latency by 0.3 milliseconds, while simultaneously improving defect recognition accuracy. Practical application evaluations confirm that this technical solution exhibits significant advantages in both detection efficiency and precision, thereby providing robust technical support for surface quality control of square billets.
  • Specific composition optimization of continuous casting mold flux in low-density high-strength steel
    DAI Jiahui, HE Chenghui, WANG Qiangqiang, HE Shengping, ZHANG Xubin
    Continuous Casting. 2025, 44(4): 69-74. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250010
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Low density steel has shown broad application prospects in the automotive industry and other fields due to its excellent lightweight, formability, corrosion resistance and fatigue strength. However, in the continuous casting process, due to the significant changes in the composition of the mold flux, the performance is usually deteriorated, which inturn affects the continuous casting process and the quality of the slab. CaO-BaO-Al2O3-CaF2-Li2O five-element mold flux system was proposed, and the specific composition area was designed by simplex method. When the Li2O content is designed to be 6.5 wt.%, the slag flow and melting properties in the composition region are studied by adjusting the content of F- and Al2O3, and finally the specific composition area of the mold flux that meets the continuous casting performance requirements of low-density steel is obtained.
  • Flow field structure optimization of six-strand tundish
    XIE Yu, CHENG Ziyi, SHEN Liang, DING Yi, WANG Zixian, LI Jiale, ZHANG Chaojie, ZHANG Liqiang
    Continuous Casting. 2025, 44(4): 75-84. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240259
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    To address the issues in the continuous casting process of a steel plant, such as insufficient flotation of large inclusions, uneven distribution of steel temperature and composition, the short service life of the tundish, and especially the inconsistent quality of cast billets, a six-strand T-shaped tundish was researched as the object, aiming to improve the uniformity of steel flow by optimizing the flow field structure. A 1:3 physical model was established using the orthogonal experimental method, and the flow field structure of the single-sided six-strand tundish was optimized and analyzed through a combination of physical and numerical simulations. The results show that, under the optimized conditions of the number and angle of the deflector holes, the uniformity of the actual mean residence time, minimum residence time, dead zone ratio, outlet temperature, and outlet velocity are improved by 15.62%, 19.45%, 27.53%, 0.03%, and 1.07%, respectively. Additionally, the proportion of dead zones in the tundish decreases by 4.19%, and the maximum temperature difference among the outlets is only 0.99 K, which is significantly reduced compared to the original condition. Furthermore, the average outlet temperature increases by 0.58 K, and the proportion of high-velocity and low-velocity zones in the tundish decreases by 2.9% and 3.65%, respectively. An effective theoretical basis is provided for improving the uniformity of steel flow, reducing outlet temperature differences, and extending the service life of the tundish.
    • Technology Exchange
  • Effect of submerged entry nozzle on fluid flow and solidification in wide and thick slab continuous casting mold with electromagnetic braking
    LI Donglin, WANG Wenxue, YAO Chenggong, ZHANG Xifeng, LI Wuhong, WU Long, MI Xiaoyu
    Continuous Casting. 2025, 44(4): 85-95. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240249
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    To reasonably control the fluid flow and level fluctuations of molten steel in wide and thick slab continuous casting mold at low casting speed, a three-dimensional fluid flow, heat transfer and solidification mathematical model of 1600 mm×350 mm slab mold was established. This model investigated the influence of different submerged entry nozzle angles on the flow field, temperature field, and shell thickness distribution of molten steel in slab mold with vertical electromagnetic braking. The results show that without vertical electromagnetic braking, the maximum steel flow velocity on the mold surface is 0.114 m/s, and the surface flow velocity is relatively low. After applying vertical electromagnetic braking, the steel flow velocity in the nozzle jet impact area and the lower recirculation area is suppressed, while the steel flow velocity in the upper recirculation area increases. The steel flow velocity on the mold surface increases, and the high temperature range expands, resulting in more uniform temperature distribution. Based on the distribution of surface flow velocity and shell thickness of the molten steel, the nozzle angle of 20° is more suitable. In this case, the surface velocity of the molten steel increases from 0.144 m/s to 0.195 m/s, and the shell thickness at the mold exit increases from 19.94 mm to 21.32 mm. Applying vertical electromagnetic braking in wide and thick slab continuous casting mold at low casting speed can effectively control the steel fluid flow, optimize the flow field and temperature field in the mold, promote slag melting, suppress slag entrapment, and improve the slab quality.
  • Homogenization process and practice of bloom continuous casting of GCr15 bearing steel
    SONG Tiepeng, LU Bingjun, WANG Deyong, XIONG Hongjin, XU Pei, ZHONG Xiaodan, QI Rui, LI Shengdong
    Continuous Casting. 2025, 44(4): 96-103. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240245
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    To solve the issue of homogenization defects such as center segregation and porosity shrinkage in GCr15 bearing steel continuous casting billets produced by 390 mm×480 mm bloom casting machine in Ben Gang Group Co., Ltd., the effects of superheat, crystallizer electromagnetic stirring (M-EMS), and heavy reduction on the quality of continuous casting billets were analyzed based on industrial experiments. The results indicate that the heavy reduction process has the most significant effect on improving the center density and center segregation of the cast billet, and the improvement effect gradually increases with the increase in reduction amount. However, superheat, and M-EMS have varying degrees of auxiliary effects. When the reduction is 40 mm, the center porosity of the continuous casting billet decreases from level 2.0 to level 1.0, compared to that without reduction, while the shrinkage cavity is basically eliminated, the center carbon segregation index decreases from 1.24 to 1.04, and the carbon range value decreases from 0.323 to 0.185. Based on the above research, the homogenization process of GCr15 bearing steel continuous casting billet is recommended with heavy reduction of 32-40 mm, a superheat of 20-33 ℃, and an appropriate current intensity for electric stirring in the crystallizer.
  • Dynamic load balance control method and application of continuous casting machine drive roller
    LI Yunbo
    Continuous Casting. 2025, 44(4): 104-110. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240253
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Due to individual differences in motors, installation positions, rotation radius of upper and lower rollers, and roller wear in continuous caster, the drive roller motors, especially the straightening segment motors, often experience load imbalance and overload, leading to malfunctions and shutdowns, which affect motor performance and frequency converter service life. In order to improve the working status of electrical equipment such as the drive roller motors and frequency converters, and ensure stable production of the continuous caster, the characteristics of the motor, the design features of the continuous casting machine, and the actual working state of the motor were analyzed, and a corresponding mathematical calculation model was established to control the motor speed and achieve load balance. Finally, through the actual production testing in the steel plant, the motor torque and current before and after using the load balancing model were compared, achieving dynamic load balancing control of multiple drive rollers by applying the model. The maximum fluctuation of all motor speeds is only 0.02 mm/min, with the fluctuation within 2%, which has almost no effect on the casting speed of the continuous casting machine and reduces the energy consumption of the entire system by ~20%. In addition, the motor alarm rate caused by excessive load is close to 0%, greatly improving the stability of the continuous casting machine, which proves the effectiveness and application value of the method described.
  • Effect of secondary cooling uniformity in width direction on solidification quality of extra-thick slab
    HU Xiantang, LI Xin, LIU Yang, XIE Cuihong, ZHAO Jing, ZHANG Hucheng
    Continuous Casting. 2025, 44(4): 111-116. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250003
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Secondary cooling uniformity in the width direction has a significant effect on the porosity and segregation of extra-thick slab during continuous casting. Numerical simulation and industrial experiments were combined to study the quantitative changes in surface temperature distribution, solidification end shape, porosity and segregation defects under different cooling methods in the width direction of the 400 mm slab. The results show that the measured temperature differences on the slab surface at 1/4 and 1/2 width under non-uniform cooling and uniform cooling methods are 116 and 71 ℃, respectively. At the solidification end, the solid phase distribution shows an “M”-shaped distribution. During non-uniform cooling, the length difference between the solidification process at the 1/4 and 1/2 positions is about 2.3 m in the casting direction, while it is only 0.6 m under uniform cooling. Compared with the non-uniform cooling method, the porosity volume at the 1/4 width of the slab decreases by 30.3%, the difference in porosity volume between the 1/4 and 1/2 width decreases by 46.9%, and the maximum segregation degree decreases from 1.15 to 1.08 after uniform cooling. By adopting a uniform cooling method, the pressing efficiency of dynamic light pressing can be effectively improved, and the solidification quality of extra-thick slab can be enhanced.
  • Effect of spray nozzle clogging on secondary cooling uniformity of continuous casting billet
    HAN Yanshen, HUANG Hua, LÜ Jin
    Continuous Casting. 2025, 44(4): 117-124. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250027
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Spray nozzle clogging in the secondary cooling zone is a common phenomenon in continuous casting, significantly impacting both the continuous casting production process and the quality of cast billets. Focusing on the nozzle clogging issue of continuous casting billet at a domestic steel plant, the spray characteristics of the nozzle were investigated using spray performance testing device, and a solidification heat transfer model considering the local water flux density distribution was established based on the explicit finite difference method through Python programming. The influence of nozzle clogging on the surface temperature of the billet was explored. The results indicate that nozzle clogging significantly alters the spray characteristics, leading to the reduced water flow rate, decreased spray coverage, poor symmetry in water distribution, and localized excessive water flow. At the water pressure of 0.60 MPa, the water flow rate decreases from 2.630 to 1.832 L/min after nozzle clogging, while the local maximum water flux density increases from 2.84 to 26.62 L/(m2·s). Nozzle clogging causes the temperature decrease in the water-concentrated areas on the billet surface and the temperature rise in other areas, severely reducing the local cooling uniformity and surface temperature symmetry. The maximum temperature difference along the billet width direction increases from 182.6 to 321.8 ℃. Besides, when clogging occurs at the beginning or the end of each segment in the secondary cooling zone, the impact on the cooling uniformity of the billet is more pronounced. The maximum surface reheating rate reaches 170.8 ℃. Therefore, it is imperative to control rigorously the quality of spray water in the secondary cooling zone and to establish a scientific operation and maintenance scheme for nozzles, thereby managing the nozzle clogging and mitigating the detrimental effects.
  • Defect formation mechanism and mold flux analysis in 2Cr13 martensitic stainless steel continuous casting billets
    LI Huan, ZHANG Lei, WANG Wei, QI Jiangtao
    Continuous Casting. 2025, 44(4): 125-132. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250039
    Abstract ( ) Download PDF ( ) XML Related Articles File   Knowledge map   Save
    Focusing on slab defects such as longitudinal cracks and depressions in 2Cr13 martensitic stainless steel produced at a steel plant, the high-temperature characteristics of the steel and the physicochemical properties of the used mold fluxes were systematically investigated. Results indicate that 2Cr13 martensitic stainless steel undergoes a peritectic reaction during solidification, with the initial solid fraction reaching 88.77% at the onset of this reaction. The DSC curves exhibit significant fluctuations at high-temperature stage, indicating a poor thermal stability of the steel. Additionally, the steel has also the characteristics of high tensile strength but low thermal plasticity. These characteristics will easy to cause the non-uniform growth of the initial solidification shell, leading to the formation of the slab defects. Comparative analysis of two commercial mold fluxes (S1 and S2) reveals similar effective chemical compositions, viscosity, and melting temperature. However, S2 flux contains a significant lower proportion of pre-melted material compared to S1 flux. During actual application, low-melting-point Na2CO3 in the S2 flux tends to melt preferentially, inducing segregation phenomena. Consequently, the Na2CO3 content in the liquid slag exceeds designed values, reducing both the viscosity and break temperature of the slag. This results in an uneven distribution of flux films and weakens the heat transfer regulation capacity, thereby increasing the propensity for longitudinal cracks and depressions in the cast slab. These findings provide crucial insights for optimizing mold flux design and casting parameters in the continuous casting of martensitic stainless steels.
Started in 1982 (Bimonthly)
ISSN 1005-4006　CN 11-3385/TG
Manager: China Association for Science and Technology
Sponsor: The Chinese Society for Metals
CISRI Boyuan Publishing Co., Ltd.
Editor-in-Chief: BAO Yanping
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