2010年, 第17卷, 第9期　刊出日期：2010-09-15

  

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工艺
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  Phosphorus Removal of High Phosphorus Iron Ore byGasBased Reduction and Melt Separation

  TANG Huiqing;GUO Zhancheng;ZHAO Zhilong

  中国钢铁期刊网. 2010, 17(9): 1-1.

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  Cold Simulation of Oxygen Transfer Rate in BOF

  WU Wei;YANG Libin;ZHENG Congjie;LIU Liu

  中国钢铁期刊网. 2010, 17(9): 7-13.

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  By measuring the mass transfer coefficient of between water and oil, the oxygen transfer rate of bath in the BOF smelting process is researched, and the influence of top and bottom blowing gas flow rate on the mechanism of mass transfer between metal and slag is discussed. The results show that when the bottom blowing gas flow rate increases on the conditions of top blowing, the mass transfer rate evidently increases, and the influence ratio of top blowing on the mass transfer is 10 percent of bottom blowing; The relation among top gas flow rate, bottom gas flow rate and lance height are established by the stirring power density. The equation between the mass transfer coefficient between metal and slag is formed, which furnishes reference for optimizing process parameters of BOF. The relation between the emulsification ratio between water and oil and the bottom blowing gas flow rate on the condition of top and bottom blowing is obtained. The result shows that with the increase of the bottom blowing gas flow rate the emulsification ratio increases in linearity, which increases the mass transfer rate of benzoic acid between water and oil.
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  Fluid Flow and Heat Transfer Modeling of AC ARC in Ferrosilicon Submerged-ARC Furnace

  M.Mohebi.Moghadam

  中国钢铁期刊网. 2010, 17(9): 14-18.

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  arc has been developed and used to predict heat transfer from the arc to the molten bath in ferrosilicon AC submerged-arc furnace. In this model the time-dependent conservation equations for mass, momentum and energy in the specified domain of plasma zone have been solved numerically coupled with the Maxwell and Laplace equations for magnetic filed and electric potential respectively. A control volume based finite difference method was used to solve the governing equations in cylindrical coordinates. The reliability of the developed model was tested by comparison with the data available in the literature. The present model showed a better consistency with the data given in the literature because of solving the Maxwell and Laplace equations simultaneously for calculation of current density. Parametric studies were carried out to evaluate the effect of electrical current and arc length on flow field and temperature distribution within the arc. According to computed results, a lower power input lead to the higher arc efficiency.
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  Intelligent OptimizationBased Production Planning and SimulationAnalysis for Steelmaking and Continuous Casting Process

  ZHU Dao fei;ZHENG Zhong;GAO Xiaoqiang

  中国钢铁期刊网. 2010, 17(9): 19-19.

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  Aiming at the limitations of the traditional mathematical model for production planning, a novel optimization model is proposed to improve the efficiency and performance for production planning in steelmaking and continuous casting (SCC) process. The optimization model combined with parallelbackward inferring algorithm and genetic algorithm is described. To analyze and evaluate the production plans, a simulation model based on cellular automata is presented. And then, the integrated system including the production plan optimization model and the simulation model is introduced to evaluate and adjust the production plan online. The test with production data in a steel plant shows that the optimization model demonstrates ability to deal with time uncertainty in production planning and to set up a conflictfree production plan, and the integrated system provides a useful tool for dynamically drawing and adjusting a production plan online. The average staying time of the production plan is about 5% shorter than that in a practical process.
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  Numerical Analysis of Electromagnetic Field and Flow Field in High Casting Speed Slab Continuous Casting Mold WithTraveling Magnetic Field

  WANG Hongdan;ZHU Miao yong;YU Haiqi

  中国钢铁期刊网. 2010, 17(9): 25-25.

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  A three-dimensional mathematical model for describing the electromagnetic field and flow field of molten steel in high casting speed slab continuous casting mold with electromagnetic level stabilizer (EMLS) system was developed, in which the effects of current intensity and frequency on the electromagnetic field and flow field were considered. Simulation results indicate that the electromagnetic force (EMF) along the mold width direction presents the centre-symmetric double-peak parabola distribution. The EMLS system leads to the flow velocity of molten steel decreases, especially near the free surface. Both the EMF increases with the current intensity and frequency (in the range of optimum frequency value), so the flow velocity of molten steel in the mold decreases obviously. As the current intensity increases from 800 A to 1000 A, the maximum free surface velocity decreases from 0.515 m/s without magnetic field to 0.155 m/s and 0.12 m/s, respectively. While the current frequency increases from 2 Hz to 6 Hz, the maximum surface velocity decreases from 0.177 m/s to 0.101m/s. The molten steel flow in mold is influenced obviously by the current intensity and frequency.
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  Control Model of Bloom Dynamic Soft Reduction

  CHEN Yong;JI Cheng;ZHU Miaoyong;WU Guorong

  中国钢铁期刊网. 2010, 17(9): 31-31.

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  There are significant effects of process parameters on internal qualities of bloom, and these process parameters are as follows: position and reduction amount, reduction distribution, reduction rate, and so on. Developing a control model is the key to apply soft reduction technology successfully. As the research object, 360 mm×450 mm bloom caster in PISCO (Panzhihua Iron and Steel Co) has been studied, and the research method for control model of dynamic soft reduction has been proposed. On the basis of solidification and heat transfer model, the position of soft reduction and reduction distribution of each frame are determined according to the bloom temperature distribution and solid fraction in bloom center calculated. Production practice shows that the ratio of center porosity which is less than or equal to 10, increased to 9727%, ratio of central segregation which is less than or equal to 05, increased to 8091%, and ratio of central carbon segregation index which is more than or equal to 110, decreased to 4% with the applying model of dynamic soft reduction.
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  A 3-D Differential Method for Solving Rolling Force of PC Hot Strip Mill

  WANG Xuesong;PENG Yan;XU Lipu;LIU Hongmin

  中国钢铁期刊网. 2010, 17(9): 36-36.

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  According to the character of the deformation zone on pair cross rolls, which is different from the regular 4-high mill, there are longitudinal and transverse two-way shear deformation in the deformation zone, the character of metal particles flowing velocity is more complicated than normal rolling. Comprehensive influences of normal stress and shear stress in rolling direction, width direction and thickness direction are considered. Establish the rolling force calculation model of PC hot strip mills. After the longitudinal and transverse discretization of deformation zone, the longitudinal and transverse distribution of rolling force is worked out by the differential method, then calculate total rolling force. Calculated results are verified by experimental data.
材料
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  Effect of Heat Treatment on Microstructure of Modified Cast AISI D3 Cold Work Tool Steel

  Shahram Kheirandish

  中国钢铁期刊网. 2010, 17(9): 40-45.

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  High chromium high carbon AISI D3 steel is used as cold-work tools and dies in industry. Microstructure of this wrought steel usually consists of chromium carbides homogenously dispersed in a ferritic or martensitic matrix. On the other hand, a eutectic network consisting of chromium carbide and austenite forms in a cast D3 steel, at the end of solidification due to the segregation of carbon and chromium. This heterogeneous microstructure gives rise to the reduced mechanical properties such as toughness, impact strength, and tensile strength. In this research, modified AISI D3 steel was developed by replacing part of Cr with Nb and Ti, in which chromium carbide was partially replaced with MC carbides. The cast samples produced by investment casting were heat treated at different conditions. The microstructures of the samples were studied by light and scanning electron microscope attached with EDS analyzer. To determine the optimized homogenizing process, the effects of homogenizing treatment on the microstructure and the morphology of carbides were also studied.
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  Effects of Thermo-Magnetic Treatment on Microstructure and Mechanical Properties of Rolling-Bearing Steel

  Constantin GHEORGHIES

  中国钢铁期刊网. 2010, 17(9): 46-52.

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  The influence of thermo-magnetic treatment of rolling-bearing steel on some its metallurgical and mechanical properties was investigated. The heating and/or cooling processes of the sample occurred in a magnetic field having certain intensities. The XRD patterns of rolling-bearing steel sample exhibited a beneficial effect of the magnetic field on the structure, phase transformation and tension state. It was found an increased reliability of rolling tribomodel made from thermo-magnetic treated steel when it was subjected to the fatigue tests.
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  Microstructure Characteristics of an FeMnC TWIP Steel After Deformation

  DAI Yongjuan;TANG Di;MI Zhenli;L Jianchong

  中国钢铁期刊网. 2010, 17(9): 53-59.

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  Abstract: The present paper investigated deformatiom microstructure characteristcsl of the Fe-Mn-C TWIP steel .The results showed that the hot rolled – cold rolled - annealed sample of Fe-Mn-C TWIP steels has excellent mechanical properties, the true stress-strain curve from tension tests exhibit repeated serrations. The deformed microstructure exhibited the typical planar glide characteristics such as no cell formation, dislocation pile ups on a single slip plane, mechanical twins and stacking faults. There are equiaxial and deep dimple structures in the fractograph, it is a typical ductile fracture. microcrack initiated from inclusions and twin-twin intersections, Its deformation and mfracture processes were the formation, growth and coalescence of microvoids. Because of high amount of anganese, there are many inclusions of strip MnS, the quantity of sulphur should be controlled during steelmaking.
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  Interaction Between Elements Nb and Mo During Precipitation in Microalloyed Austenite

  YUAN Shaoqiang;LIANG Guoli;ZHANG Xiaojuan

  中国钢铁期刊网. 2010, 17(9): 60-63.

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  Thermo-simulation test and transmission electron microscopy(TEM) have been used to investigate the interaction between the microalloying elements Nb and Mo within the precipitates during relaxation after austenite deformation for C-Ti-Mo steel and C-Nb-Mo steel. The experimental results demonstrated that the austenitic structure was preserved both in C-Ti-Mo steel and in C-Nb-Mo steel even if they were relaxed for 1000s after deformation at 850℃. The strain-induced precipitate occurs in two kinds of steel. Through the energy spectrum analysis, it was detected that the precipitated particles were Ti(C,N) and Mo-bearing Nb(C,N) respectively, and there exists a strong affinity between Mo and Nb within the precipitates. Mo atoms would enter the lattice of Nb(C,N) particles probably after Nb(C,N) formation.
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  Microstructure and Properties of Hot Rolled Ti23Al17Nb Alloy Sheets

  ZHANG Jianwei;LIANG Xiaobo;CHENG Yunjun;LI Shiqiong

  中国钢铁期刊网. 2010, 17(9): 64-68.

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  Microstructure and tensile properties of the Ti-23Al-17Nb alloy sheets rolling at （α2＋B2＋O）phase field with the various heat treatments were studied. Before rolling the microstructure of B2 phase particles embedded in O phase continuity matrix is acquired. The B2 phases deform more greatly and recrystallize more easily than α2/ O phases during the same rolling step. The (α2＋B2) two-phase equiaxed microstructure is obtain by solution treatment at (α2＋B2) phase field. The B2 phases become the continuity matrix by recrystallization and growing up of B2 grains and the anisotropy caused by rolling disappears. The microstructure obtained by solution treatment has more excellent tensile properties than the microstructure gained by subsequent aging treatment at (O＋B2) phase field because the O phases precipitate as the block structure during aging and the B2 matrix continuity is broken down.
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  Effect of MicroArea pH Value on Formation of Different Rust Phases of Weathering Steel in Initial Corrosion Period

  CHEN Xiaoping;WANG Xiangdong;LIU Qingyou;MI Fengyi;CHEN Ying;LI Yusu

  中国钢铁期刊网. 2010, 17(9): 69-72.

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  The formation of protective rust layer of atmospheric corrosion resistance was discussed for weathering steel. The Rust layers of experimental steels were made by using an accelerating industrial atmospheric corrosion test of dry-wet cyclic immersion. Furthermore XRD were used to measure and analyze the rust layers. The initial corrosion processes below thin water film were observed and the changes of micro-area PH value were measured. The results are as follows: The corrosion processes are obviously different between P-RE weathering steel and carbon steel. The surface of P-RE weathering steel rapidly forms α-FeOOH and the micro-area PH value is above 5.4 during the initial corrosion period. While the component of the rust layer for the carbon steel is mainly Fe3O4 and the micro-area PH value is below 3.8.
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  Microstructure Characterization and Mechanical Properties of FGH 95 Turbine Blade Retainers

  TAO Yu;JIA Jian;LIU Jiantao

  中国钢铁期刊网. 2010, 17(9): 73-78.

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  FGH 95 is a powder metallurgy (P/M) processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was for high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process (PREP), hot isostatic pressing (HIP) at super-solvus temperature and a heat treatment with sub-solvus solution. The material had an equiaxed grain structure (ASTM 6.5-7.5). The γ' precipitates in As-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were type of MC and precipitated at grain boundaries. The prior particle boundaries (PPB) in the material were found to originated mainly from γ' phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The As-HIP FGH 95 blade retainers showed high strength at room temperature and 650℃, excellent creep resistance and outstanding stress rupture strength at 650℃.