28 February 2026, Volume 43 Issue 1

    

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AI+Steel Rolling
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  Research progress of the State Key Laboratory of Digital Steel in "AI + steel rolling"

  WANG Guodong

  Steel Rolling. 2026, 43(1): 1-6. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260101

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  This paper examines the evolving trends in the digital transformation of the steel industry and provides a systematic overview of the research and engineering achievements of the State Key Laboratory of Digital Steel (DSL) in the domain of steel rolling. A series of high-fidelity digital twin models integrating data, physical mechanisms and empirical domain knowledge have been developed for critical production processes, including hot rolling, cold rolling and heat treatment. Intelligent optimization methods tailored for industrial production environments have been designed and implemented in large-scale steel enterprises both domestically and internationally. These innovations have yielded significant improvements in quality metrics, particularly in three-dimensional dimensional accuracy, microstructure, and mechanical properties. Finally, the paper outlines the future research and application prospects of "AI + steel rolling".
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  Prediction model of finishing rolling temperature of hot rolled strip based on mechanism-data fusion

  WANG Haiyu, FANG Kun, DONG Lijie, ZHAO Jianwei, GUO Liwei, LI Liangju

  Steel Rolling. 2026, 43(1): 7-13. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260102

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  In the production process of hot-rolled strip, the control accuracy of finishing rolling temperature directly affects the microstructure and mechanical properties of the strip, which is a key factor in ensuring dimensional accuracy and good flatness of the strip. Due to the complexity, multivariability and strong coupling characteristics of rolling process, traditional mechanism models have obvious deficiencies in prediction accuracy, which is difficult to meet the requirements for high-precision and high-performance products control.To this end, this article combines a domestic 2 250 mm hot strip mill with the GBDT algorithm and mechanism model to develop a predictive model for the finishing rolling temperature of hot-rolled strips that integrates both mechanistic models and data.This model has both the physical interpretability of a mechanism model and the ability to fully develop GBDT algorithm's advantages in data mining, enabling continuous learning and adjustment of historical data and real-time feedback, thus maintaining the stability and reliability of the model's predictive performance;At the same time, it has self-training and closed loop control functions to achieve automatic closed loop control.After applying the model online, the deviation of long-term genetic prediction for finishing rolling temperature has decreased from 14.55 ℃ to 9.85 ℃. The results show that the model has high calculation accuracy and can meet the requirements for finishing rolling temperature control under different steel grades and working conditions, thereby improving the stability of strip rolling and the precision of head finishing rolling temperature control, enhancing product competitiveness.
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  Mechanism-data fusion-driven model for heavy plate crown prediction and roll contour optimization

  HE Jun, WANG Yingrui, WANG Yanhui, LIN Yang, TANG Xingyu, BAI Bing, CAO Jianning

  Steel Rolling. 2026, 43(1): 14-22. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260103

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  Crown is one of the critical quality indicators for medium and heavy plate products, and its control level is a testament to an enterprise's production capacity and market competitiveness. With the vigorous development of artificial intelligence (AI) technology, intelligent control has become the core strategy driving the development of the iron and steel industry. However, there is still a lack of relevant research on how to apply AI technologies such as big data to improve product quality, especially in enhancing the plate crown control level during the medium and heavy plate rolling process. This study focuses on the plate crown control technology of medium and heavy plate mills. By combining mechanism models with data-driven models, an intelligent prediction model for heavy plate crown is established, achieving a hit rate of 83.04% for plate crown within the range of ±80 μm. Meanwhile, based on the theoretical framework of this model and big data analysis technology, the roll contour curve of the finishing mill work rolls is optimized. This optimization not only improves the crown control capability of medium and heavy plate mill products, but also extends the rolling cycle of work rolls, and increases both the mill productivity and product yield.
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  Steel materials elongation prediction model with mechanism-data fusion based on LightGBM

  LI Jingxian, ZHAO Guizhou, WEI Chenguang, ZHU Qingqi, YANG Ailing, ZHU Pengju

  Steel Rolling. 2026, 43(1): 23-30. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260104

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  Steel materials elongation, as a core indicator for characterizing material plasticity, directly affects the formability and service safety of steel products. To address the problems of insufficient generalization across steel grades, lack of mechanism support, and dependence on destructive experiments in existing elongation prediction models, a mechanism-data fusion based on Bayesian optimization-LightGBM prediction model is proposed. Based on industrial production data, a multidimensional input system of "conventional process/composition characteristics+mechanism characteristics" is constructed, where the mechanism characteristics include carbon equivalent (C_eq), welding crack sensitivity coefficient (P_cm), and downstream pass reduction rate; a Bayesian optimization algorithm is adopted to efficiently search for the key hyperparameters of LightGBM; finally, the performance of the model is verified through ablation experiments and comparative experiments with multiple models. The experimental results show that the coefficient of determination (R²) of the proposed model reaches 0.898 4,the hit rate with an error within ±3% is 96.6%, which provides reliable technical support for quality control in steel materials production processes.
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  Surface depth detection of stainless steel plate based on point cloud hierarchical analysis

  LUO Jiaxing, CUI Ruiqin, MA Lidong

  Steel Rolling. 2026, 43(1): 31-42. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260105

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  In the production of stainless steel plate, although the traditional contact measurement method can realize the depth detection of steel plate surface defects, it is easy to cause damage due to direct contact with the surface, which affects the measurement accuracy and evaluation reliability. Aiming at the above problems, a method PC-LDA (Point Cloud Layered Depth Analysis) based on point cloud hierarchical analysis is proposed to make up for the shortcomings of existing technology and meet the requirements of accuracy and reliability of surface defect depth detection of stainless steel plate after grinding in industrial applications. In this approach, a blue binocular structured light system is employed to acquire high-resolution point cloud data, which undergoes preprocessing and denoising to improve data quality. The least squares method is then applied to fit a reference plane, calculate the normal vector, and differentiate the sanded regions from the non-sanded surface based on the direction of the normal vector. For the sanded region, depth stratification is performed using distance information from the points to the reference plane. The local peaks and troughs are identified by analyzing the density distribution of the point cloud at each depth level. By calculating the peak widths of local peaks and adjacent troughs and traversing the point cloud data within these intervals using the Euclidean distance, both the hierarchical mean and overall mean depths are obtained, thereby accurately recovering the depth information of the polished region.To validate the accuracy and applicability of the PC-LDA method, experiments were conducted using standard blocks with a depth range of 1.0-1.1 mm and polished stainless steel surfaces from actual production environments. Tests included single-size and multi-size standard blocks. The experimental results demonstrate that the average depth measurement deviation of the PC-LDA algorithm is 0.015 mm, which is significantly below the 0.03 mm threshold. Additionally, the method effectively measures the depth of stainless steel surfaces with high precision, capturing fine geometric features of the surface undulations post-grinding. The proposed PC-LDA algorithm exhibits excellent reliability and consistency, making it well-suited to meet the technical demands of grinding quality assessment and secondary regrinding processes.
Overview
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  Construction and research progress of carbon dioxide transportation pipeline

  YANG Bowei, LI Xinling, ZHANG Kun, YAO Zhen, LIU Wenyue, WANG Shuang

  Steel Rolling. 2026, 43(1): 43-50. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260106

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  Carbon capture, utilization, and storage (CCUS) technology, as the only pathway to near-zero emissions of fossil energy at present, is crucial for reducing CO₂ emissions and supporting China′s "dual carbon" strategic goals. The large-scale, long-distance CO₂ pipelines, which connect CO₂ capture and storage sites, play decisive roles in ensuring the efficient operation of CCUS projects. In this work, the construction status of important domestic and international CO₂ pipeline projects is summarized basing on the phase characteristics and transport status of CO₂. The influence mechanisms of water content, impurity gas, and transportation technology on the corrosion behavior of CO₂ pipelines are summarized. The research progress on corrosion prevention methods such as corrosion-resistant pipeline materials, coatings, and corrosion inhibitors is reviewed. The future development direction of CO₂ pipelines is prospected. Compared with the demand of CCUS project and the mature CO₂ transportation pipeline technology in the world, there are certain gaps in the construction and experience of long-distance and large-scale CO₂ pipelines in our country, and it is urgent to deepen the engineering practice research of supercritical CO₂ pipeline transportation technology. At present, most studies on CO₂ pipelines are concentrated in the laboratory environment, and there are discrepancies in some research findings, which cannot effectively guide the construction and practical engineering application of CO₂ pipeline in China. Thus, it is urgent to establish pilot-scale experiment platforms and carry out massive experimental studies to reveal the interaction mechanism of multiple factors under actual complex working conditions. In addition, it is suggested to use cost-effective bimetallic composite pipes and develop novel types of efficient corrosion resistant coatings and corrosion inhibitors suitable for bimetallic composite pipes, in order to form a complete set of new protection technology for CO₂ pipelines.
Advanced Materials
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  Effect of hydrogen charging time on hydrogen diffusion and hydrogen embrittlement sensitivity of DH36 steel

  XING Shuming, CHEN Cui, LI Weijuan, YANG Zida, WANG Chao, ZHANG Dazheng

  Steel Rolling. 2026, 43(1): 51-56. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260107

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  To improve the safety of marine and offshore engineering structures,this paper adopts tests in cluding hydrogen permeation, hydrogen micro printing, thermal desorption and slow strain rate tensile to analyze, the laws of hydrogen atom diffusion, hydrogen trap distribution and hydrogen embrittlement sensitivity variation of DH36 steel under different hydrogen charging conditions. The results indicate that under electrochemical hydrogen charging at a current density of 10 mA/cm², the densities of reversible hydrogen traps and irreversible hydrogen traps in the DH36 steel are 3.12×10¹⁸ cm^-3 and 2.09×10¹⁸ cm^-3, respectively. Hydrogen atoms mainly exist at grain boundaries and inclusion positions, with less distribution within grains; and with the increase of hydrogen charging time, the aggregation degree of hydrogen atoms at grain boundaries and inclusion positions increases. When the hydrogen charging time is 8 min and 80 min, hydrogen desorption peaks occur at 65.2 ℃ and 445.6 ℃, and at 28.7 ℃ and 470.5 ℃, respectively, and as the hydrogen charging time increases, the desorption amount of hydrogen atoms increases. As the hydrogen charging time gradually increases to 80 min, the yield strength and tensile strength first increase and then slightly decrease, the elongation continuously decreases, and the hydrogen embrittlement sensitivity continuously increases.
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  Effect of heating temperature on interfacial microstructure and mechanicalproperties of TA10/14Cr1MoR clad plate

  WANG Mingkun, LIAO Hongyi, LUO Zongan, FAN Mingrong, ZHOU Hongyu

  Steel Rolling. 2026, 43(1): 57-65. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260108

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  In recent years, Titanium/steel clad plates have been widely utilized in the petrochemical industry due to their outstanding comprehensive properties. However, the relatively narrow roll-bonding process window constrains stable, high-quality production. Therefore, TA10/14Cr1MoR clad plates were prepared by vacuum rolling cladding technology. The effects of heating temperature on the microstructure, element diffusion behavior and interface bonding properties of TA10/14Cr1MoR clad plates were studied by means of electron probe microanalyzer (EPMA), scanning electron microscope (SEM), electron back scattering diffraction (EBSD) and shear test. The results show that the thickness of decarbonized layer, interfacial reactive layer and β-Ti layer increased with the rising of heating temperature, and the product and distribution of the interfacial reactive layer determine the interfacial bonding properties. At 850 ℃ and 900 ℃ of heating temperatures, the diffusion of Fe in α-Ti was relatively limited, resulting TiC layer at the interface, and the average shear strength was 254 MPa and 328 MPa, respectively. The fracture mainly occurred in TA10 substrate, and the discrepancy in shear strength was primarily related to the microstructure of TA10 substrate at different temperatures. At 950 ℃ of heating temperature, the concentration of the C element at the interface was reduced, and the diffusion reaction between Fe and Ti element intensifies. This results in the formation of an uneven TiC+FeTi intermetallic compounds layer at the interface, which caused brittle fracture mainly along the interface, with low shear strength and large fluctuation. Compared with commercial pure titanium, the heating temperature of TA10/steel clad plate can be increased to 900 ℃ due to its higher β phase transition temperature, and the process window for regulating the microstructure properties of steel substrate was expanded.
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  Analysis and research on laser welding performance of 316L/X65M clad plate

  KONG Wei, SUN Leilei, JIANG Defu

  Steel Rolling. 2026, 43(1): 66-73. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260109

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  Stainless steel/carbon steel clad plate as an important structural material was widely applicated in petrochemical industry, water conservancy and hydropower and ocean engineering for its excellent strength, ductility and corrosion resistance. However, the material was faced with the problem of complex and difficult welding process. This paper aims at improving the welding application of stainless steel/carbon steel clad plate. A double-sided laser welding process was developed in 2 mm +6 mm thickness stainless steel/carbon steel single-sided clad plate, in which stainless steel and carbon steel were self-fusion welded by laser with high energy density and accurate welding depth. As a result, the welding process was simplified and excellent performance in welding joint was achieved. The results indicated that the designed welding process had a good weld-ability, and a welding joint with small weld pool, small heat affected zone, uniform weld and small deformation in plate. Also, the corrosion resistance performance of the stainless steel side welds was tested and analyzed in detail. The good corrosion resistance was obtained in stainless steel layer.
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  Effect of rare earth element Ce on weldability of wear-resistant steel

  YUAN Xiaoming, SU Jiping, REN Huiping, DONG Lili

  Steel Rolling. 2026, 43(1): 74-80. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260110

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  In this paper, BTNM450-Re and BTNM450 test materials were selected to analyze the effects of rare earth element Ce on the weldability of wear-resistant steel from the microstructures, mechanical properties, welding continuous cooling transformation behavior and thermal simulation results of welding heat affected zone toughness. The results show that the martensite content of BTNM450-RE plate increases after the addition of rare earth element Ce. Under the same welding thermal cycle conditions, the martensitic structure in the superheated zone of BTNM450-Re steel lasts longer, the martensitic transition end temperature is higher than that of BTNM450 steel, and the hardness in the superheated zone is generally higher than that of BTNM450 steel. The hardenability of BTNM450-Re steel is better than that of BTNM450 steel, the microstructure of the welding heat affected zone is ideal, and the hardness and toughness are better than that of BTNM450 steel. The resistance of BTNM450-Re steel to hydrogen cooling crack is better than that of BTNM450 steel, and its hardening tendency is higher than that of BTNM450 steel.
Research and Development
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  Effect of different atmospheres on the reduction structure and selective oxidation of oxide scales of advanced high strength steel

  WANG Pengzhe, SUN Bin, LAN Qing, YAO Yuchen, LIAO Kexun

  Steel Rolling. 2026, 43(1): 81-87. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260111

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  To address the issue that the Zn wettability on the surface of advanced high-strength steels (AHSS) was severely impaired and the quality of zinc coatings was adversely affected by the selective oxidation of Mn during the annealing process, the reduction reaction kinetics and product characteristics of AHSS under different temperature and atmosphere conditions were investigated in this study. Reduction reactions of the experimental steel were carried out using a ZRT-B thermogravimetric analyzer within a temperature range of 500-900 ℃, with hydrogen-nitrogen mixed gas in two variants: one without water vapor and the other containing volume fraction of 4.5% water vapor. The results show that the reduction kinetics curves are exhibited “S” characteristics, which could be divided into an induction period, an acceleration period, and a deceleration period. As the reduction temperature is increased, the induction period is gradually shortened. With increasing temperature, the morphology of the reduction products is transformed from porous iron to dense iron. When the temperature is raised to 800-900 ℃, internal oxides of Mn are formed in the subsurface region of the substrate under two kinds of reducing atmospheres. The the oxygen partial pressure is increased by the presence of 4.5% water vapor in the reducing atmosphere, which promoted the inward diffusion of oxygen ions. Since the rate of oxygen ion diffusion inward is much higher than the outward diffusion rate of Mn ions, the internal oxides is formed.
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  Effect of solution temperature on the microstructure evolution and Cl^- corrosion resistance of 40Cr13 steel

  SHEN Qianxilong, LI Haoze, MA Lifeng, QI Jianing, GAO Ming, ZHANG Shiyuan

  Steel Rolling. 2026, 43(1): 88-96. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260112

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  40Cr13 steel is an important material for manufacturing plastic molds. The plastics release chlorides and acids during hot pressing, which accentuates the surface pitting of the mold steel and indeed degrades the surface quality of the plastics. The effects of solution temperature on the microstructure evolution and chloride ion corrosion resistance of 40Cr13 steel were investigated via X-ray diffraction, optical microscopy, scanning electron microscopy, hardness testing, electrochemical tests and immersion corrosion in this study. The results showed that the microstructure of 40Cr13 steel was composed of ferritic matrix and dispersive M₂₃C₆ carbides enriched by Cr after hot rolling and air cooling. The increased solution temperature resulted in coarsened prior austenite grains and the gradual dissolution of M₂₃C₆ carbides. In the case of solution treatments at 900 ℃ and 980 ℃, the matrix of 40Cr13 steel was dominated by martensite. By comparison, lath martensite and retained austenite were prevalent when solution treated at 1 050 ℃ and 1 130 ℃. The content of the retained austenite increased with the increase of solution temperature. The results of the electrochemical tests and immersion corrosion showed that the conduction of solution treatment improved the chloride ion corrosion resistance of 40Cr13 steel, as compared with the hot rolling sample. When the solution temperature was raised up to 1 050 ℃, the values of the corrosion weight loss and corrosion current density approached the minimums, whereas those of the corrosion potential, pitting potential, impedance arc diameter and |Z|_{0.01 Hz} reached the maximums. Meanwhile, the value of the high phase angle approached close to 85°. The reason for the best corrosion resistance demonstrated by the sample solution treated at 1 050 ℃ should be mainly ascribed to the limited amount of the M₂₃C₆ carbide which was largely dissolved into the matrix, the low content of the retained austenite and the moderate grain size of the prior austenite.
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  Study on the deformation permeability and cross-sectional shape variation of rolled piece in the SSP reduction process of hot continuous rolling

  XIA Xin, DING Jingguo, LI Ye, HU Dewei, LI Xu, ZHANG Dianhua

  Steel Rolling. 2026, 43(1): 97-107. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260113

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  In the width reduction stage of a hot continuous rolling mill, the cross-sectional "dog-bone" shape of the slab varies with the amount of reduction applied by the width reducer (sizing press). This variation leads to significant differences in shape recovery during subsequent flat rolling, ultimately impacting the precision of final width control. Therefore, understanding the metal flow behavior during roughing-width reduction is essential for improving flat-rolling width control and provides a theoretical foundation for high-precision control in downstream processes.This study investigates the influence of the deformation resistance gradient—governed by side pressure, initial thickness, and material properties—on metal flow during large-strain deformation. A finite element model of the Short-Stroke Press (SSP) width reduction process was developed using ANSYS/WorkBench. The model was used to analyze the effects of key parameters on the dog-bone peak height, the central deformation zone, and the dog-bone deformation zone. A predictive model for the dog-bone shape was established. Furthermore, the stress-strain evolution during width reduction was examined to determine the influence of the deformation resistance gradient on free width spread after flat rolling.The results demonstrate strong agreement between simulation and field data. The errors for dog-bone peak height, central thickness, dog-bone deformation zone length, and post-deformation zone length are 1.82%, 0.65%, 1.43%, and 1.94%, respectively, validating the FE model. Compared to measured data, the predictive model improved accuracy for dog-bone peak height and deformation zone length from 96.31% and 96.53% to 98.68% and 98.32%, respectively. The prediction accuracy for central thickness and dog-bone deformation zone length reached 98.57% and 98.62%, confirming the model's effectiveness.The analysis indicates that while the deformation resistance gradient has a limited effect on the overall stress distribution, it exhibits a positive correlation with local stress magnitude. Specifically, a higher deformation resistance leads to increased width strain and greater deformation penetration depth, resulting in reduced free width spread after flat rolling.
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  Effect of annealing process on microstructure and properties of 321 stainless steel ultra-thin strip

  CHEN Jingqi, ZHENG Linyun, YANG Liuqing, BAI Zhenhua

  Steel Rolling. 2026, 43(1): 108-116. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260114

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  This study investigates the effects of annealing processes on the microstructure and mechanical properties of 321 stainless steel ultra-thin strips. In the experiment, 321 stainless steel ultra-thin strips with different cold rolling reductions were adopted. By setting different annealing temperatures and holding times, combined with two cooling methods (furnace cooling and air cooling), the influences of heat treatment processes on the microstructure and mechanical properties of the experimental strips were explored. The results show that with the increase of annealing temperature, the yield strength of the strips decreases while the elongation increases, indicating that high-temperature annealing is conducive to improving the plasticity of the strips. Short holding time and rapid cooling are favorable for obtaining fine and uniform austenite grains, thereby enhancing the synergistic effect of strength and plasticity of the strips. In contrast, long holding time and slow cooling promote the precipitation of M₂₃C₆ carbides and σ phase, which increases the hardness of the strips but leads to the reduction of their plasticity. Through comprehensive consideration, the heat treatment process consisting of 1 050 ℃ annealing temperature, short holding time and rapid cooling can effectively improve the comprehensive mechanical properties of 321 stainless steel ultra-thin strips.
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  Research on the influence factors of plasticity and toughness of ultra-low carbon SPHD cold-rolled sheets

  LI Yongliang, LIN Peng, ZHANG Long, ZHANG Jueling, ZHENG Yaxu, TANG Zhenglei

  Steel Rolling. 2026, 43(1): 117-126. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260115

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  To address the issues of poor plasticity and toughness and severe longitudinal cracking in ultra-low carbon SPHD cold-rolled sheets produced by a steel mill, an automated inclusion scanner, EPMA, OM, SEM, and TEM were employed to analyze element segregation, microstructure, inclusions, and precipitates in the SPHD cold-rolled sheets. A comprehensive evaluation was conducted on the factors affecting plasticity and toughness, as well as the causes of bending-induced cracking. The results revealed that chain-like carbide precipitation at grain boundaries and band-like phosphorus segregation were the primary contributors to the poor plasticity and toughness, leading to bending-induced cracking. To improve the bending performance of ultra-low carbon SPHD cold-rolled sheets, three measures should be implemented.First, carbon content should be minimized to prevent excessive precipitation of tertiary cementite along grain boundaries. Second, a small amount of Ti can be added to fix C and form Ti(C,N), thereby inhibiting tertiary cementite precipitation. Third, the levels of harmful impurities such as P and S in the steel, as well as the number of large-sized sulfide inclusions, should be reduced to enhance the plasticity and toughness of the steel.
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  Analysis of bright spot defects on the surface of continuous hot-dip galvanized strip and adaptive coating thickness control

  ZHANG Xiaofang, WANG Ligang, ZHANG Shuyuan, LI Chuncheng

  Steel Rolling. 2026, 43(1): 127-137. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260116

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  During the production process of continuous hot-dip galvanized strip, bright spot defects on the coating surface seriously affect the corrosion resistance of products. In this paper, multi-scale characterization techniques (SEM-EDS and AFM) are used to analyze the morphology and composition of bright spot defects, revealing that their main causes are zinc dross inclusions, gas pore aggregation and abnormal local alloying. An online detection method for bright spot defects based on machine vision is proposed, and an improved U-Net network is adopted to realize real-time classification of bright spot defects, finally achieving a classification accuracy of 98.2% and above, which meets the requirements of real-time performance and high precision for bright spot defect detection in high-speed production lines of continuous hot-dip galvanized strip. The correlation between coating thickness control precision and bright spot defect suppression is studied, a fuzzy PID controller integrated with dynamic weight adjustment is designed, and the feedback data of laser thickness gauge is incorporated to realize adaptive control of coating thickness (control error within ±1.5 μm). Experiments show that this scheme reduces the defect occurrence rate by 63% and increases the coating thickness qualification rate to 99.1%.
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  Study on formation mechanism of emulsion spots on the surface of silicon steel strip

  ZHANG Zijian, XIANG Chao, WU Yousheng, CHEN Quanzhong, WANG Zhijun, HAN Enhou

  Steel Rolling. 2026, 43(1): 138-145. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260117

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  The emulsion is used as lubricant in the cold rolling of silicon steel, but it often forms emulsion spots on the surface of strip, which affects the surface quality. In this work, SEM, EDS, XPS, XRD and AFM were used to study the formation mechanism of emulsion spots on the surface of silicon steel strip. The results showed that the strip was oxidized to form the line-shape Fe₃O₄ products, which covered the surface of the strip and made the surface rough, resulting in residue of the emulsion. The water in the emulsion evaporated, while the oil in the emulsion remained in the oxidation area to form black emulsion spots. The composition of the emulsion spot on the surface of silicon steel strip is Fe₃O₄ product and oil pollution. According to the formation mechanism of emulsion spot, the formation of emulsion spots can be effectively reduced by controlling the shape of strip and strengthening emulsion management.
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  Influence of rolling process on microstructure, properties and surface red rust of HRB400E reinforced bars

  WANG Zhenxuan, TANG Zhengyou, ZHAO Li, CUI Feng, ZHANG Haoyue

  Steel Rolling. 2026, 43(1): 146-151. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260118

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  Aiming at the problems that HRB400E reinforced bars have a relatively high manganese (Mn) content and the finished products are prone to surface red rust when adopting the traditional process of high-temperature finishing rolling plus water quenching cooling after rolling, this paper optimized the temperature regime of the rolling process specifically, controlling the rolling start temperature at 960-1 000 ℃, the temperature entering the finishing rolling mills at 830-850 ℃, the temperature entering the reducing mill at 830-850 ℃, and eliminating water quenching cooling before the bars are sent to the cooling bed, and the corresponding production experiments are carried out.The results show that the produced 14 mm HRB400E reinforced bars achieve a grain size of Grade 11, a yield strength of 452 MPa, a tensile strength of 655 MPa, and a total elongation at maximum force of 14.5%. Moreover, the iron oxide scale on the bar surface is dense and intact without red rust, and the mass fraction of Mn can be reduced by 0.1%. This study provides a basis for the green and low-carbon production of HRB400E reinforced bars as well as the improvement of their mechanical properties and surface quality.
Innovation and Interflowing
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  Study on the formation mechanisms and control measures of NO_x in reheating furnaces of rolling mills

  GAO Yue, CHEN Lijuan, ZHANG Baojun, WANG Zeju

  Steel Rolling. 2026, 43(1): 152-157. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260119

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  With increasingly rigorous emission standards for industrial furnaces in the steel industry, multiple standards targeting ultra-low NO_x emissions from reheating furnaces for rolling mills have been introduced successively. The permissible NO_x concentration limit has been gradually reduced from 300 mg/m³ (before 2020) to 50 mg/m³ (at 8% O₂ reference). However, the process of controlling NO_x often leads to reduced operational efficiency of the furnace, thereby limiting the production capacity of hot rolling.This paper focuses on the formation mechanisms and control measures of NO_x in reheating furnaces for rolling mills. The influence of staged combustion on NO_x formation was studied through simulation, and experiments were conducted to analyze the impact of oxygen concentration on both measured and converted NO_x values. Furthermore, the feasibility of applying SNCR high-temperature denitration technology in reheating furnaces was examined based on their operational characteristics.The results show that by enhancing staged combustion, optimizing the combustion atmosphere, and implementing furnace temperature limitation measures, NO_x emissions can be reduced from about 200 mg/m³ to below 100 mg/m³. Moreover, the application of SNCR high-temperature denitration technology can further lower NO_x emissions from around 100 mg/m³ to below 50 mg/m³.
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  Analysis of edge cracking causes and process optimization of cold-rolled high-strength steel strip for carriage

  LÜ Lige, WANG Chang, HUI Yajun, YU Yang, QIU Yu, ZHANG Liangliang, GAO Xiaoli

  Steel Rolling. 2026, 43(1): 158-164. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260120

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  Aiming at the problems of severe equipment loss, reduced yield rate and impaired rolling stability caused by edge cracking during the cold rolling process of high-strength steel for carriage application, the causes of edge cracking were analyzed by means of scanning electron microscope (SEM), microhardness tester, thermal dilatation phase transformation tester and other instruments. The results show that the microstructure at the edge of the cold-rolled strip consists of super-cooled M-A constituents and ferrite. Due to the mismatch in cold plastic deformation capacity between M-A constituents and the surrounding ferrite matrix, interphase cracking is prone to occur at their interface, which develops into edge cracking defects under high-tension rolling. To address this issue, a series of process improvement measures were proposed: controlling the finishing rolling temperature above 900 ℃; activating the edge shielding function during the laminar cooling process; raising the coiling temperature to 750 ℃ and adopting the U-type coiling process, with laminar cooling water not applied to the head and tail of the strip to maximize the coiling temperature of these parts; stipulating that the temperature of hot coils entering the slow cooling pit should be not less than 600 ℃ after discharge. These measures can promote the formation of ferrite + pearlite microstructure at the strip edge. In addition, the cold rolling total reduction was optimally controlled at 45%-50%, and the setting values of tension and bending roll force were adjusted. Through the above comprehensive measures, the occurrence of edge cracking defects was reduced to less than 1%.
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  Research on the resistance characteristics and structural optimization of slit-jet type air box for post-galvarizing cooling

  ZHANG Jianshui, ZHANG Tingjun, DONG Qiang, XIAO Bin

  Steel Rolling. 2026, 43(1): 165-169. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260121

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  Based on theoretical design, numerical simulation and on-site measured data and feedback, the application of slot impact jet in post-palvanizing cooling design is analyzed, and calculation formulas for structural parameters and air box pressure are summarized, which can accurately select the fan type. The research findings provide reference for engineering design. At the same time, under the same energy consumption, the air boxstructure is optimized to achieve the best cooling capacity. A fitting formula of the optimal structural parameters is provided,which provides a convenient and feasible reference scheme for engineering application promotion.
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  Analysis and countermeasures of welding seam height difference of Miebach laser welding machine

  ZHAO Shuai, PENG Chunyan

  Steel Rolling. 2026, 43(1): 170-175. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260122

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  In response to the frequent occurrence of welding seam height differences in the Miebach laser welding machine during the operation of a company′s pickling and rolling mill unit, the welding seam height difference phenomenon was classified into two types,i.e.overlap type and thickness difference type, and the causes were analyzed. The results indicate that the size of the joint gap between the strips and the variation of the strip length have a significant impact on the welding seam overlap, and the thickness of the strip and the height of the lower support wheel have a major influence on the welding seam thickness difference. By controlling the parallelism of the shear blade side surfaces within 0.05 mm, ensuring the clamping force of the clamp, optimizing the defocusing amount from the original -5 mm to -7 mm, strengthening the control of strip quality defects, and ensuring the accuracy of key equipment such as the double cut shear, clamps, support wheels, and pre-rolling wheels, the daily numbers of welding seam height difference alarms has been reduced from 9 times to 3 times.
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  Analysis of the round-round-round pass of the high-speedwire rod reducing-sizing mill

  LI Jie, KOU Zhifei, SUN Shuaiqi

  Steel Rolling. 2026, 43(1): 176-179. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260123

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  To improve the dimensional accuracy of products, a detailed analysis was carried out on the deformation laws of three round pass profiles in the high-speed wire rod reducing and sizing mill unit. The deformation characteristics and metal flow behavior of round rolled pieces in the sizing mill unit were discussed from two aspects:the distribution of elongation coefficient and the structural characteristics of pass profile. It is pointed out that the metal flow in the round-round-round pass profiles is different from the "reduction-spreading" mode in the oval-round pass profiles. It is a full-compression deformation along the circumferential direction of the pass profile. A detailed analysis was conducted on the influence of the rolled pieces from the last stand of the reducing mill on the final product quality after being rounded by two sizing mill stands. The causes of the unique final product defects in the reducing and sizing mill unit were analyzed, and it was pointed out that the key to the process control of the reducing and sizing mill unit lies in the precise control of the round rolled pieces in the last stand of the reducing mill, and the defects generated here cannot be eliminated by the sizing mill.
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  Research on straightness control technologies for 60R2 grooved rail during cooling after rolling

  WANG Daiwen, LÜ Panfeng, QIN Li, DENG Changfu

  Steel Rolling. 2026, 43(1): 180-187. https://doi.org/10.13228/j.boyuan.issn1003-9996.20260124

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  Aiming at the problems such as large curvature and deflection of rail waist after cooling caused by the extremely asymmetric section characteristics of 60R2 grooved rail, such as heavy head, light foot and thin waist (the metal content of rail head is 1.8 times of the rail bottom), the technical requirements and production control difficulties are analyzed, and the straightness control technologies, including workpiece inversion, pre-bending process, straightening roller design and straightening reduction design,are studied and tested in production. The results show that the average horizontal flatness of 134 rail ends measured randomly is 0.11 mm, the standard deviation is 0.08 mm, and the maximum value is 0.36 mm by adopting technical schemes such as large deformation subsection non-uniform pre-bending and roller profile design of horizontal straightening roller on short arm. The average straightness in the vertical direction is 0.16 mm, the standard deviation is 0.09 mm, and the maximum value is 0.45 mm, all of which meet the standard requirement of not more than 0.8 mm。