欢迎访问《钢铁研究学报(英文版)》官方网站!今天是

2017年, 第24卷, 第6期 刊出日期:2017-06-15
  

  • 全选
    |
  • Wan-ming Li,Zhou-hua Jiang,,*,Xi-min Zang,Xin Deng
    中国钢铁期刊网. 2017, 24(6): 569-578.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Currently, the market demands for large-scale and high-quality slab ingots are increasing significantly. A novel electroslag remelting withdrawal (ESRW) process with two series-connected electrodes and a T-shaped mould was developed to produce large-scale and high-quality slab ingots. It is very difficult to obtain large slab ingots with good surface quality and high width-to-thickness ratio. And it is not efficient for improving the quality of slab ingots by using trial-and-error-based approaches because the ESRW mechanisms are very complex. Thus, a three-dimensional mathematical model was developed to determine the relationship between process parameters and physical phenomena during the ESRW process. The relationship between the temperature field of the ESRW process and the surface quality of slab ingots was established. A good agreement between the simulated and measured temperature fields of slab ingots was obtained. The results indicate that the maximum values of current density, electromagnetic force and Joule heat all occur at the electrode-slag interface between the two electrodes. It can be found that the flow is turbulent and the temperature distribution is uniform in the slag pool with the influences of buoyancy and electromagnetic force. The wrinkles in the narrow faces of slab ingots are caused by the relatively lower input power. Increasing the electrode width and reducing the curvature can significantly improve the surface quality of slab ingots.
  • Rui Wang,Yan-ping Bao,*,Yi-hong Li,Tai-quan Li,Di Chen
    中国钢铁期刊网. 2017, 24(6): 579-585.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Ladle slag affects steel cleanliness at the end of the Ruhrstahl-Hereaeus (RH) and holding process. The relationship between composition of ladle slag, total oxygen (TO) and inclusions was investigated using X-ray fluorescence (XRF), infrared absorption, and SEM+EDS methods. The results indicate that TO in steel at the end of RH increases linearly with increasing FeO content in slag. TO is lower when wCaO/wAl2O3 (C/A)=1.5-2.0 than that of C/A=1.0-1.4 under an approximate content of FeO. During the holding process, irregular Al2O3 inclusions are newly generated due to slag reoxidation. Additionally, Al2O3-TixO inclusions are newly generated in the steel when the content of FeO is higher. By combining experimental and thermodynamic calculation results, it is determined that the slag has a good melting property within the zone of C/A=1.2-1.8 and adsorption capacity of Al2O3 when the content of SiO2 in slag is controlled at 4%-6%. The increase in the C/A ratio and the decrease of FeO content in slag can slow down the reoxidation rate.
  • Zhong Zheng,*,Jian-yu Long,Xiao-qiang Gao
    中国钢铁期刊网. 2017, 24(6): 586-594.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    A concept of production scenario for the steelmaking-continuous casting production process and the mathematical description of such concept were proposed. The production scenario was described with the variation of the equipment status and the production material properties based on the executing production schedule. Then, the dynamic characteristics of the production process could be described with the evolution process of production scenario. Through analyzing the influence of the dynamic production scenario on production scheduling, three key points about the scheduling problems were identified: the problem for integrating the schedules of different batches that is non-neglected when making a schedule, the problem for matching the material flow with the schedule that should be solved when implementing a schedule, and the problem for eliminating the deviations between the initial schedule and implemented schedule that should be solved when rescheduling in a disturbed environment. Finally, a set of experiments were conducted, and the results demonstrated that making the production schedule and solving the rescheduling problem for steelmaking-continuous casting process with addressing the above three problems improve the adaptability of the schedule in dynamic environment.
  • Long Guo,Xing-zhong Zhang*,Chang-xi Feng
    中国钢铁期刊网. 2017, 24(6): 595-600.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    A new continuous bending and straightening casting curve with the aim of full using of high-temperature creep deformation was proposed. The curvature of bending and straightening segment varies as sine law with arc length. The basic arc segment is shortened significantly so that the length of bending and straightening area can be extended and the time of creep behavior can be increased. The distance from solidifying front in the slab was calculated at 1200°C by finite element method. The maximum strain rate of new casting curve at different locations inside the slab is 6.39×10-5 s-1 during the bending segment and it tends to be 3.70×10-5 s-1 in the straightening segment. The minimum creep strain rate is 7.45×10-5 s-1 when the stress is 14 MPa at 1200°C. The strain rate of new casting machine can be less than the minimum creep strain rate. Thus, there is only creep deformation and no plastic deformation in the bending and straightening process of steel continuous casting. Deformation of slabs depending on creep behavior only comes true. It is helpful for the design of the new casting machine and improvement of old casting machine depending on high temperature creep property.
  • Qian-qian Ren,,Yu-zhu Zhang,,*,Yue Long,Shao-sheng Chen,Zong-shu Zou,Jie Li, Chen-guang Xu
    中国钢铁期刊网. 2017, 24(6): 601-607.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Blast furnace (BF) slag is a by-product of the ironmaking process and could be utilized to manufacture slag fiber by adding iron ore tailing. The crystallization behavior of the modified BF slag is significant to the fibrosis process. To investigate the influence of basicity on the crystallization behavior, BF slag was modified by adding iron ore tailing at room temperature and melted at 1500°C. FactSage simulation, X-ray diffraction, scanning electron microscopy backscattered electron imaging coupled to an energy dispersive spectrometer, and hot thermocouple technique analysis were performed to explore the crystallization behavior of the modified BF slag during the cooling process. It was found that the initial crystallization temperature increased with the increase in basicity. Melilite, anorthite, clinopyroxene, and wollastonite could be generated during the cooling process as basicity ranged from 0.7 to 0.9. Spinel could be found as one of the phases; however, wollastonite disappeared under a basicity of 1.0. The initial crystallization temperature was controlled by the crystallization of melilite during the cooling process when the basicity of the modified BF slag ranged from 0.7 to 1.0. Moreover, the cooling rate could also influence the crystallization of the modified BF slag.
  • Xue-feng She,*,Xiu-wei An,Jing-song Wang,Qing-guo Xue,Ling-tan Kong
    中国钢铁期刊网. 2017, 24(6): 608-616.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Aiming at the current characteristics of blast furnace (BF) process, carbon saving potential of blast furnace was investigated from the perspective of the relationship between degree of direct reduction and carbon consumption. A new relationship chart between carbon consumption and degree of direct reduction, which can reflect more real situation of blast furnace operation, was established. Furthermore, the carbon saving potential of hydrogen-rich oxygen blast furnace (OBF) process was analyzed. Then, the policy implications based on this relationship chart established were suggested. On this basis, the method of improving the carbon saving potential of blast furnace was recycling the top gas with removal of CO2 and H2O or increasing hydrogen in BF gas and full oxygen blast. The results show that the carbon saving potential in traditional blast furnace (TBF) is only 38-56 kg·t-1 while that in OBF is 138 kg·t-1. Theoretically, the lowest carbon consumption of OBF is 261 kg·t-1 and the corresponding degree of direct reduction is 0.04. In addition, the theoretical lowest carbon consumption of hydrogen-rich OBF is 257 kg·t-1. The modeling analysis can be used to estimate the carbon savings potential in new ironmaking process and its related CO2 emissions.
  • Bang-fu Huang,,*,Nai-yuan Tian,Zhe Shi,,Zhi-wei Ma,
    中国钢铁期刊网. 2017, 24(6): 617-624.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The models and influencing factors of steel ladles exchange during the steelmaking and continuous casting process of H steel plant were investigated. Based on analysis of the operation process and turnover time of steel ladles, relationship models for the turnover number, turnover rate, continuous casting number, number of ladles with additional turnover, and number of ladles without additional turnover were built. The turnover rules of steel ladles for one basic oxygen furnace (BOF) matching one continuous caster (CC) and two BOFs matching two CCs modes were simulated by using a Gantt chart. The models of steel ladle exchange were proposed for casting of a single CC and overlapping casting of two CCs. By analyzing the influencing factors, the following conclusions were drawn. The exchange ladle should not have the task of transporting liquid steel in the CC that stops casting earlier. The end time of the empty ladle in the CC that stops casting earlier should be earlier than the start time of the full ladle in the CC that stops casting later. After evaluating the factors influencing the start casting time, turnover cycle, casting time, continuous casting number, and overlapping time, a prioritization scheme of steel ladle exchange was proposed based on the steel grade. First, the turnover cycle and single heat casting time were determined; based on these, a reasonable ladle turnover number was calculated. Second, the turnover number and continuous casting number were optimized for maximizing the number of ladles without additional turnover. Lastly, to reduce the casting number during the overlapping time to be lower than the turnover number, the overlapping time was shortened.
  • Zhao-xia Shi,,*,Xiao-feng Yan,Chun-hua Duan,Jin-gui Song,Ming-han Zhao,Jue Wang
    中国钢铁期刊网. 2017, 24(6): 625-633.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    The hot deformation behavior of GH4945 superalloy was investigated by isothermal compression test in the temperature range of 1000-1200°C with strain rates of 0.001-10.000 s-1 to a total strain of 0.7. Dynamic recrystallization is the primary softening mechanism for GH4945 superalloy during hot deformation. The constitutive equation is established, and the calculated apparent activation energy is 458.446 kJ/mol. The processing maps at true strains of 0.2, 0.4 and 0.6 are generally similar, demonstrating that strain has little influence on processing map. The power dissipation efficiency and instability factors are remarkably influenced by deformation temperature and strain rate. The optimal hot working conditions are determined in temperature range of 1082-1131°C with strain rates of 0.004-0.018 s-1. Another domain of 1134-1150°C and 0.018-0.213 s-1 can also be selected as the optimal hot working conditions. The initial grains are replaced by dynamically recrystallized ones in optimal domains. The unsafe domains locate in the zone with strain rates above 0.274 s-1, mainly characterized by uneven microstructure. Hot working is not recommended in the unsafe domains.
  • Shu-lin Tan,Kun Yang,,Ya-nan Ding,Xian-hong Han,,*
    中国钢铁期刊网. 2017, 24(6): 634-640.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Hot stamping has been widely used in car industry to produce safety components. Most existing researches focused on the stamping and quenching process, but less on the mechanical properties of stamped parts. The fracture behaviors of hot stamped boron steel B1500HS have been studied, and other four commonly used sheet metals with different strengths, including Q235, TRIP780, QP980 and MS1300, were also introduced for comparison. Both uniaxial tests and mechanical trimming tests were performed, and the fracture surfaces under different stress states were observed and discussed. The SEM observations showed that the fracture models are closely related to the stress states, i.e., the tensile surfaces have ductile rupture characters while the trimming surfaces have brittle rupture characters. Compared with other steels, the quenched boron steel has smaller dimple size accompanied by shear planes in the tensile surface, and has smaller burnish zone in the trimming surface, and its cutting surface with ‘S’ like shape is also very different with others. Furthermore, two fitted empirical models were derived to describe the quantitative correlations between the average dimple diameter and the steel strength and between the percentage of burnish zone and the steel strength.
  • Wei-jun Hui,*,Na Xiao,Xiao-li Zhao,Yong-jian Zhang,Yu-feng Wu
    中国钢铁期刊网. 2017, 24(6): 641-648.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Dynamic continuous cooling transformation (CCT) behavior of medium-carbon forging steels microalloyed with different V contents up to 0.29% was investigated by means of dilatometric measurement, microstructural observation and hardness measurement. The results showed that the dynamic CCT diagrams were similar and the main difference was that the fields of the transformation products were shifted to the right side of the diagrams with the increase of V content, and this effect was more noticeable with an addition of 0.29% V. The Ac1 and Ac3 temperatures showed increasing trends with increasing V content, while the critical cooling rates decreased with increasing V content. The increase of V content resulted in significant increase of hardness and this tendency was enhanced with increasing cooling rate until the formation of acicular ferrite (AF). A promising approach of remarkably improving the toughness of ferritic-pearlitic medium-carbon forging steels with suitable V addition and the introduction of AF without notable penalty on its strength level was suggested.
  • Yong-xing Jiao,Jian-sheng Liu*,Xing-wang Duan,Xiao-hua Zheng,Wen-wu He
    中国钢铁期刊网. 2017, 24(6): 649-653.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    In order to determine the critical forging penetration efficiency (FPE) of 06Cr19Ni9NbN steel, a new model was presented to describe critical FPE, which is significant to optimize the steel forging process. The plane strain compression tests were conducted to obtain the model and confirm its validity. The results indicated that the dynamic recrystallization (DRX) volume fraction increases and the grain size decreases with the rise of reduction ratio. Meanwhile, the compression process was simulated by DEFORM software. The tensile tests were conducted and the results demonstrated that the mechanical properties gradually become stable when the reduction ratio increases to 30%, 34% and 40% at 1200, 1100 and 1000°C, respectively. The calculated results based on this new model are consistent with experimental results, indicating that the model is suitable to predict the critical FPE for the steel.
  • Ze-an Lv,,Hong-wei Ni,,*,Hua Zhang,,Cheng-song Liu,,**
    中国钢铁期刊网. 2017, 24(6): 654-660.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    Studies show that manganese sulfide (MnS) inclusions in pipeline steel affect the lateral performance of steel in its rolling deformation, as well as the hydrogen-induced cracking and sulfide stress corrosion cracking resistance performance. To inhibit the precipitation of MnS and its effect on pipeline steel, a quenching experiment and a diffusion couple experiment, which investigated the evolution of MnS inclusions in Ti-bearing X80 pipeline steel, were conducted. The experimental results show that the transformation of the MnS inclusions during solidification is as follows: MnS→titanium sulfide (TiS)→Ti4C2S2. The transition temperatures of MnS to TiS and TiS to Ti4C2S2 are 1673 and 1273 K, respectively, and the overall size of the sulfide decreased as well. Thermodynamic calculation results confirm that the transition temperatures of MnS to TiS and TiS to Ti4C2S2 are 1623 and 1203 K, respectively. When the sulfur content in the X80 pipeline steel is 0.0015%, all the sulfur in the steel can be converted into Ti4C2S2 with a titanium content of more than 0.02%.
  • Pei-sheng Liu*,Guang Cui,Yi-jiao Guo,Jing-he Chen,Zi-xuan Yang
    中国钢铁期刊网. 2017, 24(6): 661-667.
    摘要 ( ) PDF全文 ( )   可视化   收藏
    A sort of lightweight porous ceramic foam ball that can float on the water was recently made from the natural zeolite. The diameters of porous ball and its macroscopic pores are around 5 and 1 mm, respectively. Such ball surface could be modified to activate in different ways, i.e. loading the active alumina or desilicating the ball. Both of modified products have been investigated to adsorb the toxic ion of arsenic (As) in water effectively. This kind of porous ceramic ball was prepared by powder sintering, using natural clinoptilolite powder as the primary raw material. An active-alumina-loaded porous ceramic product was generated by sol-gel method with pseudoboehmite (AlOOH) as the main composition. The active Al atom on the porous ball surface could also be achieved by desilicating the ceramic ball in the NaOH solution. Such a desilicated product exhibited a good activity to adsorb the arsenic ion although carrying no active alumina. With this effective porous structure, the present products can be expected to become practically advantageous.