2010年, 第17卷, 第1期　刊出日期：2010-01-15

  

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工艺
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  Analysis of Effect of Gas Temperature on Cooling Stave of Blast Furnace

  XIE Ning-Qiang Shu-Sen Cheng

  中国钢铁期刊网. 2010, 17(1): 1-1.

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  For further study on effect of gas temperature variation on cooling stave t, temperature, stress and displacement distributions of cooling stave were analyzed respectively when gas temperature inside blast furnace increased from 1000℃ to 1600℃. As shown from the results, the temperature field on cold side is under control of cooling pipes and hardly changes when gas temperature increases. The temperature gradient and changing rate with time near hot sides is greater than other regions and the later can reach to 100℃/s. The stress intensity near middle area of hot surface is up to 400MPa and that’s why there are lots of cracks at this place. The edge of stave is bended to cold side and middle regions between fixed bolts and pin moved to hot side. The displacement around fixed pin is smaller but larger on the edge and the maximum is located on hot side of top surface. The maximum displacement in Z direction is about 4mm and 3mm in Y direction. If the expansion coefficient of packing layer is 1/4, the thickness of packing layer between the cooling staves of up and down is 32mm and 24mm between sides.
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  Characteristics of Iron Droplet Ejection Caused by Gas Bubble Bursting Under Reduced Pressure

  ping lin

  中国钢铁期刊网. 2010, 17(1): 7-11.

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  Abstract: Bursting of gas bubbles on the free surface of liquid iron produces iron droplets that are ejected into the surrounding atmosphere. The influence of the freeboard pressure on gas bubble bursting was investigated by collecting and measuring the formed droplets in water and in liquid iron systems. In water modelling it was observed that gas bubbles expanded markedly during the floating up when the freeboard was evacuated but the influence of the freeboard pressure on mass of ejection is not significant when the freeboard pressure varied from 0.01 to 0.1 MPa. On the other hand, in steel melt mass of ejection increased 2-3 times when the pressure was reduced from atmospheric pressure to 66.5 Pa.
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  Activity model and its application in quarternary system CaO-FeO-SiO2-WO3

  GUO Pei-min

  中国钢铁期刊网. 2010, 17(1): 12-12.

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  The activity model of CaO-FeO-SiO2-WO3 quarternary system was established according to the coexistence theory of slag structure and the reduction thermodynamics of scheelite was discussed by applying this model. The activities of SiO2 and WO3 decrease, while that of CaO increases with increasing the basicity of slag. Among SiC, [C] and [Si] reactants, the reducing capability of SiC is the strongest, while that of [C] is the poorest at a high temperature (about 1873 K). It is advantageous to increase the yield of tungsten by increasing the content of [Si] or [C]. Oxidizability of slag has a significant effect on the yield of tungsten. Controlling of basicity and oxidizability of slag can prevent the oxidation loss of tungsten.
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  A Kind of Plate Laminar Cooling Strategy with High Response and Steady Precision

  ZHOU Na

  中国钢铁期刊网. 2010, 17(1): 18-18.

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  After Smith Predictor being used to laminar cooling system, the control law for integral regulators is introduced. New notion of plate sample length is given evading the delay time varying with the roll table speed. It is found that the integral algorithm is more controllable for system regulating process and has better steady-state precision. Compared with the traditional control strategies the new control law has faster response speed and higher steady-state precision. The controller can regulate in shorter time and response faster than routine controller and it can effectively eliminate the oscillatory instability. Owing to its easy realization and high stability, it has been applied in a plate mill. The accuracy of finish cooling temperature can be controlled in ±10℃.
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  Effect of Asymmetric Friction on Front end Curvature in Plate and Sheet Rolling Process

  Gong Wei PANG Yu-Hua Xian-bang Dong Chang-rui Liu Yong-tuan Zhao

  中国钢铁期刊网. 2010, 17(1): 22-22.

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  In this paper a formula of calculating curvature radius was deduced according to the theory of rolling combining with the characteristic of rolling process; moreover, the simulation of producing process is represented. Simulating results indicate that the curvature radius could be diminished by increasing friction coefficient, friction coefficient ratio, reduction ratio or roller radius, while be augmented by increasing the thickness of plate. Furthermore, increasing the thickness of plate would cause more effects on front end curvature, whereas reducing ratio would do less. It provides theoretic gist to eliminate the front end curvature in plate and sheet rolling industry, and it is important to protect scene controlling equipment and increase forming ratio as well.
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  Theoretical and Experimental Research on the Rolling Force in Rail Hot Rolling by Universal Mill

  DONG Yong-gang

  中国钢铁期刊网. 2010, 17(1): 27-32.

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  In rail rolling by universal mill, a simplified 3-dimention theoretical model has been built firstly. The kinematically admissible velocity field of the web, head and base of rail have been determined respectively, moreover the corresponding strain rate field and the strength of shear strain rate have been also obtained. Then the plastic deformation power of corresponding deformation zone, the powers consumed on the velocity discontinuity surface and the powers generated for backward slip and forward slip have been proposed. According to the upper-bound method, the roll force of horizontal roll and two vertical rolls can be obtained. Moreover, The process of 18kg/m light rail and 60kg/m heavy rail universal rolling have been simulated by rigid-plastic FEM(finite element method) for verifying the theoretical model. And the universal rolling experiments of 18kg/m light rail has been accomplished in Yanshan University Rolling Laboratory. Compared the results of numerical simulation and the experimental data, the roll force from upper-bound method is somewhat greater than experimental data but in general do not exceed them by 20 percent. So, it is reliable and feasible to preset and optimize the parameter of rolling technology according to the upper-bound method.
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  General Temperature Computational Method of Linear Heat Conduction Multilayer Cylinders

  CHEN Liang-yu;LI Yu

  中国钢铁期刊网. 2010, 17(1): 33-37.

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  According to the axisymmetric heat conduction of cylinder, a general method to calculate the axisymmetric temperature of linear heat conduction multilayer cylinder is deduced. Boundary conditions are summed up to four types and formulas under each type are derived. Tridiagonal linear system eouations of internal temperature are solved with pursuit method. Meanwhile, the calculating program of the simulation program is developed and the corresponding computation program and an example are given.
材料
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  Effect of Thermomechanical Controlled Processing Parameters on the Microstructure and Properties of Q460q Steel

  WANG Lei;GAO Cai-ru

  中国钢铁期刊网. 2010, 17(1): 38-43.

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  Thermal mechanical control processing (TMCP), the combination of controlled rolling and controlled cooling, provides a powerful means of developing high-strength low alloy (HSLA) steels by intensive microstructural control. In the present investigation, the effects of TMCP parameters, consisting of the finish cooling temperature and the start rolling temperature in non-recrystallization region, on the final microstructure and mechanical properties of Q460q steel have been studied by tensile, Charpy impact tests, optical microscopy. The TMCP parameters for Q460q steel have been optimized by laboratory experiments. And the microstructure and properties of industrial product were coincident with the results of laboratory experiments.
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  Texture Evolution in Ferritic Rolled Ti-IF Steel during Cold Rolling

  ZHANG Peng;GUO Yan-hui

  中国钢铁期刊网. 2010, 17(1): 44-48.

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  Texture evolution of ferritic hot rolled Ti-IF steel was investigated during cold rolling in the reduction from 15% to 85%. It was found that, α fibre intensified monotonously with the increase of the cold reduction, but γ fibre changed in a different way. As the cold reduction was in the range of 15%-35% or 45%-75%, γ fibre intensified. While the reduction was between 35%-45% or 75%-85%, the intensity of γ fibre reduced. γ fibre displayed the maximum intensity at 75% and the highest average plastic strain ratio due to the favorable recrystallization texture was obtained at this point.
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  Influence of Nb on Microstructure and Property of Low-Carbon Mn-Series air-cooled Bainitic Steel

  WANG Yong-Wei

  中国钢铁期刊网. 2010, 17(1): 49-53.

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  The effect of Nb on the microstructure evolution of low carbon Mn series air cooling bainitic steels has been discussed in this paper by using Gleeble 1500D, SEM, and TEM observation. The results show that: The amount of grain boundary allotriomorphic ferrites is relatively higher in non-Nb bearing steel than Nb-bearing steel under same deformation conditions. And the ferrites in Nb bearing steel are more finer. With the decreasing of finishing rolling temperature (FRT), the particles of Nb(CN) precipitating in Nb bearing steel are smaller and more dispersive. The properties of the Nb bearing steel is higher than that of non-Nb bearing steel at same FRT, and it is suggested that the toughness of Nb Micro-alloyed steel will be improved more effectively than that of non-Nb bearing steel with the decreasing of FRT.
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  Heat Treatment of Cold-Rolled Low-Carbon Si-Mn Dual Phase Steels

  LUO Juan-juan;SHI Wen

  中国钢铁期刊网. 2010, 17(1): 54-58.

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  The effects of over aging (OA) and vanadium on microstructure and properties of cold-rolled low-carbon Si-Mn vanadium-bearing and traditional dual-phase steel sheets are studied. The results show that the microstructure and mechanical properties of DP steels are greatly affected by over-ageing temperature. When OA below 250℃, the elongation rate increases sharply whiles both the yield strength and tensile strength decrease slightly, this is favorable to the increase of all over mechanical properties. After OA above 300℃, elongation does not increase much, but the yield strength increases and tensile strength decreases, which deteriorate the mechanical properties of the steel. Finally, the results also show that both the hardenability and the tempering stability of steel can be significantly improved by vanadium micro-alloying.
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  A New Pb-free Machinable Austenitic Stainless Steel

  LI Zhuang

  中国钢铁期刊网. 2010, 17(1): 59-63.

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  In the present paper, the machinability tests were conducted by using various processing parameters on a CA6164 lathe with a dynamometer. The metallurgical properties, machinability and mechanical properties of the developed alloy were compared with those of an austenite stainless steel 1Cr-18Ni-9Ti. The results have shown that the machinability of the austenitic stainless steels with free-cutting additives is much better than that of 1Cr-18Ni-9Ti. This is attributed to the present of machinable additives. The inclusions might be composed of MnS. Sulfur and copper addition contributes to the improvement of the machinability of austenitic stainless steel. Bismuth is an important factor to improve the machinability of austenitic stainless steel, and it has a distinct advantage over lead. The mechanical properties of the free cutting austenitic stainless steel are similar to that of 1Cr-18Ni-9Ti. A new Pb-free austenitic stainless steel with high machinability as well as satisfactory mechanical properties has been developed.
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  Influence of Aging Treatment on Precipitation Behavior of η Phase in a Ni-Co-Cr Alloy

  WAN Wen-juan;HAN Guang-wei

  中国钢铁期刊网. 2010, 17(1): 64-69.

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  The influence of aging treatment on precipitation behavior of η phase in a new Ni-Co-Cr fastener superalloy, AEREX350, was investigated by means of optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The precipitation behavior of η phase with two kinds of morphologies in this material was found to be sensitive to the temperature and time of aging treatment. Time temperature transformation curves of these two η phase were both achieved. Furthermore, diffraction patterns revealed the semi-coherent orientation relationship between η phase and γ matrix. This approach may be used to optimize the microstructure of the alloy for excellent mechanical properties.
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  Mathematical Modelling on the Microstructure Evolution of X60 Line Pipe Steel during CSP Hot Rolling

  LI Quan;LIU Zheng-dong

  中国钢铁期刊网. 2010, 17(1): 70-70.

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  An integrated process modelling system for simulating the microstructure evolution of Nb-microalloyed HSLA steel produced in CSP hot rolling process has been developed on the basis of the microstructure simulation and mechanical properties prediction technology. Thermo-mechanical coupled finite element models for simulating hot strip rolling have been developed and the distribution of equivalent plastic strain through the thickness direction in the rolled material of CSP rolling was carried out. Thus the distribution of temperature, strain and strain rate through the thickness of the steel stocks, as well as the microstructure evolution during hot rolling of X60 line pipe steel strip have been investigated by using the developed integrated process modelling system. In addition the determination and optimization of controllable process parameters during CSP hot strip rolling for the Nb-microalloyed X60 line pipe steel have been implemented, and control strategies such as adopting larger pass reduction in the first stand, and arranging appropriate pass interval times and proper rolling speed, to reduce or eliminate mixed-grains microstructure of Nb microalloyed strip in CSP processing have been proposed.