钢铁钒钛

Discussion on Technical Status and Improvement Measures for Sponge Titanium Production in China

Deng Guozhu

2009, 30(2): 1-5.

Abstract(67) PDF(4)

Abstract:
This paper reviews technical status of sponge titanium production in china.After comparing technology and technique-economy indexes for five steps of sponge titanium production in world,the improvement measures are proposed to be taken to reach international advanced level of sponge titanium production in china as following : to dispose soot dust of high-titanium slag production for improving operation condition and replace some hand operation by auto-control machine operation;to improve feeding method of chlorination charging and to achieve computer control of the fluidized chlorination;to replace the copper thread process of removing vanadium from titanium tetrachloride by aluminum powder process with one step method;To increase greatly the quality of sponge titanium in reduction-distillation step;to select the poly-polar electrolysis bath for magnesium electrolysis rather than the electrolysis bath without separating board.

Research of Acidolysis Performance of Acid-soluble Titanium Slag

Wang Bin, Cheng Xiaozhe, Han Kexi, Qin Xinghua, Ma Yong

2009, 30(2): 6-11.

Abstract(50) PDF(2)

Abstract:
The acidolysis performance of acid-soluble titanium slag is studied via phase and content analyzing in this paper.The experiment results show that the acidolysis rate of titanium slag was affected by the mass content of TiO₂ and Rutile and phase in titanium slag.The acidolysis performance of anosovite impact directly on the acidolysis rate of titanium slag, particularly the Fe content in anosovite.Additionally, the mass content of TiO₂ and rutile in titanium slag would affect the performance of titanium slag too.The FeO and MgO in titanium slag is beneficial to the enhancement of titanium slag while the CaO、SiO₂ and Al₂O₃ go against.Keeping TFe (equivalent) /TTi ratio upper 0.28 in titanium slag would make the acidolysis rate come up to 95% or higher.

Influence of Nano-TiO₂ Content on Properties ofSEBS/TiO₂ Composites

Shi Ruicheng

2009, 30(2): 12-16.

Abstract(36) PDF(1)

Abstract:
With the use of nano-titanium dioxide as bacteriostat and surface modifier improving the compatible capability between nano-TiO₂ and SEBS, the SEBS/TiO₂ nano-composites with special use were prepared and the influence of TiO₂ dosage on composite properties was also researched.The dispersed performance of nano-TiO₂ in SEBS was characterized with SEM and its bacteriostasis performance was measured with yellow index.The result showed that the tensile-strength, elongation and bacteriostasis performance of SEBS/TiO₂ nano-composites increased firstly and then reduced with increase of surface modifier.And the tensile-strength, elongation and yellow index of SEBS/TiO₂ nano-composites rose with increase of content of TiO₂.Expecially, when the amount of surface modifier and the nano-TiO₂ are 4%, the yellow index of SEBS/TiO₂ nanocomposites can reach a maxium of 27, the antibacterial properties of the material is best at this time, it also can achieve very good mechanical properties.

Study on Preparation and Structure Properties of Limonite/TiO₂ Composite Photocatalysis Agent

Du Jinkui, Gong Wenqi, Rao Boqiong, Han Pei

2009, 30(2): 17-21.

Abstract(54) PDF(1)

Abstract:
Limonite/TiO₂ composite photocatalysis agent was prepared by sol-gel method in this paper.The XRD、SEM measurement and characterization and the degradation treatment experiments showed that, it had been loaded with a homogeneous TiO₂ film on its surface, and it had a firm nuclear/membrane structure, the removal rate of CODCr attained 70% after treatment and the residual CODCr was about 78.3 mg/L as compared with 251 mg/L under the condition of pH=4、catalyst dosage of 5 g/L and illumination time of 2 h, so it had better degradation effect, it also had superior recovery rate and better photocatalysis properties after recycle experiments.

Investigation on Precipitation Law of Titanium Compounds in Hot Metal Saturated with Carbon

Ding Yuehua, Li Xinsheng

2009, 30(2): 22-27.

Abstract(43) PDF(1)

Abstract:
The equilibriums between titanium compounds and titanium in hot metal saturated with carbon were investigated by oversaturation precipitation method.Experimental results showed that titanium contents balanced with Ti (C, N) in hot metal were much less than that with TiC, and the solubility of titanium was in approximately linearly direct proportion to temperature, whereas inversely proportional to nitrogen partial pressure.There were much titanium precipitates in the bottom and side surface of crucible whereas less in inside and surface layer of hot metal by SEM analysis of experimental iron samples, which show that titanium compounds were precipitated by heterogeneous nucleation crystals and that graphitic refractory were more in favor of heterogeneous nucleation than other materials.

Numerical Simulation on Molten Steel Flow and Circulation Flow Rate in RH Vacuum Degassing Process

Sun Liang, Ai Liqun, Zhao Junhua, Huang Zongze

2009, 30(2): 28-32.

Abstract(29) PDF(2)

Abstract:
A three-dimensional mathematical model for the simulation of molten steel flow based on the parameters of 300 t RH-MFB has been established, discussing the factors of influencing circulation flow rate.The gas-liquid two-phase flow has been treated and described by two-fluid model.The influences of process parameters under the same vacuum condition on steel flow field and circulation flow rate are simulated, such as argon blowing flux, depth of snorkel, nozzles arrange.The results show that keeping argon blowing flux no more than 4 000 NL/min, circulation flow rate would increase with argon blowing flow rate increasing and with the increase of depth of snorkel a certain extent;it was more proper to arrange nozzles in interleaving way than others.

Water Model Study on Optimization of Internal Structure in Six Strand Continuous Casting Tundish

Han Lihui, Wang Jingsong, Wang Yongsheng

2009, 30(2): 33-39.

Abstract(49) PDF(1)

Abstract:
The water model with 1∶3 ratio was built for studying on the flow field of Lai Steel six strand continuous casting tundish.The results showed that short road flow and side road flow were found in the original tundish, the volume of dead zone is large and the effect of mixing is bad.The flow field characteristics of the optimal tundish were improved remarkably by setting up proper turbulence inhibitor and baffle.It could get optimal effects that the "V" shape baffle and ameliorated turbulence inhibitor were used together.The minimum retention time for near nozzle strand is increased about one time and the volume of dead zone is decreased by 70%.

The Structural Optimization of Tundish and Metallurgical Effect

Tang Haiyan, Li Jingshe, Gao Jinguo

2009, 30(2): 40-45.

Abstract(61) PDF(2)

Abstract:
The flow field of four-strand tundish of round billet under three different weirs has been studied by water model experiments.The results show that a big difference in fluid flow characteristics exists between the two outlets at the same side of the tundish controlled by the original weir.Compared with the inside outlet, the outside outlet has longer minimum residence time and peak concentration time and larger dead zone volume.So the original weir can not meet the technical requirements for inclusion floatation and temperature homogenization.U-shape weir can satisfactorily settle the flow synchronism between outlets, but has short minimum residence time and large dead zone volume.Y-shape weir is the optimal shape of the three, which can change the fluid flow of the tundish efficiently and improve inclusion removal and raise steel cleanliness.The industrial test shows that Y-shape weir is better than the original one in reducing total oxygen and inclusions of billets.

Industrial Experiment on Desulphurization in RH Process by Using CaO+Al₂O₃ Based Fluxes with Low Fluoride

Guo Shangxing, Wang Jianjun, Zhou Li, Li Qingyun, Zhang Caigui

2009, 30(2): 46-49.

Abstract(30) PDF(1)

Abstract:
The industrial experiments on deep desulphurization by using (CaO+Al₂O₃) complex based fluxes instead of conventional CaO-CaF₂ fluxes were carried out through flux addition in RH process.The results show that the average De-S rate of 53.44% has been achieved and the sulphur content in molten steel after RH refining is cut down to less than 24×10^-6.The influence of modification treatment of the ladle top slag and final slag composition at the end of RH treatment on De-S is analyzed.The optimum composition of De-S agent is determined to be CaO+BaO (60%~65%) -Al₂O₃ (20%~25%) -MgO (5%~7%) -CaF₂ (<5%).

Experimental Study on Desulfurization Performance of 12CaO·7Al₂O₃ Premelted Refining Slag

Cao Yuliang, Yuan Shouqian, Lu: Ranchao, Qiu Bing, Song Meijuan

2009, 30(2): 50-54.

Abstract(82) PDF(3)

Abstract:
In the laboratory, premelting technology and desulphurization ability of premelted refining slag of 12CaO·7Al₂O₃ were studied.The results show that premelted refining slag of 12CaO·7Al₂O₃ can acquire better desulphurization effect.It can decrease the S-content from 0.048% to 0.020% with 3% premelted refining slag at 1 600 ℃, which makes the desulphurization ratio attainability 58.33%.Its desulphurization ability is to be highly improved by adding a lot of lime in premelted refining slag of 12CaO·7Al₂O₃, especially it fits to Al-deoxidization steel desulphurization.

Influence of Deformation Parameters on Microstructure of Micro-alloyed High Strength Steel

Chen Zhenye, Xu Guang

2009, 30(2): 55-60.

Abstract(48) PDF(1)

Abstract:
The experiments of a micro-alloyed high strength steel under different strain, strain rates, deformation passes and cooling rates were conducted on the thermal-simulator of THERMECMASTOR-Z.The effects of deformation parameters on microstructure and phase transformation of the micro-alloyed high strength steel were analyzed.It has been found that the Ar3 temperature decreases with the increase of the cooling rate.The higher the strain rate, the higher phase transformation temperature.Phase transformation temperature increases with the increase of strain.The ferrite grain will be refined and the pearlite amount will be decreased by the increase of strain, using multi-pass deformation and high cooling rate.The temperature range of dual-phase region (γ+α) is more than 140 ℃.

Key Technology Development for 360 mm×450 mm Bloom Caster at PISCO

Chen Yong, Chen Jianping, Wu Guorong, Yang Subo

2009, 30(2): 61-67.

Abstract(53) PDF(1)

Abstract:
The integrated technologies for 360 mm×450 mm bloom caster and its application results at PISCO (Panzhihua Iron & Steel Co.) were presented.The internal defects of continuous casting bloom such as center looseness, central segregation and center line cracks, were greatly reduced by optimizing secondary cooling scheme, mold electromagnetic stirring (M-EMS) and dynamic soft reduction process.The surface depression defect was remarkably decreased by designing proper mold structure, cooling scheme and mold flux.The production practice in the past two years showed that the rate of central looseness, segregation, shrinkage and crack ratings lower 1.0 was up to 99.03%, the center segregation index of carbon was in the range from 1.01 to 1.05 (mean value of 1.03), and the surface defect-free rate of bloom was up to 99.54%.These achievements have provided PISCO important technology supports to optimize the steel product structure, and to develop the high quality, property, and value added products.

Effect of Added Titanium on Hot Dip Galvanizing Steel Plate

Gui Yan, Xia Caijun, Li Xiaoman

2009, 30(2): 68-70.

Abstract(51) PDF(1)

Abstract:
The effect of Ti added in Zn bath on HDG (Hot Dip Galvanizing) process of steel plate was studied using SEM.The results show that, when the titanium content in the zinc bath increased, the growth of ζ phase in coating was restrained distinctly, the thickness of coating decreased.Titanium can effectively restrain the excess growth of coating for reactive steel containing silicon during the hot dip galvanizing process.When the titanium content in the zinc bath was over 0.05%, the Γ₂ phase particles were formed in the coating.Adding 0.03%~0.05%Ti to Zn bath for 0.09% Si steel could completely restrain the Sandelin effect.But adding titanium to the zinc bath had no effect on the 0.36% Si steel.

Study on Micro-inclusions Behavior of Beam Blanks

Zhang Yaoping, Wang Shuoming, Zhang Shujiang, Zhang Caijun

2009, 30(2): 71-74,79.

Abstract(45) PDF(1)

Abstract:

The type, magnitude, size and distribution of non-metallic inclusions in beam blanks were researched via systemic sampling and adopting metallographic analysis and SEM/EDS, and the origin of inclusions in H beam was analyzed through method of tracer.The result show that the average of T[O] is 70.8×10^-6, the volume ratio of micro-inclusions is 0.15%.Micro-inclusions mainly have three kinds: A, B and C, the total micro-inclusions contain 89.7% of A and B, the chemic elements of A and B are similar, the main difference of A and B is that they have different amount of Al, Ca.And C holds 10.3% in the micro inclusions, which has high content of S.The inclusions'size is mostly less than 10 μm.The distribution trait of inclusions in slab is mainly decided by them.

Process,Microstructure and Properties of Thick X80 Pipeline Steel Produced by Hot Continuous Rolling

Zhu Tao, Jiang Haitao, Xu Hongxun, Tian Zhiqiang, Li Zhongyi

2009, 30(2): 75-79.

Abstract(52) PDF(1)

Abstract:

The microstructure, precipitates and mechanical properties of thick X80 pipeline steel produced by hot continuous rolling of Masteel were studied.The result shows that through reasonable composition design and rolling process, the microstructures of thick X80 pipeline steel produced by hot continuous rolling are uniform and reasonable, its precipitates are fine dispersion.The precipitates consist of Nb, V, Ti, they can be divided into two types based on their shape, one is (Ti、Nb) (C、N) in which Ti plays the main role, its main function is preventing austenite growth;another one is (Nb、Ti) C in which Nb plays the main role, its main function is precipitation strength.Under the circumstance of making full use of fine-grained strength, dislocation and sub-boundary strength, precipitation strength, the thick X80 pipeline steel has excellent mechanical properties:The yield strength is 580 MPa, the ratio of yield to strength is proper;the impact energy and shear area are respectively 290 J, 100% at-20 ℃, the DWTT shear area is 100% at-15 ℃.All the performance meet the demand of the second West-East Gas Transmission.

Sintering Behavior,Phases and Microstructure of（Ti,V）C Steel Bonded Carbide

Gong Wei, Li Hua, Yao Xiaopeng

2009, 30(2): 80-85.

Abstract(39) PDF(1)

Abstract:

(Ti, V) C steel bonded carbide was produced by in-situ sintering technology with titanium powder, ferrovanadium powder, carbon powder, ferromolybdenum powder, ferrochromium powder and iron powder.The phases, microstructure and composition of the composites were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrum (EDS).The results show that the sintering temperature and sintering time significantly affect the densification of the alloys.The optimal sintering temperature for TiC, (Ti, V) C steel bonded carbide is 1 420 ℃, 1 400 ℃, respectively.The optimal sintering time is for 1 hour.The main phases of (Ti, V) C alloy are (Ti, V) C、α-Fe、Fe₃C、 (Cr, Fe)₇C₃.Compared with TiC particles, the (Ti, V) C particles present spherulitic morphology.

2009 Vol. 30, No. 2