2011年, 第18卷, 第6期　刊出日期：2011-06-15

  

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工艺
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  Ability for SelfPelletization of Iron Ores and Magnetite Concentrates

  Francik Przemystaw,Jan Mróz

  中国钢铁期刊网. 2011, 18(6): 1-7.

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  A procedure for evaluating the susceptibility of raw materials for the process of sintering of ironore mixes is presented. The procedure relies on the evaluation of the amount and quality of the finest grain fraction. The method is based on determination of particular grain fractions. For the grain less than 015 mm, the determination of the amount is performed using an IPS (Infrared Particles Sizer) grain size analyzer and for the grain larger than 015 mm, the fraction is determined using the (wet and dry) screening methods. This allows for quantity assessment of the quality of material in terms of its susceptibility to selfpelletizing by calculating Total Ability for SelfPelletizing (TASP) index fT. The presented method, in combination with the grain size and chemical analyses, can serve for evaluation of suitability of raw material and mixes for the sintering process. Furthermore, the TASP index for 10 types of iron ores and concentrates was determined. The usability of the TASP index was verified by determination of its impact on yield of sintering process both in laboratory and in industry scale.
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  Analysis of VanadiumBearing Titanomagnetite Sintering Process by Dissection of Sintering Bed

  BAI Yongqiang,CHENG Shusen,BAI Yanming

  中国钢铁期刊网. 2011, 18(6): 8-15.

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  Many problems appear in the sintering process of vanadiumbearing titanomagnetite, such as high energy consumption and low productivity; sinter quality is also very poor for its low tumble strength and high reduction degradation. Sinter productivity and quality are dominated by bed permeability and mineralogy structure, which are highly influenced by the thermal state of sintering bed, so the sintering process of titanomagnetite is researched by bed dissection in this work. Temperature evolution curves of sinter materials were measured, and the results show that melting duration, peak temperature duration and sintering temperature of different layers differ greatly from each other; flame front speed and vertical sintering speed of bed lower region are much smaller than those of bed upper region. Simultaneously, sinter samples were collected from different layers, and their mineralogy characteristics are analyzed; sinters from bed lower region have poor mineralogy structure, and the amounts of perovskite and dicalcium silicate increase intensively, which are bad for sinter strength and reduction degradation property. Measures are proposed to improve the quality and productivity of titanomagnetite sinter.
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  Activity Model of FeSiB Ternary Metallic Melts

  ZHAO Dingguo,GUO Peimin,ZHAO Pei

  中国钢铁期刊网. 2011, 18(6): 16-21.

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  According to the ion and molecule coexistence theory, the activity model of FeSiB ternary system was established, and the influence of ratio xSi/xFe, boron content and temperature, etc on the activity of the melt compound was investigated. The results show that the FeB activity is high in the liquid iron, when xSi/xFe is 05; the activity of boron increases with increasing the boron content for different contents of xFe and xSi, and the activity of boron at the ratio xFe=04 is about one order of magnitude higher than that for the xFe=08; The activities of the melt compound were also affected by temperature, but the influencing extent was little. The equal activity diagrams of silicon and boron were drawn for the first time according to the model results.
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  Industrial Experiment of Reducing Superheat of Steel by Nozzle Cooling

  YAN Huicheng,,QIU Shengtao,,TONG Taiqin,CAI Yunteng,WANG Zhongying,ZHAO Pei

  中国钢铁期刊网. 2011, 18(6): 22-25.

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  Nozzle cooling equipment is developed to supervise and control the heat flux by changing water flux. An industrial experiment is held in billet caster in Huaigang . The results show that cooling control system works stably and effectively to control the heat fluxes by the temperature of copper tube. The superheat of steel in mould is reduced and the equiaxed crystal ratio, as well as compact degree of steel is raised.
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  CrossWedge Rolling of Shafts With an Eccentric Step

  Zbigniew Pater

  中国钢铁期刊网. 2011, 18(6): 26-30.

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  A new concept for forming eccentric shafts on the basis of the crosswedge rolling (CWR) process was presented. This concept was based on the application of special guides, which, by acting on a billet, lead to its controlled movement in the vertical direction. This movement made possible eccentric cutting of tools into the billet. FEM calculations and experimental rolling tests clearly confirmed the effectiveness of the proposed forming method.
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  Change in Carbon Dioxide (CO2) Emissions From Energy Use in China′s Iron and Steel Industry

  SUN Wenqiang,CAI Jiuju,MAO Hujun,GUAN Duojiao,

  中国钢铁期刊网. 2011, 18(6): 31-36.

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  As the largest energy consuming manufacturing sector and one of the most important sources of carbon dioxide (CO2) emissions, the China′s iron and steel industry has paid attention to the study of changing trend and influencing factors of CO2 emissions from energy use. The logarithmic mean Divisia index (LMDI) technique is used to decompose total change in CO2 emissions into four factors: emission factor effect, energy structure effect, energy consumption effect, and steel production effect. The results show that the steel production effect is the major factor which is responsible for the rise in CO2 emissions; whereas the energy consumption effect contributes most to the reduction in CO2 emissions. And the emission factor effect makes a weak negative contribution to the increase of CO2 emissions. To find out the detailed relationship between change in energy consumption or steel production and change in CO2 emissions, the correlation equations are also proposed.
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  Treatment of Reused Comprehensive Wastewater in Iron and Steel Industry With Electrosorption Technology

  ZHANG Yunhua,,GAN Fuxing,LI Meng,WANG Dihua,HUANG Zhongmai,GAO Yunpeng

  中国钢铁期刊网. 2011, 18(6): 37-72.

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  Electrosorption technology was used to treat the reused comprehensive wastewater from iron and steel industry. A problem of relatively high conductivity of wastewater which greatly affects the reuse was examined, and industrial test was conducted for the reused water advanced deionization and purification in a comprehensive wastewater treatment plant of WISCO [Wuhan Iron and Steel (Group) Corporation]. The results of the onsite industrial test showed a satisfactory treatment performance for the reused water even at a flow rate of 1000 L/h in a standard 500 L/h unit. The average conductivity decreased by about 70%, from 580-780 μS/cm to 100-350 μS/cm. The average removal efficiency of Cl- and Ca2+ was about 75% and 68%, respectively, and CODCr of the treated water was also reduced in some degree while the pH value was almost unchanged. The energy consumption was as low as 06 kWh/t, which was remarkably superior to the conventional technologies. Therefore, it is entirely feasible that the novel electrosorption technology can be used in enhanced desalination and purification treatment of reused comprehensive wastewater in iron and steel industry.
材料
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  Microstructure Evolving Behaviors of Undercooled Ultrafine Austenite Grains During Deformation

  YAO Shengjie,DU Linxiu,LI Guanglong,JIAO Xing,WANG Guodong

  中国钢铁期刊网. 2011, 18(6): 43-48.

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  Samples with ultrafine grained austenite were prepared by repetitive rapid heating and quenching for three times and were used to investigate the dynamic microstructural evolving behaviors at different temperatures. A simultaneous development of dynamic straininduced transformation (DSIT) and austenite grain growth was detected at the deformation temperatures above Ar3, while only DSIT happened as the deformation proceeded at lower temperatures close to and below Ar3. In addition, a reverse ferritetoaustenite transformation was also observed. Most of the straininduced ferrite nucleated on the boundaries of ultrafine prior austenite grains, especially at the corners and no evidence about intragranular nucleus was obviously obtained.
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  Effects of Niobium and Vanadium on HydrogenInduced Delayed Fracture in High Strength Spring Steel

  ZHANG Chaolei,LIU Yazheng,JIANG Chao,XIAO Jinfu

  中国钢铁期刊网. 2011, 18(6): 49-53.

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  Influence of vanadium and/or niobium additions on delayed fracture behavior in high strength spring steel was studied by hydrogen permeation method and slow strain rate technique (SSRT), and its mechanism was analyzed. The results show that apparent diffusion coefficient of hydrogen in microalloyed spring steels NbVsteel and Nbsteel is lower than that in nonmicroalloyed steel 60Si2MnA. Percentage of strength reduction in SSRT in air after precharged hydrogen of the microalloyed steels is smaller than that of 60Si2MnA. Addition of the microalloys changes the fracture characteristics. Thence, vanadium and/or niobium additions are a very effective and economy means to improve the hydrogeninduced delayed fracture resistance of high strength spring steel.
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  Simulation of Secondary Dendritic Arm Spacing of Free Cutting Steel 38MnVS

  XIA Yunjin,WANG Fuming,WANG Jinlong

  中国钢铁期刊网. 2011, 18(6): 54-60.

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  The secondary dendritic arm spacing (SDAS) of free cutting steel 38MnVS during continuous casting process was simulated based on a Mixed Lagrangian and Eulerian Method (MiLE Method) and SDAS model. The simulation results are basically in agreement with measured ones. The effect of composition, superheat and casting speed on SDAS are studied, and the relationship between SDAS and interdendritic segregation is discussed. The results show that SDAS increases with increasing carbon and silicon content, and decreases with increasing manganese and sulfur content. The increase of superheat and casting speed also makes SDAS increase. The permeability of columnar mushy zone which is parallel to the primary dendritic arms is calculated based on CarmanKozeny relationship, and the increase of SDAS makes the permeability increase, which exacerbates interdendritic segregation of columnar crystal zone.
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  Nonequilibrium Grain Boundary Segregation of Sulfur and Its Effect on Intergranular Corrosion for 304 Stainless Steel

  WANG Kai,XU Tingdong,SHAO Chong,YANG Chun

  中国钢铁期刊网. 2011, 18(6): 61-66.

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  The data obtained by bending tests for intergranular embrittlement after 45 h and 450 h exposure to Strauss solution have been reported for 304 stainless steel. The results show that an embrittlement peak appears at 650 ℃ for all samples quenched from 1260 ℃ and then sensitized for 150 h at 480, 565, 650, 730, 815 and 900 ℃ respectively. The temperature corresponding to the embrittlement peak is decreased to 565 ℃ when the sensitizing time is prolonged to 1500 h. In this paper, these data are analyzed with an isothermal kinetic model of nonequilibrium grain boundary segregation, indicating that the embrittlement peak is related to the critical time for nonequilibrium grain boundary segregation of sulfur.
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  Industrial Atmospheric Corrosion Resistance of PRE Weathering Steel

  MI Fengyi,,WANG Xiangdong,LIU Zhipu,WANG Bing, PENG Yun,TAO Dongping

  中国钢铁期刊网. 2011, 18(6): 67-73.

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  The corrosion behavior of lowcarbon steel (CS), Pbearing steel (PS) and PRE weathering steel (PREWS) exposed for two years in Jiangjin of China was investigated. The results showed that during 2year exposure test, corrosion data of the experimental steels followed the bilogarithmic equation, and the average corrosion depth of PS and PREWS was decreased by 195% and 282% respectively compared with that of CS. Scanning electron microscope, electrochemical impedance spectroscope and Fourier transform infrared spectroscope were used to characterize the corrosion products. The research results showed that P in steel could promote the formation of an amorphous ferric oxyhydroxide layer near the substrate. The addition of RE could effectively increase the charge transportation resistance of rust.
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  Thermal Expansion Behavior of Amorphous FeSiB Alloys

  SU Chao,NIU Yuchao,LI Haifeng,HUANG Guowei,WANG Xianzhong

  中国钢铁期刊网. 2011, 18(6): 74-78.

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  To study the thermal expansion of amorphous FeSiB alloys, the amorphous Fe78Si9B13 and Fe735Nb3 Cu1Si135B9 and their crystallized alloys were detected using thermal dilatometer. The results indicate that at the same temperature, the relative length change (ΔL/L0) values of the two Febased amorphous alloys decrease with increasing heating rate, but those of their crystallized alloys show an opposite trend. It is concluded that the effect of heating rate on the ΔL/L0 of amorphous and crystallized alloys is related to free volume and defects, respectively.