Steelmaking

Development and application of Compound dephosphorizer for converter refining

ZENG Jing-hua;ZHANG Min;YANG Su-bo;GE Wen-sun;LIU Xin

2007, 23(06): 1-4. doi:

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In light of the actual condition in Pangang Group the high efficient compound dephosphorizer is developed by use of the dephosphorizing technology “single slag process” in converter smelting. By application of this process the average dephosphorizing ratio reaches 89.41%, which is almost the same as that by the dephosphorizing technology “double slag process” in converter pretreatment and the phosphorus in the finished product in trial heat is less than 0.015%, and in the meanwhile the smelting period remains the same as ever before. The new technology can be used as effective technological support for consistently producing such a few steel grades as 350km/h high speed rail and so on for high speed railway purpose.

Application of RH oxygen top-blowing technology in No.2 steel-making Plant,WISCO

LI Dam-ing;ZHANG Wen-hui;LIN Li-ping;LIU Liang-tian

2007, 23(06): 5-9. doi:

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This paper presents devices,opration techniques and application of RH oxygen top-blowing technology in No.2 steelworks WISCO. The RH oxygen top-blowing technology performs multi-functions such as decarbonizing,increasing temperature with Al added,cleaning slag in RH vacuum slot,etc.In steel-making process,the technology could decrease the product cost,increase the yield rate of metal,enlarge product scale in converter steelworks and optimize completely continous casting production.

The BOF high efficient blowing process using on CSP cold rolling sheet producing

SHEN Chang; PAN Yuan-wang;TAO Cheng-gang;ZHONG Liang-zhi

2007, 23(06): 10-11,1. doi:

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The optimizing of LD process was discussed in this paper due to the high demand of [C],[P],[S] and steel cleanness on CSP cold rolling sheet and the unmatched convert cycle time with the CSP cycle time. Through optimizing the process model, the end [P],[S] a[O] were reduced, the end [C] and Temp. hitting ratio was increased, and the process of directly tapping was developed, the cycle time of convert and CSP was matched. In 2006 1.63 million ton cold rolled sheets was produced, nearly 69 % of the total output of CSP.

Analysis on resulphurization in the process of hot metal desulphurization in No.3 Steel-making Plant in Hangang

PAN Shu-min;DONG Jin-qiang;JU Jian-Tao;WANG Yu-sheng;CHANG Li-shan;GAO Wei-gang

2007, 23(06): 12-15. doi:

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By analyzing factors causing to the hot metal resulfurization in the process of hot-metal desulphuriztion in converter refining the main reasons for resulfurization are determined to be primarily the inconsistency of the sulphur content in the hot metal, variation of alkalinity of final slag, existence of slag remainder in converter and hot-metal residue in the ladle. The proper measures are suggested in order to reduce resulfurization in refining low sulfur steel.

Analysis on causes to corner cracks in Q345B continuous casting slab

XIN Jian-qing;YUE Er-bin

2007, 23(06): 16-19. doi:

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The mechanical property of steel Q345B at elevated temperature is tested and the type of the precipitates existing at the cracks identified and thereupon cause to formation of the corner cracks analyzed and the processing measures to eliminate the defect accordingly put forward.

Study on mechanism of nozzle clogging in slab continuous casting of liquid steel refined by CAS－OB

WANG Xiao-feng;CHEN Wei-qing;PEI Feng-juan;HOU Cheng

2007, 23(06): 20-22,2. doi:

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Though the phase composition analysis of nozzle clogging samples from slab continuous casting and the inclusion detection in steel, the clogging mechanisms of submerged nozzle and long nozzle as well as slide gate have been studied by means of SEM. It‘s found that CaO•Al2O3 and CaS are the phases of submerged nozzle clogging, and CaO•2Al2O3 is that of long nozzle and slide gate clogging. Results show that it’s precipitation and adherence of the similar type of inclusions in steel to the inside wall of nozzle that causes to the nozzle clogging. The influences of m(Ca)/m(Al) and [S], [Al] contents in steel on nozzle clogging are discussed. For preventing nozzle clogging, it is suggested that the contents of [S], [Al] should be controlled below the curve of 12CaO•7Al2O3 creation and keep m(Ca)/m(Al) more than 0.13.

Research and development of solidification and heat transfer model for baosteel 1930 mm slab continuous casting

MEI Feng;RUAN Xiao-ming;WEN Guang-hua;TANG Ping;HAN Zhi-wei

2007, 23(06): 23-27. doi:

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Based on the theory of two-dimensional non-steady-state heat transfer model and the law of heat dissipation in the secondary cooling zone of continuous casting, the heat transfer process in between the neighboring pinch rolls is divided into four different processes, namely heat transfers (1) by pinch roll contact, (2) by steam evaporation, (3) by water flushing and (4) by radiation. In light of the current condition of Baosteel 1930 mm slab caster, the mathematical model of solidification and heat transfer in slab continuous casting has been developed. By using the object-oriented computer language Visual Basic 6.0, the computer simulation software of secondary cooling in slab continuous casting has been developed. The infrared ray temperature measurement has been conducted to validate the results of model. The difference between the measured slab temperature and calculated one is less than 20℃,and the deviation range is well controlled within 1.0 %～2.5 %. All this shows that the simulation model and results are good and reliable. By using the simulation software, the secondary cooling system of Baosteel 1930 mm slab caster can be researched and optimized for guiding the practical production.

Research on inclusions in billet continuous casting of steel ML08Al

LIANG Fu-bin;LIU Xin-sheng

2007, 23(06): 28-31,4. doi:

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In refining the cold heading steel ML08Al in a converter, shapes and behavior of the non-metallic inclusions have been improved and the quality of the steel raised by optimization of refining processes, particularly by examination of the continuous casting slab and thoroughly investigation in the morphology and behavior of the non-metallic inclusions in the cold heading slab ML08Al. In the meanwhile measures and methods to improve the quality of the products and cleanliness of the steel have been put forward.

Effects of antioxidant additive on carbon pickup of ULC steel from Al2O3-C refractory

RUAN Guo-zhi;;LI Nan;ZHANG Zhi-hui;

2007, 23(06): 32-35. doi:

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The effect of carbon containing refractory on the carbon pickup of ultra-low carbon steel (ULC) has been studied in an intermediate frequency induction furnace. In the experiments an Al2O3-C crucible is prepared using the white fused alumina and flake graphite as the starting materials with addition of various antioxidant. Results of the study show that carbon pickup of the liquid steel due to carbon bearing refractory can be very effectively prevented against by addition of certain antioxidant additives into the refractory materials. In adding different kinds of antioxidants to the refractory it’s demonstrated that the best preventative effect is shown on Al, and better is on Si and the worst is on SiC. The primary reason for the preventative effect of the antioxidant additive on the carbon pickup is found to be that by addition of the antioxidant additives the preventability of the refractory against hot metal infiltration as well as corrosion resistance of the refractory can be improved and in the meanwhile the diffusion of carbon in the hot metal has been reduced due to an increase in the viscosity of the hot metal.

Water model study on mixing time in a 210 t ladle in the CAS process

JIN You-lin;BAO Yan-ping;YUE Feng;ZHANG Ting;CUI Heng

2007, 23(06): 36-39. doi:

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In the present paper effects of the nozzle position variation, the flow rate of the bottom blow and the submerging depth of the submerged tube on the mixing status of the hot metal in the 210t ladle in the process of C.A.S refining have been studied and the law of influence of those parameters on the mixture of the hot metal found out by hydraulic model experiments in a specific Steel-making Plant in the Country. Taking into full considerations of the phenomena occurring in the water modeling and other factors the optimal technology parameters for the 21t ladle are obtained as below: the position of nozzle approximately (0.5~0.6)r, the flow rate of bottom blowing approximately 500～600 L/min and the submerging depth of submerged tube about 200mm.

Development and application of hollow core copper pipe electromagnetic stirrer in continuous bloom casting

CHEN Yong;; WU Guo-rong;LEI Guo-ao

2007, 23(06): 40-42,5. doi:

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The hollow core copper pipe mold electromagnetic stirrer (M-EMS) for continuous bloom casting developed by Chengdu Oriental Leishen Standard Electric Implement Ltd. is of superior performance in both insulation and heat insulation. The insulation resistances of M-EMS coil are 3.4 MΩ and 690 MΩ with and without cooling water flow over respectively. When the heat dissipation between M-EMS coil and cooling water comes to 136.4Kw and the current to 500A the magnetic flux density of M-EMS rises to 536Gs. Production practice shows that subsurface blow-hole and subsurface inclusion of rail bloom produced by application of the M-EMS are ≤0.5, central porosity ≤1.0 and moreover of all rail blooms produced those with ≤0.5 central porosity takes up 98.98%, and central segregation index of carbon is ≤1.05. The results achieved in the research have laid an important foundation for further improvement in the rail bloom quality.

Model of Prediction for The Terminal Temperature of Molten Steel in LF Refining

WU Xiao-dong;LIU Xu-lan;ZHENG Jian-zhong

2007, 23(06): 43-46. doi:

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Based on multi-component regression analysis, the model of prediction for the terminal temperature of molten steel in LF refining of No.1 steel plant of Baosteel has been established: The model had been used to predict the terminal temperature in LF refining. And there results of statistic analysis on prediction temperature showed that the hitting probability of prediction deviation of ±10 ℃ was 90 %.

Improvement in second cooling control of slab continuous casting by data mining technology

YAO Geng-yun;WANG Chang-song;XUE Jian-guo;ZHAO Shi-wei

2007, 23(06): 47-50,5. doi:

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In this paper, a data mart has been constructed based on the practical data of the continuous casting process in a specific domestic steel plant The influence of superheat fluctuation is fed into the second cooling control model as the feed-forward signal and the data mining technology is applied to improve the original drawing speed cascade control model in the PLC. Comparing the original drawing speed cascade control model with the two improvised superheat feed-forward control models it’s obviously clear that the latter models are superior over the former one according to the result of statistic analysis.

Study on fracture and intermediate temperature low cycle fatigue property of ladle shell material SM490B

ZHANG Li;XU Hong;CUI Jian-jun;LIAO Li-bao

2007, 23(06): 51-54. doi:

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Tests on fracture toughness and fatigue crack growth rate at room temperature and low-cycle fatigue at 350℃ (maximum service temperature of ladle shell) were carried out for new-type ladle shell material SM490B. The results show that the strength and fracture toughness of SM490B steel are much higher than that of SM41A and 20g steel used before. Compared with above-mentioned two materials, fatigue crack growth rate of SM490B steel is relatively higher at the stress intensity factor range in the test. The low cycle fatigue life of SM490B steel at 350 ℃ is longer than that of 16MnR steel at 300 ℃. Using SM490B steel as ladle material will reduce the possibility of cracking of ladle shell, prolong lifetime and enhance application safety of new-type ladle.

Generation of Oxidized Round Spot in Isothermal Condition

PENG Kai;LIU Ya-zheng;XIE Bin

2007, 23(06): 55-57. doi:

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The effects of temperature and soaking time on generation of the oxidized round spot of silicon steel have been studied in order to determine the forming procedure of it .It is inferred that the oxidized round spot could very possibly occur in the process of rough rolling in consideration to the on-site hot rolling process. The regression relation between temperature, soaking time and oxidized round spot layer is deduced based on Wagner’s internal oxidation dynamics equation and the oxidized round spot layer during the on-site hot rolling process is calculated by the regression equation.

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