2011年, 第18卷, 第3期　刊出日期：2011-03-15

  

• 全选
  |

工艺
• Select
  Reduction of 1-3 mm Iron Ore by CO on Fluidized Bed

  PANG Jian-ming,GUO Pei-min,ZHAO Pei

  中国钢铁期刊网. 2011, 18(3): 1-5.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The reduction-degree of the sample increases and the utilization ratio of gas decreases when the reaction lasts longer time, which indicates that the reaction is faster at the beginning of reduction, while it becomes slower in subsequent process. The higher the reaction temperature, the higher the utilization ratio of gas and the reduction-degree are, but the difference of utilization ratio among the different temperatures becomes smaller with time. The utilization ratio of gas can reach about 8% and the reduction-degree is 80% for 20 min reduction at 850 ℃, indicating that the reduction reaction by CO is very fast at high temperature. The higher the reaction temperature, the higher the apparent reaction rate constant is, but the difference of apparent reaction rate constant among the different temperatures becomes bigger. The apparent activation energy is about 5911 kJ/mol in the fluidized bed experiment. The increase of reduction-degree with gas velocity shows quite good linearity, indicating that at high temperature even higher velocity of reducing gas can be used to improve the productivity of reactor when CO is used as reducing gas. With the increase of charge height, the metallization ratio and the reduction-degree decrease, but the utilization ratio of gas increases.
• Select
  Properties and Structural Optimization of Pulverized Coal for Blast Furnace Injection

  JIANG Hai-bing,ZHANG Jian-liang,FU Jian-xun,CHANG Jian,LI Jing

  中国钢铁期刊网. 2011, 18(3): 6-12.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The properties of mixed coals were studied on the basis of known various properties of the injecting coals in the treatise. The structure of the injecting coals was optimized and put into practical application. It was found that the ignition point was lowered with mixed coals, however, both combustibility and grindability were improved, and explosibility of the mixed coals were decreased as well. Hence, mixed coals injection not only can improve the amount of the injecting coals greatly, but also improve the economical and technical indexes of the blast furnace.
• Select
  Diffusion Coefficient of Calcium Ion in CaO-Al2O3-SiO2 Melts

  ZHANG Guo-hua,CHOU Kuo-chih,

  中国钢铁期刊网. 2011, 18(3): 13-16.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The Nernst-Einstein equation is used to calculate the diffusion coefficient of calcium ion in the CaO-Al2O3-SiO2 system based on the data of the density and electrical conductivity. It is assumed that all the aluminium ions form tetrahedral structure and merge with chain or ring in the case of molar concentration of CaO higher than Al2O3. And in this case, calcium ion is assumed to be the conclusive charge carrier. A formula between the diffusion coefficient and concentration of calcium ion as well as temperature is deduced, which gives an increasing function relation between the diffusion coefficient and the concentration of calcium ions.
• Select
  A Fuzzy Shape Control Method for Stainless Steel Strip on Sendzimir Rolling Mill

  HUR Yone-gi,CHOI Young-kiu

  中国钢铁期刊网. 2011, 18(3): 17-23.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The strip shape in the stainless steel process has made an issue of the strip quality. The objective of the shape control is to minimize the shape deviation and to maintain symmetrical shape patterns in the lateral direction. The method of the shape recognition employs the least square method. The shape deviation is controlled by the fuzzy shape controller (FSC). The experiments have been performed online for various stainless materials, thicknesses, and strip widths. The test results show very efficient performances in respect of stable target tracking and symmetrical and minimal fluctuation of the strip shape.
• Select
  Application of Temperature Inference Method Based on Soft Sensor Technique to Plate Production Process

  DING Jing-guo,QU Li-li,HU Xian-lei,LIU Xiang-hua

  中国钢铁期刊网. 2011, 18(3): 24-27.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  There is a certain extent of measuring error for each pyrometer in plate production process, which has a great impact on process control system. A soft sensor technique is used to calculate the confidence interval of measuring temperature data from pyrometers and an inference estimator is designed by partial least square method, then the pyrometer with highest confidence is considered as the reference one, with which inference estimation for measured data on-line of other pyrometers is started and the measuring error is conformed. From actual application it can be found that this method can improve the measuring accuracy by 3%-5%, and has high field application value.
• Select
  Application of Improved Fuzzy Immune PID Controller to Bending Control System

  REN Xin-yi,DU Feng-shan,HUANG Hua-gui,ZHANG Shang-bin

  中国钢铁期刊网. 2011, 18(3): 28-33.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Based on the hydraulic bending control system, the electrohydraulic servo pressure control simulation model is built. Taking into account of the inadequacy of P-type immune feedback controller, an improved fuzzy immune PID controller is put forward. Drawing on immune feedback principle of biological immune system, the P-type immune feedback controller is connected with conventional PID controller in series and then in parallel with design fuzzy immune PID controller. The controller parameters can be adjusted on line by the rules of immune feedback controller and fuzzy controller. In order to gain the optimal parameters of the controller, the parameters of the controller are off-line optimized by the best multiple optimal model PSO algorithm. The simulation results indicate that the method has characteristics of small overshoot, short adjusting time and strong anti-interference ability and robustness. The quality of the strip shape can be further improved.
材料
• Select
  Influence of Mold Preheating and Silicon Content on Microstructure and Casting Properties of Ductile Iron in Permanent Mold

  Jafar Khalil-Allafi,Behnam Amin-Ahmadi

  中国钢铁期刊网. 2011, 18(3): 34-39.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The effects of the mold preheating and the silicon content of ductile iron on the percentage of carbides, graphite nodule counts and shrinkage volume were investigated. The results showed that the percentage of carbides and the shrinkage volume decreased when the mold preheating increased. The ductile iron with the carbon equivalent of 445 % and the silicon content of 25% without any porosity defects was achieved when the mold preheating was 450 ℃. Increasing the silicon content in the range of 21%-33% led to the increase in graphite nodule count and graphite size and the decrease in percentage of carbides. It is due to the increase in induced expansion pressure during the graphite formation with the increasing of silicon content. The suitable condition for casting a sound product of ductile iron without the riser at the mold preheating temperature of 300 ℃ is the silicon content of 33% and carbon equivalent of 47%.
• Select
  Texture of Cold Rolled Strip of Fe-3Si Steel Produced by Thin Slab Casting and Rolling

  LI Chang-sheng,YANG Hua,WANG Yan-fang,YU Yong-mei

  中国钢铁期刊网. 2011, 18(3): 40-46.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The hot rolled strip of Fe-3Si steel was experimentally produced by thin slab casting and rolling (TSCR) process in the laboratory. The texture evolution rule was investigated during hot rolling and cold rolling. The texture distribution of cold rolled strips with four kinds of cold rolling reduction schedules was observed through X-ray diffraction method, and the orientation density variation of 1/16 layer, 1/8 layer, 1/4 layer, and 1/2 layer in thickness was analyzed. The cold rolled texture of steel A with four kinds of cold rolling reduction schedules was mainly composed of α and γ fibers. Cold rolling reduction ratio of 70% was more beneficial for obtaining more γ fibers. The γ fiber texture orientation density of {111}<011> and {111}<1 12> was the largest on the 1/8 layer and 1/4 layer and the least on the 1/16 layer and 1/2 layer for steel B. The texture orientation density of {001}-{223}<110> in the α fibers for steel C was increased, but the texture orientation density of {332}-{110}<110> was low.
• Select
  Mechanism of Embrittlement and De-Embrittlement for 225Cr-1Mo Steel

  ZHANG Xi-liang,ZHOU Chang-yu

  中国钢铁期刊网. 2011, 18(3): 47-51.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The constant embrittlement curve for constant segregation concentration on grain boundary of impurity element P and relationship between equilibrium grain boundary segregation concentration and operation time for 225Cr-1Mo steel were derived based on the theory of equilibrium grain boundary segregation. The mechanism of step-cooling test and mechanism of de-embrittlement for 225Cr-1Mo steel were explained. The segregation rate will increase but equilibrium grain boundary segregation concentration of impurity element P will decrease as temperature increases in the range of temper embrittlement temperature. There is one critical temperature of embrittlement corresponding to each embrittlement degree. When the further heat treating temperature is higher than critical temperature, the heat treating will become a de-embrittlement process; otherwise, it will be an embrittlement process. The critical temperature of embrittlement will shift to the direction of low temperature as further embrittlement. As a result, some stages of step-cooling test would change into a de-embrittlement process. The grain boundary desegregation function of impurity element P was deduced based on the theory of element diffusion, and the theoretical calculation and experimental results show that the further embrittlement or de-embrittlement mechanism can be interpreted qualitatively and quantitatively by combining the theory of equilibrium grain boundary segregation with constant embrittlement curve.
• Select
  Effects and Mechanisms of RE on Impact Toughness and Fracture Toughness of Clean Heavy Rail Steel

  LIU Cheng-jun,HUANG Ya-he,JIANG Mao-fa

  中国钢铁期刊网. 2011, 18(3): 52-58.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting, forging and rolling. Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated. In addition, the appropriate range of RE content for clean high carbon steel was determined. Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE, consequently the impact toughness and fracture toughness were improved evidently. When the RE content exceeded a critical value, the pearlite lamellar spacing was increased, because RE was segregated on the austenite grain boundaries, damaged the orientation relationship of pearlite transformation, caused the disorder growth and morphology degenerating of pearlite. With the increasing of RE content, both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased. It was found that when the RE content was between 00081% and 00088%, both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best. The maximum ballistic work was 212 J (20 ℃) and 122 J (-20 ℃), respectively. The maximum plane-strain fracture toughness was 4567 MPa·m1/2 (20 ℃) and 3704 MPa·m1/2 (-20 ℃), respectively.
• Select
  Relationship Among Microstructure and Properties and Heat Treatment Process of Ultra-High Strength X120 Pipeline Steel

  ZHOU Min,DU Lin-xiu,LIU Xiang-hua

  中国钢铁期刊网. 2011, 18(3): 59-64.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  The variation of heat treatments including directed quenching and tempering off-line after controlled rolling (DQT) and quenching off-line and tempering off-line after controlled rolling (RQT) with microstructure and mechanical properties of a low-carbon microalloyed steel was compared and analyzed. For DQT, the quenched steel was obviously banded microstructure, with increasing tempering temperature, lath martensite coarsened, the cusp carbide precipitated at grain boundaries, the yield strength fluctuated slightly, and the fracture-separation was obvious. The impact toughness was better in the steel tempered at 500 ℃ for 1 h. In RQT, with increasing tempering temperature, lath martensite degenerated, intragranular and intergranular finer precipitations with smaller than 30 nm precipitated and grew up and were distributed dispersedly, the stripe-like carbides were distributed at grain boundaries, and the yield strength and tensile strengthen decreased obviously. The impact toughness of RQT process was much better than that of DQT process, and the comprehensive mechanical properties were better for the steel tempered at 500 ℃ for 1 h of RQT process.
• Select
  Effect of Hot Pressing on Microstructure and Mechanical Properties of Bulk Nanocrystalline Fe3Al Materials Containing Manganese Element

  LI Yu-feng,LA Pei-qing,WEI Yu-peng,LU Yang,YANG Yang

  中国钢铁期刊网. 2011, 18(3): 65-71.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Bulk nanocrystalline Fe3Al materials containing manganese of 10% were prepared by aluminothermic reaction. Hot pressing of those materials was performed at different temperatures and times. The microstructures of the alloy were investigated by optical microscope (OM) and electron probe microanalyzer (EPMA). The grain sizes of the materials were analyzed by X-ray diffraction (XRD) and transmission electron microscope (TEM). The results showed that the grain sizes of the materials increase after hot pressing. The grain sizes of the materials decrease with increasing the hot pressing times at the same temperature and the grain sizes of the materials increase with increasing hot pressing temperatures at identical times. The hardness and compressibility of the materials were also tested. The results showed that the hardness decreases with increasing hot pressing times at 800 ℃ and hardness increases with increasing the hot pressing temperatures. The variation of hardness with grain size of the nanocrystalline Fe3Al materials after hot pressing is contrary to the Hall-Petch relation. The materials are not broken during hot pressing and exhibit good plasticity and compressibility.
• Select
  Morphological Changes During Annealing of Electrodeposited Ni-Cr Coating on Steel and Their Effect on Corrosion in 3% of NaCl Solution

  Manpreet Singh Marwah,Vajjala Srinivas,Ajoy Kumar Pandey,Shyam Ranjan Kumar4,Koushik Biswas,Joydeep Maity5

  中国钢铁期刊网. 2011, 18(3): 72-76.

  摘要 ( ) PDF全文 ( )   可视化   收藏

  Steel containing carbon of 02% was coated with Ni and Cr through electrodeposition, and subsequently annealed at 400 and 600 ℃ for 5 min, 30 min, 1 h and 2 h. During annealing at 400 ℃, the formation and growth of oxides occurred in the form of petals along with voids, cracks and porosities. However, at 600 ℃, the nucleation and growth of chromium oxide whiskers produced a surface almost free from crack, porosity and void for 1 h and 2 h of holding. In accordance with the surface morphology, the bare steel, as-deposited steel, all specimens deposited and annealed at 400 ℃, and specimens deposited and annealed at 600 ℃ for 5 and 30 min exhibited continuous corrosion in 3% of NaCl solution. However, the specimens deposited and annealed at 600 ℃ for 1 and 2 h exhibited an improved corrosion resistance in 3% of NaCl solution with high pitting potential due to presence of a dense passive oxide film almost free from voids at the surface.