20 June 2026, Volume 45 Issue 3

    

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  Preface

  MAO Xinping

  Continuous Casting. 2026, 45(3): 0.

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  Introduction to Guest Editor-in-Chief

  Continuous Casting. 2026, 45(3): 0.

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Column of Homogenization Technology by Pulse Magneto-Oscillation Solidification
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  Application of PMO technology in continuous casting of SWRCH22A billet

  JIA Jixiang, TANG Xuefeng, WANG Haiwei, GUAN Yong, XU Zhishuai, LIU Haining, LI Lijuan, ZHAI Qijie

  Continuous Casting. 2026, 45(3): 1-6. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250170

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  Pulsed Magneto-Oscillation (PMO) solidification homogenization technology is an original technology developed by the Advanced Solidification Technology Center of Shanghai University, which is used to solve the problems of microstructure refinement and homogenization during metal solidification. To further improve the continuous casting production level of SWRCH22A cold-heading steel of Angang Steel Co., Ltd., this technology was applied to its industrial production, and a series of industrial tests were carried out under different PMO process parameters. The results show that after the application of PMO technology, the central defects of continuous casting billets, such as centerline shrinkage cavities, centerline porosity and centerline carbon segregation, are effectively controlled. The ratio of samples with centerline shrinkage cavities, centerline porosity and centerline carbon segregation not higher than grade 0.5 reaches nearly 100%. The central equiaxed crystal ratio increases significantly with the increase of PMO parameters, with the maximum reaching 18.37%, and the proportion of equiaxed crystals reaches 26%. Meanwhile, PMO technology can significantly improve the radial carbon segregation of cast billets, and the improvement degree of centerline segregation increases with the increase of PMO parameters. When the PMO voltage is 290 kV, the centerline carbon segregation decreases from the original 0.245% to 0.20%, a reduction of 18.4%.
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  Improving quality of ø 250 mm SWRH82B hard-wire steel continuous casting billets by PMO

  LIU Xingchen, PI Pengfei, XU Zhishuai, CHEN Xiangru, ZHAI Qijie, LIU Haining, LIU Jian

  Continuous Casting. 2026, 45(3): 7-15. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260033

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  Due to its high carbon content, SWRH82B high-carbon steel is significantly affected by selective crystallization and solute enrichment effects during the continuous casting of ø250 mm round billets, which easily leads to severe central carbon segregation and shrinkage cavity defects, and further induces wire breakage problems in subsequent drawing processes. To improve the quality of ø250 mm SWRH82B hard wire steel continuous casting billets, Pulsed Magneto-Oscillation (PMO) solidification structure homogenization technology was introduced into the continuous casting production line of Tianjin Rockcheck United Iron and Steel Group Co., Ltd., the effects of PMO on the solidification structure and central segregation of ø250 mm continuously cast SWRH82B steel were studied. The results show that after applying PMO, the central carbon segregation index of the billet cross-section decreased from 1.19 to 1.09, with a maximum reduction of more than 43%. The width of the equiaxed crystal zone of the billet increased from 13.1 cm to 15.4 cm, the equiaxed grain ratio increased from 27.4% to 37.9%, the maximum value of the secondary dendrite arm spacing decreased from 185.9 μm to 159.9 μm, and the solidification structure was significantly refined.
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  Application of PMO technology in industrial production of ø 250 mm round billets

  LIU Jian, LIAO Zhengjun, LI Qiang, ZHAO Changchun, LIU Haining, XU Zhishuai, LI Lijuan, ZHAI Qijie

  Continuous Casting. 2026, 45(3): 16-23. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250169

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  Based on the production practice of applying Pulsed Magnetic-Oscillation (PMO) solidification homogenization technology on the ø 250 mm round billet continuous caster of Tianjin Rockcheck United Iron & Steel Group Co., Ltd., this study explores the improvement effect of this technology on the center defects and macrosegregation of round billets. The results show that the PMO technology can significantly improve the centerline shrinkage cavities of ø 250 mm round billets, with the best effect achieved when the voltage is controlled at 225k_U-235k_U V (k_U represents the equipment coefficient, i.e., the calibration parameters of different equipment). Additionally, the PMO technology has a significant improvement effect on the macrosegregation of cast billets, and the optimal regulation effect is obtained when the voltage is around 220k_U V and the frequency is medium frequency. Moreover, this technology has high process tolerance; increasing the casting speed by 10%-20% does not affect its regulation effect on the center defects and macrosegregation of cast billets. Meanwhile, production practice indicates that the PMO technical equipment operates stably and reliably, with no product objections since its commissioning nearly a year ago.
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  Practice of PMO renovation for ø 250 mm round billet continuous casting machine

  MA Lei, ZHANG Lin, SUN Yusong, ZHOU Haichuan, XU Zhishuai, LIU Haining

  Continuous Casting. 2026, 45(3): 24-32. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260042

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  Aiming at the quality problems such as central shrinkage cavity and central carbon segregation existing in the casting process of the ø250 mm round billet continuous caster at Tianjin Rockcheck United Iron and Steel Group Co., Ltd., targeted technical transformation was carried out on the continuous caster by adopting the Pulsed Magneto-Oscillation (PMO) solidification homogenization technology. This paper briefly introduces the equipment assembly, technical transformation scheme of PMO technology, and analyzes the effects of PMO technical transformation on the effective diameter of the central equiaxed crystal zone, central shrinkage cavity rating, element segregation and other aspects of continuous casting billets through industrial test results. Production practice shows that after PMO technical transformation, the effective diameter of the central equiaxed crystal zone of the casting billet increases from 117 to 157 mm, with an average increase of 34%; the proportion of grade 0 central shrinkage cavity of the casting billet rises from 20% to 63.6%, with an average increase of 218%. Meanwhile, PMO technology can effectively reduce the segregation degree of solute elements in the center of continuous casting billets. On the premise of ensuring that the internal quality of the casting billets stably meets the standards, it significantly increases the continuous casting speed, realizing the coordinated optimization of product quality and production efficiency.
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  Application of PMO technology to improve quality of ø 600 mm vertical continuous casting 8418 die steel large round billet

  GONG Zheng, GAO Yingli, LI Mingqi, LIN Huijie, LI Renxing, LIU Haining

  Continuous Casting. 2026, 45(3): 33-45. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260047

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  To alleviate solidification structure defects and macrosegregation in ø600 mm large round billets of 8418 die steel produced by vertical continuous casting, this study adopts a combined method of numerical simulation and industrial experiments to investigate the regulatory effect and internal mechanism of Pulsed Magneto-Oscillation (PMO) on the flow field, temperature field, solidification structure and macrosegregation of continuous casting billets. Numerical simulation results show that PMO can induce an upper and lower dual-circulation flow structure near the coils in the secondary cooling zone. Under the working condition of 500k_U A (where k_U represents the equipment coefficient of PMO), the peak flow velocity of the upper circulation reaches 91.29 mm/s, and that of the lower circulation is 38.58 mm/s. The intense convection promotes circulating heat exchange of high-temperature molten steel between the solid-liquid interface and liquid core, realizing cooling of the liquid core and reheating of the billet surface, which optimizes the heat transfer environment during solidification. Industrial experimental results indicate that PMO promotes the nucleation of molten steel at the front of the solid-liquid interface to form a "crystal rain", thereby refining the solidification structure of the billets. The dual-circulation flow further accelerates heat dissipation at the billet center, reducing the area fraction of central cracks from 10.86% to 3.22%. Meanwhile, PMO effectively improves the compositional homogeneity of billets, decreasing the maximum carbon segregation index from 1.31 to 1.19 and significantly mitigating the segregation fluctuation of Cr, Mo and V elements at the central and 1/2 radius positions of the billets. The research demonstrates that PMO technology can synergistically optimize the solidification structure, central cracks and macrosegregation of ø600 mm 8418 die steel large round billets fabricated by vertical continuous casting, providing a reliable technical support for the production of high-quality large-section high-alloy die steel round billets.
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  Industrial practice of improving quality of 220 mm×260 mm rectangular billet using PMO technology

  GUI Zhonglin, LI Huicheng, WANG Xianghong, TU Xingkuang, QU Zhidong, LIU Haining

  Continuous Casting. 2026, 45(3): 46-50. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260041

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  The former Electric Furnace Plant of Zenith Iron and Steel Group was the first to adopt the Pulsed Magneto-Oscillation (PMO) homogenization technology originally developed by Shanghai University for the continuous casting of 220 mm×260 mm rectangular billets. Taking low-carbon gear steel, medium-carbon tool steel and high-carbon bearing steel as research materials, this paper explores the influence of PMO technology on the internal quality of continuous casting billets via industrial trials. The improvement effect and variation rules of casting speed and superheat on the equiaxed grain ratio of billets are comparatively analyzed. Industrial production results indicate that compared with billets treated merely by final electromagnetic stirring (F-EMS), the equiaxed grain ratio of billets processed with PMO rises by 50% to 100% on average. Such growth becomes more prominent as casting speed and superheat increase. While enhancing the quality of continuous casting billets, PMO technology remarkably expands the process window for continuous casting, offering another key technical approach for the research and engineering application of homogenization technology in continuous casting.
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  Effect of PMO power on macrostructure quality of 225 mm×270 mm rectangular 45 steel casting billet

  LI Huicheng, LIU Haining, GUI Zhonglin, WANG Xianghong, YANG Chengwei

  Continuous Casting. 2026, 45(3): 51-57. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260043

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  Taking medium-carbon 45 steel as the research object, the Pulse Magneto-Oscillation (PMO) homogenization technology was adopted to perform pulse magnetic field treatment on 225×270 rectangular casting billets under high, medium and low power process parameters. The results show that a certain power level is required for PMO treatment. Under high power conditions, the central shrinkage cavity of the casting billet is completely eliminated, the proportion of equiaxed crystals increases by 66.07% and 19.62% respectively, and the central segregation index of the casting billet can be reduced to 1.02. Appropriately reducing the PMO power can still significantly improve the central shrinkage cavity defect and central segregation of the casting billet; however, selecting low PMO power fails to achieve the ideal metallurgical effect. Under the appropriate PMO process parameters, increasing the continuous casting speed has little impact on the PMO homogenization effect.
Monographic Study
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  Research status and prospect of surface oxidation of high-Mn high-Al steel

  LIU Zijia, SONG Mingming, ZHU Haoran, XIAO Chuankang, ZHAO Jinming, JIANG Liheng

  Continuous Casting. 2026, 45(3): 58-70. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250110

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  While Cr-Ni heat-resistant steels remain prevalent in aerospace, nuclear energy, and automotive applications, escalating material costs have driven alloy innovation toward Mn-Al based alternatives. The emerging high-Mn high-Al steels demonstrate a remarkable combination of high-strength and super-plasticity, offering promising solutions for lightweight high-temperature equipment. However, challenges in oxide scale control during manufacturing processes have become increasingly critical. This review systematically investigates the oxidation kinetics of high-Mn high-Al steels across varying thermal gradients and alloy configurations, summarizing the critical impacts of oxidation temperature, alloy composition, ambient atmosphere, and surface topography on oxide scale formation. Through comprehensive thermodynamic analysis and kinetic modeling, we overview effective control strategies encompassing surface engineering, process parameter optimization, and compositional design. It finally points out that future research should focus on variable-temperature oxidation behavior, multi-component synergistic mechanisms and phase transformation at the oxide scale/substrate interface, providing theoretical support for the development of new-generation high-performance high-Mn high-Al steels.
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  Optimization of filling process in single-strand tundish and steady-state casting procedure

  PENG Feng, CHENG Guoguang, WANG Guanbo, DENG Feng, DAI Weixing, FENG Bo, WANG Qiming, HU Yuexia

  Continuous Casting. 2026, 45(3): 71-81. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250133

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  During the molten steel filling process in the tundish for the first heat of continuous casting, unreasonable design of flow control devices can easily lead to secondary oxidation of molten steel, erosion of refractory materials, and significant impacts on steel cleanliness, though few related studies exist. This study investigates an 8 t single-strand small rectangular tundish in an industrial plant. Physical and numerical simulations were combined to analyze the molten steel flow behavior in the prototype tundish, and a mathematical model was used to calculate the degree of secondary oxidation. To address deficiencies in the prototype, the original baffle with flow holes was replaced with an optimized dam-weir configuration. The effects of dam/weir heights and positions on molten steel flow were systematically studied. The results show that the prototype tundish exhibited severe secondary oxidation and refractory erosion near the front wall during initial filling, along with short actual residence time. The dam-weir configuration demonstrated effective suppression of secondary oxidation. The optimal parameters were determined as follows: weir height 180 mm from the tundish bottom, dam height 300 mm, and 370 mm distance between the stopper rod center and dam. Industrial implementation confirmed significant improvements: total oxygen content decreased, MgO·Al₂O₃ inclusions were notably reduced, front-wall refractory erosion weakened markedly, and dead zone proportion decreased to 1.2% after optimization.
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  Coupled numerical simulation on heat transfer and cooling water flow of chamfered mold copper plates

  LIU Qilong, TAO Hongbiao, DONG Jianfeng, CAO Chenghu, LU Qiang, LUO Xiao, LI Xiongjie

  Continuous Casting. 2026, 45(3): 82-87. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250136

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  Based on actual dimensions of the copper plate and the back plate, a physical model was constructed. Meanwhile, a three-dimensional heat transfer and cooling water flow mathematical model of the copper plate of the mold was established. Coupled numerical simulations were conducted on the heat transfer and cooling water flow of the narrow-face copper plates of the right-angle and chamfered mold. The results show that when the water volume is 510 L/min, the macroscopic average water velocity of the right-angle and chamfered mold are 8.8 m/s and 7.4 m/s, respectively. The water velocity in the circular holes near the corner of the copper plate of the chamfered mold is only 4.8 m/s to 5.1 m/s, while the water velocity in the water gap near the edge of the right-angle mold reaches more than 8 m/s. In the meniscus area, the corner temperatures of the narrow copper plates of the right-angle and chamfered molds reached 677 K and 763 K respectively. When the diameter of the circular hole at the water inlet of the copper plate in the chamfered area is increased from 10 mm to 14 mm and the water volume on the narrow side of the mold is increased to 540 L/min, the water velocity at the edge circular hole can be raised to 6 m/s, which is conducive to enhancing the cooling intensity at the corner of the chamfered mold.
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  Study of precipitation rule on TiN inclusion in continuous casting slab of titanium microalloyed steel

  YANG Xiaojiang, LI Zhe, YANG Jie, LI Yanjie, MA Chao, JIANG Renbo, ZHANG Dayong, ZHEN Changliang

  Continuous Casting. 2026, 45(3): 88-96. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250128

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  In order to mastering the precipitation rule of TiN inclusions in continuous casting slab, we compared and analysed that quantity, granularity, and distribution characteristics of TiN inclusions in the slab of titanium microalloyed ultra-low carbon steel, peritectic steel, medium carbon steel and high carbon steel by means of phase analysis facilities such as OM, SEM and Aspex. we found that the particle size and surface density of TiN tended to increase with the increase of carbon content, also found an increasing trend from surface layer of slab to solidification center of slab. we observed that the change of TiN inclusions in slab before and after simulation by using high temperature tube furnace to heating the slab, and analyzed that the reason of TiN change before and after simulated heating.
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  Study on motion behavior of bubbles in argon blowing through a tundish stopper rod

  ZENG Jiaxiang, CUI Fuxiang, ZHANG Hui, WANG Minglin, LIU Shuai, LIU Yang, WANG Guobin

  Continuous Casting. 2026, 45(3): 97-106. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250247

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  Argon blowing through the stopper rod is a key technique in the continuous casting process for preventing nozzle clogging and improving molten steel quality. To optimize the stopper rod argon blowing process in continuous casting tundishes this study establishes a 1∶1 water-argon physical model based on a prototype tundish from a specific plant and combines it with numerical simulation. The study systematically investigates the influence of argon blowing hole position casting speed argon flow rate and stopper rod opening on argon bubble behavior flow field and turbulent kinetic energy distribution.The results indicate that the B1 position located above the sealing face of the stopper rod head yields optimal performance as its gas flow can effectively scour the sealing face. At an argon flow rate of 3 L/min bubbles are able to fully enter the nozzle at specific stopper rod openings corresponding to different casting speeds: specifically 33.75 mm at 1.3 m/min, 36.80 mm at 1.5 m/min and 41.90 mm at 1.7 m/min.Casting speed has a significant effect on bubble motion. For instance at a 30 mm opening and a 3 L/min argon flow rate increasing the casting speed from 1.3 m/min to 1.7 m/min increases the average bubble diameter from 12.5 mm to 15.1 mm. Conversely this speed increase reduces the average flow area width from 51.9 mm to 42.7 mm. Adjusting the argon flow rate simultaneously alters bubble volume and their range of motion within the nozzle. When the argon flow rate is reduced from 5 L/min to 1.8 L/min, the average bubble diameter decreases from 18.1 mm to 12.4 mm. Consequently the average bubble flow area width narrows sharply from 47.8 mm to 32.7 mm.The B1 position is suitable for a stopper rod opening up to approximately 40 mm with smaller openings generally resulting in better blowing effectiveness. However if the opening exceeds 50 mm the gas streams merge or float upward. This behavior not only loses the scouring effect on the stopper rod head but also increases the risk of erosion to the stopper rod at the molten steel surface in the tundish.
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  Influence of mixed casting of different steel grades in continuous casting slab on slab cleanliness and mechanical properties of steel plates

  ZHOU Baohui, ZHANG Long, GUO Yiran, LIU Haitao, SONG Sicheng, AN Hanghang

  Continuous Casting. 2026, 45(3): 107-115. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250134

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  Lowering the liquid level in tundish in the mixed casting of different steel grades is adopted to reduce the intermixed slab length but the increase of inclusions in slab arises, however non-lowering the liquid level in tundish is applied to implement steady-state operation and increase the intermixed slab length. Non-lowering the liquid level in tundish was applied in the mixed casting mixed casting of the SPHC and DC01 in a steel factory, the cleanness of the intermixed slab and the influence of it on mechanical properties of steel plate were comprehensively evaluated by optical microscope, scanning electron microscope analysis, Sample-electrolyzing method and multi-use mechanical testing machine. The results showed that content difference of total oxygen between intermixed slab and normal slab was 10×10^-6 to 15×10^-6, nitrogen content maintained about 70×10^-6. Distribution density difference of inclusions was 8.54 to 8.89 per/mm², content difference of large inclusions was 2.6 mg/10 kg, morphology and type of large and micro inclusions were basically consistent. tensile strength, yield strength, elongation after fracture of corresponding steel plate of the intermixed slab was more 11 MPa,32 MPa and 5.7% than that of normal slab in turn. Therefore, the intermixed slab and corresponding steel plate generated by non-lowering the liquid level in tundish should be degraded to reduce the rejection rate.
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  Analysis of time-frequency characteristics of liquid level fluctuations in thin slab mold

  HUANG Zhi, ZHANG Muyuan, WANG Hongxing, LI Zhaoyang, ZHANG Huantao, LIU Tiecheng, TIAN Peng, CUI Heng

  Continuous Casting. 2026, 45(3): 116-123. https://doi.org/10.13228/j.boyuan.issn1005-4006.20260012

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  Abnormal liquid level fluctuation in the thin slab continuous casting mold easily disturbs the stability of the meniscus, causes mold powder entrapment and uneven solidification of the shell, which is a major inducement for inclusion defects of cast slabs. This study, based on the process parameters of a thin slab mold in a domestic steel plant, established a water model with a similarity ratio of 0.5 to the industrial prototype. A wave height meter and a three-dimensional particle velocimetry system were used to collect liquid level fluctuations and surface velocities, and wavelet transform was combined to perform quantitative analysis of the liquid level fluctuations. The results show that the main frequencies of fluctuations in the mold are concentrated in the range of 0-1.09 Hz. With increasing casting speed, the frequency composition of fluctuations exhibits a trend of first increasing and then decreasing, while the amplitude gradually increases. As the SEN (submerged entry nozzle) depth increases from 130 mm to 170 mm, the amplitude gradually decreases, and the wavelet energy at each location migrates to lower frequency bands. Specifically, the proportion of low-frequency (0-0.135 Hz) energy near the SEN increases from approximately 0.35 to 0.75. Furthermore, the total wavelet energy and the average wave height show a consistent trend, with the wide 1/4 region being the main area for fluctuations. The amplitude is positively correlated with the surface velocity, but there is no obvious correlation with the frequency. This study reveals the time-frequency evolution law of fluctuations in thin slab mold, providing a reference basis for stable control of the mold level fluctuation and dynamic diagnosis of operating conditions.
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  Research and control of straight cracking after slab rolling

  LIN Wenbing, ZHANG Guozhu, CHI Yunguang, HUANG Yuantao

  Continuous Casting. 2026, 45(3): 124-128. https://doi.org/10.13228/j.boyuan.issn1005-4006.20250234

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  Aiming at the problem of linear edge cracks on steel plates occurring in Hunan Valin Xiangtan Iron and Steel Co., Ltd., the crack morphology was observed via an optical microscope. It is confirmed that the defect is induced by surface folding during the rolling process, rather than the inheritance of cracks from continuous casting billets. The effects of key factors including the narrow face profile of casting billets, rolling widening ratio, and the temperature difference between the upper and lower surfaces of billets before rolling were comparatively analyzed through rolling tests. The optimization of rolling process parameters and the development of convex crystallizers and matching foot rolls have effectively controlled the linear edge cracks of steel plates.