2025年, 第32卷, 第3期　刊出日期：2025-03-25

  

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REVIEWS
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  A review on production and application of direct reduced iron in gas-based shaft furnace-electric arc furnace route

  Ling-zhi Yang, Zeng Feng, Hang Hu, Guang-sheng Wei, Bo-tao Xue, Yu-feng Guo, Tao Jiang

  钢铁研究学报（英文版）. 2025, 32(3): 485-518.
  https://doi.org/10.1007/s42243-024-01377-1

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  The iron and steel industry, standing as a quintessential manufacture example with high consumption, pollution and emissions, faces significant environmental and sustainable development challenges. Electric arc furnace (EAF) steelmaking process mainly uses scrap as raw material and is characterized by environmentally friendly and recyclable process. However, the further development of EAF route in China is limited by the reserve, supply, availability and quality of scrap resource. Direct reduced iron (DRI) is one of typical low-carbon and clean charges, which can effectively make up for the adverse effects caused by the lack of scrap. The physical and chemical properties, classifications, and production technologies of DRI are firstly reviewed. In particular, the reducing gas types, reduction temperature, and reduction mechanism of the DRI production with gas-based shaft furnace (SF) technology are detailed. Considering the crucial role played by DRI application in EAF, the influences of DRI addition on EAF smelting rules and operations including the blending and charging process, heat transfer and melting in molten bath, slag formation operation, refractory corrosion, and slag system evolution are then further discussed. Finally, the comparative analysis and assessment of the consumption level of material and energy as well as the cleaner production both covering the clean chemical composition of molten steel and the clean environment impact in EAF steelmaking with DRI charged are conducted. From perspectives of metallurgical process engineering, a suitable route of hydrogen generation and application (from coke oven gas, methanol, and clean energy power), CO₂ capture and utilization integrated with SF-EAF process is proposed. In view of the difficulties in large-scale DRI application in EAF, the follow-up work should focus on the investigation of DRI charging and melting, slag system evolution and molten pool reaction rules, as well as the developments of the DRI standardized use technology and intelligent batching and control models.
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  Precipitation behavior and its effect on surface transverse cracks during continuous casting

  Peng Lan, Yi-fan Lu, Ying-chun Wang, Li-rui Zhang, Jia-quan Zhang

  钢铁研究学报（英文版）. 2025, 32(3): 519-535.
  https://doi.org/10.1007/s42243-024-01412-1

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  Precipitation of carbides, nitrides, and carbonitrides is an important factor influencing the formation of surface transverse cracks in the continuous casting of microalloyed steel, affecting the quality and yield of the final product. Based on previous investigation, the precipitation sequence and temperature, position and mode, as well as the size, morphology, and number of different types of precipitates were reviewed. The effects of C, N, Nb, Ti, and V on the precipitation behavior and surface transverse cracks in continuous casting slabs were summarized, with a particular emphasis on the new achievements concerning Ti addition. The critical amounts of different elements to avoid serious surface cracks during continuous casting were proposed. The control mechanisms and industrial effects of composition optimization, cooling design, and chamfered mold configuration to improve surface transverse cracks in continuous casting slabs were also illustrated, and the recent application of surface microstructure control technology was emphasized. The characteristics, advantages, and shortcomings of existing theoretical and experimental methods in investigating continuous casting surface cracks regarding precipitation are finally discussed, and a new setup with advanced functions is introduced.
ORIGINAL PAPERS
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  Process mechanism research on direct vortex melting reduction of vanadium-titanium magnetite

  Yong-chao Han, hi-he Dou, Zhan-ning Yang, Wei Xie, Ting-an Zhang

  钢铁研究学报（英文版）. 2025, 32(3): 536-549.
  https://doi.org/10.1007/s42243-024-01290-7

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  In response to the new mechanism of direct vortex melting reduction of vanadium-titanium magnetite, the reaction control mechanism and the migration regularity of valuable components in the process of direct melting reduction were inves-tigated using kinetic empirical equation by fitting and combining with X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy-dispersive spectrometry, and optical microscopy. The results show that iron reduction is controlled by the mass transfer process of (FeO_x) in the slag, while vanadium reduction is controlled by both the mass transfer of (VO_x) in the slag and the mass transfer of [V] in the molten iron, and the slag-metal interfacial reaction is the only pathway for vanadium reduction. The reduction of iron and vanadium is an obvious first-order reaction, with activation energy of 101.6051 and 197.416 kJ mol^-1, respectively. Increasing the vortex rate and reaction temperature is beneficial to improving the reaction rate and reduction efficiency. The mineral phase variation of iron and vanadium in the slag during the reduction process is Fe₂O₃→Fe₃O₄/FeV₂O₄→FeTiO₃ and FeV₂O₄→MgV₂O₅; titanium in slag is mainly in the form of Mg_xTi_3-xO₅ (0≤x≤1) and CaTiO₃. As the reaction time went on, the molar ratio (n_Ti/n_Mg)in MgxTi₃-xO₅ (0≤x≤1) and the Ti₂O₃ content in the slag gradually went up, while the area proportion of MgxTi₃-xO₅ (0≤x≤1) went up and then down, and the porosity of the slag and the grain size of MgxTi₃-xO₅ (0≤x≤1) got smaller.
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  Iron recovery and dephosphorization behaviors from high-phosphorus oolitic hematite by gas-based direct reduction and magnetic separation

  Fang Liu, Yi-chi Zhang, Wang Zeng, Jun Ni, Yun-peng Si, Heng Zhou, Tian-xiang Zhang, Sheng-li Wu, Ming-yin Kou

  钢铁研究学报（英文版）. 2025, 32(3): 550-563.
  https://doi.org/10.1007/s42243-024-01249-8

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  With the depletion of high-quality iron ore resources, high-phosphorus oolitic hematite (HPOH) has attracted great attention due to its large reserve and relatively high iron content. However, HPOH is very difficult to be used in ironmaking process due to its special structure. A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce phosphorus. The results showed that the powdery reduced iron produced contained 92.31% iron and 0.1% phosphorus, and the iron recovery was 92.65% under optimum reduction condition, which is suitable for following steelmaking. The apatite will be reduced under long reduction time and a large reducing gas flow rate, resulting in more phosphorus found in the metallic iron. Increasing the hydrogen-carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic structure. Careful adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.
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  Evaluation of MgO on hematite swelling dynamics during CO-driven stepwise reduction

  Fang Zhang, Jun Peng, Shuang Liu, Yong-bin Wang, Fan Yang

  钢铁研究学报（英文版）. 2025, 32(3): 564-577.
  https://doi.org/10.1007/s42243-024-01312-4

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  The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized. The swelling behaviors of pellets during the stepwise reduction by CO were assessed. The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900 °C. The existence states of MgO in hematite, magnetite, and wu¨stite were investigated through thermodynamic calculations. The magnetite strip samples were subjected to oxidizing roasting at 1250 °C for 30 min to produce hematite strip samples. The strip samples with 0.49, 1.49, 2.49, and 3.49 wt.% MgO were analyzed for length change. It was observed that the sample with 2.49 wt.% MgO exhibited the least significant length change. The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe₂O₃→Fe₃O₄,FeO₄→FeO, and FeO →Fe were 615, - 25, and - 378 lm, respectively. The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation. During the reduction stage from wu¨stite to metallic iron, a substantial contraction occurred, while the slag phase was able to retain its original basic shape. The enclosed areas, as indicated by the expansion change curves of the samples with 0.49, 1.49, 2.49, and 3.49 wt.% MgO, were measured at 3.76 × 10⁶, 3.23 × 10⁶, 3.05 × 10⁶, and 3.17 × 10⁶ lm s, respectively.
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  Prediction of BOF endpoint carbon content and temperature via CSSABP neural network model

  Xiao-feng Qiu, Run-hao Zhang, Jian Yang

  钢铁研究学报（英文版）. 2025, 32(3): 578-593.
  https://doi.org/10.1007/s42243-024-01369-1

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  To predict the endpoint carbon content and temperature in basic oxygen furnace (BOF), the industrial parameters of BOF steelmaking are taken as input values. Firstly, a series of preprocessing works such as the Pauta criterion, hierarchical clustering, and principal component analysis on the original data were performed. Secondly, the prediction results of classic machine learning models of ridge regression, support vector machine, gradient boosting regression (GBR), random forest regression, back-propagation (BP) neural network models, and multi-layer perceptron (MLP) were compared before and after data preprocessing. An improved model was established based on the improved sparrow algorithm and BP using tent chaotic mapping (CSSA-BP). The CSSA-BP model showed the best performance for endpoint carbon prediction with the lowest mean absolute error (MAE) and root mean square error (RMSE) values of 0.01124 and 0.01345 mass% among seven models, respectively. And the lowest MAE and RMSE values of 8.9839 and 10.9321 °C for endpoint temperature prediction were obtained among seven models, respectively. Furthermore, the CSSA-BP and GBR models have the smallest error fluctuation range in both endpoint carbon content and temperature predictions. Finally, in order to improve the interpretability of the model, SHapley additive interpretation (SHAP) was used to analyze the results.
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  Optimizing power-saving process for a 120-t ladle furnace

  Jian Song, Jiong-ming Zhang, Yan-bin Yin, Xin-gang Zhen

  钢铁研究学报（英文版）. 2025, 32(3): 594-605.
  https://doi.org/10.1007/s42243-024-01320-4

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  Ladle furnaces are known for their high power consumption, making research on power-saving process crucial. In response to the defect of thin slag thickness in the industrial production of a 120-t ladle furnace at a steel plant, with its production of ship plate steel DH36 as the focus, experiments involving adding the foaming agent and shifting power delivery gears were conducted. Based on the principle of measuring alternating current by Rogowski coils, the power consumption during the ladle furnace refining process was calculated theoretically, and the actual industrial power consumption matched with it basically, confirming the accuracy of the theoretical calculations. Additionally, the impacts of argon flow rate, foaming agents, and shifting power delivery gears on power consumption were studied. The results showed that adding 0.59 and 0.50 kg/t foaming agents in two batches improved the refining process of the ladle furnace, allowing for effective submerged-arc operations and saving electric energy of 7.2382 kWh per ton of steel. Similarly, utilizing a power supply mode of 7-step short arc during the refining process significantly enhanced the desulfurization rate of molten steel and saved electric energy of 11.6387 kWh per ton of steel.
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  Coordinated control of decarbonization efficiency and oxygen absorption rate in Ruhrstahl-Heraeus degasser based on mechanism model and BP neural network

  Lu-heng Jiang, Min Wang, Jia-qi Zhao, Cheng Yao, Li-dong Xing, Xin-gang Ai

  钢铁研究学报（英文版）. 2025, 32(3): 606-618.
  https://doi.org/10.1007/s42243-024-01334-y

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  A mathematical model of the decarburization reaction zone was established for the Ruhrstahl-Heraeus (RH) forced oxygen blowing decarburization process by Matlab R2022b software. For the problem of inaccurate prediction due to the large variation range of oxygen absorption rate under different process conditions, we statistically analyzed the main factors affecting the oxygen absorption rate. The backpropagation neural network was used to train and predict the oxygen absorption rate and was used to calculate the RH decarburization reaction zone model. We designed and developed a mathematical modeling software with process control of decarburization in RH degasser, which can realize the change of operating process parameters in the dynamic prediction process. The optimized mathematical model has more than 95% of the furnaces whose absolute error in calculation of carbon content is within ± 5× 10^-6, more than 90% of the heats whose relative error in calculation of oxygen content is within ± 15%, and the average absolute error of calculation of oxygen content is 26.4× 10^-6. Finally, we studied the influence of oxygen blowing timing, oxygen blowing volume and initial oxygen content on the forced decarburization process.
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  Refining mechanism of tin-bismuth alloy solidified structure upon applying direct current attached mold

  Si-yao Liu, Ye Zhou, Xin-cheng Miao, Qing-he Xiao, Rui Guan, Xin-gang Ai, Sheng-li Li

  钢铁研究学报（英文版）. 2025, 32(3): 619-628.
  https://doi.org/10.1007/s42243-024-01238-x

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  Herein, the effect of direct current (DC) attached the mold on refining the microstructure and alleviating the central segregation of a tin-bismuth (Sn-10 wt.% Bi) alloy ingot during the solidification process has been investigated. The experiment used a self-made device, which can achieve the effect of refining the solidified structure and alleviate the segregation of the metal casting. Numerical simulations were performed to calculate the Lorentz force, Joule heating and induced melt vortex flow for the magneto-hydrodynamic case. Our results show that the maximum velocity of the global electro-vortex reached 0.017 m s^-1. The DC-induced electro-vortex was found to be the primary reason of refining the equiaxed grain and alleviating the segregation of the b-Sn crystal boundary. The grain refining effect observed in these experiments can be solely attributed to the forced melt flow driven by the Lorentz force. DC field attached the mold can lead to grain refinement and alleviate the segregation of the ingot via a global vortex. The technology can be applied not only to opened molds, but also toward improving the quality in closed molds.
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  Effect of alternative magnetic fields with different intensities on microstructure and mechanical properties of M50 steel during vacuum arc remelting

  Guo-dong Deng, Zhi-bin Xia, Cheng-kuan Ma, Yi-feng Guo, Zhong-hao Sun, Ming-liang Zhang, Qi-zheng Chen, Qiang Li, Zhe Shen, Biao Ding, Tian-xiang Zheng, Chun-mei Liu, Yun-bo Zhong

  钢铁研究学报（英文版）. 2025, 32(3): 629-645.
  https://doi.org/10.1007/s42243-024-01355-7

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  The use of an alternative magnetic field during vacuum arc remelting (VAR) can have significant effects on the primary carbide and mechanical properties of M50-bearing steel. The solidification structure and the primary carbide morphology of the VAR ingot were analyzed by optical microscopy and scanning electron microscopy. Characterization and analysis of the growth direction of primary carbides were conducted using high-resolution rapid electron backscatter diffraction. Solute elements segregation was analyzed using an electron probe microanalyzer. FLUENT was utilized to conduct numerical simulations to validate the experimental findings and elucidate the underlying mechanism. Compared to tra-ditional VAR, magnetic-controlled VAR generates a horizontal circulation, which makes a shallower and flatter molten pool and a more even temperature distribution. In the time dimension, the local solidification time is shortened, and the concentration of solute elements will be alleviated. In the spatial dimension, the secondary dendrite arm spacing decreases, alleviating the degree of inter-dendritic segregation. Consequently, the possibility of forming a segregation diminishes. Both aspects promote the even distribution of solute atoms, resulting in less segregation and hindering the development of primary carbide. This leads to the refinement of primary carbide size and its uniform distribution. The magnetic-controlled vacuum arc melting not only refines the dendritic structure in the M50 ingot, causing it to expand more axially along the ingot, but also refines primary carbides and improves tensile and wear-resistant mechanical properties.
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  Quantitative characterization of reaction behavior between La-bearing FeCrAl melt and CaO-Al₂O₃-La₂O₃-based slags and its guidance for design of mold flux

  Lei Fan, Tian-peng Qu, De-yong Wang, Cheng-jun Liu

  钢铁研究学报（英文版）. 2025, 32(3): 646-658.
  https://doi.org/10.1007/s42243-024-01233-2

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  The reaction behavior between CaO-Al₂O₃-La₂O₃-based slags and La-bearing FeCrAl melt was quantitatively charac-terized, which was further compared with the reaction behavior of CaO-SiO₂-based slags. Based on this, the new type of mold flux for La-bearing FeCrAl alloy continuous casting was designed and its basic properties were evaluated. The results showed that the order of reaction degree of fluxing agents in CaO-Al₂O₃-La₂O₃-based slags is (Na₂O) [ (B₂O₃) [ (Li₂O), and the percentages of mass change of fluxing agents were 85.8, 54.29 and 42.35 wt.%, respectively. Moreover, the addition of (Li₂O) and (Na₂O) promoted the reaction between (CaO) and [Al], and the reaction degree of the former was weaker than that of the latter, which was due to the greater effect of (Na₂O) on the activity of (CaO) and (Al₂O₃) than (Li₂O). Compared with the reactivity of CaO-SiO₂-based slags, the percentages of mass change of Al and La caused by slag-steel reaction decreased by 10.63-14.36 and 39.78-50.49 wt.%, respectively. The percentages of mass change of (Al₂O₃), (La₂O₃) and (CaO) in slags highest increased by 17.71, 17.98, and 7.81 wt.%, respectively. The reactivity of CaO-Al₂O₃-La₂O₃-based slags was significantly weakened. Ultimately, the new type of mold flux was designed and the composition range was determined. The fundamental properties of new mold flux basically meet the theoretical require-ments for La-bearing FeCrAl alloy continuous casting.
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  Numerical simulation and experimental investigation of manufacturing route of directional casting super slab

  Ming Li, Jun Fu, Neng Ren, Biao Tao, Alan Scholes, Jun Li, Jian-guo Li, Hong-biao Dong

  钢铁研究学报（英文版）. 2025, 32(3): 659-670.
  https://doi.org/10.1007/s42243-024-01235-0

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  We proposed a new technique route of directional solidification for the manufacture of super slab. A 7-t laboratory-scale thick slab was casted and characterised for trial. To further understand the process, the evolution of the multiple physical fields during the directional solidification was simulated and verified. Similar to the convectional ingot casting, a negative segregated cone of equiaxed grains was formed at the bottom, and a seriously positive segregated region was formed beneath the top surface of the slab. Specific measures on the lateral walls, base plate, and free surface were strongly recommended to ensure that the slab is relatively directionally casted. A water-cooling copper base plate accelerates the solidification rate and the columnar growth along the vertical direction. It inhibits the sedimentation of equiaxed grains and enlarges the columnar zone. Based on the simulation analysis, it can be concluded that the directional solidification technique route is promising to manufacture super slab with lower segregation level, and less porosities and inclusions.
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  Interfacial heat transfer and solidification structure of sub-rapid solidified silicon steel using a novel droplet solidification apparatus

  Wan-lin Wang, Yun-li Zhang, Pei-sheng Lyu, Cheng Lu, Kang-yan Chen, Liang Hao, Hua-long Li

  钢铁研究学报（英文版）. 2025, 32(3): 671-681.
  https://doi.org/10.1007/s42243-024-01329-9

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  A novel droplet solidification technique was developed to emulate sub-rapid solidification and facilitate the formation of deposited films during the strip casting of silicon steels (w(Si): 2.5 and 3.5 wt.%). With the increasing number of droplet ejection experiments, the peak heat fluxes between droplet and substrate decreased firstly (1rd-5th ejection), then increased (5th-7th ejection), and finally decreased again ([ 7th ejection). In the first five experiments, the interfacial thermal resistance between the droplet and the substrate improved with increasing film thickness. However, at the onset of the 6th droplet ejection experiment, the deposited film initiated its melting process due to the accumulated thermal resistance, which has the potential to eradicate the cavity or air space existing between the droplet and the substrate. Consequently, the interfacial contact condition was improved gradually with the increasing melting area from 5th to 7th droplet ejection experiments, leading to an increase in heat fluxes. Increased SiO₂ content in deposited films for 3.5 wt.% Si steel led to lower peak heat fluxes than for 2.5 wt.% Si steel. The solidification structure of the 2.5 wt.% Si steel droplet sample comprised a fine grain zone at the base, a columnar grain zone in the center, and an equiaxed grain zone at the top. However, the solidification structure of the 3.5 wt.% Si steel droplet only contained columnar grains and equiaxed grains, with a larger average grain size due to the lower interfacial heat flux.
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  Crack sensitivity of high-manganese cryogenic steels in initial solidification during continuous casting

  Yang Li, Johann Winkler, Peter Presoly, Christian Bernhard, Xu-feng Qin, Chang-gui Cheng

  钢铁研究学报（英文版）. 2025, 32(3): 682-694.
  https://doi.org/10.1007/s42243-024-01421-0

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  Cryogenic steels, i.e., steels with maximum toughness at particularly low temperature, are increasingly becoming the focus of research. Cryogenic steels are usually alloyed with 5%-9% nickel. Ni can also be substituted by manganese as an austenite former. These high-manganese cryogenic grades are a cost-effective alternative to nickel-alloyed steels for use in liquefied natural gas storage tanks. The Mn content can then be more than 20 wt.% and lead to problems in production, particularly in the continuous casting process. In continuous casting of high-Mn-grades, quality issues and even breakout may result from the initial solidification behavior of the steel grades at high temperatures. Hot cracks form when a critical load is exceeded during solidification, close to the solidus temperature of the steel. A selected high-Mn-steel grade was characterized with respect to liquidus and solidus temperatures by means of thermal analysis and computational ther-modynamics. In addition, so-called submerged split chill tensile tests were carried out to further understand the crack sensitivity of the solidifying shell for high-manganese cryogenic steels. The results reveal the presence of coarse hot tears, and also, a high frequency of hot cracks was observed at the location with the maximum accumulated strain, which is in line with the applied cracking criterion of Pierer and Bernhard for this investigation. In summary, the initial solidification phase of continuous casting poses a high risk of cracking for high-manganese cryogenic steel.
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  Soft reduction control investigation of spot segregation in continuous casting bloom for 42CrMoA crankshaft steel

  Hai-jie Wang, Ze Zhang, De-guo Fan, Chuan-hui Jiang, Bin-bin Zhang, Pu Wang, Jia-quan Zhang

  钢铁研究学报（英文版）. 2025, 32(3): 695-706.
  https://doi.org/10.1007/s42243-024-01295-2

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The crankshaft is subjected to complex rotational centrifugal force, periodic gas inertia force, and reciprocating inertia force during its working process. Consequently, the homogeneity requirement for crankshaft steel is exceptionally high. The distribution characteristics of center segregation and spot segregation of continuous casting bloom 42CrMoA crankshaft steel were analyzed by experiments, and the control mechanism of spot segregation by soft reduction zone and reduction amount was discussed. When the center solid fraction is between 0.61 and 1.00, an 8-mm soft reduction has a negligible impact on the flow of liquid steel at the end of solidification. Although it effectively improves center segregation, the improvement of spot segregation is limited. On the other hand, when the center solid fraction is between 0.31 and 1.00, a reduction of 10-12 mm, along with an expanded reduction zone and increased reduction amount, significantly promotes the flow of liquid steel at the end of solidification, reduces the size of equiaxed grains, mitigates the center negative segregation, and decreases the maximum size of spot segregation from 2954.29 to 1354.07 lm. The number of spot segregations and the solutes enrichment degree of C, Cr, and Mn have also been significantly improved. An appropriate soft reduction zone and reduction amount can markedly ameliorate the semi-macro spot segregation of crankshaft steel blooms, thereby providing high-quality raw materials for subsequent products and enhancing the competitiveness of crankshaft products.
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  Optimization of reheating furnace rolling delay strategies based on a minimum energy consumption principle

  Jing-qi Qiu, Jun-xiao Feng, Xian-mo Huang, Zhi-feng Huang

  钢铁研究学报（英文版）. 2025, 32(3): 707-719.
  https://doi.org/10.1007/s42243-024-01227-0

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  To provide an energy-efficient and slab-demand-compliant rolling delay strategy, the simulation software is utilized to calculate the rolling delay process of the reheating furnace. Based on energy consumption evaluation, two optimization methods were employed. The bisection approach uses the needs of the slab to estimate the rolling delay temperature, and the golden section search method uses the energy consumption analysis of the slab to determine the high-temperature insulation duration. Generally, the slab closest to the discharge position in the control zone is selected as the optimization target. The optimized slab does not show a significant temperature rise after the end of the rolling delay process. When comparing the optimized rolling delay strategies with the traditional ones, the optimized rolling delay strategies not only meet the output requirements for slabs but also offer significant advantages in terms of energy efficiency, and this advantage increases with rolling delay time.
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  Hybrid prediction model for strip width based on improved mechanism and data-driven model

  Jia-liang Wang, Jing-cheng Wang, Chao-bo Chen, Kang-bo Dang, Song Gao

  钢铁研究学报（英文版）. 2025, 32(3): 720-732.
  https://doi.org/10.1007/s42243-024-01400-5

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Accurate prediction of strip width is a key factor related to the quality of hot rolling manufacture. Firstly, based on strip width formation mechanism model within strip rolling process, an improved width mechanism calculation model is delineated for the optimization of process parameters via the particle swarm optimization algorithm. Subsequently, a hybrid strip width prediction model is proposed by effectively combining the respective advantages of the improved mechanism model and the data-driven model. In acknowledgment of prerequisite for positive error in strip width prediction, an adaptive width error compensation algorithm is proposed. Finally, comparative simulation experiments are designed on the actual rolling dataset after completing data cleaning and feature engineering. The experimental results show that the hybrid prediction model proposed has superior precision and robustness compared with the improved mechanism model and the other eight common data-driven models and satisfies the needs of practical applications. Moreover, the hybrid model can realize the comple-mentary advantages of the mechanism model and the data-driven model, effectively alleviating the problems of difficult to improve the accuracy of the mechanism model and poor interpretability of the data-driven model, which bears significant practical implications for the research of strip width control.
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  Effect of compact strip processing on segregation behavior and mechanical properties of Q&P steel

  Ming-yue Yang, Sheng-wei Wang, Shui-ze Wang, Yu-he Huang, Xin-ping Mao

  钢铁研究学报（英文版）. 2025, 32(3): 733-742.
  https://doi.org/10.1007/s42243-024-01259-6

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  The microstructure and mechanical properties of the compact strip production (CSP) processed quenching and partitioning (Q&P) steels were investigated through experimental methods to address the challenge of designing high-performance Q&P steels. Compared with the conventional process (CP) produced samples, with slightly reduced strength, the total elongation of the CSP produced samples was increased by nearly 7%. Microstructural analysis revealed that variations in austenite stability were not the primary cause for the differences in mechanical properties between the CSP and the CP. The CSP processed Q&P steel exhibited milder center segregation behavior in contrast to the CP processed Q&P steel. Consequently, in the CSP processed Q&P steel, a higher proportion of austenite and a lower proportion of martensite were observed at the center position, delaying the crack initiation in the central region and contributing to the enhanced ductility. The investigation into the CSP process reveals its effect on alleviation of segregation and enhancement of mechanical properties of the Q&P steel.
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  Effect of phase content on deformation compatibility in ferrite and bainite dual-phase steel: experimental and crystal plasticity finite element analysis

  Xian-bo Shi, Xing-yang Tu, Bing-chuan Yan, Yi Ren, Wei Yan, Yi-yin Shan

  钢铁研究学报（英文版）. 2025, 32(3): 743-755.
  https://doi.org/10.1007/s42243-024-01232-3

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  The phase volume fraction has an important role in the match of the strength and plasticity of dual phase steel. The different bainite contents (18-53 vol.%) in polygonal ferrite and bainite (PF + B) dual phase steel were obtained by controlling the relaxation finish temperature during the rolling process. The effect of bainite volume fraction on the tensile deformability was systematically investigated via experiments and crystal plasticity finite element model (CPFEM) sim-ulation. The experimental results showed that the steel showed optimal strain hardenability and strength-plasticity matching when the bainite reached 35%. The 3D-CPFEM models with the same grain size and texture characters were established to clarify the influence of stress/strain distribution on PF + B dual phase steel with different bainite contents. The simulation results indicated that an appropriate increase in the bainite content (18%-35%) did not affect the interphase strain difference, but increased the stress distribution in both phases, as a result of enhancing the coordinated deformability of two phases and improving the strength-plasticity matching. When the bainite content increased to 53%, the stress/strain difference between the two phases was greatly increased, and plastic damage between the two phases was caused by the reduction of the coordinated deformability.
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  Precipitation of secondary Laves phases and its effect on notch sensitivity

  Wei-wei Zhang, Yuan-guo Tan, Yu Lai, Qi Chen, Yang Zhou

  钢铁研究学报（英文版）. 2025, 32(3): 756-768.
  https://doi.org/10.1007/s42243-024-01261-y

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  The precipitation of secondary Laves phases and its effect on notch sensitivity are systematically studied in Thermo-Span alloy. The results show that the precipitation peak temperature of secondary Laves phases is 925 °C. Below 925 °C, the volume fraction of secondary Laves phases increases with the rise of the temperature, and its morphology changes from granular to thin-film; above 925 °C, the volume fraction of secondary Laves phases shows an opposite trend to temperature, and its morphology changes from thin-film to granular. A detailed explanation through linear density (p) is provided that the influence of secondary Laves phases at the grain boundaries (GBs) on notch sensitivity depends on the coupling competition effect of their size, quantity, and morphology. Notably, the granular Laves phases are more beneficial to improving the notch sensitivity of the alloy compared with thin-film Laves phases. Granular secondary Laves phases can promote the formation of γ^' phases depletion zone to improve the ability of GBs to accommodate high strain localization, and effectively inhibit the crack initiation and propagation.
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  Strength and toughness mechanism of single Ti microalloyed steels

  Yi Wang, Zhi-chao Che, Yu-feng Chen, Shu-feng Yang, Jun-fen Zhang, Qi-he Xue

  钢铁研究学报（英文版）. 2025, 32(3): 769-782.
  https://doi.org/10.1007/s42243-024-01315-1

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  The mechanism of strength and toughness variation in Ti microalloyed steel within the range of 0.04-0.157 wt.% was investigated. By adding 0.13 wt.% Ti, the steel achieves higher strength while maintaining a certain level of elongation and low-temperature impact toughness. With increasing Ti content, the grain size in the steel decreased from 17.7 to 8.9 lm. This decrease in grain size is accompanied by an increase in the percentage of low-angle grain boundaries and dislocations, which act as barriers to hinder crack propagation. The Ti microalloyed steel exhibits a 20% increase in yield strength and a 14% increase in tensile strength. The transformation of steel plasticity occurs when the Ti content exceeds 0.102 wt.%. The low-temperature impact toughness of the steel gradually decreases with increasing Ti content. At low Ti content, the low-temperature impact toughness is reduced due to crack initiation by large-size inclusions. At high Ti content, the low-temperature impact toughness of the steel deteriorates due to several factors. These include the narrower tough-brittle transition zone, grain boundary embrittlement caused by small-sized grains, and the decrease in the solid solution strengthening effect.
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  Elemental segregation, microstructure, and mechanical properties of TMCP-treated high-manganese wear-resistant steel

  Yang He, Jian-hua Liu, Guan-yong Huang, Hao Xu, Ning Liu, Jiang-hua Qi

  钢铁研究学报（英文版）. 2025, 32(3): 783-798.
  https://doi.org/10.1007/s42243-024-01340-0

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  The elemental segregation, microstructure, and mechanical properties of thermo-mechanical control process (TMCP) treated high-manganese wear-resistant steel (HMWS) were experimentally investigated. Firstly, the initial elemental segregation in the continuous casting slab of HMWS was characterized using the original position analysis. The results showed that the elemental segregation predominantly occurred near the quarter and the center regions of the slab. The homogenization of manganese (Mn) in the slab was not as obvious as that of other elements after the heating process. Subsequently, a series of hot-rolling tests were carried out on HMWS slab samples under different TMCP conditions, and the elemental segregation and microstructure of the TMCP-treated HMWS were investigated by microscopic analysis methods. The findings demonstrated that the segregations of carbon and silicon were effectively eliminated after the TMCP treatment, while Mn segregation presented a band-shaped arrangement and could be reduced at lower finishing rolling temperatures. The matrix phase of HMWS remained austenite regardless of the TMCP conditions, and the average size of austenite grains increased with the increasing finishing rolling temperature. Carbide particles were observed to form within austenite grains and even along grain boundaries at higher coiling temperatures. Finally, the mechanical tests were performed on the TMCP-treated HMWS at room temperature. The mechanical properties including tensile stress, yield stress, Charpy impact energy, and microhardness were discussed considering the effects of Mn segregation band, microstructure, and carbide precipitation.
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  Fatigue failure analysis and heat treatment strategy optimization of torsion bar spring for automobile suspension system used in light vehicles

  Jia-xing Liu, Yong-jin Wu, Chao-lei Zhang, Wan-li Sun, Wen-bin Ding, Shuai-jun Dong

  钢铁研究学报（英文版）. 2025, 32(3): 799-811.
  https://doi.org/10.1007/s42243-024-01305-3

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  The failure analysis was conducted on unqualified torsion bar spring in automobile suspension system used for light vehicles during engine test. The effects of through hardening, surface induction hardening, quenching and tempering, and tempering temperature on the microstructure and fatigue life of 45CrNiMoVA steel torsion bars were also investigated. Results showed that only the torsion bar spring after through quenching and tempering is subjected to surface induction quenching and tempering to achieve the fatigue life of the qualified torsion bar. The fatigue life of torsion bar spring reaches 3×10⁵ cycles more than the required 2×10⁵ cycles. This is because the distribution of gradient microstructure was helpful to relieve the applied stress during the fatigue process. The microstructure of the non-hardened region, which consists of tempered sorbite regardless of whether it is tempered at 330 or 430 °C, contributes to minimizing the impact of temper brittleness on the fatigue life of the torsion bar. Consequently, the fatigue life of the torsion bar is relatively unaffected by temper brittleness due to the presence of tempered sorbite in its non-hardened regions. And the reason for the unqualified fatigue life was that the depth and hardness of the hardened region did not meet the standard requirements of 5-7 mm and 47-52 HRC, respectively.
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  Microstructural evolution of GH4742 superalloy during hot deformation and subsequent solvus treatment

  Wen-wen Zhang, Xin-gang Liu, Shuai-jie Wang, Yu-jiao Ke, Ying Guo, He-yong Qin, Qiang Tian

  钢铁研究学报（英文版）. 2025, 32(3): 812-832.
  https://doi.org/10.1007/s42243-024-01352-w

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  Isothermal compression tests were used to establish constitutive models of the hot deformation of GH4742 superalloy. The microstructural evolution of double cone samples with large strain gradients during hot deformation and subsequent solvus treatment was studied. The results showed that the grain size during dynamic recrystallization (DRX) did not exceed 6 lm, and the volume fraction during DRX did not exceed 45% at all reduction rates when it deformed below the γ^' solvus temperature (1080 °C). When deformed near the γ^' solvus temperature (1110 °C), the volume fraction and grain size increase significantly during DRX due to the dissolution and coarsening of some γ^' precipitates. When deformed above the γ^' solvus temperature (1140 °C), even at a high reduction rate of 20 mm/s, the volume fraction during DRX reached 75%, and the grain size during DRX increased to 25 lm. At a reduction rate of 0.5 mm/s, the grain size during DRX reached 65 lm. When the sample is deformed below the γ^' solvus temperature (1080 °C), stored strain energy accumulates in the sample, which is beneficial for the development of post dynamic recrystallization during subsequent subsolvus heat treatment, resulting in a noticeable increase in the recrystallization volume fraction. The recrystallization volume fraction of predeformed samples deformed at 1110 and 1140 °C, followed by subsolvus heat treatment, was almost unchanged. The microstructure of the predeformed sample following supersolvus heat treatment consists of coarse equiaxed grains.