2007年, 第14卷, 第2期　刊出日期：2007-03-15

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Metallurgy and Metal Working
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  MultiObjective Optimization and Analysis Model of Sintering Process Based on BP Neural Network

  ZHANG Junhong;XIE Anguo;SHEN Fengman

  中国钢铁期刊网. 2007, 14(2): 1-0.

  摘要 ( 2452 ) PDF全文 ( 23 )   可视化   收藏

  A multiobjective optimization and analysis model of the sintering process based on BP neural network is presented. Genetic algorithms are combined to simplify the BP neural network, which can reduce the learning time and increase the forecasting accuracy of the network model. This model has been experimented in the sintering process, and the production cost, the energy consumption, the quality (revolving intensity), and the output are considered at the same time. Moreover, the relation between some factors and the multiobjectives has been analyzed, and the results are consistent with the process. Different objectives are emphasized at different practical periods, and this can provide a theoretical basis for the manager.
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  Analysis of AllCarbon Brick Bottom and Ceramic Cup Synthetic Hearth Bottom

  ZHAO Hongbo;CHENG Shusen;ZHAO Minge

  中国钢铁期刊网. 2007, 14(2): 6-0.

  摘要 ( 2400 ) PDF全文 ( 66 )   可视化   收藏

  One of the bottlenecks of the blast furnace (BF) campaign is the life length of hearth bottom. The basic reason for the erosion of hearth bottom is its direct contact with hot metal. According to the theory of heat transfer, models of BF hearth bottom are built based on the actual examples using software and VC language, and the calculated results are in good agreement with the data of BF dissection after blowing out. The temperature distribution and the capability of the resistance to erosion for different structures of hearth bottom are analyzed, especially the two prevalent kinds of hearth bottom arrangements called “the method of heat transfer” for allcarbon brick bottom and “the method of heat isolation” for ceramic synthetic hearth bottom. Features of the two kinds of hearth bottoms are analyzed. Also the different ways of protecting the hearth bottom are clarified, according to some actual examples. After that, the same essence of prolonging life, and the fact that the existence of a “protective skull” with low thermal conductivity between the hot metal and brick layers is of utmost importance are shown.
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  Numerical Analysis of Blast Furnace Performance Under Charging IronBearing Burdens With High Reducibility

  CHU Mansheng;GUO Xianzhen;SHEN Fengman;YAGI Junichiro;NOGAMI Hiroshi

  中国钢铁期刊网. 2007, 14(2): 13-0.

  摘要 ( 2331 ) PDF全文 ( 27 )   可视化   收藏

  The reducibility of ironbearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluated using a multifluid blast furnace model. The effects of reaction rate constants and diffusion coefficients were investigated separately or simultaneously for clarifying the variations of furnace state. According to the model simulation results, in the upper zone, the indirect reduction of the burdens proceeds at a faster rate and the shaft efficiency is enhanced with the improvement under the conditions of interface reaction and intraparticle diffusion. In the lower zone, direct reduction in molten slag is restrained. As a consequence, CO utilization of top gas is enhanced and the ratio of direct reduction is decreased. It is possible to achieve higher energy efficiency of the blast furnace, and this is represented by the improvement in productivity and the decrease in consumption of reducing agent. The use of highreducibility burdens contributes to a better performance of blast furnace. More efforts are necessary to develop and apply highreducibility sinter and carbon composite agglomerates for practical application at a blast furnace.
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  Endpoint Prediction of EAF Based on Multiple Support Vector Machines

  YUAN Ping;MAO Zhizhong;WANG Fuli

  中国钢铁期刊网. 2007, 14(2): 20-0.

  摘要 ( 2206 ) PDF全文 ( 45 )   可视化   收藏

  The endpoint parameters are very important to the process of EAF steelmaking, but their online measurement is difficult. The soft sensor technology is widely used for the prediction of endpoint parameters. Based on the analysis of the smelting process of EAF and the advantages of support vector machines, a soft sensor model for predicting the endpoint parameters was built using multiple support vector machines (MSVM). In this model, the input space was divided by subtractive clustering and a submodel based on LSSVM was built in each subspace. To decrease the correlation among the submodels and to improve the accuracy and robustness of the model, the submodels were combined by Principal Components Regression. The accuracy of the soft sensor model is perfectly improved. The simulation result demonstrates the practicability and efficiency of the MSVM model for the endpoint prediction of EAF.
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  Effect of Additives on Melting Point of LATS Refining Ladle Slag

  WANG Hongming;LI Guirong;DING Zhentao;DAI Qixun;LI Bo

  中国钢铁期刊网. 2007, 14(2): 25-0.

  摘要 ( 2163 ) PDF全文 ( 33 )   可视化   收藏

  To avoid slag sticking on the ladle immersion cover during the LATS refining and alloying process, the effect of Al2O3 on the melting point of the ladle slag was studied and the additives including CaF2, B2O3, Li2O, and CaO were used to decrease the melting point of the ladle slag. The melting point was measured using the hemisphere method. The results show that the addition of Al2O3 to the ladle slag increases the melting point. The fluxing action is not remarkable if only CaF2 or CaO is used as the additive. The fluxing action of the composite additive obtained by the mixing of CaO and CaF2 in the mass proportion of wCaO∶wCaF2=2∶1 is preferred. The fluxing action of B2O3 is also notable. When the B2O3 content in mass percent is in the range from 2% to 10%, the corresponding melting point is 1 380 ℃ to 1 290 ℃. The fluxing action of Li2O is the most remarkable. When the Li2O content is up to 5%, the melting point of the slag is lower than 1 300 ℃.
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  Flow of Steel in Mold Region During Continuous Casting

  ZHANG Xingguo;ZHANG Wenxiao;JIN Junze;J. W. Evans

  中国钢铁期刊网. 2007, 14(2): 30-0.

  摘要 ( 2450 ) PDF全文 ( 23 )   可视化   收藏

  The particle image velocimetry (PIV) technique was used to study the fluid flow phenomena that occurred during continuous casting, using a water model with dimensions of 1 840 mm×280 mm. Two types of solidified shells, ie, the smooth type and the coarse type, were used to characterize the dendrite in order to simulate different liquidsolid interfacial conditions. The influence of the nozzle angle and the immersion depth of nozzle, as well as the casting speed on the flow behavior was investigated quantitatively. The results were as follows: (1) There are two large recirculations above and below the fluid jet in the mold, respectively, under the smooth interface condition. However, in the case of the dendrite solidified shell, it was found that the flow velocity of the fluid decreased and more smaller vortices appeared in the upper region of the mold. (2) The angle and the immersion depth of nozzle are two important factors affecting the flow pattern, and they are also capable of bringing about the change in the flow direction. (3) The higher the casting speed, the higher are the jet stream and the impacting point on the narrow face. However, the high casting speed causes serious fluctuation of the meniscus, and correspondingly leads to various defects.
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  Improvement on Conventional Load Distribution Algorithm in Hot Tandem Mills

  LI Haijun;XU Jianzhong;WANG Guodong;LIU Xianghua

  中国钢铁期刊网. 2007, 14(2): 36-0.

  摘要 ( 2118 ) PDF全文 ( 23 )   可视化   收藏

  Load distribution is a key technology in strip hot rolling process, which influences the coil′s microstructure and performance. Currently, NewtonRaphson algorithm is applied to load distribution of hot tandem mills in many hot rolling plants and has some serious defects such as having a strict restriction on initial iterative calculation value and requiring coefficient matrix of nonlinear equations to be nonsingular. To eliminate these defects and improve the online performance of the process control computer, Newton descendent numeric algorithm is introduced to this field to widen the initial value range and a new model named error conversion algorithm is put forth to deal with special conditions when the coefficient matrix is singular. Furthermore, considering the characteristics of load distribution, a condition of strip thickness distribution abnormality and corresponding solutions are provided which ensure that rolling parameters can be calculated normally. Simulation results show that the improved algorithm has overcome the defects of the NewtonRaphson algorithm and is suitable for online application.
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  Prediction of Rolling Load in Hot Strip Mill by Innovations Feedback Neural Networks

  ZHANG Li;ZHANG Liyong;WANG Jun;MA Futing

  中国钢铁期刊网. 2007, 14(2): 42-0.

  摘要 ( 2340 ) PDF全文 ( 27 )   可视化   收藏

  Because the structure of the classical mathematical model of rolling load is simple, even with the selfadapting technology, it is difficult to accommodate the increasing dimensional accuracy. Motivated by this fact, an Innovations Feedback Neural Networks (IFNN) was presented based on the idea of Kalman prediction. The neural networks used the Back Propagation (BP) algorithm and applied it to the prediction of rolling load in hot strip mill. The theoretical results and the offline simulation show that the prediction capability of IFNN is better than that of normal BP networks, namely, for the prediction of the rolling load in hot strip mill, the prediction precision of IFNN is higher than that of normal BP networks. Finally, a relative complete rolling load prediction system was developed on Windows 2003/XP platform using the OOP programming method and the SQL server2000 database. With this system, the rolling load of a 1700 strip mill was calculated, and the prediction results obtained correspond well with the field data. It shows that IFNN is valid for rolling load prediction.
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  Calculating Method for Influence of Material Flow on Energy Consumption in Steel Manufacturing Process

  YU Qingbo;LU Zhongwu;CAI Jiuju

  中国钢铁期刊网. 2007, 14(2): 46-0.

  摘要 ( 2313 ) PDF全文 ( 21 )   可视化   收藏

  From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.
Material
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  An Improved BP Algorithm and Its Application in Classification of Surface Defects of Steel Plate

  ZHAO Xiangyang;LAI Kangsheng;DAI Dongming

  中国钢铁期刊网. 2007, 14(2): 52-0.

  摘要 ( 2310 ) PDF全文 ( 37 )   可视化   收藏

  Artificial neural network is a new approach to pattern recognition and classification. The model of multilayer perceptron (MLP) and backpropagation (BP) is used to train the algorithm in the artificial neural network. An improved fast algorithm of the BP network was presented, which adopts a singular value decomposition (SVD) and a generalized inverse matrix. It not only increases the speed of network learning but also achieves a satisfying precision. The simulation and experiment results show the effect of improvement of BP algorithm on the classification of the surface defects of steel plate.
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  Effect of Thermomechanical Processing on Microstructures of TRIP Steel

  TANG Zhengyou;DING Hua;DU Linxiu;DING Hao;ZHANG Xin

  中国钢铁期刊网. 2007, 14(2): 56-0.

  摘要 ( 2412 ) PDF全文 ( 49 )   可视化   收藏

  In order to control retained austenite, the effect of hot deformation in the intercritical region on the microstructure of hotrolled transformationinduced plasticity (TRIP) steel was studied on a Gleeble 1500 hot simulator. Compressive strains varying in amounts from 0 to 60% were imposed in the intercritical region, and effects on the formation of polygonal ferrite, carbidefree bainite and retained austenite were determined. With increasing the hot deformation amount and the ferrite content and decreasing the carbidefree bainite content, the volume fraction of retained austenite decreases. Increased dislocation density, grain refinement of ferrite and carbon enrichment are the main factors which control retained austenite stability.
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  Recrystallization Modelling of Hot Deformed SiMn TRIP Steel

  ZHU Lijuan;WU Di;ZHAO Xianming

  中国钢铁期刊网. 2007, 14(2): 61-0.

  摘要 ( 2580 ) PDF全文 ( 37 )   可视化   收藏

  By means of hot compression single and double hit experiments, the kinetics of dynamic and static recrystallization in hotrolled SiMn TRIP steel was studied, and the emphasis was put on the influence of high silicon content. The results show that the calculated parameters are consistent with the experimental ones, and addition of silicon retards both dynamic and static recrystallization as well as increases the flow stress of austenite, and the nonrecrystallization zone can be enlarged by increasing the silicon contents.
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  Computer Model of Phase Transformation From HotDeformed Austenite in Niobium Microalloyed Steels

  XU Yunbo;YU Yongmei;LIU Xianghua;WANG Guodong

  中国钢铁期刊网. 2007, 14(2): 66-0.

  摘要 ( 2340 ) PDF全文 ( 31 )   可视化   收藏

  Based on thermodynamics and kinetics, a new mathematical model was developed to calculate the CCT diagrams and the transformation kinetics in low carbon niobium steels, in which the effect of deformation on the degree of supercooling was taken into account. The undercooling caused by deformation is the major reason for the increase of the starting transition temperature during continuous cooling. The critical cooling rate of bainite formation is within 2-5 ℃/s for the studied niobium steels and deformation is suitable for the occurrence of pearlite. The ferrite volume fraction increases with the increase of the austenite boundary area, and decreases with the increase of the cooling rate. The calculated CCT diagrams and the volume fraction of each phase are in good agreement with the measurements.
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  Application of Ceramic Coat Synthesized by InSitu CombustionSynthesis to BF Tuyere

  YANG Dazheng;GUAN Yong;ZHANG Yue;LI Jing;HU Junge;LI Wenzhu

  中国钢铁期刊网. 2007, 14(2): 70-0.

  摘要 ( 2104 ) PDF全文 ( 21 )   可视化   收藏

  A novel technology of tuyere protection is introduced. The ceramic coat is synthesized by using insitu combustion process as the internal, external, and nose protecting coat of BF tuyeres. It can effectively protect the tuyeres and reduce heat loss by cooling water. The technology is quickacting, easy to use, energysaving and can make tuyeres have long service life. The feasibility of the application of the tuyere ceramic coat is discussed and the energysaving effect of the tuyere is compared with that of the tuyeres lined with refractory.
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  Development of Glass Ceramics Made From Ferrous Tailings and Slag in China

  LIU Chengjun;SHI Peiyang;ZHANG Dayong;JIANG Maofa

  中国钢铁期刊网. 2007, 14(2): 73-0.

  摘要 ( 2089 ) PDF全文 ( 25 )   可视化   收藏

  A great amount of ferrous tailings and slag cause severe damage to the ecological environment, which must be reclaimed and utilized. The composition, type, and characteristics of ferrous tailings and slag in China were introduced. The research status and the application outlook of glass ceramics made from ferrous tailings and slag were discussed. Glass ceramics made from ferrous tailings and slag can be applied to various fields, and it will be environmentally conscious materials in the 21st century.