20 February 2026, Volume 45 Issue 1

    

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Refractory Materials Column
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  Research progress of low-carbon Al₂O₃-C refractories for steelmaking and continuous casting

  TIAN Xuekun, LIU Xusheng, QIN Jiayue, HOU Xinmei, JIA Quanli, MA Chengliang, LIU Xinhong

  Continuous Casting. 2026, 45(1): 1-11. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250122

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  Al₂O₃-C refractories are widely used in sliding nozzles and continuous casting components due to their excellent thermal shock resistance and corrosion resistance. However, conventional high-carbon Al₂O₃-C materials suffer from issues such as carbon pickup in molten steel and CO₂emissions due to oxidation, as well as a loose microstructure that leads to performance degradation. These problems negatively affect clean steel production, environmental protection, and the service life of the materials. Therefore, there is an urgent demand to develop low-carbon Al₂O₃-C materials. However, key properties such as thermal shock resistance and corrosion resistance are insufficient to meet application requirements with carbon reduction. Optimizing carbon sources and additives is essential for improving the performance of low-carbon Al₂O₃-C materials. The effects of different carbon sources and additives on the composition, structure and properties of low-carbon Al₂O₃-C materials are reviewed in this paper, and the potential application of biochar as a green, renewable and highly reactive carbon source is prospected. The aim is to provide new ideas for the green preparation and performance improvement of low-carbon Al₂O₃-C materials.
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  Research progress on functional MgO-C refractories for stopper rods in continuous casting tundishes

  WANG Xuan, YU Chao, MA Beiyue, DING Jun, LIU Zhenglong, ZHU Hongxi, DENG Chengji

  Continuous Casting. 2026, 45(1): 12-20. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250192

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  As a critical functional refractory component in continuous casting, the tundish stopper rod directly influences process continuity, molten steel cleanliness, and final product quality. Traditional Al₂O₃-C stopper rods face technical limitations—including chemical erosion, carbon oxidation, and insufficient high-temperature strength—when casting calcium-treated steels, high-manganese steels, and high-oxygen steels. This paper examines the performance advantages of MgO-C refractories as an alternative, focusing on their erosion-resistance mechanism and its effects on steel cleanliness and thermal shock resistance. Studies indicate that MgO-C materials inhibit the formation of low-melting-point phases due to the high melting point and low reactivity of MgO with steel components; a dense MgO reaction layer formed on the surface effectively blocks molten steel penetration; and the graphite component provides excellent thermal shock resistance and high-temperature structural stability. Furthermore, MgO-C materials help improve steel cleanliness by adsorbing inclusions such as Al₂O₃ and SiO₂ and mitigating carbon pickup. However, challenges remain for industrial application, including balancing carbon-free requirements with high performance, ensuring reliability in long-sized stopper rod structures, and controlling costs. Future efforts should promote wider adoption of MgO-C stopper rods in efficient continuous casting through multi-scale simulation, composite design, and process optimization.
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  Influence of w(B₂O₃)/w(CaF₂) on crystallization of base system of CaO-Al₂O₃-Li₂O-B₂O₃-CaF₂ mold fluxes

  QI Jie, WANG Jinhui, SHI Yuanxin, DOU Yingying, LIU Chengjun, JIANG Maofa

  Continuous Casting. 2026, 45(1): 21-29. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250183

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  Taking the base slag system of low-reactive CaO-Al₂O₃-Li₂O-B₂O₃-CaF₂ mold fluxes as the object, and with the aid of equipment such as the single hot thermocouple technique, scanning electron microscope, and X-ray diffraction analyzer, the effects of substituting B₂O₃ for CaF₂ on the properties of the slag such as crystallization temperature, critical cooling rate, crystallization incubation time and crystalline phases were investigated, and the crystallization kinetics analysis was carried out. The results show that using B₂O₃ instead of CaF₂ can effectively reduce the crystallization tendency of the slag. When the w(B₂O₃)/w(CaF₂) ratio increases from 0.44 to 2.25, the critical cooling rate rises. When the ratio of w(B₂O₃) to w(CaF₂) is 2.25, the critical cooling rate reaches 12 ℃/s, and the crystallization performance is the weakest. With the increase of the substitution amount of B₂O₃ for CaF₂, the crystallization inoculation time shows a trend of first increasing and then shortening. During the cooling process of the slag, the initial crystalline phase formed changes from CaAl₂O₄ to CaAl₄O₇. The change law of the full crystalline phase is CaAl₂O₄+CaF₂→CaAl₄O₇+CaF₂→CaAl₄O₇+CaF₂+Ca₅B₃O₉F. Kinetic analysis indicates that when w(B₂O₃)/w(CaF₂) is less than 1.6, the crystal growth changes from three-dimensional to two-dimensional as the temperature drops, with a transition temperature of 1 100 ℃. When w(B₂O₃)/w(CaF₂) is greater than or equal to 1.6, the crystals precipitated in the slag always grow in three dimensions. Moreover, as the substitution amount of B₂O₃ for CaF₂ increases, the precipitation of Ca₅B₃O₉F promotes the three-dimensional growth of the crystal. When the ratio of w(B₂O₃) to w(CaF₂) is 0.625 to 1, the crystallization performance of the slag is relatively weak, and the types of crystalline phases are fewer, which is more conducive to the regulation of crystallization performance.
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  Effect of light-burned ascharite powder on properties of MgO-C bricks for ladle slag lines

  DAI Chenchen, QIAN Fan, WANG Shushan, NIE Bohua

  Continuous Casting. 2026, 45(1): 30-36. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250187

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  To enhance the overall performance of magnesia-carbon bricks for ladle slag lines, this study introduced light-burned ascharite powder into a conventional formulation. Its effects on the physical properties, high temperature modulus of rupture, thermal shock resistance, and slag resistance of the bricks were systematically investigated. Results demonstrate that the composite addition of light-burned ascharite and metallic aluminum powder exhibits superior high temperature modulus of rupture, slag resistance, and thermal shock resistance compared to the formulation with ascharite alone. The synergistic effect is attributed to two mechanisms. The first involves aluminum powder, which at low to medium temperatures forms Al₄C₃ fibers, subsequently oxidized to Al₂O₃ and transformed into spinel. This process effectively fills and seals pores through the associated volume expansion and solid-phase deposition, thereby improving the medium-to-high temperature strength and slag resistance. Simultaneously, an appropriate amount of light-burned ascharite powder generates a dispersed magnesium borate liquid phase at high temperature, which promotes sintering densification, alleviates thermal stress, and strengthens the matrix through pinning effect, thereby significantly enhancing the high-temperature performance and thermal shock stability.
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  Effect of reactive alumina micro-powder on properties of Al₂O₃-C refractory

  WANG Jianguo, QIAN Fan, YANG Wengang, CAO Mei

  Continuous Casting. 2026, 45(1): 37-43. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250174

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  Al₂O₃-C materials were prepared using high-alumina bauxite clinker as the primary raw material, flake graphite as the carbon source, metallic silicon and silicon carbide as additives, and phenolic resin as the binder, with varying proportions of reactive alumina micropowder incorporated. The particle size distribution, bulk density, and flowability of the granulated feedstock, along with the cold modulus of rupture, apparent porosity, bulk density, permanent linear change after heating, hot modulus of rupture, thermal expansion, and thermal shock resistance of the Al₂O₃-C materials, were measured in accordance with relevant standards. This study investigated the effect of reactive alumina micropowder addition on the properties of Al₂O₃-C refractories for the three major continuous casting components, based on a formulation with high-alumina bauxite clinker as the main raw material and the mass fraction of graphite is 23%. The results indicated that with increasing reactive alumina micropowder content, the granulation quality and flowability of the Al₂O₃-C granules first improved and then deteriorated. Incorporating reactive alumina micropowder into the Al₂O₃-C refractories reduced the apparent porosity and enhanced the bulk density, cold modulus of rupture, and hot modulus of rupture. Following heat treatment at 1 100 ℃ and 1 600 ℃, all samples exhibited varying degrees of shrinkage, with the linear shrinkage increasing progressively as the reactive alumina micropowder content increased. Moreover, with higher additions of reactive alumina micropowder, the thermal expansion coefficient of the high-alumina bauxite clinker-based Al₂O₃-C refractories gradually increased, while their thermal shock resistance progressively deteriorated.
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  Influence of magnesium-aluminum spinel on properties of spinel carbon refractories

  GUO Hairong, LI Xia, LI Hualong, QIAN Fan, YANG Wengang, LI Hongxia

  Continuous Casting. 2026, 45(1): 44-52. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250124

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  Spinel carbon refractories exhibit outstanding thermal shock resistance and corrosion resistance by molten steel, rendering them well-suited for applications in continuous casting components. Two types of spinel carbon refractories were prepared using fused spinel, sintered spinel, graphite, and Al-Si alloy powders as primary raw materials, and the physical property and corrosion tests were carried out. The results show that: At relatively high temperatures (above 1 400 ℃), the Al-Si alloy powders reacts with CO in vapor form to produce Al₂O₃ and SiC fibers, which strengthen the bonding of the matrix, and part of the silicon forms SiC with a granular morphology under corrosion conditions; Fused spinel, with its high density, can physically impede the infiltration of molten slag, and the erosion it undergoes is primarily characterized by chemical dissolution at the raw material boundary. In contrast, sintered spinel has a lower density than fused spinel, leading to weaker resistance against molten slag penetration. Nevertheless, it boasts higher activity compared to fused spinel and a stronger capacity to dissolve MnO and FeO in the slag, thereby demonstrating enhanced resistance to glass phase dissolution. As a result, both spinel carbon refractories exhibit excellent corrosion resistance.
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  Effect of C/MgAl₂O₄ composite powders on properties of low-carbon MgAl₂O₄-C refractories

  WANG Cangshuo, DING Donghai, LEI Changkun, XIAO Guoqing, DAI Liming, LÜ Lihua, FENG Chunzhuo

  Continuous Casting. 2026, 45(1): 53-62. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250148

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  With the increasing demand for low-carbon and ultra-low-carbon steel smelting, low-carbon spinel-carbon refractories for continuous casting are subject to more rigorous requirements for slag corrosion resistance and thermal shock resistance. This study systematically investigates the effect of nano-carbon/magnesium aluminate spinel (C/MgAl₂O₄) composite powder content on the properties of low-carbon magnesia-alumina spinel-carbon (MgAl₂O₄-C) refractories for stopper rods. The results indicate that the composite powder consists primarily of irregularly shaped particles with rough surfaces, in which nano-carbon is distributed between MgAl₂O₄ grains and adhered to spinel particle surfaces, forming a unique clustered morphology. The optimal performance of MgAl₂O₄-C refractories was achieved with 6.3% composite powder addition (sample C/MA-2), showing 15.4%, 19.6%, and 45% enhancements in the cold modulus of rupture (CMOR), the cold crushing strength (CCS), and the hot modulus of rupture (HMOR), respectively, compared to the composite-free sample (C/MA-0). Sample C/MA-2 exhibited the best thermal shock resistance, showing a 11.9% higher the thermal shock resistance of than C/MA-0. Furthermore, the erosion depth of C/MA-2 was reduced by 19.6% relative to C/MA-0, demonstrating superior slag corrosion resistance.
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  Erosion mechanism and optimization of spinel-carbon shopper rod in high-oxygen steel casting

  GAO Zhi, PAN Lei, FAN Haibo, WANG Zuochuang, YANG Qin, MA Beiyue

  Continuous Casting. 2026, 45(1): 63-69. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250073

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  In the continuous casting process, the stopper rod plays a pivotal role in regulating the flow of molten steel from the tundish into the mold. Its performance has a direct impact on the stability of the molten steel levels in both the tundish and the mold, as well as the control of the flow rate from the tundish. Spinel-carbon refractory materials are extensively utilized for the stopper rod owing to their superior chemical stability and resistance to molten steel erosion. However, when casting certain steel grades with excessively high oxygen content, severe erosion was observed on the stopper rod, which even compromised normal flow control. To address this situation, an analysis of the used stopper rod was conducted, revealing that the oxygen content and calcium content in the steel, along with the density of the stopper rod, are crucial factors influencing erosion. Based on these findings, an optimization study was carried out to adjust the contents of spinel, flake graphite, and SiC in the stopper rod, aiming to enhance its mechanical properties, thermal shock resistance, oxidation resistance, and erosion resistance. Among the samples, A3 exhibited superior performance compared to the control sample A0. Under the condition of maintaining excellent thermal shock resistance, the high-temperature strength of sample A3 increased by 2.9 MPa (approximately 30%), and its oxidation resistance improved by approximately 35%. During steel plant trials, the optimized screw head A3 demonstrated remarkable application performance. Compared with the original screw head, it significantly enhanced the erosion resistance during the casting of high-oxygen steel grades.
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  Effects of w(CaO+BaO)/w(Al₂O₃) and B₂O₃ substitution for SiO₂ on wetting characteristics between CaO-Al₂O₃- based mold flux and Fe-Mn-Al-C low-density steel

  FAN Lei, WANG Zineng, QU Tianpeng, WANG Deyong

  Continuous Casting. 2026, 45(1): 70-80. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250161

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  The wetting characteristic of mold flux is an important factor affecting the surface quality of low-density steel billets. By using a high-temperature contact angle measuring instrument in combination with interfacial structure characterization, the effects of (CaO+BaO)/Al₂O₃ mass ratio and substitution of B₂O₃ for SiO₂ on the wetting characteristic between CaO-Al₂O₃-based mold flux and low-density steel are studied. Results show that as the (CaO+BaO)/Al₂O₃ mass ratio increases from 0.87 to 1.59 and B₂O₃ gradually replaces SiO₂, the initial temperature at which the contact angle begins to rapidly reduce decreases from 1 480 ℃ to 1 330 ℃, 1 170 ℃, and first decreases from 1 300 ℃ to 1 170 ℃ and then increases to 1 180 ℃, respectively. The evolution behavior of contact angle and adhesion work is similar to the change in temperature. As the (CaO+BaO)/Al₂O₃ mass ratio increases, the thickness of element diffusion layer at the steel-slag interface increases from 1 μm to 5 μm. As B₂O₃ replaces SiO₂, the thickness of element diffusion layer at the interface first decreases from 9 μm to 5 μm and then increases to 15 μm. Mn diffuses and transfers from the steel matrix to the interface, and its content gradually decreases. Al diffuses and transfers from the steel matrix to the interface, and due to the high Al content in the slag at the interface, its content shows an increasing trend. The change of Si content is not obvious. Based on this, the mass ratio of (CaO+BaO)/Al₂O₃ is controlled at around 1.59, and the contents of B₂O₃ and SiO₂ are controlled at 5%, which are conducive to maintaining the low reactivity of mold flux and improving its wetting characteristics with low-density steel.
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  Optimization of material, structure and surface coating of safe and stable stopper rod in continuous casting tundish

  LIU Yang, WEN Zhen, ZHOU Congrui, CAO Dongliang, ZHU Yanyi, CAO Weixian

  Continuous Casting. 2026, 45(1): 81-88. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250115

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  In order to mitigate fracture and abnormal erosion of stopper rods in continuous casting tundishes and thereby enhance production safety and stability, a comparative analysis was conducted on two commonly used slab tundish stopper rods. The study examined their internal structure, chemical composition, phase constitution, and physical properties at both room and high temperatures. The results indicate that the HN-1 stopper rod, featuring a phosphate-bonded corundum-mullite anti-adhesion coating, a tightly adherent anti-oxidation coating, and a MgAl₂O₄-C head material, demonstrates excellent oxidation and erosion resistance. However, its slag line, composed of a low-ZrO₂ Al₂O₃-C material, exhibits reduced erosion resistance, leading to fracture during operation. In contrast, the HY-1 stopper rod employs an Al₂O₃-C/MgO-C composite structure in its slag line, providing superior erosion resistance. Nevertheless, the composition design of its anti-oxidation coating and the inadequate oxidation resistance of the rod body result in uniform internal oxidation of the stopper rod. Through optimization of the slag line material for the HN-1 rod and adjustments to the glaze composition and matrix oxidation resistance for the HY-1 rod, the sequence length for continuous casting of low-carbon steel was increased from 22 heats to 27-32 heats. These improvements effectively ensured the safety and stability of the continuous casting process.
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  Research on water distribution optimization in secondary cooling area of 70 steel continuous casting based on GA-ACO collaboration

  LI Yihong, ZHANG Haodong, XIONG Pengfei, WANG Dong, GUAN Wenbo, ZHANG Hongxu, HUA Chengjian

  Continuous Casting. 2026, 45(1): 89-99. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250146

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  This paper addresses the issue of center carbon segregation during the continuous casting process of 70 steel and proposes a Genetic Algorithm-guided Ant Colony System (GA-guided ACO). The Genetic Algorithm is used to pre-generate the initial pheromone distribution, and a dynamic hybrid update mechanism incorporating the genetic algorithm is introduced. This effectively solves the premature convergence problem commonly encountered in traditional Ant Colony Optimization (ACO) algorithms in multi-objective optimization. In the later stages of the iteration, the ACO continues to leverage its powerful global search ability. Compared to the traditional ACO, the convergence speed is improved by 53.13%. In this work, a coupled solidification and heat transfer model was implemented, which outputs key parameters such as temperature gradient and solid fraction, providing the basis for the objective function calculation for the algorithm. This forms a closed-loop control framework of "model prediction-algorithm optimization". The industrial applications show that the optimized secondary cooling process reduces the center segregation index by 5.8% at a casting speed of 2.2 m/min. The segregation index is reduced by 5.38% and the total water consumption is decreased by 4.63%, when the casting speed is 2.4 m/min. The 70 steel billet segregation quality is improved and production cost is reduced. The experimental results demonstrate that the improved algorithm provides an effective solution for the optimization of the segregation of 70 steel continuous casting process.
Technology Exchange
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  Effect of an asymmetric side-port submerged entry nozzle on spatial distribution of inclusions in bloom during continuous casting

  ZHAO Ziwen, JIA Qi, WANG Qiang, ZHU Chengyi, LI Guangqiang

  Continuous Casting. 2026, 45(1): 100-110. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250135

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  To optimize the inclusion control level of GCr15 bearing steel and explore the influence of an asymmetric side-port submerged entry nozzle on the spatial distribution of inclusions in continuous casting bloom, field sampling and analysis were performed on the bloom. A numerical model was established that simultaneously considers the three-dimensional unsteady flow, heat transfer, solidification and the coupling of inclusion movement throughout the continuous casting process, as well as the capture of inclusions at the solidification front, to realize the prediction of the spatial position of residual inclusions in the continuous casting bloom at different times. The proportion of inclusions floating to the slag/steel interface increased from 1.9% to 17.9% when the particle size increased from 1 μm to 50 μm during the continuous casting process. Residual inclusions within the bloom exhibited an asymmetric distribution, with a tendency to accumulate 7.8-10.5 mm beneath the bloom surface. Inclusions less than 10 μm were more likely to be transported by molten steel flow into the deeper regions of the liquid pool, while inclusions with a particle size greater than 10 μm tend to accumulate at 1/4 to 1/3 of the inner arc side of the bloom.
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  Development and application of on-line quality monitoring and judgment system for casting slabs

  LU Zhiqiang, QIN Hongbo, ZHEN Jingyan, WANG Jijun

  Continuous Casting. 2026, 45(1): 111-118. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250040

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  To address the challenges of delayed quality monitoring and inefficient manual judgment in continuous casting production, an online quality monitoring and judgment system for casting slabs was developed based on multi-source data fusion. A three-tier architecture of "data acquisition, rule engine, and intelligent judgment" was designed, incorporating a real-time data acquisition module covering 707 process parameters across critical processes such as mold vibration and secondary cooling water distribution. A dynamically configurable three-tier metallurgical quality rule base was innovatively proposed, establishing a core rule engine for slab judgment to support real-time process parameter monitoring and anomaly warnings based on statistical process control (SPC), while achieving multi-level collaborative responses through sound-light alarms and WeChat notifications. To resolve defect traceability challenges, a three-dimensional coupling judgment model was established for mold level fluctuations, casting speed variations, and stopper rod movements, with formula-based characterization of the mapping relationship between process parameter fluctuations and quality defects. Application at a steel plant in Tangshan demonstrated significant improvements: through dynamic optimization of the metallurgical rule base and closed-loop feedback mechanisms for process parameters, the internal defect judgment accuracy increased from 25% to 85.6%, comprehensive judgment accuracy reached 98.5%, and manual re-inspection workload was reduced by over 75%. This research provides a full-process solution of "rule configuration, process monitoring, and quality traceability" for digital control of continuous casting, effectively addressing industry pain points such as outdated knowledge updates in traditional expert systems and insufficient interpretability of data-driven models.
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  Distributions of content and size of inclusions in unsteady transition slab of automotive outer panel

  GAO Jinqiao, YANG Jian, GONG Jian, HUANG Fuxiang, PEI Xingwei, ZHU Keran, LIU Fenggang, LIU Zhentong

  Continuous Casting. 2026, 45(1): 119-125. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250037

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  A statistical analysis was performed on both micro-inclusions and macro-inclusions in a 31-meter-long unsteady-state transition slab from two heats (A and B) of IF steel for automotive outer panels produced at a steel plant. Analysis of micro-inclusions larger than 5 μm revealed that the number density of inclusions increases significantly and remains elevated from 1 m before to 13 m after the start of casting heat B. Typical macro-inclusions larger than 30 μm, extracted via large-sample electrolysis, mainly consist of: blocky Al₂O₃ inclusions around 250 μm, irregular blocky mold flux inclusions around 600 μm, Al₂O₃+SiO₂ inclusions generally ranging from 50 μm to 200 μm, and spherical calcium aluminate inclusions with sizes between 30 μm and 100 μm. The content of macro-inclusions rises notably and stays high from 3 m before to 14 m after the start of casting heat B. Thus, the length of the transition slab with severely compromised molten steel cleanliness is approximately 17 meters.
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  Development and application of arc angle mold copper plate for high-speed thin slab continuous casting

  SONG Weidong, YANG Guoming, JIA Yugang, ZHENG Xutao, LIU Junkai, WU Zhihui, WU Jinzhong, ZHANG Lipeng

  Continuous Casting. 2026, 45(1): 126-133. https://doi.org/10.13228/j.boyuan.issn1005-4006.20240268

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  The high-speed thin slab continuous casting and rolling production line has developed rapidly due to its short process, low energy consumption, and high output characteristics. It mainly produces a series of steel grades such as low-carbon and low silicon steel, weathering steel, automotive steel, medium carbon steel, and high carbon steel. The high-speed thin slab continuous casting quickly forms a thick enough shell to achieve high casting speed with its excellent mold heat transfer performance. The special shape design of the narrow copper plate meets the concept of no sufficient roller support, but the bulging amount of the narrow surface of the casting billet exacerbates the problems of longitudinal cracking at the edge and folding at the corner during rolling. By developing the narrow surface arc angle mold copper plate process, on the one hand, it fundamentally improves the temperature field of the initial shell corner during solidification in the mold, and on the other hand, weakens it. The stress folding of the protruding corners during the rolling process fundamentally solves the problems of longitudinal cracking at the edges and folding during corner rolling. This article improves the problem of excessive two-dimensional heat transfer at the corner of the casting billet in the mold by developing and applying narrow arc angle copper plates. The average temperature inside the mold is increased by 25.2 ℃, and the form of the casting billet arc angle also reduces the product quality problem of black lines at the edge of the strip steel during the rolling process from the source.
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  Cause analysis of disqualification of AK-B3 steel in flaw detection and processes improvement

  QIN Zhe, ZHAO Chenglin, ZANG Yan, ZHANG Jianyuan, DU Dongfu, WU Jiawen, ZHANG Long, JIA Jixiang

  Continuous Casting. 2026, 45(1): 134-140. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250016

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  The problem of low qualification rate of AK-B3 ball mill steel had been appeared, the microstructure, inclusions and precipitation around defects of flaw detection were detected and analyzed by OM, SEM and metal in situ analyzer, the segregation of chemical elements of continuous casting billets was analyzed. The results show that there were strip shaped cracks, micro-cracks and micro-viods distributed along rolling direction. The side morphology of cracks were cleavage fracture, inclusion of MnS and TiN occurred around cracks. Chemical elements of Mn, P and S of continuous casting billet exhibited obviously segregation, which was the main reason for the low qualification rate of flaw detection. The qualification rate of flaw detection increased from 85% to 94% through improving smelting and continuous casting processes, enhancing the cleanliness of molten steel and the internal quality of casting billets, optimizing processes of slow cooling of billets and heating process of furnace diminution thermal stress and increasing rolling reduction of continuous casting billets.
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  Formation mechanism of sliver defects for tinplate and process optimization

  GUO Xiaolong, YANG Shan, DONG Wenliang, DING Guohui, ZHOU Haichen, ZHANG Congcong

  Continuous Casting. 2026, 45(1): 141-147. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250019

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  High speed casting was used to cast the low carbon steel grades used for tinplate due to the narrow width. Sliver defects were frequently detected in tinplate, which caused high downgrade ratio and production cost. The micro analysis revealed that the primary cause of these linear defects was FeO type with small oxide points. Under high casting speeds, the heat flux density of the molten steel exceeded the critical heat flux density, resulting in longitudinal slab cracks , which subsequently evolved into linear defects during rolling. By reducing the Na₂O content to 1.47%, increasing the Li₂O content to 1.7%, and controlling the fluid flow through optimization the current parameters of FC mold, the FeO type sliver defects were sharply decreased.