2019年, 第26卷, 第1期　刊出日期：2019-01-25

  

• 全选
  |

• Select
  Cavity formation in cross-wedge rolling processes

  Zbigniew Pater, Janusz Tomczak, Tomasz Bulzak

  钢铁研究学报(英文版). 2019, 26(1): 1-10.
  https://doi.org/http://doi.org/10.1007/s42243-018-0075-6

  摘要 ( )   可视化   收藏

  The problem of end-face cavity formation in parts produced by cross-wedge rolling was studied in order to reduce material consumption. The cavity depth was measured by the displacement method. Twenty-one different cases of rolling were analysed by finite element method to determine the effects of process parameters such as the wedge tool angle, the temperature of material, the tool velocity and the reduction ratio on the depth of end-face cavities. Relationships between these parameters are examined in order to establish dependencies enabling quick and simple selection of a concavity allowance in order to remove the cavities. The equations for calculating the concavity allowance were verified in an experimental process for manufacturing ball pins with the use of flat tools. Rolling tests were performed using a billet with its length selected in compliance with the established dependencies. The experimental results demonstrate that the proposed solution is a viable method for end-face cavity removal.
• Select
  Mechanisms of ultrafine particle formation during coal combustion in a new swirl modification device

  Jun-xiang Guo, Ling-ling Zhang, Wen-bin Dai, Li-ying Qi, Ru-fei Wei, Da-qiang Cang

  钢铁研究学报(英文版). 2019, 26(1): 11-19.
  https://doi.org/http://doi.org/10.1007/s42243-018-0190-4

  摘要 ( )   可视化   收藏

  A new swirl combustion device was designed and enhanced, which realized the utilization of steel slag, achieved highly efficient and clean coal combustion, and simultaneously realized a fully elemental utilization of coal. The distribution laws of different sized particulate matter (PM) emission and the enrichment laws of elements in particles under diverse conditions (such as various excess air coefficients and different coal ratios) were systematically studied. The enrichments of PM under both non-staged and fuel-staged conditions were also investigated. The results indicated that fuel-staged combustion is more helpful in reducing PM emissions than non-staged combustion, and a suitable coal ratio is also beneficial for reducing PM emissions. The melted liquid steel slag drop captured the fly ash produced from pulverized combustion, thus reducing PM emission. The alkali metal elements (K, Na, and Mg), the trace elements (As and Ti), and S have an obvious enrichment tendency in PM1 and PM2.5. A different coal ratio under fuel-staged combustion has a significant influence on the enrichment of Al, Si, Ca, and Fe in PM1, whereas in PM2.5, PM4, and PM10, the effect of different coal ratios on the enrichment of each element is slight.
• Select
  Aluminum, titanium and oxygen control during electroslag remelting of stainless steel based on thermodynamic analysis

  Dong Hou, Zhou-hua Jiang, Tian-peng Qu, De-yong Wang, Fu-bin Liu, Hua-bing Li

  钢铁研究学报(英文版). 2019, 26(1): 20-31.
  https://doi.org/http://doi.org/10.1007/s42243-018-0107-2

  摘要 ( )   可视化   收藏

  Experimental investigation and thermodynamic calculation were carried out to study the effect of slag on alloying elements during electroslag remelting with developing a thermodynamic model to control titanium and aluminum in ingot. The thermodynamic model based on ion and molecule coexistence theory and conservation law of element atoms was established to analyze the change in aluminum and titanium along the height of ingot. The results show that low CaO slag is suitable for electroslag remelting of metal containing high titanium-to-aluminum ratio. As electroslag remelting process consists of slag temperature-rising and temperature-stable periods, TiO2 should be added into water-cooled copper mold during temperature-rising period in order to keep the thermodynamic equilibrium between titanium and aluminum, and the amount of TiO2 is the difference value calculated by the reaction between titanium and alumina at 1477 and 1677 C.
• Select
  In situ observation of iron ore particle reduction above 1373 K by confocal microscopy

  Lei Guo, Jin-tao Gao, Sheng-ping Zhong, Qi-peng Bao, Zhan-cheng Guo

  钢铁研究学报(英文版). 2019, 26(1): 32-41.
  https://doi.org/http://doi.org/10.1007/s42243-018-0078-3

  摘要 ( )   可视化   收藏

  The reduction behavior of single iron ore particle was investigated at high temperatures (above 1373 K) with CO/CO2 mixture. A high-temperature laser scanning confocal microscope for in situ observation and a vertical quenching furnace for offline characterization were designed. The reduction process of ore particles at different temperatures and in different atmospheres was videoed using the confocal microscope. In the temperature range studied, the transformation of Fe2O3– FeO firstly occurred in the ore particles, and there was no metallic iron until the ore particles completely converted to FeO phase. During the formation of FeO phase, its crystal lattice transforms along the most close-packed direction of its closepacked plane (111). The gangue-rich area firstly melts during reduction around 1573 K. Above 1673 K, the iron ore particles melt and form spherical liquid drops with metallic iron in the center. The gas-based reduction behavior of iron ore particles above 1373 K is deduced and graphically presented.
• Select
  Effect of high Na2O addition on distribution of phosphorus in low-basicity converter slag

  Chang Su, Ning-ning Lv, Jin-xing Yang, Liu-shun Wu, Hai-chuan Wang, Yuan-chi Dong,

  钢铁研究学报(英文版). 2019, 26(1): 42-51.
  https://doi.org/http://doi.org/10.1007/s42243-018-0096-1

  摘要 ( )   可视化   收藏

  In order to improve the dephosphorization efficiency of low-basicity converter slag and decrease the consumption of solid CaO, the effect of high Na2O addition (0–15 mass%) on the distribution of P2O5 between solid solution and matrix phase was investigated. The thermodynamic properties of slag samples were calculated by FactSage 7.0 software. Then, the dissolution behavior of phosphorus element from slag was studied. The results show that the mass fraction of 2CaO SiO2– 2CaO Na2O P2O5 solid solution increases when the Na2O content is increased in slag. However, the amount of formed solid solution changes little when the Na2O addition is more than 10 mass%. Moreover, the content of Na2O in solid solution would reach saturation when adding 15 mass% Na2O into the slag. With the increase in Na2O content in slag, the distribution ratio of P2O5 between solid solution and matrix phase increases. The values are evidently higher than the results reported in the literature. Meanwhile, the activity of P2O5 in matrix phase and the activity coefficient of P2O5 in solid solution are decreased with increasing the Na2O content in slag. Furthermore, the dissolution ratio of phosphorus in citric acid solution could be improved by adding Na2O into slag, but the increment of dissolution ratio would decrease when the Na2O content exceeds 10 mass% in slag.
• Select
  Effect of shot peening on microstructure, nanocrystallization and microhardness of Ti–10V–2Fe–3Al alloy surface

  Hai-zhong Zheng, Sheng-hua Guo, Qin-hao Luo, Xiao-yong Shu, Gui-fa Li

  钢铁研究学报(英文版). 2019, 26(1): 52-58.
  https://doi.org/http://doi.org/10.1007/s42243-018-0206-0

  摘要 ( )   可视化   收藏

  Severe plastic deformation of Ti–10V–2Fe–3Al alloy in the surface region was caused by shot peening at air pressure of 0.6 MPa with processing time ranging from 1 to 45 min. The results showed that the thickness of surface deformation layer was proportional to the processing time, the microhardness of the shot-peened surface increased from 280 to 385 HV, and the depth of highly hardening layers arrived at 200 lm. It was worth noting that a grain size gradient from nanocrystalline on the surface toward coarse grain in the matrix was obtained during the shot peening process and the minimum grain size in the top surface after shot peening was about 100–200 nm.
• Select
  Structure and electrochemical performances of as-milled LaMg12-type alloy–Ni composites

  Wen-gang Bu, Wei Zhang, Jin-liang Gao, Yan Qi, Dong-liang Zhao, Xiao-ping Dong, Yang-huan Zhang

  钢铁研究学报(英文版). 2019, 26(1): 59-68.
  https://doi.org/http://doi.org/10.1007/s42243-018-0208-y

  摘要 ( )   可视化   收藏

  LaMg11Ni1 x wt.% Ni (x = 100, 200) alloys were prepared by ball milling and researched by various methods to study their structure and electrochemical hydrogen storage property. The outcomes reveal that increasing Ni content contributes to improving its electrochemical performance. Particularly, the discharge capacity of as-milled (40 h) alloy will be increased from 157.3 to 1053.5 mAh/g through enhancing Ni percentage from 100 to 200 wt.% when discharging at 60 mAh/g. Ball milling obviously affects the electrochemical performance of alloys. With milling duration prolonging, the discharge capacity of x = 100 alloy keeps increasing, while that of the x = 200 alloy has a maximum value. Milling time also affects the cycle stability of experimental alloys. Extending milling duration clearly decreases the cycle stability of x = 100 alloy but weakens that of the x = 200 alloy at first and strengthens it later. In addition, prolonging milling time makes the milling prepared x = 100 and 200 alloys get the maximal values of high rate discharge ability of 81.60% and 84.52%, respectively.
• Select
  Effect of simulated thermomechanical processing on transformation behavior and microstructure of 82B steel

  He Wei, Yin-li Chen, Lan Su, Di Tang

  钢铁研究学报(英文版). 2019, 26(1): 69-77.
  https://doi.org/http://doi.org/10.1007/s42243-018-0209-x

  摘要 ( )   可视化   收藏

  The effects of loop-laying temperature and austenite deformation on the phase transformation behavior during continuous cooling, microstructure, and pearlite interlaminar spacing in 82B steels were investigated. Static and dynamic continuous cooling transformation (CCT) diagrams were measured with a Gleeble-3500 thermal simulator, and the mechanisms governing changes in the initial temperature, initial time, and duration of the phase transformation zone were also analyzed and discussed. The results show that CCT diagram shifted to the bottom right, the initial temperature of the phase transition decreased, the initial time of the phase transition increased, the duration of the phase transition increased, and the lamellar spacing of pearlite was finer as the loop-laying temperature increased. The initial phase transition time decreased, and the phase transition duration first reduced, then increased, and finally decreased in the static condition and in the dynamic condition at 850 C as the cooling rate increased. Meanwhile, the phase transition duration continuously decreased in the dynamic condition at 900 C. At a given loop-laying temperature, the lamellar spacing in pearlite was finer due to austenite deformation compared with the undeformed case. Compared with the results shown in the dynamic CCT diagram, the corresponding phase diagrams of the static CCT diagram slightly shifted to the bottom right. Moreover, there was a clear linear relationship between the reciprocal of the lamellar spacing in pearlite and the average undercooling degree in the phase transformation zone.
• Select
  Effect of trace Ce on high-temperature oxidation behavior of an Al–Si-coated Ni-based single crystal

  Xiao-juan Pang, Shu-suo Li, Lu Qin, Yan-ling Pei, Sheng-kai Gong

  钢铁研究学报(英文版). 2019, 26(1): 78-73.
  https://doi.org/http://doi.org/10.1007/s42243-018-0214-0

  摘要 ( )   可视化   收藏

  Ni-based single crystal superalloy IC21 with different Ce contents was prepared by screw selection method, and Al–Si coatings were prepared by pack cementation. Cyclic oxidation and transient oxidation were carried out at 1150 C to investigate the effect of Ce on the high-temperature oxidation behavior of Al–Si coatings. After cyclic oxidation at 1150 C, the addition of trace Ce decreased the mass gain of the Al–Si-coated samples and effectively improved oxidation performance and spallation resistance. In specimens without Ce doping, microstructure examination revealed that bulky c0- Ni3Al precipitated in oxidized coating because of high Al consumption, and this finding suggests that Ce inhibits the consumption of Al in the coating during oxidation. Ce slows down the transformation of h-Al2O3 to a-Al2O3 and improves the adhesion of the oxide scale.
• Select
  Influence of N/C ratio on microstructure and properties of new high-strength weathering steels

  Jian Cheng, Yue-hua Guo, Ming Liu, Hou-fa Shen

  钢铁研究学报(英文版). 2019, 26(1): 84-90.
  https://doi.org/http://doi.org/10.1007/s42243-018-0217-x

  摘要 ( )   可视化   收藏

  Influence of the N/C ratio on the microstructure and properties of new-generation high-strength weathering steels was investigated using calculation of phase diagram (CALPHAD) and experiments. The microstructures of weathering steels containing different N/C ratios were predicted by a CALPHAD approach, and only three phases were predicted in these steels within the rolling temperature range of 850–1050 C. The precipitation fraction of VN/V(C, N) increases with increasing N/C ratio. Microstructures of the four tested steels were all experimentally determined to contain bainite, ferrite, and VN precipitates after air cooling to room temperature. The bainite fraction increases with increasing N/C ratio, and it is 85% in the steel containing 0.038% N and 0.032% C. The results of the tensile tests and impact tests demonstrated that the yield strength and tensile strength of the steel containing 0.038% N and 0.032% C are greater than 550 and 650 MPa, respectively, and the elongation is greater than 24%, which satisfies the design objectives for mechanical properties. The impact toughness values of the four steels at 0, - 20, and - 40 C are all greater than 24 J. With increasing N/C ratio, the bainite fraction and the precipitation fraction of VN/V(C, N) increase, resulting in increasing yield strength and tensile strength.
• Select
  Experimental characterization of anisotropic tensile mechanical behavior of pure titanium tube

  Jin-biao Zhou, Peng-yan Sun, Chang-yu Zhou, Xiao-hua He

  钢铁研究学报(英文版). 2019, 26(1): 91-101.
  https://doi.org/http://doi.org/10.1007/s42243-018-0210-4

  摘要 ( )   可视化   收藏

  The anisotropic tensile mechanical properties of pure titanium (TA2) tubes were studied by means of theoretical analysis, finite element simulation and tensile tests. Based on the stress analysis of circumferential tensile of TA2 tube, an equation for calculating the tangential force of circumferential tensile specimen was established, and the relationship among tangential force, friction and position of ring specimen was analyzed. The finite element simulation analysis of circumferential tensile process of TA2 ring specimen was carried out, which verified the tangential force equation derived from theoretical analysis. The effect of gauge length and friction on necking and tensile load was analyzed, and the optimal gauge length was selected for the ring hoop tensile test. Finally, the axial and circumferential tensile digital image correlation experiments were carried out to verify the theoretical and finite element simulation results. The friction coefficient between TA2 tube and D-blocks (using Teflon lubricant) was determined by the inverse finite element method and the friction experiment, and the true stress–strain curve of TA2 tube was obtained. The results show that the axial and circumferential mechanical behaviors of TA2 tubes are significantly different and anisotropic.
• Select
  Microstructural features and precipitation behavior of Ti, Nb and V microalloyed steel during isothermal processing

  Qi Zhou, Zhuang Li, Zhan-shan Wei, Di Wu, Jin-yu Li, Zhen-yao Shao

  钢铁研究学报(英文版). 2019, 26(1): 102-111.
  https://doi.org/http://doi.org/10.1007/s42243-018-0215-z

  摘要 ( )   可视化   收藏

  Thermal simulations of Ti, Nb and V microalloyed steel were conducted using a thermomechanical simulator, and the microstructural evolution and the precipitation behavior during isothermal processing were analyzed. The results show that with increasing holding time, the microstructural constituents change from the martensite and bainitic ferrites to granular bainite and polygonal ferrite. The maximum hardness is obtained for the specimen after isothermal holding for 5 s due to the martensite strengthening effect. The hardness of the specimen decreases after isothermal holding for 10 s, because the strengthening contribution of fine dispersed precipitates becomes weaker. The hardness values of the specimens increase and then remain high after isothermal holding for 60 and 600 s. This is attributed to the contribution of the interphase precipitation hardening to the hardness of the studied steel. The precipitates in the specimen are coarsened after isothermal holding for 3600 s, even though the coarsening is not remarkable. These precipitates are fcc (Ti, Nb)(N, C) particles and belong to the MX-type precipitates. The beneficial effects of precipitation strengthening are lost. The hardness decreases to a minimum hardness value due to the presence of large amounts of polygonal ferrite after isothermal holding for 3600 s. Relatively coarse precipitates are the primary origin of the hardness decrease.