20 March 2025, Volume 37 Issue 3
    

  • Select all
    |
    Reviews
  • Research progress on service damage repair technology of superalloy turbine blades
    WANG Zhicheng, QIN Hailong, ZHOU Haijing, QIAO Lijie, FENG Keyun, HAO Chen, YUAN Xiaofei, XIE Jinli, BI Zhongnan
    Journal of Iron and Steel Research. 2025, 37(3): 269-282. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240237
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The turbine blades made of superalloy are among the most critical components in the hot section of aero-engines and gas turbines. Operating within a complex environment of high temperatures, stress, and gas corrosion over extended periods, they are susceptible to various forms of damage. Turbine blades made of superalloy is costly, so it is not economical to replace blades with only minor damage. Therefore, research on the turbine blades damage and repair technology is crucial for reducing the overall repair and manufacturing cost associated with superalloy turbine blades. The necessity for researching turbine blade damage and repair technology was firstly clarified. Then, the main types of service damage experienced by superalloy turbine blades were classified, including internal metallurgical microstructure damage and apparent damage. Various repair technologies were summarized, including welding repair technology, damage repair technology based on additive manufacturing, and recovery heat treatment technologies while analyzing their respective advantages, disadvantages and applicability. Finally, it provides an outlook on the future development direction of superalloy turbine blade repair technologies.
  • Development and progress in grain-oriented electrical steel
    CHU Shuangjie, ZHOU Bohao, PAN Zhendong, MAO Bo
    Journal of Iron and Steel Research. 2025, 37(3): 283-296. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240180
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Grain oriented electrical steel (GOES) is one of the most fundamental and important materials in the construction of modern power energy systems, playing an indispensable role in high-efficiency power transmission and transformation. Due to its complex manufacturing process, high precision requirements for equipment functionality, and stringent process control challenges, producing high-performance GOES necessitates significant breakthroughs both in manufacturing equipment and process technologies. The technological advancements and development of GOES throughout its entire production process were explored, including composition design, microstructure control, and processing techniques. The roles of alloying elements in GOES and the key manufacturing technologies to achieve the target composition were specifically analyzed, the microstructural evolution during the rolling and heat treatment processes was summarized, the impact of critical process parameters in rolling and heat treatment on the microstructure of GOES was investigated, and the characteristics of key post-processing coatings and magnetic domain refinement technologies were outlined. Finally, in light of the severe challenges faced by GOES development, the future research directions and development trends in this field were proposed.
    • Smelting and Working
  • Study on characteristics of mixed coal injection in industrial production of biohydrochar blast furnace
    WANG Guangwei, LI Haibo, WU Junyi, SUN Guojun, NING Xiaojun, WANG Chuan
    Journal of Iron and Steel Research. 2025, 37(3): 297-306. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240240
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Pulverized coal injection technology is the main technology to reduce iron-making production costs and improve blast furnace (BF) smelting efficiency. Biomass used for BF injection is one of the key technologies to achieve low-carbon iron-making due to renewable low-carbon energy source property. Three types of biomass hydrochar produced industrially were used to investigate the feasibility of applying the hydrothermal carbonization products (hydrochar) of low-quality biomass to BF injection. The results showed that hydrochar has high volatile content and low calorific value, while orange peel and olive pomace hydrochar have low ash and alkali metal content, which can be used as substitutes for bituminous coal for BF injection. The experiments of hydrochar mixed with anthracite show that hydrochar has strong explosiveness. Mixing anthracite with hydrochar can effectively suppress explosiveness. When the proportion of hydrochar added is less than 20%, the mixed sample has no explosiveness. Hydrochar has a lower ignition point and excellent combustion performance. As the mixing ratio of hydrochar increases, the ignition point of the mixed sample decreases, and the combustion curve moves towards the low-temperature zone, gradually improving the combustion performance. Based on the above research, hydrochar produced from orange peel and olive pomace can be used as BF injection fuel, and the proportion of hydrochar added to mixed anthracite should be controlled below 20%.
  • Mechanism of high volatile matter in coal promoting non-isothermal reduction of Fe3O4
    YANG Yongkun, WANG Guanjie, ZHOU Xin, SHEN Wenting, WANG Weian, WANG Guohua, LI Xiaoming
    Journal of Iron and Steel Research. 2025, 37(3): 307-316. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240231
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    With the development of electric arc furnace, the demand for direct reduced iron will also increase. The use of low temperature reduction to optimize magnetite is an important source of direct reduced iron. In order to study the mechanism of Fe3O4 reduction promoted by high volatile matter in coal, the pyrolysis gas composition and pyrolysis characteristics of Guanghui coal were analyzed. The pyrolysis of Guanghui coal and Fe3O4 reduction were studied by non-isothermal kinetics analysis method. The activation energy of the reaction was calculated by FWO, KAS and Starink methods. The Satava-Sestak method was used to fit the reaction model. The difference of kinetic mechanism of Fe3O4 reduction between activated carbon and coal was emphasized. The results show that the retorting gas of Guanghui coal is mainly composed of H2, CH4, CO and CO2. In the reduction temperature range, the H2 content and CO content of coal pyrolysis can reach 55 and 25 vol.%,respectively,which provides a good atmosphere for the reduction of Fe3O4. The temperature range of activated carbon reduction of Fe3O4 is 980-1 140 ℃, and the initial activation energy is 319.66 kJ/mol, while the reduction temperature range of Guanghui coal is 680-1 030 ℃, and the initial activation energy is 288.62 kJ/mol. The results show that the high volatile matter in Guanghui coal plays a catalytic role in the reduction process and significantly reduces the reduction temperature and activation energy.
  • Low-carbon super-high bed sintering for iron ores based on industrial sintering bed analysis
    XU Liangping, YANG Xiduan, ZHAO Yuchao, XIONG Lin, ZHANG Tieliang, ZHONG Qiang, LI Guanghui, JIANG Tao
    Journal of Iron and Steel Research. 2025, 37(3): 317-325. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240245
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Super-high bed sintering is an important route to reduce carbon emissions in the steel industry. However, as the sintering bed depth increases in practice, the severe inhomogeneity of sinter products adversely affects the blast furnace production. Joint analysis of mixture and sinter was carried out on more than 10 industrial sintering machines in China with bed depth of not less than 900 mm. It is revealed that the inhomogeneous quality of sinter products mainly manifested in the longitudinal direction, transverse direction, and between the strands. The root reason is that the uneven liquid phase composition and heat caused by unreasonable distribution of mixture particle size, chemical composition, and air cannot satisfy the requirements of liquid phase homogeneous mineralization. To address the above problems, an ideal bed structure matching the liquid phase and heat was developed. Besides, the optimized ore blending technology for liquid phase composition regulation, the enhanced mixing and granulation technology, synergistic feeding technology, and air reorganization sintering technology were developed to achieve this bed structure. By optimizing the chemical composition of liquid phase, regulating the distribution of liquid phase within the sintering bed, and matching the heat with the liquid phase quantity, the efficiency of heat and suction was improved, and homogeneous mineralization was achieved. After the implementation of those technologies, the solid fuel consumption was reduced by 1.2-7.9 kg/t, the tumble index increased by 3%-6%, and the difference of tumble index within the sintering bed was reduced to 5.08%. Furthermore, the metallurgical performance of the sinter improved, with the reduction disintegration index RDI+3.15 mm increasing by 10% and the difference of RDI-0.5 mm decreasing to 1.99%. The productivity of the blast furnace improved, and the solid fuel consumption was reduced by 6.58 kg/t at the highest.
  • MgO on viscosity and thermal stability of laterite nickel ore blast furnace slag
    REN Yize, XING Xiangdong, LÜ Ming, LIN Xuhui, YU Zhiheng, WANG Baorong, GUO Penghui
    Journal of Iron and Steel Research. 2025, 37(3): 326-334. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240236
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The influence of MgO on the viscosity and free running temperature of laterite nickel ore smelting slag was investigated. The structural change of the slag was analyzed by Fourier infrared spectroscopy and Raman spectroscopy. Meanwhile, the heat capacity, enthalpy change and extreme heat release of laterite nickel ore smelting slag were calculated by thermodynamics. The results show that the viscosity of laterite nickel ore smelting slag decreases with the increase in MgO content, and the viscosity is lower than 1.0 Pa·s at temperatures higher than 1 450 ℃. The free running temperature increases slightly, which exhibits good fluidity. The heat capacity, enthalpy change, and the extreme heat release of laterite nickel ore smelting slag gradually increase with the increase in MgO content. The Q0 and Q1 structural units in laterite nickel ore smelting slag increase, while the Q2 and Q3 structural units decrease significantly. The average NBO/Si increases from 1.79 to 2.06 with MgO content. The slag structure becomes simpler and increases the fluidity. The addition of MgO can effectively improve the fluidity of laterite nickel ore blast furnace smelting slag, and has a positive effect on improving the thermal stability of laterite nickel ore smelting slag.
  • Rapid prediction model of ladle bottom blowing refining based on POD decomposition and BP neural network
    NIE Zhongfu, DAI Wei, JIA Qi, HE Zhu, LI Guangqiang, WANG Qiang
    Journal of Iron and Steel Research. 2025, 37(3): 335-345. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240235
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to meet the requirement of real-time acquisition of 3D flow field data in ladle bottom-blowing refining, a fast prediction model of 3D flow field based oncomputational fluid dynamics (CFD) and proper orthogonal decomposition (POD) was established. The three-dimensional flow field data of single-nozzle bottom blowing of ladle were simulated and calculated by establishing the numerical model and the water model, and the data set was established. The mode and mode coefficient of the data set were extracted by the POD method. Through the back propagation neural network (BPNN), the mapping relationship between operating parameters and modal coefficients was constructed, and the velocity field and three-phase volume fraction in the bottom-blowing ladle can be predicted quickly. The results show that the proposed model can reconstruct the main characteristics of the flow field in the ladle through a few modes. The POD-BPNN prediction model has a high accuracy of calculation results, and the average relative error of calculation results is less than 4%. The calculation speed of the model is fast, and the average calculation time to obtain the flow field in the ladle is reduced from about 246 h required by CFD simulation to about 54.6 h by the POD method.
  • Effect of CO2-CO atmosphere on decarbonization of 3.5% Si silicon steel
    QIAN Na, AI Liqun, HONG Lukuo, SUN Caijiao, ZHOU Meijie, TONG Shuai, SUN Lingyan, CHEN Jiansong
    Journal of Iron and Steel Research. 2025, 37(3): 346-356. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240242
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Ultra-low carbon silicon steel was prepared using a short process technology in a CO2-CO atmosphere. The experiment focuses on a thin strip of Fe-0.1%C-3.5%Si alloy with a thickness of 0.5 mm. The thermodynamic equilibrium phase diagram of Fe-C-Si alloy thin stripwas calculated through thermodynamic software and solid-state decarburization experiments in CO2-CO atmosphere were conducted. The results show that when the temperature is between 800 ℃ and 1 300 ℃ and the PCO2/PCO value is lower than 0.22, SiO2 is preferentially generated in the cross-section of the thin strip. The comparison between surface XRD phase analysis and thermodynamic analysis shows that the results are basically consistent. When PCO2/PCO=0.08, the decarbonization effect is better when the carbon content is 0.005 97 wt.% after 10 min of decarbonization. The carbon content after decarburization at 1 150 ℃ for25 min is 0.002 62 wt.%, indicating good decarburization effect and meeting the carbon content requirements of ultra-low carbon silicon steel. The thinner the Fe-0.1%C-3.5%Si alloy ribbon thickness, the faster the decarburization rate and the faster the growth rate of the oxide layer. Calculations from the study of the kinetics show that the average carbon content of Fe-0.1%C-3.5%Si alloy thin strips with different thicknesses varies exponentially with time; the decarburization of Fe-0.1%C-3.5%Si alloy thin strips of 1 mm in thickness by gas-solid reaction can be approximated as an apparent first-order reaction, and the apparent decarburization rate constant k can be approximated as 0.083 49.
  • Analytical model of cold roller straightening process of plate using curvature integration method
    HAN Wen, MA Weishi, HU Dianzhang, LIU Rui, LI Hongbo
    Journal of Iron and Steel Research. 2025, 37(3): 357-366. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240146
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the effect and efficiency of cold straightening of plate in medium plate production line, an analytical model of nine-roll cold straightening process was established based on curvature integration method. The influence of different plate factors and process strategies on the main parameters such as curvature ratio and straightening force was discussed. It was verified that the total straightening force deviation of the model was within 10%. With this model, the influence of different plate factors on straightening force and residual curvature was analyzed. Among them, the influence of steel grade and plate thickness is greater, and that of initial curvature ratio is smaller. With this model, the influence of the reduction of No.1, No.2, No.8 and No.9 straightening rollers on the straightening was analyzed. Among them, the residual curvature ratio and the total straightening force increase with the increase in the reduction. The No.8 roller has the strongest ability to control the residual curvature ratio after straightening, and the No.2 roller has the greatest influence on the total straightening force.In contrast, the effects of No.1 and No.9 rollers are small.Referring to this research results, the field straightening strategy is adjusted. The proportion of plates that need to be straightened for 3 passes or more is reduced from 30%-35% to 10%-15%.
    • Materials Research
  • Austenite grain size and distribution models of Nb-Ti microalloyed steel
    LI Mingjie, ZHANG Xinyue, WANG Siqiao, ZHANG Xinyao, ZHOU Xiaoguang, LIU Zhenyu
    Journal of Iron and Steel Research. 2025, 37(3): 367-374. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240173
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to investigate the effect of austenitizing process on the grain growth behaviors of Nb-Ti microalloyed steel, thermal simulation experiments were conducted to study the austenite grain growth behavior of the experimental steel within the range of austenitizing temperature (1 140-1 220 ℃) and holding time (180-540 s). The mathematical models for austenite grain growth and its distribution were established. The results indicate that when the holding time is kept constant, the austenite grains tend to grow larger and become more uniformly distributed. When the austenitizing temperature is held constant, prolonging the holding time slows down the growth rate of austenite grains, and the size distribution of the austenite grains will also tend to become more uniform. The mathematical models for the average austenite grain size and its distribution closely match the measured values. Contour plots are generated for the average austenite grain size and grain size distribution parameter under different austenitizing process conditions, which provide a theoretical foundation for determining reasonable austenitizing processes for experimental steels.
  • Effect of annealing temperatures on non-magnetic structural steel 20Mn23AlV
    DI Yanjun, PING Lingling, TANG Xingchang, ZHANG Zhijian, CHENG Ganghu
    Journal of Iron and Steel Research. 2025, 37(3): 375-385. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240154
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Different temperature annealing treatments of non-magnetic structural steel hot-rolled sheets were used to study the changes in microstructure, mechanical properties and magnetic properties. The results show that with the increase in annealing temperature, the tensile strength of non-magnetic structural steel hot rolled plate shows a decreasing trend, and the elongation increases slowly. A large number of deformation twins are generated within the austenitic grains of non-magnetic structural steel in different states after stretching, and these deformation twins can obstruct the dislocation motion and crystalline slip, which increases the hardness of non-magnetic structural steel. The XRD analysis shows that the hot rolled non-magnetic structural steel sheets did not induce phase transformation after annealing at different temperatures. Meanwhile, the magnetic permeability test results show that the relative magnetic permeability fluctuates between 1.002 18 and 1.002 06, which meets the requirements of non-magnetic structural steel for magnetic properties.
  • Microstructure and properties of DC53/42CrMo bimetallic composites
    ZHANG Saikang, CAO Yulong, ZHANG Zhongxin, MA Chongsheng, LI Guangqiang
    Journal of Iron and Steel Research. 2025, 37(3): 386-395. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240169
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The plate DC53/42CrMo composite casting billet was successfully prepared by electroslag remelting equipment. After annealing at 750 ℃, the microstructure, composition and interfacial element transition were studied by OM, SEM and EBSD, and the mechanical properties at the bimetal composite interface were characterized. The results show that the prepared DC53/42CrMo bimetallic composite casting billet has good bonding without slag inclusion and porosity. Element diffusion occurs at the composite interface, in which element C diffuses upslope from the 42CrMo side with low C content to the DC53 side with high C content. During the bimetallic liquid-solid recombination process, the activity of C in 42CrMo is much higher than that in DC53. On the 42CrMo side, there is a ferrite matrix + lamellar pearlite structure. On the 42CrMo side, there is a heat affected zone with a width of about 100 μm near the binding interface, and on the DC53 side, there is an element diffusion affected zone with a width of about 30 μm. The DC53 side is composed of pearlite matrix and undissolved carbide. The microhardness of the composite decreases first from 42CrMo to DC53, and then increases. The hardness of the heat-affected zone on the 42CrMo side is the lowest, with an average hardness of 192.9HV. The average tensile strength of the interface of the composite sample is 632.73 MPa and the shear strength is 586.12 MPa. The tensile fracture position of the composite sample is located at the 42CrMo side rather than the bonding interface, indicating that the bimetal interface is not a weak area and the interface bonding performance is good. The internal relationship between interface structure and properties was investigated, which provided reference for the preparation of bimetal composite cutter ring.
  • Effects of intercritical quenching on microstructure and precipitates of high strength steel Q890
    AN Tao, GUO Chengyu, LI Tianyi, DAI Chunduo, ZHANG Chi, ZHANG Zhe
    Journal of Iron and Steel Research. 2025, 37(3): 396-404. https://doi.org/10.13228/j.boyuan.issn1001-0963.20240176
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Q890 high-strength structural steel was used to explore the influence of intercritical quenching temperature and tempering temperature on the microstructure and precipitates by using ThermoCalc software, transmission electron microscope and tensile testing machine. The results indicate that with decreasing the intercritical quenching temperature (840, 800, 760 ℃), the proportion of ferrite increases, and the types of the precipitated particles increase, and the average diameter and the volume fraction of the precipitated particles decreases. After 840 and 800 ℃ quenching, the strength of the tested steel is similar. After reducing the quenching temperature to 760 ℃, the yield strength of the tested steel decreases by about 200 MPa, and the fracture elongation increases to 18.5%. With the increase in tempering temperature (200, 400, 600 ℃), the dislocation density of the texted steel decreases, and the matrix softens; the type of the precipitated particles increases, and the average diameter and the volume fraction of the precipitated particles increase, and thus the precipitation strengthening is significantly increased. As the tempering temperature increases, the yield strength of the tested steel gradually decreases (1 210, 1 120, 817 MPa), and the fracture elongation gradually increases (14.0%, 14.2%, 21.8%).
Copyright © Journal of Iron and Steel Research, All Rights Reserved.
Tel: 010-62182340　
E-mail：gtyjxb@163.com
Powered by Beijing Magtech Co. Ltd,.