2010年, 第17卷, 第11期　刊出日期：2010-11-15

  

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工艺
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  Numerical and Experimental Investigation on Heat Propagation Through Composite Sinter Bed With Non-Uniform Voidage: Part II Prediction of Process Efficiency

  Sergey V Komarov;Hiroyuki Shibata;Naohito Hayashi;et al

  中国钢铁期刊网. 2010, 17(11): 1-6.

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  Effect of CaCl2 on RDI and RI of Sinter

  ZHANG Xu;ZHANG Jian-liang;HU Zheng-wen;et al

  中国钢铁期刊网. 2010, 17(11): 7-7.

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  On the premise of maintaining the reducibility of sinter unchanged, it is of great significance to reduce the RDI of sinter, which will improve the permeability of blast furnace burden column, so as to realize stable and smooth performance, and keep high yield and low consumption. Under laboratory conditions, a study was proposed on the RDI and RI of sinter, which was immersed with different types and concentrations of solutions. The results show that Cl- is the main factor for reducing the RDI of sinter, and the RDI and RI of sinter decrease with the increase of Cl- concentration. With comprehensive consideration of the RDI and RI of sinter, when the concentration of Cl- is 2%, the RDI of sinter will be significantly reduced and RI will not be affected. In order to study the mechanism of CaCl2 effect on the RDI and RI of sinter, analysis based on the methods of IR Spectra, SEM and chalcography was adopted.
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  Mathematical Models Developed by Zone Method Considering Non-Gray Radiation Properties of Gas in Combustion Chamber

  CUI Miao;CHEN Hai-geng;GAO Xiao-wei

  中国钢铁期刊网. 2010, 17(11): 13-18.

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  Water vapour and carbon dixocide as the main products in combustion chamber have strong non-gray radiation properties. This paper presents multidimensional mathematical models developed by zone method considering non-gray radiation properties of gas in combustion chamber. Edwards exponential wide band model (EBWM) is adopted to calculate non-gray radiation properties of gas, and the three-point Gauss-Legendre integral formula is applied to calculate direct radiative exchange areas. Reflected radiative heat fluxes are obtained by Gauss elimination method, and energy balance equations are solved by main variable correction method. An example is given to validate the developed models, and further investigation of effects of flame distribution on heat transfer is carried on.
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  Finite Element Analysis of 100 t Hot Metal Ladle in Process of Tipping

  TIAN Hong-yu;CHEN Fu-rong;XIE Rui-jun; et al

  中国钢铁期刊网. 2010, 17(11): 19-19.

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  Hot-metal ladle is an important part in continuous casting production line and its stress distribution has direct influence on its life. In the process of design and calibration of the large sized hot-metal ladle, it’s of great significance to determine the stress distribution of each part of the ladle for safely and reliably running the device. Based on 100t hot-metal ladle which is designed by Baotou Iron & Steel Group, a simulation of stress field was made by finite element software ANSYS 10.0 in the different dumping angles. Through modeling, loading, restricting and calculating, strain and stress field distribution of the hot-metal ladle were acquired. Finally, an assessment of strength and stiffness was made on the hot-metal ladle. The results show that in the process of tipping for the hot-metal ladle, maximum stress is 137MPa, maximum strain is only 0.681‰, maximum stress and strain have appeared in the stiffener plate which is located at the bottom of the trunnion, and strength and stiffness are qualified. The method which is convenient and practical, reasonable and reliable provides theoretical evidence for checking analysis and further optimal design of the hot-metal ladle.
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  Exergy Analysis and Optimization of Ladle Furnace Refining Process

  MIN Yi;JIANG Mao-fa

  中国钢铁期刊网. 2010, 17(11): 24-24.

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  In this paper, exergy analysis was applied to the ladle furnace refining process of modern clean steelmaking. Results showed that, exergy loss induced by unavailable electric energy is the largest, and the electric energy efficiency is 46.20%. To cut down the unavailable electric energy, industrial experiments of submerged arc heating were carried out combined with slag composition modification. Results showed that, submerged arc heating can be achieved within most heating period, average heating rate increased by 0.5℃•min-1, unavailable electric energy decreased by 21.730 MJ per ton steel, and electric energy efficiency enhanced by 14.84%.
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  Upward Molten Flow for Optimization of Fluid Flow in Continuous Casting Tundish

  A R Alaei;H Edris;E Shirani

  中国钢铁期刊网. 2010, 17(11): 29-33.

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  The effects of flow control devices, casting speed of liquid steel, and inclusion size on inclusion removal in the continuous casting tundish were investigated using water modeling systems. Upward molten flow is investigated in this paper. Convection fluid flow, fluid flow pattern, and buoyancy force support the motion of non-metallic inclusions toward the tundish slag. To understand the fundamentals of the process, physical and mathematical modelings have been conducted in this work. Physical modelling is carried out with the utilization of a 1:4 scale model. Numerical modelling is carried out in line with the physical modeling to examine details of the flow pattern and rotational effect caused by the upward flow with the commercial CFD package environment, FLUENT. The mathematical model proposed is validated by comparing the predicted and measured results with VoF (Volume of Fluid) method.
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  Multi-Objective Optimization for Tandem Cold Rolling Schedule

  YANG Jing-ming;ZHANG Qing;CHE Hai-jun;et al

  中国钢铁期刊网. 2010, 17(11): 34-39.

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  Based on rolling feature of continuous tandem cold rolling mill, such as multi-variable, strong coupling, non-linear, analyze and set the equal relative load, preventing slippage and profile well as the multi-objective optimization goal, BP neural network with self-learning function is adopted to replace traditional rolling force models and then Levenberg-Marquardt algorithm is adopted to predict the rolling force. Then use multi-objective fuzzy theory to solve the problem of multi-objective optimization of tandem cold rolling schedule. With the example of 1370mm tandem cold rolling, the rolling schedule of the common rolling, the single-object optimization design and the multi-objective fuzzy optimization design are compared with each other, optimization result shows the proposed optimization method decreases the value of three objective functions simultaneous. The performance of the optimal rolling schedule is satisfying and it is promising.
材料
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  Effect of Substructure on Toughness of Lath Martensite/Bainite Mixed Structure in Low-Carbon Steels

  LUO Zhi-jun;SHEN Jun-chang;SU Hang;et al

  中国钢铁期刊网. 2010, 17(11): 40-48.

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  Substructure of M/B mixed structure in a low carbon NiCrMoV steel obtained through different cooling mode were quantitative analysis by optical microscope, SEM, EBSD and TEM to investigate the effect of the substructure on toughness. The results indicated that with the same prior austenite grain size and mixed by different ratio of M and B, toughness of steel enhanced with decrease of packet and block size and the lath width was about 0.38um. Calculation showed that packet and block boundary have the same effect on delaying crack extension, furthermore, effect of block width on impact energy was notably bigger than packet one. Therefore, block could work as a contributing microstructure controlled substructure in low carbon martensite steels, which means that block size was “the effect grain size controlling toughness”.
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  Three-Dimensional Morphology and Growth Behavior of Ferrite Allotriomorphs Formed at Grain Boundary Edges

  WAN Xiang-liang;CHENG Lin;WU Kai-ming

  中国钢铁期刊网. 2010, 17(11): 49-53.

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  Three-dimensional morphology of ferrite allotriomorphs nucleated on grain boundary edges in a low carbon steel were revealed by means of serial sectioning in conjunction with computer-aided three-dimensional reconstruction techniques. The typical morphology of ferrite allotriomorphs nucleated on grain boundary edges was of an elongated triangular pyramid. The length, width and thickness of ferrite allotriomorphs were measured on the basis of 3-D reconstructed images. The aspect ratio (length/width) of ferrite allotriomorphs was 4.5 on an average and scattered from 3 to 6. The measured sizes from the 3-D reconstructed images were smaller than those calculated, which was probably attributed to solute drag-like effect of manganese in the alloy.
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  Effect of Heating Rate on Microstructure Evolution and Magnetic Properties of Cold Rolled Non-Oriented Electrical Steel

  WANG Jian;LI Jun;WANG Xin-feng;et al

  中国钢铁期刊网. 2010, 17(11): 54-61.

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  The effects of rapid heating (heating rate ranging from 15℃/s to 300℃/s) during the final annealing process on microstructure evolution and magnetic properties of cold rolled non-oriented electrical steel had been investigated. It was found that the heating rate increasing could cause the substantially refined structures for the recrystallization grains and this grain refinement would decline when the heating rate beyond 50℃/s. The recrystallization texture exhibited pronounced improvement with hearting rate, such as the intensity decrease of {111}//ND fiber and the intensity increase of {110}<100> Goss component. The texture improvement and grain size refinement caused by heating rate increasing resulted in complicated variation of the magnetic properties. The magnetic induction (B50) keeps increasing while the heating rate increasing from 15℃/s to 300℃/s and the core losses variation (P1.5/50) is reverse, but it begins to increase when the heating rate ranges from 100 to 300℃/s. The results indicate that recrystallization texture and the magnetic properties of the non-oriented electrical steel have been improved definitely by the rapid heating during the final annealing treatment.
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  Calculation of Austenite Formation Kinetics of Copper-Bearing Steel During Continuous Heating

  LI Dan;MIN Yong-an;WU Xiao-chun

  中国钢铁期刊网. 2010, 17(11): 62-66.

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  Abstract:The kinetics of austenite formation in a new type copper-bearing steel, with initial microstructure composed of ferrite and bainite during continuous heating, by using dilatometric analysis and measurements. The formation of austenite was observed to occur in two stages. The first stage is the dissolution of ferrite and most bainite, followed by the bainite to austenite. The first stage takes place through diffusion and the second step through shear. The critical temperature of austenite formation in continuous heating increases with increasing heating rates, which therefore exerts a greater influence on the As1 temperature of the austenite formation. Kinetic calculation shows that the process is mainly controlled by diffusion when the heating rate is over 1℃/s.
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  Phase Transformation and Its Effects on Mechanical Properties and Pitting Corrosion Resistance of 2205 Duplex Stainless Steel

  ZOU De-ning;HAN Ying;ZHANG Wei;et al

  中国钢铁期刊网. 2010, 17(11): 67-72.

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  The effects of phase transformation on mechanical properties and pitting corrosion of 2205 duplex stainless steel have been investigated. The amount of σ phase in the test specimen was varied up to a maximum of 6% by thermal treatment at 850°C for period of time of up to 60 min. The results showed that σ phase both markedly increased the hardness and decreased the impact toughness of the test steel. But the increasing tendencies of the ultimate tensile strength and the yield strength were not obviously, while the total elongation abruptly decreased with the aging time from 5 min →15 min →60 min. SEM impact microfracturegraphs analysis revealed that the types of impact fracture changed from ductile mode to transcrystalline mode when the specimens aged from 5 min to 60 min. Furthermore, the extent of pitting potential reducing was found to be strongly temperature dependent, being more pronounced at the higher temperature. During the incubation period of σ phase nucleation, the pitting corrosion test temperature and the aging time had collaborative effects on evidently displacing the pitting potential towards less noble values. After 15 min, the higher temperature contributed more on decreasing the pitting potential than the aging time did.
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  Precipitation Behavior and Its Strengthening Effect of X100 Pipeline Steel

  NIU Tao;KANG Yong-lin;GU Hong-wei;et al

  中国钢铁期刊网. 2010, 17(11): 73-78.

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  Using TEM, electron diffraction, EDX analysis and physicochemical phase analysis, the morphology, crystal structure, size distribution and chemical composition of precipitates in the microstructure of high strength Nb-microalloyed X100 pipeline steel were investigated, and the strengthening effect of precipitation was quantitatively calculated with Ashby-Orowan correction model. The precipitates obtained in X100 pipeline steel can be divided into two kinds: “complex” and “single” particles by morphology. The EDX analysis of single precipitates reveals that the chemical composition matches well with particle dimensions, especially the Nb/Ti ratio regularly reduces with the increase of particle size. The yield strength increments in the way of precipitation strengthening of X100 pipeline steel reached about 52MPa, which suggests that the precipitation strengthening is not the dominative strengthening mechanism for X100 pipeline steel.