2003年, 第10卷, 第3期　刊出日期：2003-08-25

  

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  Long Campaign of BF with Overheating-Free Cooling Stave

  CHENG Su-sen, YANG Tian-jun, CANG Da-qiang

  钢铁研究学报（英文版）. 2003, 10(3): 1-5.

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  A basic idea of permanent lining in designing long campaign of BF was put forward. BF designer should follow a chain of thinking procedure: Cooling water—Cooling system—Refractory lining. The temperature field of BF wall and cooling stave was calculated using heat transfer model and the results were proved by a 1000-1200℃ test nig. The over heating-free cooling stave with different parameters was designed, and such a long campaign of BF (15years) was going to put into construction.
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  Effect of Strong Basic Oxide (Li₂O, Na₂O, K₂O and BaO) on Property of CaO-Based Flux

  LI Gui-rong

  钢铁研究学报（英文版）. 2003, 10(3): 6-9.

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  It is found that strong basic oxides including Li₂O, Na₂O, K₂O and BaO, which are used to replace a part of CaO in CaO-based fluxes, can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li₂O to CaO-based fluxes was recommended.
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  Dephosphorization Thermodynamics of Crude Steel Using CaO-Based Flux

  YANG Yin-dong, McKague A R, McLean A, Sommerville I D

  钢铁研究学报（英文版）. 2003, 10(3): 10-15.

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  The experiments were carried out at 1175-1450℃ to study the phosphorus distribution ratio between molten CaO-based slags and carbon saturated hot metal. The phosphate capacity of the slags and the activity coefficient of PO₂5 were calculated from the phosphorus distribution ratio. The effect of addition of CaF₂ and/or CaCl₂ on the thermodynamic properties of slags was discussed. The correlation of optical basicity with phosphate capacity of slags was studied, and the dephosphorization ability of CaO-based fluxes with various additives was compared with the results from different studies.
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  Numerical Simulation of Linear Electromagnetic Stirring in Secondary Cooling Region of Slab Caster

  HUANG Jun-tao, WANG En-gang, HE Ji-cheng

  钢铁研究学报（英文版）. 2003, 10(3): 16-21.

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  According to the theory of alternating magnetohydrodynamics and magnetic boundary renewal method, mathematical models were proposed for electromagnetic stirring in secondary cooling region (SEMS)of slab caster. The magnetic fields and flow fields of melt were simulated with SEMS. It’s shown that the electromagnetic forces with inward and sidelong components produced by travel magnetic field at the wide faces of slab make the melt whirling in horizontal section, and the convection of the melt is strengthened obviously there. In addition, magnetic flux density attenuates from the edge to the center of slab, and the profile of the melt velocity along slab thickness in the center of the horizontal section takes a two-opposite-peak configuration. Ultimately, the stirring intensity and features are deter-mined by the electromagnetic parameters, coil arrangement and stirring types.
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  Influence of Billet Size on Flow, Solidification and Solute Transport in Continuous Casting

  ZHANG Hong-wei, WANG En-gang, HE Ji-cheng

  钢铁研究学报（英文版）. 2003, 10(3): 22-27.

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  The influence of billet size on continuous casting was studied using the 3-D coupled turbulent flow, solidification and solute transport model. It is shown that the larger the billet size is, the larger the inlet velocity is; The deeper the stream penetration is and more liquid steel is pushed by mainstream, the stronger turbulent flow is observed in the upper part of mold. For Fe-C binary alloy system, the thickness of solidified shell is determined by temperature and solute concentration. The more serious macrosegregation and thinner shell are observed for smaller billet, thus a longer mold should be used.
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  Mechanical Analysis of Dead Load Crown and Structure Parameter of Hydraulic Elastic Bulging Roll

  ZHAO Chang-cai, LI Wei-min, LIU Zhu-bai

  钢铁研究学报（英文版）. 2003, 10(3): 28-31.

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  The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam, and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve, the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put for-ward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.
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  Laser Welding of Ultra-Fine Grained Steel SS400

  PENG Yun, TIAN Zhi-ling, CHEN Wu-zhu, WANG Cheng, BAO Gang

  钢铁研究学报（英文版）. 2003, 10(3): 32-36.

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  The effects of laser welding on microstructure and mechanical properties of ultra-fine grained steel SS400 were studied. The plasma are welding and MAG welding were conducted to make a comparison between these weldings and laser welding. The coarse grain heat-affected zone (HAZ)of laser welding was simulated using thermomechanical simulation machine, and the impact toughness was tested. The deep penetration laser welding produces weld of large depth and narrow width. The weld metal and HAZ of laser welding was heated and then cooled rapidly. The prior austenite grain size of coarse grain HAZ is 1/10 of that for arc welding. For laser welding, the toughness of weld metal is higher than that of base metal, and the toughness of the coarse grain HAZ of laser welding is on a level with that of base met-al. Matching lower laser power with lower welding speed, the hardening tendency of the weld metal and the coarse grain HAZ can be decreased. There is no softened zone. The tensile strength of welded joint formed by laser is higher than that of base metal. The joint has good bending ductility.
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  Effect of Mineral on Metallurgical Coke Solution Loss Reaction in Blast Furnace

  YANG Jun-he, FENG An-zu, DU He-gui

  钢铁研究学报（英文版）. 2003, 10(3): 37-40.

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  The catalytic effects of minerals (oxides)on solution loss reaction of coke were investigated in detail by adding oxides to coal which produces coke or absorbing oxides on coke surface. The mineral catalysis index (MCI)which can be used to evaluate catalytic effects of minerals on solution loss of coke comprehensively was proposed. Using the volatility of coal in dry basis and MCI of coal as independent variables to control coke reactivity, the mathematical models of predicting coke reactivity index, coke strength of reactivity were constructed on the basis of the experimental results.
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  Damage Mechanics of Ferrite Ductile Iron under Uniaxial Stress

  LIU Jin-hai, LI Guo-u, FU Han-guang, HAO Xiao-yan, LIU Gen-sheng

  钢铁研究学报（英文版）. 2003, 10(3): 41-45.

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  According to the principle of damage mechanics, the damage characteristics of ferrite nodular cast iron under uniaxial stress were studied by measuring electric resistance. The results show that the damage in nodular cast iron occurs when the applied stress is more than a certain extent, and the damage variable increases with stress. The evolutional law of damage variable as a function of stress was obtained. The damage threshold of nodular cast iron increases with nodularity, but it is below the yield strength, which provides reference significance to the design of machinery structure and the choice of materials. The critical damage variable is not related to the nodularity, which is about 0. 060-0. 068.
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  Study on Liquid Structure of Iron-Rich Fe-Si Alloy

  TENG Xin-ying, LIU Han-Hian, WANG Huan-rong, YE Yi-fu

  钢铁研究学报（英文版）. 2003, 10(3): 46-49.

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  The liquid structure of iron-rich Fe-Si alloys (the silicon content is 22, 32, 34, 50 at%, respectively) was studied by high temperature θ-θ diffractometer at 1550 ℃. The results show that the coordination number of atoms decreases with increasing silicon content. A visible pre-peak was observed in the structure factor of Fe-Si alloys, especially for the liquid Fe₇₈Si₂₂ and Fe₆₈Si₃₂ alloys. The special study was given on the liquid structure of Fe₆₈Si₃₂ alloy at temperature from 1250 to 1550 ℃. A distinct pre-peak was found at scattering vector Q=15. 5nm^-1 in the structure factor. That means there are ordered D0₃ structure clusters in the liquid Fe₆₈Si₃₂ alloy. The correlation between silicon atoms in the Fe₃Si compounds leads to the pre-peak in the structure factor.
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  Influence of Rare Earth on Property of Low Chromium Semi-Steel

  LIU Jian-hua, XIE Dan-yang, LI Chang-heng, SHAO Li, ZHANG Rui-jun

  钢铁研究学报（英文版）. 2003, 10(3): 50-53.

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  The influence of rare earth (RE) content on mechanical properties and abrasion resistance of low chromium semi-steel was studied by means of metallographic examination, scanning electron microscopic examination and mechanical property test. The experiment results show that RE can improve the comprehensive properties, especially in combination with proper heat treatment. The optimum properties of low chromium semi-steel modified by RE of 0. 25% could be obtained by normalization at 950 ℃ for 3 h. The main reason is the change in morphology and distribution of eutectic carbide and the precipitation of granular carbides.
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  Effect of Primary Factor on Cavitation Resistance of Some Austenitic Metals

  WANG Zai-you, ZHU Jin-hua

  钢铁研究学报（英文版）. 2003, 10(3): 54-58.

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  The cavitation resistance of six kinds of austenitic metals was investigated using a rotating disc rig. The research results show that cavitation resistance of the austenitic metals is obviously raised due to cavitation-induced martensite and greatly influenced by mechanism of martensitic trans-formation. The cavitation resistance of two stress-induced martensite Fe-Mn-Si-Cr shape memory alloys is much better than that of three strain-induced martensite austenitic stainless steels. The Fe-Mn-Si-Cr shape memory alloys possess excellent cavitation resistance mainly because of their excellent elasticity in local small-zone. The first principal factor for cavitation resistance of metastable austenitic metals is unloaded ebounding depth, and the second one is energy dissipation resulted from cavitation-induced martensite.
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  Sensitivity to Stress Concentration of Steel at High Temperature

  XIAO Feng, YANG Ren-hui

  钢铁研究学报（英文版）. 2003, 10(3): 59-63.

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  A new experimental method was developed to simulate the generation of the surface trans-versal crack on the continuous casting slab with a discontinuous sample. A high temperature property of steel named “the sensitivity to the stress concentration of steel at high temperature”was defined to evaluate the effect of stress concentration on thermal plasticity of steel. "The sensitivity parameter to the stress concentration of steel at high temperature” was available to determine the temperature range in which steel is sensitive to the stress concentration.
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  Fatigue Strength Improvement of Welded Joint by Ultrasonic Peening in Ultra-Fine Grain Steel

  TIAN Zhi-ling, ZOU Gang, HE Chang-hong, ZHANG Xiao-mu

  钢铁研究学报（英文版）. 2003, 10(3): 64-66.

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  The ultrasonic peening of weld toes in ultra-fine grain steel was applied to enhance the fatigue behavior. The test results show that the ultrasonic treatment remarkably shifts the S-N curve to the right. The FAT (fatigue strength at 10⁶ cycles) is increased by 66%. The fatigue life at ∆σ=200 MPa is extended by 58 times. The mechanism of fatigue strength improvement by ultrasonic treatment was studied. It is shown that two mechanisms improve the fatigue strength of welded joint by ultrasonic treatment: one is the decrease of the stress concentration ratio at weld toes, and the other is the building-up of a compressive residual stress at the weld.
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  Influence of Rare Earth on Carbide in Weld Metal

  ZHANG Yuan-Bin, REN Deng-Yi

  钢铁研究学报（英文版）. 2003, 10(3): 67-70.

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  The influence of rare earths (RE) on carbides in high carbon steel weld metal was studied by transmission electron microscope (TEM) and energy dispersive X-ray microanalysis (EDX). It is found that rare earth markedly affects the quantity, morphology and distribution of carbides. The precipitating mechanism of carbides was proposed in which rare earth compounds with high surface energy serve as the nucleation sites for carbides in superheated liquid metal and the induced carbides are precipitated extensively and distributed evenly. The preferential precipitation of carbides decreases the carbon content in matrix, which is transformed into low carbon lath martensite after welds are chilled to room temperature.
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  Effect of Powder Particle Size on Microstructure and Mechanical Property of Ni-Based P/M Superalloy Product

  ZHANG Ying, ZHANG Yi-wen, ZHANG Feng-ge, TAO Yu, CHEN Xi-chun

  钢铁研究学报（英文版）. 2003, 10(3): 71-74.

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  The physical characteristics of Ni-based superalloy powder with different particle sizes produced by plasma rotation electrode process (PREP)and the microstructure and mechanical properties of P/M superalloy products were investigated. The experimental results show that the optimum powder particle sizes should be in the range of 50-100 μm or 50-150 μm, which can reduce production cost, simplify process and guarantee P/M product quality.
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  Formation and Sintering Behavior of Nanocrystalline Fe-Ni Powder by Mechanical Alloying

  CHEN Wen-ge, GU Chen-qing, DING Bing-jun

  钢铁研究学报（英文版）. 2003, 10(3): 75-78.

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  The solid sintering behavior and mechanical properties of Fe-Ni powders prepared by mechanical alloying of elemental powders and hot pressing sintering in vacuum atmospheres were investigated. It was observed that the microstructure of the powder particles evolves in three stages. The alloy powder with average grain size of 20-30 nm was obtained. The sinter densification depends crucially on the particle re-arrangement and the large amount of internal strain introduced during milling. The theoretical density of over 95% was obtained after hot pressing sintering at 800℃ for 30 min with pressure of 50 MPa. No significant grain growth was observed during sintering. And also relatively high hardness was obtained.