钢铁钒钛

Numerical Simulation on Heat Equilibrium of BF COG Injection

Li Haokun, Liu Keming, Sha Yongzhi

2011, 32(1): 1-5.

Abstract(30) PDF(2)

Abstract:
Based on the material balance and heat balance,according to lager-scale blast furnace production data,mathematical model on blast furnace with coke oven gas injection is established.The effects of COG(coke oven gas) injection quantity on theoretical combustion temperature,BF bosh gas volume,BF bosh gas composition and hearth total heat have been analyzed through theoretical calculation in this paper.These studies will provide the basis for the comprehensive evaluation of the feasibility of the new COG injection process.

Simulation Experiment of Blast Furnace Shaft Reduction in the Condition of Oxygen Enrichment

Guo Weixing, Zhang Jianliang, Chen Yongxing, Kong Dewen, Wu Zhihong

2011, 32(1): 6-10.

Abstract(24) PDF(2)

Abstract:
The variation regularity of ore indirect reduction degree with different oxygen enrichment is researched through experiment simulation.The results of the experiment indicate that the indirect reduction degree increases with the increase of oxygen enrichment ratio,and the improvement of blast furnace shaft reduction is because of oxygen enrichment injection happening more than 700℃.The reduction degree is up to 89.92% and 98.49% while oxygen content is 45% and 100% at 900℃,which exceeds the reduction degree at 1 000℃ with unenriched oxygen content.

Influence of Control of the Lower Zone on Burden Motion in Blast Furnace by DEM

Zhang Jianliang, Fan Zhengyun, Chen Yongxing, Yang Guangqing, Yang Tianjun, You Shandalang

2011, 32(1): 11-16.

Abstract(23) PDF(1)

Abstract:
The behaviour of solid flow in 4 000 m³ blast furnace was investigated by 3D-discrete element method.It is found that the increase of blast momentum and depth of raceway would not influence the structure and distribution of burden layer in the upper side of blast furnace.However,the decrease in size of deadman results in the weakness of supporting effect of deadman and the increase of the velocity of burden descending in the upper part which enhances the smelting strength of blast furnace.The velocity and stress of burden tend to uniformity in the 2 m zone above tuyere level.The operation of clogged tuyere leads to the decrease of velocity and increase of stress in the vicinity of the clogged tuyere.The influence is limited in the zone below belly of blast furnace.

Research on the Preparation of Welding Rod Coating Using Ilmenite Carbothermic Reduction

Lei Ying, Li Yu, Peng Jinhui, Li Wei, Guo Shenghui

2011, 32(1): 17-22.

Abstract(15) PDF(1)

Abstract:
The preparation process of welding rod coating by ilmenite carbothermal reduction was investigated.When the conditions are oxidized temperature 850~900℃,content of composite additive 3%~5%,reduce temperature 1 100~1 150℃ and roast time 240~270 min,it can be obtained for the reduced ilmenite of which TiO 2 more than 52%,FeO less than 5%,and the harmful elements of C,S,P all less than 0.03%.Phase,morphology and compositions of ilmenite were analyzed by XRD、SEM、EDS and TGA,and the results indicated that oxidized roast and present of composite additive can change the crystal construction of ilmenite,making the mineral porous and increasing the reduction reaction rate and reduce reduction temperature.The SEM and EDS results showed that a good appearance of reduced ilmenite is obtained,which almost contains no harmful elements such as C,S and P.

Cause Analysis of Fracture for TB5 Slab

Huang Deming, Yang Xiongfei, Wei Qingfeng, Wang Huailiu, Zhou Maohua, Chen Xin, Zhao Tongxin, Xu Cong

2011, 32(1): 23-28.

Abstract(16) PDF(1)

Abstract:
Chemical composition,fracture features and microstructure of TB5 slab were investigated.The results indicated that chemical compositions of slab are uniform and meet the national requirements.The fracture feature of slab was cleavage or quasi-cleavage.There were precipitated phases in the fracture,but no inclusions in it.The microstructure of slab was rough equiaxed grains,in which there are long needle-like precipitation phases,and the distribution of the phases are uniform.The analysis results showed that the slab fracture was not related to chemical composition but to the rough grains and the coarse precipitation phases existed in the grains,which cut the β-matrix apart and impeded dislocation movement,therefore reduced greatly plasticity of TB5 slab.

Basic Study on Vanadic Titanomagnetite Milling in Panzhihua

Li Liang, Yang Cheng

2011, 32(1): 29-33,46.

Abstract(27) PDF(1)

Abstract:
With the laser microscopic spectral analysis,spectrum quantitative analysis,electronic quantitative analysis,the chemical compositions,phase component and the storage state of usefull elements of vanadic titanomagnetite are in detailed researched.According to the compositions and phase of the vanadic titanomagnetite,appropriate scheme is formulated.Through broken and grinding in a closed road,the original ore carry on with two times of magnetic separation and one time of scavenging,then the ferrovanadium concentrate is gained.Granulous ilmenite is gained from magnetic separation tailings,satisfactions process:chute and spiral milling-flotation(sulfur minerals)-electrical select process.The basic experiment study is carried on in the laboratory.Experiments indicate that when the grinding granularity rise up to 0.2 mm(the outside of the mine is 0.15 mm) and the iron grade in ferrovanadium concentrate is about 55%;titanium mineral and pyroxe ne have been separated by the electrical select and ilmenite of high titanium content is gained.when coarse grains gained in floatation are grinded again,the cobalt content in the sulphur cobalt concentrate can rise up to 0.38%.

Improvement on the Mixing Effect in Low-intensity Stirring Area for CAS Ladle by Double-nozzles Bottom Blowing Technology

Zhou Meng, He Ping

2011, 32(1): 34-40.

Abstract(37) PDF(1)

Abstract:
Based on a water model with the size of one fifth of the real CAS ladle,the improvement of the mixing effect in CAS-OB process using double-nozzles bottom blowing technology was researched by analyzing the flow field and determining the mixing time.Results show that double-nozzles bottom blowing technology could greatly reduce the mixing time,also could change the flow field in the low-intensity stirring area of ladle and improve the mixing effect in the middle and lower part of ladle.The experimental formula for expressing the effect of bottom blowing flow rate Q and depth of inserting snorkel H on mixing time $\frac{\tau-\tau_0}{\tau_0}=0.59 Q^{-0.74}\left(\frac{H}{H_L}\right)^{0.52}$ is obtained by free factors analysis.

Study on the Water Simulation of Blowing Argon in Slab Mould

Hou Zewang, Wang Yongsheng, Wang Xinhua

2011, 32(1): 41-46.

Abstract(21) PDF(1)

Abstract:
The method of water simulation of blowing argon in slab mould was set forth in the paper,and then the influence of blowing argon in slab mould on the flow field of steel/slag interface of the mould was mainly studied,and the effects of process parameters on the distribution of argon bubble were studied too,such as the mould width,casting speed,submergence depth of SEN,etc,which are all carried out with a full-size water model and the co ncave shape SEN with the angle of 15°.

Study on Cleanliness of IF Steel Production for ASP

Yue Feng, Yuan Xiaofeng, Li Penghuan, Xiao Chaoping, Wu Weishuang

2011, 32(1): 47-52.

Abstract(21) PDF(1)

Abstract:
The total oxygen content,nitrogen content as well as evolution behavior of the inclusions during RH refining and continuous casting in IF steel production were investigated.The following results were found.Firstly,the average total oxygen content and nitrogen content in the slab were 29×10^-6 and 35.7×10^-6 respectively,and calcium treatment were responsible for nitrogen pick-up.Lumpy,bar-like single alumina inclusions and loose groups were observed in steel bath the first minute after Al addition,and the fluid flow enhanced the formation and densification of clusters within the next 1~2 min.The addition of Ti resulted in the formation of Al-Ti-O complex inclusions which were changed into sphere as time passed.77% of the inclusions were between CaO·2Al₂O₃ and CaO·6Al₂O₃ after the calcium treatment.In addition to spherical Ca-Al-Ti-O-S complex inclusions,rectangular or multi-dentate TiN inclusions precipitated during solidification were found in the slab.Ultimately,the macro-inclusions were mainly from entrapment of SEN deposits,ladle drainage sand,mold powder and so on.

Influence of Solid Solution Temperature on Microstructures and Mechanical Properties of 00Cr25Ni7Mo3N Steel

Li Shujian, Song Zhigang, Zheng Wenjie, Tao Dongping

2011, 32(1): 53-56.

Abstract(35) PDF(1)

Abstract:
The changes of microstructrue and mechanical properties of 00Cr25Ni7Mo3N duplex stainless steel have been studied at different solid solution temperatures by using metallographic image analysis.The experimental results showed that in this paper:①A large number of σ phase on phase boundary of austenite and ferrite precipitated at 900~980℃,leading to the decrease of plasticity and toughness of steel;②When the solid solution temperature is higher than 1 000℃,σ phase dissolved gradually with the temperature increase further,the ratio of α phase increased sharply,the plasticity and toughness of steel increased gently;③Appropriate phase scale and mechanical property are obtained for 00Cr25Ni7Mo3N in the temperature range of 1 000~1 100℃.

Effect of Al on Inclusions in 430 Stainless Steel Containing Titanium

Shi Xiaofang, Cheng Guoguang, Zhao Pei

2011, 32(1): 57-61.

Abstract(28) PDF(1)

Abstract:
Experiments were carried out in laboratory to investigate the effect of Al content on the Ti/Al inclusion in 430 stainless steel containing titanium.It was found that the size of the inclusions increased with the Al content increasing.And some solid solution of Ti₂O₃ and Al₂O₃ were observed in high Al content's sample.The disregistry between Ti₂O₃ and Al₂O₃ was calculated.It was proved that Ti₂O₃ easily attached to Al₂O₃ to form nuclei.In order to prevent forming larger inclusion,a thermodynamic study was undertaken to analyze the effect of Al on forming titanium oxides.The equilibrated relations between Al-Ti-O was calculated and the optimal ratio of[Ti]/[Al] was put forward.

Microstructure and Toughness in the Coarse Grain Region of Low Carbon Bainite High Strength Steel Plate for Q690CFD

Dong Xianchun, Zhang Xi, Chen Yanqing

2011, 32(1): 62-66.

Abstract(31) PDF(1)

Abstract:
The microstructure and toughness of the coarse-grained heat-affected zone(CGHAZ) of low carbon bainite high strength steel for Q690CFD with different welding processes were investigated by thermal simulation with a Gleeble-2000 thermal simulator.The experimental results indicate that the lath martensite is the dominate microstructure of the CGHAZ,and the toughness of CGHAZ decreases with cooling time increase at 500~800℃.With the stress relief(SR) temperature increasing,the impact toughness of the CGHAZ decreases.The CGHAZ has good toughness when the SR temperature at 250~500℃.

Effect of Lepidolite on Dephosphorization of CaO-FeO-CaF₂ Slags in the Hot Metal Pretreatment

Li Jin, Wang Yicheng, Wang Minglin, Chou Shengtao

2011, 32(1): 67-70.

Abstract(31) PDF(1)

Abstract:
At 1 340~1 360℃ under laboratory conditions,the research on the dephosphorization of the CaO-FeO-CaF₂ slags additive lepidolite in hot metal pretreatment has been completed.Influences of lepidolite additive quantity on the slag melting point and dephosphorization effects have been researched.The results show that with lepidolite content increasing,the melting point of CaO-FeO-CaF 2 slags decreases;at 1 340~1 360℃,the silicon content is controlled at 0.01% in the molten iron,and when w_CaO/w_FeO=1.29,adding 10% lepidolite to the hot metal,the phosphorus content can be down to 0.005%;In the conditions of 2% fluorite and 10% lepidolite,when w_{(CaO+lepidolite)}/w_FeO in the range of 1.83~1.86,the dephosphorization rate of molten iron can be maintained at 95%.

Influence of Mn-Si-Ti-Mg Complex Deoxidation on the Oxide Inclusions of Steel

Yang Fei, Li Guangqiang, Song Yu

2011, 32(1): 71-78.

Abstract(17) PDF(1)

Abstract:
From the viewpoint of oxide metallurgy,influence of Mn-Si-Ti-Mg complex deoxidation on the oxide inclusions of steel was studied.SEM and Qwin image analysis software were used to investigate the morphology,chemical compositions and size distribution of inclusions in steel in each complex deoxidation condition.The effects of Ti and Mg contents on inclusions were investigated.The results showed that Mn plays a vital role in the morphology and size of inclusions in the steel;when Ti content more than 0.138%,the increase of Mg content can effectively change the type and size of oxide inclusions in steel,and the size of oxide inclusions is mainly in the range of 0.5~1.0 μm.

Optimization of Secondary Cooling System of Slab Continuous Casting for Ship-plate Steel CCSA

Dong Jinming, Wang Huixia, Chou Shengtao, Gan Yong

2011, 32(1): 79-83,88.

Abstract(26) PDF(1)

Abstract:
For the higher incidence of transverse corner cracks of CCSA slab in a steelmaking plant,it is analyzed that the main reason of transverse corner cracks is unreasonable temperature distribution caused by secondary cooling system,based on the research of high temperature mechanical property of CSSA and the measurement of slab surface temperature.So two measures have been taken to optimize the secondary cooling system:firstly,part of the nozzle types is changed and the nozzle arrangement was adjusted;secondly,secondary cooling water is optimized by the modified solidification heat transfer model of slab continuous casting.The industrial test shows that the temperature at the corner of slab is improved and the rate of transverse corner crack is reduced from 3.7% to 0.41% after optimization.

Optimization of Continuous Casting Parameters for High Carbon Steel Billet and Control of Central Segregation of Billets

He Hongyin, Liu Haitao, Chen Weiqing, Wang Guojun, Fu Jun, Liu Huijie

2011, 32(1): 84-88.

Abstract(21) PDF(1)

Abstract:
The effects of casting speed,secondary cooling intensity,F-EMS current intensity and stirring frequency on the central segregation of high carbon steel SWRH82B billets,which were produced by billet casters using both M-EMS and F-EMS,were studied.It was shown that compared with manganese and chromium,carbon has the severest central segregation,the other two obviously have central segregation too.With F-EMS current intensity increases,V-segregation is scattered,and central segregation index for carbon increases after decreases,it has the lowest level when current intensity is 350 A.With F-EMS stirring frequency increases,central segregation index for carbon increases after decreases,it's profitable to set stirring frequency as 6 Hz in order to control segregation.It is favorable to control the central segregation of billets by improving secondary cooling intensity.The faster casting speed is,the severer central segregation becomes.Cas ting speed of billet casters can be risen if F-EMS is used,and the central carbon segregation of billets can be control at a low level simultaneously.

Analysis on Formation Causes of Crack of H-type Steel

Wang Shuoming, Ding Zhijun, Yu Heng, Zhang Caijun

2011, 32(1): 89-92.

Abstract(17) PDF(1)

Abstract:
Formation reasons of cracks in H beam steel produced by semi-open way in a large H beam steel factory of Hebei were researched.26 specimens of representative crack in the plant were selected.The study shows that:the crack of stomach plank are mainly caused by inclusions in steel,and T[O] in steel is studied to find that the average T[O] in tundish is 94×10^-6 and the average T[O] in slab is 60.8×10^-6.Meanwhile,in contrast with the T[O] in 1 and 2 strem flow slab,it can be found that flow field distribution of the tundish is not reasonable.The existing tundish in the plant was simulated by FLUENT soft and it was found that the short dam of stabilized is lower in tundish,cannot completely eliminate short circuit flow,especially in the late stage of casting,short dam was used up not to work,and serious short circuit flow should be optimized.

2011, 32(1): 93-94.

Abstract(20) PDF(1)

Abstract:

2011 Vol. 32, No. 1