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2015年, 第22卷, 第9期 刊出日期:2015-09-15
  

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    Review
  • Yang-huan ZHANG,,Zhi-chao JIA,,Ze-ming YUAN,Tai YANG,Yan QI,Dong-liang ZHAO
    中国钢铁期刊网. 2015, 22(9): 757-770.
    摘要 ( )   可视化   收藏
    Hydrogen, as a secure, clean, efficient, and available energy source, will be successfully applied to reduce and eliminate greenhouse gas emissions. Hydrogen storage technology, which is one of the key challenges in developing hydrogen economy, will be solved through the unremitting efforts of scientists. The progress on hydrogen storage technology research and recent developments in hydrogen storage materials is reported. Commonly used storage methods, such as high-pressure gas or liquid, cannot satisfy future storage requirement. Hence, relatively advanced storage methods, such as the use of metal-organic framework hydrides and carbon materials, are being developed as promising alternatives. Combining chemical and physical hydrogen storage in certain materials has potential advantages among all storage methods. Intensive research has been conducted on metal hydrides to improve their electrochemical and gaseous hydrogen storage properties, including their hydrogen storage capacity, kinetics, cycle stability, pressure, and thermal response, which are dependent on the composition and structural feature of alloys. Efforts have been exerted on a group of magnesium-based hydrides, as promising candidates for competitive hydrogen storage, to decrease their desorption temperature and enhance their kinetics and cycle life. Further research is necessary to achieve the goal of practical application by adding an appropriate catalyst and through rapid quenching or ball milling. Improving the kinetics and cycle life of complex hydrides is also an important aspect for potential applications of hydrogen energy.
  • Metallurgy and Metal Working
  • Hong-ming LONG,Qing-min MENG,Ping WANG,Tie-jun CHUN,Yong-lin YAO
    中国钢铁期刊网. 2015, 22(9): 771-776.
    摘要 ( )   可视化   收藏
    Chromium slag (CS) has become one of the most hazardous solid waste containing chromium and iron. Based on its characteristics, the technology of reduction roasting and magnetic separation was employed to treat CS. The major impurity element of CS is magnesium and it exists in magnesium ferrite phase, which is hard to recover iron in the absence of additives. During reduction roasting, additives (Al2O3 and CaF2) could destroy the structure of magnesium ferrite and improve the iron grade and recovery. The final product, i.e. chromium-iron powder, contains 72.54% Fe and 13.56% Cr, with the iron recovery of 80.34% and chromium recovery of 80.70%.
  • Shui-xuan CHEN,Wei-gang LI,Xiang-hua LIU
    中国钢铁期刊网. 2015, 22(9): 777-784.
    摘要 ( )   可视化   收藏
    Considering the effect of work roll shifting on roll temperature field, a finite difference method of PR format for roll temperature field was presented, which can meet the requirements of accuracy and speed of online calculation. The step-by-step accumulation method was used to simulate the roll temperature field and thermal crown, and the evolution of roll thermal crown in a rolling campaign was studied. And then, the effects of strip width, rolling rhythm and work roll shifting on roll thermal crown were analyzed. It is found that work roll shifting can disperse the thermal expansion of the roll body especially the edge to make roll thermal contour uniform. The effect of work roll shifting on roll thermal crown is mainly concentrated in regions around twice of roll shifting stroke, and the change range of roll thermal crown is ±30 μm or so in the same roll body location.
  • Yong MA,Cheng PENG,Wei GUI,Fang-yin WANG
    中国钢铁期刊网. 2015, 22(9): 785-794.
    摘要 ( )   可视化   收藏
    The mould friction is an important parameter reflecting the initial shell and mould lubrication conditions. The research of mould friction is very important to the optimization and developing of continuous casting. The measured mould friction under hydraulic oscillation mode was researched with wavelet analysis to reveal its time-frequency characteristics. Firstly, the mould friction signals under different production conditions were monitored and the mould friction was calculated. Then, mother wavelet function was selected from three wavelet functions which were chosen preliminary according to the characteristics of mould friction and wavelet theory. Through wavelet transformation, mould friction signal was projected onto the wavelet domain, and the time-frequency characteristics of mould friction under different production conditions were obtained and discussed. Mould friction under different production conditions such as different oscillation mode, casting speed fluctuation, increasing and decreasing stage of casting speed and breakout occurrence was reported in detail in the wavelet time-frequency maps. The characteristics of mould friction were reflected well through wavelet transformation which proved that wavelet analysis had a good feasibility for mould friction study and can further reveal the nature of mould friction.
  • Yu-jiao ZENG,Yan-guang SUN
    中国钢铁期刊网. 2015, 22(9): 795-803.
    摘要 ( )   可视化   收藏
    A generalized formulation for short-term scheduling of steam power system in iron and steel industry under the time-of-use (TOU) power price was presented, with minimization of total operational cost including fuel cost, equipment maintenance cost and the charge of exchange power with main grid. The model took into account the varying nature of surplus byproduct gas flows, several practical technical constraints and the impact of TOU power price. All major types of utility equipments, involving boilers, steam turbines, combined heat and power (CHP) units, and waste heat and energy recovery generators (WHERG), were separately modeled using thermodynamic balance equations and regression method. In order to solve this complex nonlinear optimization model, a new improved particle swarm optimization (IPSO) algorithm was proposed by incorporating time-variant parameters, a self-adaptive mutation scheme and efficient constraint handling strategies. Finally, a case study for a real industrial example was used for illustrating the model and validating the effectiveness of the proposed approach.
  • Ying XU,Yao-guang WU,Cai-jun ZHANG,Li-guang ZHU
    中国钢铁期刊网. 2015, 22(9): 804-811.
    摘要 ( )   可视化   收藏
    The formation and growth behavior of inclusions in the liquid steel were studied based on 45 steel by virtue of high temperature confocal laser scanning microscope. The structures of all kinds of complex inclusions formed in the process of cooling and solidification of liquid steel were analyzed, and disregistries between various inclusions were calculated. The results showed that inclusions with high melting point precipitated firstly, and inclusions with low disregistries precipitated later. The latter precipitated and grew up on the surface of the former, and finally clear layered complex inclusions formed. The low disregistry mechanism could not fully explain the forming reasons of all complex inclusions, but no matter which kind of mechanism leading to the formation of complex inclusions, its basic principle is that the first precipitated phase provides a low nuclear power interface for the latter, which can reduce the nucleation interface and strain energy barrier of the latter.
  • Guo-qing LIU,Qing-cai LIU,Xiao-qing WANG,Fei MENG,Shan REN,Zhen-peng JI
    中国钢铁期刊网. 2015, 22(9): 812-817.
    摘要 ( )   可视化   收藏
    The combustion characteristics and kinetics of anthracite, pine sawdust and their blends were investigated under combustion condition by thermogravimetric analysis, respectively. The fractions of pine sawdust in the blended samples were set to be 30%, 50%, and 80%. The results showed that the ignition and burnout temperatures of pine sawdust were lower and the maximum combustion rate was higher than those of anthracite. With the increase of pine sawdust content, the ignition temperature and burnout temperature of the blends decreased, while the maximum mass loss rate and the combustible index of the blends increased; that is, the comprehensive combustion property became better. The kinetic parameters for the blends combustion under air condition were calculated based on experimental results using Coats-Redfern model. When the pine sawdust content varied in the range of 30%-80%, the combustion processes of these blends could be divided into two stages and the combustion reactions belong to the first-order reaction. The values of apparent activation energy at two individual stages decreased from 68.78 to 47.28 kJ·mol-1 and from 113.53 to 46.43 kJ·mol-1, respectively.
  • Material
  • Zhi-yu GAO,,Tao PAN,Zhuo WANG,Guo-quan LIU,,5,Hang SU
    中国钢铁期刊网. 2015, 22(9): 818-826.
    摘要 ( )   可视化   收藏
    Hot deformation behavior of a novel Ni-Cr-Mo-B heavy plate steel was studied by hot compression tests, which were conducted on a Gleeble-3800 thermo-mechanical simulator corresponding to the temperature range of 850-1 150 ℃ with the strain rates of 0.01-10 s-1 and the true strain of 0.8. The results suggest that the majority of flow curves exhibit a typical dynamic recrystallization (DRX) behavior with an apparent single peak stress followed by a gradual fall towards a steady-state stress. Important characteristic parameters of flow behavior as critical stress/strain for initiation of DRX and peak and steady-state stress/strain were derived from curves of strain hardening rate versus stress and stress versus strain, respectively. Material constants of the investigated steel were determined based on Arrhenius-type constitutive equation, and then the peak stress was predicted by the equation with the hot deformation activation energy of 379 139 J/mol, and the predicted values agree well with the experimental values. Furthermore, the effect of Zener-Hollomon parameter on the characteristic points of flow curves was studied using the power law relation, and the ratio of critical stress and strain to peak stress and strain were found to be 0.91 and 0.46, respectively.
  • Fei GAO,Fu-xiao YU,Hai-tao LIU,Zhen-yu LIU
    中国钢铁期刊网. 2015, 22(9): 827-836.
    摘要 ( )   可视化   收藏
    The hot deformation behavior of ultra purified 17% Cr ferritic stainless steel stabilized with Nb and Ti was investigated using axisymmetric hot compression tests on a thermomechanical simulator. The deformation was carried out at the temperatures ranging from 700 to 1 100 ℃ and strain rates from 1 to 10 s-1. The microstructure was investigated using electron backscattering diffraction. The effects of temperature and strain rate on deformation behavior were represented by Zener-Hollomon parameter in an exponent type equation. The effect of strain was incorporated in the constitutive equation by establishing polynomial relationship between the material constants and strain. A sixth order polynomial was suitable to represent the effect of strain. The modified constitutive equation considering the effect of strain was developed and could predict the flow stress throughout the deformation conditions except at 800 ℃ in 1 s-1 and at 700 ℃ in 5 and 10 s-1. Losing the reliability of the modified constitutive equation was possibly ascribed to the increase in average Taylor factor at 800 ℃ in 1 s-1 and the increase in temperature at 700 ℃ in 5 and 10 s-1 during hot deformation. The optimum window for improving product quality of the ferritic stainless steels was identified as hot rolling at a low finisher entry temperature of 700 ℃, which can be achieved in practical production.
  • Jia-yong SI,,Xiao-hang LIAO, Li-qiang XIE,Kai-rui LIN
    中国钢铁期刊网. 2015, 22(9): 837-846.
    摘要 ( )   可视化   收藏
    The flow behavior of delta-processed Inconel 718 was studied in temperature range of 900-1 060 ℃ and strain rate range of 0.001-0.5 s-1. The effects of friction and temperature on the compressive deformation behavior were investigated, and the flow stress-strain error caused by friction was revised. The results showed that the effect of the friction was obvious with increasing strain rate and decreasing deformation temperature. The revised flow stress is decreased by increasing temperature and decreasing strain rate and exhibits a typical dynamic recrystallization behavior. The constitutive model has been developed through a hyperbolic-sine Arrhenius type equation to relate the flow stress, strain rate and temperature. The influence of strain has also been incorporated by considering the variation of material constants as a function of strain. The prediction accuracy of developed constitutive model has been assessed using standard statistical formulae. According to the analysis results, the proposed deformation constitutive equation gives an accurate and precise estimate of flow stress of delta-processed Inconel 718 alloy.
  • Kun LING,Zheng-dong WANG,Fu-zhen XUAN
    中国钢铁期刊网. 2015, 22(9): 846-851.
    摘要 ( )   可视化   收藏
    An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone (HAZ). The fracture parameters J and C* are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS. A middle crack tension (M(T)) specimen is utilized in the analysis for different material properties and geometries of the weldment. The influence of mechanical property and geometry on the fracture parameters J and C* of the specimen is discussed for the welded joints with HAZ crack. The results suggest that the HAZ property is a significant factor in the estimation of J and C* for the mismatched welded joint with HAZ crack.
  • Jing QIN ,Ping YANG,Wei-min MAO, ,Feng YE
    中国钢铁期刊网. 2015, 22(9): 852-857.
    摘要 ( )   可视化   收藏
    The 0.2-0.3 mm thick cold-rolled sheets and annealed sheets of high silicon steel were produced by rolling process, then punching tests were carried out at room temperature to 150 ℃. The punchability and punching fracture behavior were investigated by means of scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). It is found that cold-rolled sheets of high silicon steel show good punchability under the condition of 0.01 mm punch-die clearance and at the temperature of 100 ℃; the punchability of annealed sheets with fine grain size is better than that of annealed sheets with coarse grain size; the punching temperature of 150 ℃ is suitable for annealed high silicon steel sheets especially with coarse grain size on account of punching edge quality. The major cleavage planes of annealed high silicon steel sheets are {100} crystallographic planes on which brittle fracture occurs at low temperatures. The cleavage systems include {100}<110> and {100}<100>, and cleavage fracture is completed by one or both of them. The punchability of high silicon steel sheets is related with punching temperature, grain size and ordering degree. Reducing ordering degree, increasing punching temperature, as well as refining grain size can improve the ductility and punchability of high silicon steel sheets.
  • Jia JU,Feng XUE,Hong LI
    中国钢铁期刊网. 2015, 22(9): 858-863.
    摘要 ( )   可视化   收藏
    The influence of rare earth element Dy on martensitic transformation and magnetic properties of Co-Ni-Al alloy was studied. The results showed that the microstructure of the sample has a dual-phase structure (γ-phase and martensite). The rare earth element Dy was segregated in Co-rich γ-phase and took the place of Co after its addition into the Co-Ni-Al alloy. As Dy content increased to over 0.5 at.%, the grain was refined and the rare earth intermetallic compounds Co5Dy were precipitated in γ-phase. Meanwhile, one-step thermo-elastic martensitic transformation occurred in the sample, wherein the phase transformation temperature significantly increased with rising Dy content. The martensite had a tetragonal L10 structure with a (111) twinning plane. Furthermore, the sample exhibited obvious hysteresis behaviors in the magnetic hysteresis loops. In addition, the saturation magnetization, coercivity, retentivity and magnetocrystalline anisotropy were significantly enhanced owing to the bigger radius of Dy which took the place of Co in the alloy.
  • Xin-ning ZHANG,Ying-dong QU,Rong-de LI
    中国钢铁期刊网. 2015, 22(9): 864-869.
    摘要 ( )   可视化   收藏
    The impact toughness of EN-GJS-400-18-LT ductile iron was measured by Charpy V-notch impact test at temperature between -80 and 20 ℃. The fracture properties were tested under instrumented impact loading. Total impact fracture energy, crack initiation and propagation energy, dynamic loads and the ductile to brittle temperature were measured. Three-dimensional reconstruction of impact fracture morphology was accomplished by confocal laser scanning microscope. The results of quantitative fractography indicate that cleavage fracture produces flatter fracture surfaces accompanying with less absorbed energy during the impact fracture process. It indicates that fracture roughness has a close relationship with crack propagation energy at low temperature.
  • M.A.MORADPOUR,S.H.HASHEMI,K.KHALILI
    中国钢铁期刊网. 2015, 22(9): 870-878.
    摘要 ( )   可视化   收藏
    Submerged arc welding (SAW) is one of the main welding processes with high deposition rate and high welding quality. This welding method is extensively used in welding large-diameter gas transmission pipelines and high-pressure vessels. In welding of such structures, the selection process parameters has great influence on the weld bead geometry and consequently affects the weld quality. Based on Fuzzy logic and NSGA-II (Non-dominated Sorting Genetic Algorithm-II)algorithm,a new approach was proposed for weld bead geometry prediction and for process parameters optimization. First, different welding parameters including welding voltage, current and speed were set to perform SAW under different conditions on API X65 steel plates. Next, the designed Fuzzy model was used for predicting the weld bead geometry and modeling of the process. The obtained mean percentage error of penetration depth, weld bead width and height from the proposed Fuzzy model was 6.06%, 6.40% and 5.82%, respectively. The process parameters were then optimized to achieve the desired values of convexity and penetration indexes simultaneously using NSGA-II algorithm. As a result, a set of optimum vectors (each vector contains current, voltage and speed within their selected experimental domains) was presented for desirable values of convexity and penetration indexes in the ranges of (0.106, 0.168) and (0.354, 0.561) respectively, which was more applicable in real conditions.