2022年, 第29卷, 第12期　刊出日期：2022-12-25

  

• 全选
  |

论著
• Select
  Preface

  Chuan-jun Li, Wan-ming Li

  钢铁研究学报(英文版). 2022, 29(12): 1899-1900.
  https://doi.org/10.1007/s42243-022-00777-5

  摘要 ( )   可视化   收藏
综述
• Select
  A review on prediction of casting defects in steel ingots: from macrosegregation to multi-defect model

  Jun Li, Xiao-wei Xu, Neng Ren, Ming-xu Xia, Jian-guo Li

  钢铁研究学报(英文版). 2022, 29(12): 1901-1914.
  https://doi.org/10.1007/s42243-022-00848-7

  摘要 ( )   可视化   收藏

  Due to the nature of the solute redistribution, the reduction in the solidification rate with time in a square root relationship, and the multiphase melt flow during the solidification, casting defects such as macrosegregation, shrinkage cavity, and porosity will inevitably occur in the steel ingot and intensify with the increase in ingot size. These defects directly affect the performance of the final product and severely restrict the choice of subsequent thermal processing methods and process windows. Therefore, the solidification defects including macrosegregation, shrinkage/porosity, and inclusions encountered in the preparation of large steel ingots and their formation mechanisms were reviewed. The development progress and the latest development of the macrosegregation model for steel ingots were introduced in detail, especially the latest progress in the coupling prediction of macrosegregation and shrinkage as well as macrosegregation and inclusions. Some methods to reduce macrosegregation of ingots were discussed as well. Finally, a new casting method called layered casting was introduced in detail. This method can effectively improve the uniformity of the macrostructure and reduce the macrosegregation of the large ingots and therefore is a promising method for preparing large ingots with high homogeneity.
论著
• Select
  Application of heat absorption method to reduce macrosegregation during solidification of bearing steel ingot

  Sheng Yu, Long-qiang Zhu, Jin-hu Lai, Ming-xu Pan, Yue-yun Liu, Wei-dong Xuan, Jiang Wang, Chuan-jun Li, Zhong-ming Ren

  钢铁研究学报(英文版). 2022, 29(12): 1915-1926.
  https://doi.org/10.1007/s42243-022-00763-x

  摘要 ( )   可视化   收藏

  The control of macrosegregation is still a difficult problem for the production of large steel ingots. In order to develop new techniques for producing low-macrosegregation and high-quality steel ingots, the effect of the heat absorption method (HAM) used by the inorganic material rods to cool the liquid steel on the formation of macrosegregation during solidification of a 5-t GCr15SiMn bearing steel ingot was studied using experiment and mathematical simulation. The inorganic material was a mixture of CaF₂ and CaO. The levels of macrosegregation in the longitudinal sections of two ingots with and without HAM were compared. Experimental results showed that the application of HAM reduced the positive segregation in the upper part of the ingot and the negative segregation in the lower part. The levels of carbon segregation along the longitudinal centerline and horizontal direction at different heights were all alleviated and the fluctuation of carbon segregation was significantly reduced. The simulation results confirmed that the melting and floating of the inorganic material could carry the sensible heat to the top of the liquid steel quickly. This leads to the acceleration of the cooling rate of the liquid steel, thereby alleviating the level of macrosegregation.
• Select
  Roll profile electromagnetic control characteristics under roll heterogeneity

  Ting-song Yang, Yu-hang Bai, Yang Hai, Qi-fa Chen, Feng-shan Du

  钢铁研究学报(英文版). 2022, 29(12): 1927-1938.
  https://doi.org/10.1007/s42243-022-00779-3

  摘要 ( )   可视化   收藏

  The electromagnetic control roll (ECR) and electromagnetic stick (ES) are the core elements and the main driving parts of roll profile electromagnetic control technology (RPECT). To prolong the service life, it is necessary to treat ECR and ES surfaces. According to the heterogeneous characteristics of surface treatments, the roll profile electromagnetic control characteristics were analyzed for different parameters. An electromagnetic-thermal-force coupled axisymmetric finite element model was built to explore the differences in performance as a result of several treatment strategies, and the model was verified by experimental results measured with a roll profile electromagnetic control experimental platform. This model was used to analyze the influence of the heterogeneity of ECR inner hole and ES on the roll crown, the roll profile, the average contact pressure, and the stress state during RPECT process. The results indicate that the heterogeneous layer at ECR inner hole has a restrictive effect on RPECT and that the heterogeneous layer of ES can enhance the profile control ability of RPECT. A reasonable configuration scheme between the heterogeneity of ECR inner hole and the ES can increase the life of ECR and maintain the control ability of RPECT.
• Select
  Improving ingot homogeneity by modified hot-top pulsed magneto-oscillation

  Fan Zhang, Hong-gang Zhong, Yu-qian Yang, Ming-xu Pan, Ren-xing Li, Qi-jie Zhai

  钢铁研究学报(英文版). 2022, 29(12): 1939-1950.
  https://doi.org/10.1007/s42243-022-00785-5

  摘要 ( )   可视化   收藏

  Heavy ingots, especially the ingot of more than 10 t, often contain detrimental heterogeneous defects, such as macrosegregation, shrinkage pipes, and cracks. Hot-top pulsed magneto-oscillation (HPMO) can refine the solidified structure of ingot and improve their homogeneity. However, it may exacerbate the positive segregation at the upper part of the ingot body. Thus, a round table HPMO riser with a feeding part was designed, and the microstructure and macrosegregation of Al–Si alloy ingots solidified with and without HPMO were investigated. The simulation and experimental results indicated that round table HPMO riser could enable fine and uniform solidified structures in the whole ingot body; in the meantime, feeding part allowed the melt with enriched solute to gather in the upper part of the riser until the last solidification stage of ingot. This provides an effective approach for obtaining highly homogenized ingots.
• Select
  Effect of hollow insulation riser on shrinkage porosity and solidification structure of ingot

  Ying-jie Liu, Chun-lin Peng, Wan-ming Li, Xiao-lei Zhu, Ming-gang Shen, Xiang-wei Liao, Kun Liu, Chong-yi Wei, Yusuf Abba Yusuf, Ji Yang, Chang-you Cai

  钢铁研究学报(英文版). 2022, 29(12): 1951-1960.
  https://doi.org/10.1007/s42243-022-00790-8

  摘要 ( )   可视化   收藏

  The thermal insulation performance of riser is very important to the shrinkage porosity and solidification structure of ingot, but it is difficult to significantly improve due to the limit of thermal conductivity of riser material. A new type of hollow insulation riser was proposed based on the low thermal conductivity of air, which aims to improve the thermal insulation performance of riser. A 14.5-t steel ingot was prepared using the hollow insulation riser, and the casting temperature was 1500 °C. The temperature evolution of the external surface of mold during solidification was measured using an infrared temperature instrument. A numerical model was established to simulate the porosity and solidification structure of ingot. The reliability of numerical simulation was verified by comparing simulation and experimental results. Results show that the insulation performance of the riser can be significantly improved through application of the hollow insulation sleeve. Compared with solid insulation sleeve, the shrinkage cavity depth was decreased and the position of porosity was raised when hollow insulation riser was applied.
• Select
  Multi-scale analysis of void evolution in large-section plastic mold steel during multi-directional forging

  Xuan Chen, Bo-ya Wu, Bo-liang Wu, Xiao-chun Wu, Jun-wan Li

  钢铁研究学报(英文版). 2022, 29(12): 1961-1977.
  https://doi.org/10.1007/s42243-022-00792-6

  摘要 ( )   可视化   收藏

  The void evolution of large-section plastic mold steel during multi-directional forging (MDF) was investigated using multiscale analysis. To simulate the forging process of the plastic mold steel (SDP1 steel) and realize micro-void reconstruction in a representative volume element (RVE), MDF experiment and void-characteristic evaluation of the SDP1 steel were carried out. Traditional upsetting and stretching forging (TUSF) and MDF were simulated to comparatively analyze the evolution of temperature, effective stress, and effective strain. By embedding RVE with a micro-void and using boundary condition by point tracking into the forging process, the single-void evolution in TUSF and MDF was studied. The effect of void orientation on single-void evolution was also investigated. The multi-scale analysis revealed the following results. (1) Compared with TUSF, MDF achieved a higher efficiency in void closure. (2) The closing efficiency of the void increased with the increase in angle h (the angle between the Z and long axes of the void). (3) The closing efficiency increased with the increase in the orientation angle during the forging process. On the basis of the important role of the main stress in each forging step on the void closure, an integral formula of the main stress was proposed. When main compressive-stress integration reached - 0.4, the closed state of the void could be accurately determined.
• Select
  Role of radiative and convective heat transfer during heating of an ingot product in a tubular furnace: experiment and simulation

  Wen-chao Yang, Yang Zhou, Jian Zhang, Huan Liu, Ying-jie Ren, Jia-jun Chen, Xian-guang Zhang

  钢铁研究学报(英文版). 2022, 29(12): 1978-1985.
  https://doi.org/10.1007/s42243-022-00797-1

  摘要 ( )   可视化   收藏

  Convective heat transfer and radiative heat transfer are two essential heat transfer modes in the heating process of steel; it is important to understand the role of them during the heating process clearly. The effects of the convective and radiative heat transfer during the heating process of a cast ingot in a tubular furnace have been studied by the designed natural and forced convection experiments and mathematical simulations. The heating time for the center of the ingot to reach the furnace temperature is decreased with the increase in furnace temperature. According to the experimental and simulation results, a model is proposed regarding the role of radiative and convective heat transfer in the heating process. At low temperature, the convective heat transfer plays a dominant role, while at high temperature, the influence of radiative heat transfer is larger. And a critical temperature exists between them. The forced convective heat transfer can enhance the influence of the convective heat transfer. The critical temperature can be shifted to higher temperatures.
• Select
  Effect of cerium addition on microstructure and mechanical properties of as-cast high grade knives steel

  Xi-ya Qiao, Xiao Han, Zhi-jun He, Zhen Zhuang, Xin Yang, Fei-xiong Mao

  钢铁研究学报(英文版). 2022, 29(12): 1986-1994.
  https://doi.org/10.1007/s42243-022-00798-0

  摘要 ( )   可视化   收藏

  The carbides and mechanical properties of as-cast high grade knives steel with and without cerium (Ce) addition were studied. The as-cast microstructure of the steel, the size of carbide precipitation, carbide morphology, and mechanical properties were systematically studied through optical microscopy, scanning electron microscopy, and X-ray diffraction. Besides, through the Equilib module of the FactSage thermodynamics software, the changes in the precipitation type of the inclusions with Ce during the solidification of the steel were calculated. The results indicate that the rare earth Ce is added into the steel to refine the as-cast microstructure of the steel. The types of inclusions in the steel are changed by the addition of Ce. The precipitated carbide morphology changes from a complex rod shape to a relatively single lamellar shape. The rare earth inclusions formed in steel by a moderate addition of Ce can be severed as the core of heterogeneous nucleation of carbides, which reduce the size of carbide precipitation, promote the uniform distribution of carbide in the as-cast steel, and improve the mechanical properties of the as-cast high grade knives steel.
• Select
  Evaluation and improvement of pearlite microstructure and mechanical properties in 45Cr4NiMoV and 50Cr5NiMoV steels

  Kai-quan Liu, Xue-jiao Zhang, Xiao-yang Song, Lin Zhao, Lin Zhu

  钢铁研究学报(英文版). 2022, 29(12): 1995-2005.
  https://doi.org/10.1007/s42243-022-00799-z

  摘要 ( )   可视化   收藏

  The microstructure and mechanical properties of pearlite in 45Cr4NiMoV and 50Cr5NiMoV steels were studied and compared. The microstructural characteristics of pearlite of two steels were carefully examined by optical microscopy, scanning electron microscopy and transmission electron microscopy (TEM), and the type, size and relative amount of extracted carbide particles were analyzed by X-ray diffraction and TEM coupled with selected area electron diffraction. The hardness, tensile property, impact and fracture toughness of pearlite of two steels were also evaluated. Besides, the carbide dissolution kinetics of 45Cr4NiMoV and 50Cr5NiMoV steels were clarified. The results indicated that the carbides in 50Cr5NiMoV steel exhibited higher dissolution temperature than those in 45Cr4NiMoV steel, which induced different morphologies of pearlite after eutectoid transformation. Compared to the pearlite with lamellar M₂₃C₆ carbides in 45Cr4NiMoV steel, the pearlite with the mixture of spheroidized M₇C₃ and lamellar M₂₃C₆ carbides in 50Cr5NiMoV steel possessed higher impact and plane-strain fracture toughness but lower hardness and strength, because different pearlite morphologies led to different mechanical properties. In order to further improve the comprehensive properties of the steels, the fraction of M₇C₃ for the material with acceptable properties was examined and dissolution kinetic of M₇C₃ was calculated. Therefore, the austenitizing temperature and holding time could be appropriately selected to keep enough undissolved M₇C₃ in the steels.
• Select
  An innovative process of clad teeming for preparing slab ingot

  Wen-bin Ma, Yao-hui Jin, Yu-an Jing, Wen-bin Li, Wei-da Yu, Guang-long Li, Wan-ming Li

  钢铁研究学报(英文版). 2022, 29(12): 2006-2015.
  https://doi.org/10.1007/s42243-022-00802-7

  摘要 ( )   可视化   收藏

  An innovative process of clad teeming was proposed to prepare slab ingot, which featured a built-in cold core to inhibit solidification defects. A 20-kg clad ingot was prepared in the experiment, using a volume ratio of solid core to molten steel of 1:13 and a preheating temperature of cold core of 573 K. Solidification microstructures of the clad ingot were analyzed by comparing with a reference ingot without cold core. Interfacial morphologies and mechanical properties of the clad ingot were studied before and after hot rolling. The effect of cold core on heat transfer and nucleation during the solidification in clad ingot was analyzed. Results show that the solidification microstructures in the clad ingot are refined and homogenized obviously. The grain size in the center of the reference ingot is 2–3 times greater than that of clad ingot, and there is almost no columnar grain in the clad ingot. The interfacial shear strength reaches 318 MPa, which shows excellent metallurgical bonding at the interface of cold core and molten steel. Tiny defects at the interface are eliminated, and interfacial shear strength reaches 426 MPa after hot rolling with a 68.4% total reduction ratio. The experiment and analysis of this process are expected to provide a new idea to prepare large ingots with refinement and homogeneity at a low cost.
• Select
  Investigation on bonding interfaces of an SA508 steel billet manufactured by additive forging

  Xin-jin Zhang, Tian-sheng Wang, Zhi-chao Zhu, Lin Zhu

  钢铁研究学报(英文版). 2022, 29(12): 2016-2023.
  https://doi.org/10.1007/s42243-022-00803-6

  摘要 ( )   可视化   收藏

  An experimental steel billet of SA508 reactor pressure vessel material was manufactured by the additive forging method, and microstructure and mechanical properties of the hot-compression bonding interface were systematically investigated. The result indicated that oxidation levels of bonding interfaces were well controlled using vacuum electron beam welding. It was easy to discriminate interfaces from base materials during the optical microstructure observation, since interfaces were characterized by grain or phase boundaries in a straight line. Test results of uniaxial tensile experiments (at 20 and 350 °C) and Charpy V-notched impact tests (at 0 and 20 °C) showed that fracture behaviour of all those samples appeared at the base material, and bonding interfaces showed advantage of strength and toughness at the forge bonding state.