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双月刊，1985年创刊
主管：宝山钢铁股份有限公司
主办：武汉钢铁有限公司
　　　中国金属学会
主编：吴　杰
编辑出版：《炼钢》编辑部
广告经营许可证号：
　　　　武市场广登字[2020]2号
邮发代号:38-377
国外发行代号： BM1662
国内连续出版物号：CN 42-1265/TF
国际连续出版物号：ISSN 1002-1043

Table of Content

    05 August 2010, Volume 26 Issue 4
    Previous Issue    Next Issue
    生产实践
    Comparison on desulphurization effect between single bottom hole lance and double side hole lance
    2010, 26(4):  1-4,11.  doi:
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    In light of the problems existing in the process of hot metal desulphurization by injecting Mg-CaO compound, such as low end hit ratio, high Mg powder consumption, frequent slag splashing, big temperature loss and long powder injection time the structure of the lance has been revamped and a new double side hole lance adopted and the processing parameters optimized as well. As the results prominent effect has been achieved. Under the conditions of initial S content of 0.03~0.04% and final S of 0.0020% for the hot metal, the end hit ratio has been increased by 7% and Mg powder consumption decreased by 0.11kg/t, temperature loss decreased by 6℃ and injection time shortened by 2.5 minutes and in the meanwhile the cost for desulphurization has been largely reduced.

    Practice of hot meatal desiliconizing by injecting ferrous powder
    2010, 26(4):  5-7,23.  doi:
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    The ferrous powder is injected into the violently stirring hot metal by exploiting the natural agitating kinetic energy of the tapping hot metal from the hot metal mixer. Thanks to the favorable reduction atmosphere and stirring the ferrous element in the powder has been reduced by 100 % and Si element in the hot metal partially reduced. Automatic control technology has been adopted in the process of hot metal desiliconizing and “one key” operation realized and the new process has been successfully applied in the 50 ton ladle at No.1 Steel-making plant of Jinan Iron & Steel Co., Ltd., thus providing technological support for application of the ferrous powder in the iron & steel plant.
    2010, 26(4):  8-11.  doi:
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    In light of the problem of excessive fluctuation of the end-point carbon-oxygen equilibrium at the two 150 t converters in the steel-making plant of meishan iron & steel Co., Ltd., the factors affecting the end-point carbon-oxygen equilibrium have been analyzed from view points of thermodynamics and dynamics. Results show that the bottom blowing, thickness of furnace and the final position of the lance are three primary causes to the excessive fluctuation of carbon-oxygen equilibrium. The limit of fluctuation is prominently reduced (within the range of 0.002 2～0.002 8) since adoption of appropriate control measures)
    2010, 26(4):  12-15.  doi:
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    By installation of a set of side blown elements on the wall of the 30t top-bottom combined blown converter bath the top-bottom-side blown converter is formed and through simulation experiments in the laboratory the mixing time of the converter bath for different blow stirring technologies are measured. Results show that best effect is obtained by top-bottom-side blown process and the mixing time of the bath for the new technology is reduced by 65% in comparison with the original top-bottom process and the mixing time of the bath shows the law of top-bottom-side blow＜top-side blow＜bottom blow exclusively＜top-bottom combined blow＜top blow exclusively. The industrial scale experiment of this technology is firstly carried out at the 30t top-bottom combined blown converter of the Steel-making Plant of Sanming Iron & Steel Group Corp., by installing a set of side blow tuyeres on the side wall of the converter bath. Results demonstrate that the TBS blown converter possesses lower [%C]×[%O], better dephosphorization degree, and quicker decarburization rate. The side tuyeres are observable during the whole TBS blowing campaign and the metallurgical technique indexes are improved greatly.
    2010, 26(4):  16-19.  doi:
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    In order to solve the problems of dilute slag, high oxidation and surging of slag at the mouth of furnace in converter tapping without turn-down of the furnace, 500 to 1000kg cold slag and 50 to 200 kg carbonaceous materials have to be charged into the furnace at the end-point of converter blowing so as to achieve the purpose of pressing slag, thickening slag and tapping without turn-down of furnace. In comparison with the conventional process by adoption of the new one the deslagging quantity is reduced, [P] decreased by 0.004 %, [S] increased by 0.001 %, consumption of deoxidizer and alloy cut down by 62 kg/heat, erosion rate of furnace lining dropped down by 0.1mm/heat, consumption of furnace materials for furnace protection by slag splashing reduced by 200 to 300 kg/heat and the slag splashing time shortened by 1.0 to 1.5 min and thus better results of furnace protection by slag splashing have been achieved. By introduction of the new technology not only the raw materials are saved and the liquid steel quality improved, but a new approach to the comprehensive utilization of the steel slag resource also developed
    2010, 26(4):  20-23.  doi:
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    The present paper analyzes the causes to breakout of the continuous casting machine in the No.1 Steel-making Plant of Rizhao Iron ＆ Steel Co.,Ltd., including the equipment, process parameters, compositions of molten steel, mould powder performance and operating condition. The corresponding measures have been taken and good effect achieved.
    Causes of longitudinal surface cracks on wide continuous casting slab and control measures
    2010, 26(4):  24-27.  doi:
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    In light of the actual conditions that longitudinal surface crack on the wide CC slab as well as the longitudinal crack on the rolled sheet products frequently occur in the wide continuous caster of the No3 Steel-making Plant of Shaoguan Iron & Steel Co., Ltd, the present paper analyzes the real causes to the formation of those defects. The longitudinal surface cracks on the slab have been improved significantly and the occurrence rate of the longitudinal surface crack on the slab is reduced to 0.46 % from original 4.98 % and the comprehensive qualified rate of the rolled stock raised to 99 % from 87.5 % since appropriate counter measures were taken in the Plant.
    2010, 26(4):  28-32.  doi:
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    The present paper introduces the process design and production practice of Q370qE bridge steel plate and points out that controlling the carbon equivalent ≤0.425%, Nb microalloying and strictly controlling the [P] and [S] contents are key to the processing schedule. It also studies and analyzes the effect of various processing factors on the properties of the steel plates in the production of Q370qE bridge steel plate by 120tLD-LF-VD-CC process route. Practice results indicate that quality of the Q370qE bridge steel produced by this process is completely in conformity with the requirements of technological agreement and the economical and social benefits are also prominent.
    试验研究
    Experimental study on reduction of MoO3 by pure liquid iron
    2010, 26(4):  33-36，5.  doi:
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    The experimental study on reduction of MoO3 by pure liquid iron was carried out in the lab by the comparison of reduction effects with various feeding modes and different process parameters of the end-point refining of converter. The results show that MoO3 can be reduced and absorbed quickly by pure liquid iron. MoO3 reduction can be completed in a few minutes and molybdenum yield may come up to 96% when MoO3 powder is first fed on the surface of liquid iron and slags followed. The MoO3 final reduction ratio is above 95% under all feeding modes. Under the mode of admixture adding both the MoO3 reduction rate and final reduction ratio increase or show a tendency to increase with increase of temperature and decrease of w(FeO) whereas slag basicity has no effect on them.
    2010, 26(4):  37-39，5.  doi:
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    In order to realize the purpose of refining the low sulphur and even extra-low sulpur steel and optimally control the chemical compositions and properties of the ladle slag the optimal chemical compositions and feeding schedule of the refining flux for low sulphur steel production , the feeding schedule of the modifier for the ladle slag as well as the relative ladle bottom argon blowing regime have been developed and the technologies for refining the low sulphur steel optimized on the basis of taking full consideration of the influence of the converter tapping, the slag oxidability and the oxygen activity on the chemical compositions and properties of the ladle slag. As the results the sulfur content in steel as low as 6.6×10-6~40×10-6 is achieved in the production of low sulfur steel.
    2010, 26(4):  40-42.  doi:
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    By means of lead sinking method measurements were made on the end position and section shape of liquid core of CC bloom under various casting speed and carbon content conditions. Results show that the length of the liquid core extends with the increase of the casting speed and the carbon content and by and large the longitudinal section and the cross section of the liquid core are “V” shaped and “O” shaped respectively. The X-ray intensity test further proved the existence of the solid/liquid dual phase along the outside of the liquid core and the heterogeneity during bloom solidification. The measurement results can be used as the important technical basis for optimizing the secondary cooling schedule and the dynamic soft reduction process parameters
    2010, 26(4):  43-45，4.  doi:
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    The present article introduces the principle of the forecast modeling for alumina inclusion in clean steel. A forecast model is built for forecasting the content and granularity of the alumina inclusions on the basis of PDA electro-optical direct reading spectrometer，and the newly developed model is applied to IF steel refining. Results show that the model in possession of considerable accuracy is of greater significance in guiding the production of the IF steel. In the meanwhile it offers theoretical basis for development of the inclusion forecast model of the similar kind.
    2010, 26(4):  46-49.  doi:
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    There exist some problems in the process of low alloy steel casting and calcium treatment at PISCO (Panzhihua Iron & Steel Co.). For the sake of problems solution, effective measures have been taken such as improvement of slag property, increase and stabilization of calcium content and the ratio of w(Ca)/w(AlS)in molten steel, and so on. On this basis, nozzle clogging and unsteady flow in casting process of low alloy steel have been resolved successfully and the casting property has been improved as well. Furthermore, non-metallic inclusion content in molten steel was reduced and steel quality improved effectively.

    High temperature ductility of SCM435 continuous cast slab

    2010, 26(4):  50-54.  doi:30
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    High temperature ductility of SCM435 continuous cast slabs is investigated through high temperature tensile test on GLEEBLE-1500 hot simulator and observation of the fracture and microstructure of the tensile sample made by optical microscope and scanning electron microscope. Results indicate that the section shrinkage rate of steel SCM435 at 1000 to 1200 ℃ is more than 60% and its ductility is excellent. In the material exist two brittle temperature zones with shrinkage rate less than 60% and their brittle temperature ranges are approximately controlled within the melting points of 1350℃ and 1000～750 ℃ respectively. Therefore it’s imperative to avoid those zones or stay in the zones as less as possible in drawing up the continuous casting and hot rolling schedules.

    <P class=MsoNormal style=
    2010, 26(4):  55-59.  doi:
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    Study on the effect of various cooling rates on the solidification structure and phosphorus macrosegregation of the weather resistant steel has been made by utilizing alumina temperature holding mould, steel mould and water cooling copper mould. Results show that accelerated cooling may refine the cylindrical crystal and equiaxed crystal and effectively diminish the macrosegregation of phosphorus at the same time. In order to further study the mechanism of effect of the cooling rate on the phosphorus macrosegregation of weather resistant steel directional solidification samples of various pulling speed are prepared by the directional solidification equipments and at the same time the mushy zone is analyzed by the electron probe. And in the end the solute distribution coefficients of phosphorus of weather resistant steel sample with different cooling rates are determined. Study shows that the grain size can be refined, the musy zone widened, the concentration of the solute in the mushy zone reduced and the solute distribution coefficient of phosphorus in the weather resistant steel enlarged.The macrosegregation of phosphorus in the weather resistant steel is prominently lowered as well.
    Temperature prediction model in RH-TB refining process
    2010, 26(4):  60-62.  doi:
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    A hot metal temperature prediction model for RH-TB refining is established according to the hot metal thermal equilibrium theory in comprehensive consideration with various factors such as oxygen blowing, alloy adding, vacuum chamber and ladle condition and in combination with the artificial neural network algorithm and industrial data. For 120 heats of RH-TB processed IF steel ( temperature measured per heat) those with temperature difference of ±5℃ between the model off-line calculated value and actual measured value take up more than 85% of the total, and at the same juncture the software of RH-TB refining temperature prediction model is developed by means of Microsoft Visual.Basic.net program design software and Microsoft SQL Server 2000 database software and very desirable results have been achieved in application of the software in the actual production.
    辅助技术、材料及设备
    2010, 26(4):  63-66.  doi:
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    Certain molten states of the high basicity covering flux for tundish were studied in this paper. The thermal simulation results show that it is more appropriate for the molten samples cotaining10 % to 12 % Na2CO3 and CaF2 (WN+C); and its initial melting temperature is lower than 1350℃. When the value of R=(CaO+MgO)/(SiO2+Al2O3) is about 2.5 and the value of WN+C·R is 0.2 ~0.3, molten samples have best wetting performance for the MgO container. The value of R·WF·WCO2/WN+C may influence on the heat insulation of covering flux, and is linearly correlated with the average thickness of molten sample.
    Influence of magnesia-calcium tundish coating on total oxygen content of IF steel
    2010, 26(4):  67-69，7.  doi:
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    The change of oxygen content of IF steel in the lining of magnesia-calcium coating was investigated from start to the end of melting. The reacted layer of coating and liquid steel was studied by SEM and EDS. It is found that three areas are formed after the steel contacts with the refractory for a certain time. With the extension of smelting time the total oxygen content of IF steel increases gradually and reaches maximum after 120 minutes, then the total oxygen content begins to decline.
    2010, 26(4):  70-74.  doi:
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    The behavior of carbon thermal reduction of the converter slag is studied by microwave
    heating at 1100 to 1400℃。 Results show that Fe-C alloy in10~20mm diameter can be obtained in the microwave field by use of steel slag with addition of appropriate carbon reductive agent. The higher the carbon equivalent, the higher the temperature, the smaller the particle size and the longer the holding time, the higher the content of the reduced Fe and P will be. The effect of reduction can be improved by increasing the SiO2content in the slag. Study also confirms the promotion role of the microwave field to the reduction reaction. Under the low temperature condition dephosphorization by steel slag is realized and the the dephosphorization rate reaches as high as 91.5 %.
    综 述
    2010, 26(4):  75-78.  doi:
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    The technologies to control the content of N in the liquid steel during the latter blowing period of BOF process in some steelmaking works in Japan are introduced. The lower content of N than 0.0015% can be obtained by optimizing bottom blowing process, increasing slag foaming height during the latter period of blowing, and controlling the positive pressure of the converter interior at the blowing end point. Moreover, the control level of the content of N of liquid steel at the blowing end point between the steelmaking works in China and those in Japan is compared.