2004年, 第11卷, 第5期　刊出日期：2004-09-25

  

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  Progress of Sintering Technology in Handan Iron and Steel Company

  LIU Zheng-ping, WANG Yi-fang, WU Jin-bo

  钢铁研究学报（英文版）. 2004, 11(5): 1-7.

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  As one of the biggest iron and steel companies in China, Handan Iron and Steel Co has made a substantial progress in the sintering process. The mini-pellet sintering technology has been successfully applied based on lab investigation and industrial trials. Equipment enlargement was realized through replacing small sintering strands with the construction of huge sintering machine with a grate area of 400m². The productivity, iron content and the metallurgical properties of sintering process have been improved.
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  Semisolid Slurry Preparation of Die Steel with High Chromium Content

  MAO Wei-min, ZHAO Ai-min, ZHANG Li-juan, ZHONG Xue-you

  钢铁研究学报（英文版）. 2004, 11(5): 8-12.

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  The semisolid slurry preparation of die steels Cr12 and Cr12MoV with high chromium content was studied. The results show that the semisolid slurry of both steels with solid of 40 %—60% can be made by electromagnetic stirring method and is easy to be discharged from the bottom little hole of the stirring chamber. The sizes of the spherical primary austenite in the slurry of die steels Cr12 and Cr12MoV are 50—100μm and 80—150μm, respectively. The homogeneous temperature field and solute field for both steel melts are obtained. The strong temperature fluctuation in the melt with many fine primary austenite grains occurs and the remelting of the secondary arm roots at the same time is accelerated because of the electromagnetic stirring. These are the most important reasons for deposition of spherical primary austenite grains.
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  Hot Strip Laminar Cooling Control Model

  WANG Jun, WANG Guo-dong, LIU Xiang-hua

  钢铁研究学报（英文版）. 2004, 11(5): 13-17.

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  The control model of laminar cooling system for hot strip, including air-cooling model, water-cooling model, temperature distribution model along thickness direction, feed forward control model, feedback control model and self-learning model, was introduced. PID arithmetic and Smith predictor controller were applied to feedback control. The sample of model parameter classification was given. The calculation process was shown by flow chart. The model has been proved to be simple, effective and of high precision.
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  Dynamic Model of Gap Loop for HCW Mill

  YANG Jing-ming, YANG Qiu-xia, CHE Hai-jun, CHANG Ling-fang

  钢铁研究学报（英文版）. 2004, 11(5): 18-21.

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  The hydraulic automatic gauge control system using gap loop for cold mill was de-signed. The stiffness of HCW cold mill was defined for gap loop, and the dynamic model of gauge control system for gap loop was built with mechanism analysis. The stiffness for gap loop and the cylinder displacement loop were measured.
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  Application of Crown-Flatness Vector Analysis in Plate Rolling Schedule

  HU Xian-lei, WANG Zhao-dong, JIAO Zhi-jie, ZHAO Zhong, LIU Xiang-hua, WANG Guo-dong

  钢铁研究学报（英文版）. 2004, 11(5): 22-26.

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  A simple plate crown model was introduced, and the crown-flatness vector analysis method was analyzed. Based on the plate rolling technology, the rolling schedule design of elongation phase is divided into three steps. First step is to calculate the reductions of first pass of elongation making full use of the mill capability to decrease the total pass number. The second step is to calculate the pass reduction for the last three or four passes to control crown and flatness by crown-flatness vector analysis method. In the third step, the maximum rolling force limit and the total pass number are adjusted to make the plate gauge at exit equal to target gauge with satisfactory flatness. The on-line application shows that this method is effective.
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  Simulation of Hot Strip-Rolling Process Based on Dislocation Density Variation

  XIAO Hong, ZHANG Guo-min, CHEN Zhan-fu

  钢铁研究学报（英文版）. 2004, 11(5): 27-31.

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  Based on the variation of dislocation density, which is influenced by rolling variables in hot strip-rolling process, a yield stress model was constructed. An integrated model was built to predict the temperature variation and microstructure evolution, in which the Orowan formula was used to calculate the stress and strain, and the finite difference method was adopt-ed to determine the temperature field. This model was applied to predict the temperature variation, austenite grain size and phase transformation in hot strip-rolling process, and the prediction results are in good agreement with the measured ones on 2050 mm continuous hot strip-rolling mill.
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  B₃Spline Function Method Used in Simulating Flatness and Profile of Cold Rolled Strip

  LI Jun-hong, QI Xiang-dong, LIAN Jia-chuang

  钢铁研究学报（英文版）. 2004, 11(5): 32-36.

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  Flatness and profile are important quality indexes of strip. Combining the influence function method to solve the elastic deformation of roll system with the variational method to solve the lateral flow of metal, the flatness and profile of the strip during cold continuous rolling were simulated. The B₃spline function was used to analogize the lateral distribution of strip thickness. The transverse distributions of the exit thickness and the front tension stress for each pass were obtained. Compared with the measured results, it is proved that using the spline function to analogize the lateral distribution of strip thickness can improve the calculation accuracy of flatness and profile largely.
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  Constraint Cooling of Hot Rolled Coil

  WANG Li-juan, ZHANG Chun-li

  钢铁研究学报（英文版）. 2004, 11(5): 37-40.

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  The layer thermal conductivity during constraint cooling of hot rolled coil was de-scribed by using equivalent thermal conductivity model and finite element method. Two radial stress concentration zones in constraint cooled coil were shown by numerical analysis, and the tension stress was assumed to be the main factor to induce stress corrosion. The experimental results show that the longer the water cooling time is, the smaller the grain size and the more uniform the grains are.
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  Glass Forming Ability and Magnetic Property of Fe₇₄Al₄Sn₂ (PSiB)₂₀ Amorphous Alloy

  CHEN Fei-fei, ZHOU Shao-xiong

  钢铁研究学报（英文版）. 2004, 11(5): 41-43.

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  Amorphous ribbons of Fe₇₄Al₄Sn₂(PSiB)₂₀ alloy have been synthesized by melt spin-ning and axial design method. The thermal properties of the amorphous ribbons have been measured by differential scanning calorimeter (DSC). The DSC results show that the Fe₇₄Al₄Sn₂P₁₂Si₄B₄ amorphous alloy has relatively wider supercooled liquid region with a temperature interval of 40. 38 K (∆T=T_x-T_g). The alloys with a higher phosphorous content in the metalloid element composition triangle of Fe₇₄Al₄Sn₂(PSiB)₂₀ have high glass forming ability. The amorphous alloys also show good magnetic properties in which Fe₇₄Al₄Sn₂P_6.67Si_6.67B_6.67 alloy has a large maximum permeability (um), Fe₇₄Al₄Sn₂P₃Si₃B₁₀ alloy exhibits a high squareratio (B/B₁₀) and Fe₇₄Al₄Sn₂P₄Si₁₂B4 shows a low core loss (P_0.5/13T). High glass forming ability and good magnetic properties make Fe₇₄Al₄Sn₂(PSiB)₂₀ amorphous alloys valuable in future research.
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  Prediction and Control of Wrinkle and Fracture for Stamping Regular Polygonal Box

  LEI Jun-xiang

  钢铁研究学报（英文版）. 2004, 11(5): 44-49.

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  Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model, the criterion of regular polygonal box stamped parts without wrinkle was deduced and used to predict and control the wrinkle limit. According to the fracture model, the criterion of regular polygonal box stamped parts without fracture was deduced and used to predict and control the fracture limit. Combining the criterion for stamping without wrinkle with that without fracture, the stamping criterion of regular polygonal box stamped parts was obtained to predict and control the stamping limit. Taken the stainless steel OCr18Ni9 (SUS304) sheet and the square box stamped part as examples, the limit diagram was given to predict and control the wrinkle, fracture and stamping limits. It is suitable for the deep drawing without flange, the deep drawing and stretching combined forming with flange and the rigid punch stretching of plane blank. The limit deep-drawing coefficient and the minimum deep-drawing coefficient can be determined, and the appropriate BHF (blank holder force) and the deep-drawing force can be chosen. These provide a reference for the technology planning, the die and mold design and the equipment determination, and a new criterion evaluating sheet stamping formability, which predicts and controls the stamping process, can be applied to the deep drawing under constant or variable BHF conditions.
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  Mechanical Property of Low Chromium Semi-Steel Grinding Ball Prepared by Cross Rolling

  CHANG Li-min, MENG De-liang, NIE Pu-lin, LIU Jian-hua

  钢铁研究学报（英文版）. 2004, 11(5): 50-54.

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  The preparing method, rolling technology and mechanical properties of low chromium semi-steel grinding ball by cross rolling were studied. The results show that when the low chromium semi-steel bar is forged from Φ55 mm to Φ50 mm, cross-rolled into grinding ball at 1000—1050℃, air cooled and tempered at 550℃ for 2h, the best mechanical properties, especially the abrasive resistance under the action of hard abrasive, can be obtained.
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  Bending Strength and Fracture Behavior of Ni₅₀Mn₂₉Ga₂₁ Alloy with Terbium

  ZHAO Zeng-qi, XIONG Wei, WU Shuang-xia, WANG Xin-lin

  钢铁研究学报（英文版）. 2004, 11(5): 55-58.

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  The bending strength and fracture behaviors of Ni₅₀Mn₂₉Ga₂₁ alloy with terbium were investigated. The results show that the bending strength of the alloy is increased dramatically with the increase of terbium content. The fracture appearance of the sample without terbium is dominated by grain boundary fracture, while that with terbium is dominated by cleavage fracture with the increase of terbium content. Moreover, the grains are refined obviously and the oxygen content is decreased after adding terbium.
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  Oxidation Mechanism of Ni-0. 5Y Microcrystal Coating Sputtered by Magnetron at 1000℃

  JIN Hui-ming, ZHANG Lin-nan, LIU Xiao-jun

  钢铁研究学报（英文版）. 2004, 11(5): 59-62.

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  The isothermal and cyclic oxidation behaviors of bulk pure nickel and its Ni-0. 5Y microcrystal coating sputtered by magnetron at 1000 ℃ in air were studied. The scanning electronic microscopy (SEM)and transmission electronic microscopy (TEM) were used to examine the structures of the coating and the NiO oxide films. The laser Raman spectrum was also used to measure the stress level in NiO films formed on bulk nickel and the coating. It is found that the Ni-0. 5Y microcrystal coating has lower oxidation rate, and the grain size of NiO formed on Ni-0. 5Y coating is also relatively smaller than that formed on bulk nickel. Meanwhile, the compressive stress level of oxide film formed on Ni-0. 5Y coating was lower than that formed on bulk nickel, and the high temperature plasticity of oxide film was much improved in coating case. The improvements of anti-oxidation properties of the sputtered Ni-0. 5Y coating are due to the microcrystal structure and yttrium.