Steelmaking

Practice of oxygen blow in 250 t converter refining

LU Kai;CHEN Nian-you

2008, 24(05): 1-4. doi:

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The present pasper introduces the information about appropriate use of oxygen in the converter of No.3 Steel-making Plant of WISCO. By selection of suitable nozzle of the oxygen lance and reasonable processing parameters of the oxygen blow for the converter and by optimization persistently of the position control of the oxygen lance as well as the slagging schedule in the process of the converter refining the end point control of the converter and all the technical and economical indicators have been prominently improved.

Effect of CaO-CaF2 on properties of ladle refining slag

LI Bo;ZHANG Xue-jun;WANG Hong-ming

2008, 24(05): 5-8. doi:

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To reduce slag sticking to the snorkel during ladle alloying process, CaO-CaF2 (mass ratio 2:1) was employed to modify the ladle slag. The effects of modifier on the properties of ladle slag were investigated. The results show that the melting temperature and viscosity of slag are decreased effectively. By adding 10% CaO-CaF2,the melting temperature of slag is decreased from 1 439 ℃ to 1 400 ℃. At 1 500 ℃,the viscosity of ladle slag without modifier is 6.5 Pa•s, whereas the viscosity of modified slag is decreased lower than 2 Pa•s. The results of experiments on sulfur and phosphorus partition equilibrium between metal and slag indicate that the sulfur content can be further decreased by the modified slag,whereas slight rephosphorization occurs.. The results of test in practice, the slag sticking to the snorkel has been reduced by the slag modification. The operation life of snorkel is doubled.

Cause analysis on breakout of slab continuous caster due to sticking of Solidified shell

Lian Lei

2008, 24(05): 9-12,4. doi:

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The present article carefully analyzes and studies the problem of breakout due to sticking of the solidified shell in the production of 1300mm slab caster of MeiShan Iron and Steel Co Ltd ，finds out the specific cause of conglutinating breakout during casting process and works out preventive measures in order to ensure smooth production of the slab casting in MeiShan.

Study on liquid steel temperature control technology under the 100% continuous casting codition

FENG Yuan-chao

2008, 24(05): 13-16,2. doi:

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By investigaing in and analyzing on the law of variation of the process temperature of the liquid steel and its influencing factors of the slab continuous caster prior to its being put into commissioning of 100% continuous casting in PanGang the hot metal process temperature control pattern under the 100% continuous casting condition has been established. Moreover this schedule has been optimized and improvized in light of the results of application and problems existing on-site.

Practice on extend in mold copper life of high casting speed slab caster

Wang yu-min

2008, 24(05): 17-18,4. doi:

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The defects such as peeling off and chapping of the meniscus coating frequently occur in the high casting speed mold copper plate of the high drawing speed medium-thin slab caster and such phenomena are seldom seen in the conventional continuous caster. On the basis of analysis on the current control data and processing conditions the real causes to the defects have been found out and counter measures put forward and executed。The life of mold copper have been increased largely。

Control of Non-metal Inclusion in Ultra-low Oxygen Spring Steel

LI Hai-bo;WANG Xin-hua;ZHANG Wei;YANG Wei-zhong;ZHOU De-guang

2008, 24(05): 19-22. doi:

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To make the non-metal inclusion less harmful for aluminum killed steel the deoxidized products Al2O3 Inclusions should be transformed to low melting point calcium-aluminate inclusions through reactions between steel and slag as well as steel and inclusion.The following points have to be made clear: firstly if the (CaO/MgO) ratio of the slag is large the inclusions in the hot metal are very easily transformed into the Al2O3 inclusions; the second one in the medium stage of LF refining when (CaO/MgO) ratio of the slag is larger than 8 the inclusions are promptly transformed into calcium-aluminate from MgO•Al2O3; the third one, the oxidation of slag (FeO+MnO) can delay the transformation of inclusions into the calcium-aluminate; and the fourth the inclusions can easily be controlled in the low melting area of the CaO-Al2O3-CaS ternary phase diagram only if [Al%] and [S%] are controlled in a very small margin; and the last, along with the reduction of the total oxygen in steel the proportion of oxide inclusions reduces and CaS proportion increases.

Research on model for optimization of converter burden ratio

SUN Zong-hui;SUN Shou-xiang

2008, 24(05): 23-24,2. doi:

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Based on the analysis on metallurgical effects of converter charge and the steelmaking principle,the model of linear programming on burden ratio is obtained and the optimum metal burden ratio for converter is found out,providing a theoretical base for improvement in the economical of the steel-making.

Experimental Rresearch of Hot Metal Pre-treatment dephosphorizer

WEI Ying-juan;YUAN Shou-qian;ZHANG Xi-feng;GU Kun-wen;Liang De-an;ZHANG Qi-ye

2008, 24(05): 25-28. doi:

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In the experimental research of hot metal pre-tratment dephosphorizer consisting of CaO-oxide scale-CaF2, it is proved that both pre-melted dephosphorizer and solid synthesis dephosphorizer can reduce the P-content to less than 0.02%. In the meanwhile the pre-melted dephosphorizer has the advantages of high dephosphorizing ratio and high slag-forming rate, short per-treatment time (in 5 minutes the P-content can be dephosphorized to a relatively low level and further more the temperature drop of molten iron is of insignificance and the dephosphorization efficiency is very high. Therefore it can be used as a high efficient, high speed and an environmental friendly dephosphorizer.

Preliminary experiments on fast absorption of CO2 by steel slag of converter

DONG Xiao-dan

2008, 24(05): 29-32. doi:

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Since the converter steel slag contains a large quantity of strong basic free calcium oxides volume expansion may occur as soon as it is in contact with water.For this reason fracture may take place frequently due to the volume expansion if it is used as the building materials. Therefore the existence of large quantity of the free calcium oxides in the slag has already been the bottle neck in application of the converter slag. The present paper studies how to epeedily modify the converter steel slag in various grain sizes under the conditions of temperatures 350 to 800℃,reaction time duration 0.5 to3 hours and the volume fraction of CO2 20 to 80% in order to transform the free calcium oxides in large quantity in the steel slag into the carbonates and achieve the purpose of volume stabilization and weakening of the basicity of the slag. As he results the effective application of the converter steel slag will have a very broad prospect.

Numerical simulation of magnetic field and flow field in electromagnetic stirring in ladle furnace

HUANG Jun;WANG Bao-feng;LI Jian-chao;ZHAO Li-ping

2008, 24(05): 33-36,5. doi:

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Electromagnetic stirring in ladle furnace (LF-EMS) is an important stirring means of ladle furnace refining process. The magnetic field and flow field of a 90 t LF-EMS in a specific steel-makinfg plant are studied by numerical simulation in this paper. It is found that the melt flow turns to be a large and single loop in ladle furnace under the action of the electromagnetic stirring. The distribution of velocity and turbulent kinetic energy in ladle furnace is homogeneous.

Analysis of the microstructure of ladle slag building-up

Li ji-zheng;Wu Yuan-bing;Zhang hong-lei;Liu li

2008, 24(05): 37-39,6. doi:

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By petrographic analysis the microstructure characteristics of ladle slag building-up has been researched and the process and mechanism of the ladle slag building-up discussed. The result shows that the CaO in the steel slag is reacted with aluminium oxide in the bricks to form the CA6 and CA2 ; the steel slag with high content of Al2O3 and MgO is easier to attach to the brick; and the primary cause to the slag building-up is found to be occurrence of phases with high melting-point from reaction between the slag and lining of the ladle.

Research of high temperature mechanical properties for as-cast steel of thin slab

Wang Ying-chu;Zhang Li;Fang yuan

2008, 24(05): 40-44. doi:

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In order to improve the simulation precision and provide a high temperature stress-strain model for the structure of rolled stock with liquid core in the thin slab rolling process, the as-cast steeel 20 samples along columnar crystal direction were selected to perform the high temperature compressing experiment according to the special characteristics of technology. The test temperatures adopted are 900 ℃、1 100 ℃、1 200 ℃ and 1 250 ℃ and the strain rates, 0.001/s、0.005/s、0.01/s and 0.05/s respectively. The rheological behavior and influence of temperature and strain rate on the rheological stress of material were analyzed in the investigation. In the meanwhile the relation model of stress and strain of material thermal deformation were studied by multivariate nonlinear regression so as to provide a precise material model for the succedent rolling process simulation.

Analysis of flow and solidification characteristics in front of nip point during twin-roll casting process

JI Chen-xi;ZHANG Jiong-ming;WANG Xin-hua

2008, 24(05): 45-48. doi:

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With the special continuous casting simulation software Calcosoft, the temperature field and flow field of twin-roll strip casting was simulated. Flow of liquid steel above the nip point was specially studied. Combined with the study on solidification microstructure, effect of flow on the microstructure was analysed. It is concluded that the most ideal processing condition.is to control the flow of the nip point liquid steel in the coherent zone.

Features and influence factors of stuffing sand used for ladle

ZHU Hong-xi;DENG Cheng-ji;BAI Chen;ZHANG Wei-gang

2008, 24(05): 49-53. doi:

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Based on the slide gate packing technology the present paper reviews and analyzes the factors affecting the performance of the stuffing material, the real load the stuff bears, categories of materials and the other relative factors, discusses the problems around the relationship between the materials features and usage na puts forward the method for optimization of stuffing sand usage as well as the related control parameters.

A new Fuzzy-PID based C C mold level control method

ZHANG Hui-xiang;MENG Xiang-ning;ZHU Miao-yong

2008, 24(05): 54-57. doi:

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In order to solve the problem of severe liquid level fluctuation in the mold in the process of transient casting the present paper puts forward a composite control srategy which combines the Fuzzy control with the PID control in view of the characteristics of the parallel structure of the fuzzy controller and the PID hybrid controller and then designs out the relative modules to solve the problems of the disturbance and time variation of the system. The results of simulation well demonstrate the feasibility and availability of the design method.

Summary of methods for shrinkage of Fe-C alloy during peritectic phase transformation

GAO Zhong;ZHANG Xing-zhong;YAO Shu-fang

2008, 24(05): 58-62. doi:

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In production, steel with carbon content around 0.10 wt% strongly shrinks because of peritectic phase transformation leading to more serious cracks on slab than that on the other carbon containing steel slab. Relationship between cracks on slab and shrinkage of Iron-Carbon alloy during phase peritectic transformation are analysed and some methods and reseach progress on the shrinkage of Iron-Carbon alloy during peritectic phase transformation introduced, in the paper.

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