钢铁钒钛

Present Status and Prospects of Vanadium and Chromium Separation in Vanadium Extraction from Vanadium-chromium Slag

Wang Xuewen, Wang Mingyu, Fu Zibi, Meng Yuqi, Gao Daxiong, Chen Bianfang

2017, 38(6): 1-5. doi: 10.7513/j.issn.1004-7638.2017.06.001

Abstract(54) PDF(3)

Abstract:
The present status and prospects of vanadium and chromium separation in vanadium extraction from vanadium-chromium slag were introduced in this paper,and the advantages and drawbacks of the existing vanadium-chromium separation and recovery processes were analyzed. Combined with the latest developments in the areas of vanadium-chromium separation and recovery,it is proposed that besides obtaining qualified vanadium and chromium products,the improvement of vanadium extraction from vanadiumchromium slag mainly lies in the energy conservation and emission reduction,realizing the cycle and utilization of water and major raw materials in the processes.

Research Progress of Selective Enrichment and Precipitation of Titanium in High Titanium Blast Furnace Slag

Xu Renze, Zhang Jianliang, Chang Zhiyu, Jiao Kexin

2017, 38(6): 6-12. doi: 10.7513/j.issn.1004-7638.2017.06.002

Abstract(233) PDF(13)

Abstract:
Based on lots of research work on Ti-bearing blast furnace slag utilization,current situations of comprehensive utilization of Ti-bearing blast furnace slag and technologies of enrichment and precipitation of Ti in high titanium slag were summarized. The ways of titanium extraction from Ti-bearing slag mainly include titanium alloy production,acid treatment,alkali treatment or high-temperature carbonization and low-temperature chlorination of high titanium slag,and extraction of Ti-enriched phases by selective separation techniques.The research progress of crystallization behaviors of Ti enrichment phases such as perovskite,rutile and anosovite in high titanium slag was emphatically introduced. The effective enrichment and separation of Ti-containing phases and industrial production are the research focus and direction.It is important to effectively extract Ti from high titanium slag,which has great economic value and practical significance for comprehensive utilization of Ti-bearing slag.

Study on the Application Technology Route for the Titanium Slag Reduced from Titanium Vanadium Iron Concentrate in Direct Reduction Process

Piao Rongxun, Ma Lan, Yang Shaoli, Tang Ling

2017, 38(6): 13-22. doi: 10.7513/j.issn.1004-7638.2017.06.003

Abstract(114) PDF(6)

Abstract:
The predecessors reported more about research on application technology roadmap of acid-soluble titanium slag and high titanium slag.There is no report on the use of 50 titanium slag from the direct reduction of non-blast furnace smelting technology,but there are no reports on the use of 50 titanium slag from the direct reduction of non-blast furnace smelting technology. Thus,this paper has investigated the application technology route of 50 titanium slag as raw material for the production of titanium products.At first,the chemical composition and phase of 50 titanium slag are studied,and then three main titanium production lines of 50 titanium slag are discussed,such as the preparation of 70 titanium iron,the preparation of titanium dioxide and titanium aluminum alloy. Using raw materials proportioning calculations and the theoretical composition calculations of the product study its feasibility.In addition,the effect of CaO on the content of slag has been studied,and the optimum content of CaO which is conducive to slag-alloy separation has been discussed.Finally,the environmental protection,energy consumption analysis and economic balance analysis of the three technical routes are discussed,and it is found that the preparation of titanium aluminum alloy with 50 titanium slag as the raw material is the best technical route program.

The Oxidation Dynamics of Ilmenite

Kang Liwu, Zeng Jun, Huang Yonggang

2017, 38(6): 23-26. doi: 10.7513/j.issn.1004-7638.2017.06.004

Abstract(98) PDF(7)

Abstract:
In this paper,the oxidation mechanism of ilmenite was discussed by respectively studying the oxidation kinetics of ilmenite in medium and high temperature ranges.The apparent activation energies of the reactions are 227.50 kJ/mol and 99.25 kJ/mol in the temperature range of 600~750 ℃ and 750~900 ℃,respectively.The ilmenite oxidation reaction is transformed from lattice diffusion to grain boundary diffusion at 750 ℃.Therefore,the oxidation reaction of ilmenite is controlled by the diffusion of oxygen ions.

Analysis of the Impact of Hydrolysis Process on the Grey Point

Lu Ruifang

2017, 38(6): 27-32. doi: 10.7513/j.issn.1004-7638.2017.06.005

Abstract(68) PDF(5)

Abstract:
In this work,spectrophotometry was used to characterize the grey point of the hydrolysis process of titanium dioxide by sulfuric acid process. Based on the relationship between the transmittance and time during two hydrolysis processes （without and within addingexternal seeds）,the impact of hydrolysis process on the grey point was investigated.Further,according to the current hydrolysis process within adding external seeds,the research of the effects of hydrolysis degree at grey point on H₂TiO₃ particle size,and the relationship between hydrolysis degree and the transmittance are carried out,aiming at determine the transmittance range corresponding the better H₂TiO₃ particle size with the established scanning wavelength and dilution ratio.

Effect of Slag Content Control on Vanadium Loss in Ferrovanadium Smelting Process

Yu Bin, Sun Zhaohui, Zhang Wei, Liang Bin

2017, 38(6): 33-36. doi: 10.7513/j.issn.1004-7638.2017.06.006

Abstract(66) PDF(2)

Abstract:
Based on the smelting performance and slag control situation during the ferrovanadium industrial preparation process,the theoretical amount of slag produced by different vanadium oxides and different smelting stages was analyzed,and the slag amount and precise slag control technology of multi-stage electroaluminothermic ferrovanadium smelting process were proposed.The effects of knotting process,slag distribution and smelting period on slag compositions,slag weight and vanadium loss in slag were investigated.Experimental results indicated that the weight of Al₂O₃ by thermite reaction was calculated to be 0.78 kg and 0.91 kg when the purity（TV,total vanadium）of V₂O₃ and V₂O₅ was 63.5% and 55.2%,respectively.Increasing the knotting strength and density,reducing the proportion of casting slag and prolonging the smelting period were beneficial to reduce the actual slag weight and the vanadium loss in the slag.The average MgO content in ferrovanadium slag reduced from 16.4% to 8.0% and the content of Al₂O₃increased from 61.1% to 69.3% through the optimization of smelting and ramming process.The ratio and the vanadium content of casting slag respectively decreased by 20.2% and 38.4% on the basis of the total slag amount reduced by 11.8%,and the corresponding vanadium loss was reduced from 79.0 to 61.1 kg per furnace,which means that the recovery rate of FeV50 alloy increased by 0.39% under the optimal conditions.

Research Progress on Microstructure and Mechanical Properties of（Ti,M）（C,N）-based Cermets

Wang Xiru, Zhang Xuefeng, Chen Min

2017, 38(6): 37-42. doi: 10.7513/j.issn.1004-7638.2017.06.007

Abstract(137) PDF(4)

Abstract:
(Ti,M)（C,N）-based cermets are important tools and coating materials.The domestic and abroad research progress of microstructure and mechanical properties of （Ti,M）（C,N）-based cermets was reviewed,and the characteristics of black core-white inner ring-gray outer ring and white core-grey ring microstructure in（Ti,M）（C,N）-based cermets were elaborated. The effects of TiC/TiN content,Co,Ni binder phase content,Mo,WC,VC,Cr₃C₂,TaC and NbC additives on the microstructure and mechanical properties of（Ti,M）（C,N）-based cermets were introduced. The next research directions was also pointed out.

Nonspherical High-purity Titanium Powders Prepared by Molten Salts Electrolysis for 3D Skeletal Printing

Fan Yazhuo, Deng Bin, Mu Tianzhu, Zhao Sanchao, Miao Qingdong, Xie Bo, Zhu Fuxing

2017, 38(6): 43-46. doi: 10.7513/j.issn.1004-7638.2017.06.008

Abstract(56) PDF(3)

Abstract:
Nonspherical high-purity titanium powders were prepared by molten salts electrolysis for 3D skeletal printing,its manufacture cost is less than 10% of spherical titanium powders.Nonspherical titanium powders by molten salts electrolysis own the characteristics of high purity and specific surface area that can easily form porous structure in 3D skeletal printing,and the high-purity ensures the health for human body.The microstructure of nonspherical high-purity titanium powders was analyzed by SEM. Because only one step of electrodeposited reaction happened in the process of titanium powders preparation,the formed titanium particles were very uniform.That is why the morphology of electrolysis titanium powders was not spherical,but it still had good flowability.The process of electrodeposition of titanium ions was analyzed by cyclic voltammetry curves,and then the deposition potential of titanium powders was confirmed.

Study on Thermodynamic and Kinetics for Preparation of Vanadium-aluminum Alloy Based on Thermite Reaction

Duan Shengchao, Wang Zhuqing, Guo Hanjie, Guo Jing, Shi Xiao, Liu Shuai, Yu Mengxi

2017, 38(6): 47-54. doi: 10.7513/j.issn.1004-7638.2017.06.009

Abstract(199) PDF(12)

Abstract:
A thermodynamic model for calculating the mass action concentration of structural units in Al-V binary melts system was established based on the atom-molecule theory.The standard equilibrium constants for generating Al₈V₅ and Al₄V were calculated using the activities of Al-V binary system respectively at 2 000,2 073,2 173 and 2 273 K reported on the literatures and the expressions of standard mole Gibbs free energy for the reactions were further obtained.Meanwhile,the mechanism and chemical kinetics for preparation of vanadium-aluminum alloy based on thermite reaction at different heating rates were investigated by TG-DSC.There was respectively an exothermic and endothermic peak on the differential scanning calorimetry curve （DSC curve） at 660~690 ℃ indicating the variation of reaction mechanism.The kinetics parameters of the thermite reactions were separately calculated by Kissinger and Kissinger-Crane equations and the kinetics equation was established. The apparent activation energy （E） was calculated to be 448. 96 kJ·mol^-1,the frequency factor A=1.98×10²⁹ m·s^-1 and the reaction order n = 0.83.

Effect of Heat Treatment Temperature on Properties of Vanadium and Titanium Modified Automobile Transmission Shaft Steel

Zhang Bin

2017, 38(6): 55-58,63. doi: 10.7513/j.issn.1004-7638.2017.06.010

Abstract(55) PDF(3)

Abstract:
The vanadium and titanium modified automobile transmission shaft steels were heat treated with various normalizing temperatures,quenching temperatures and tempering temperatures. The impact property and wear resistance were tested and analyzed. The results show that both of the impact property and wear resistance of the steel first increase and then decrease,with increase of normalizing temperature from 800 ℃ to 880 ℃,or quenching temperature from 790 ℃ to 870 ℃,or tempering temperature from 520 ℃ to 600 ℃.The optimized normalizing temperature,quenching temperature and tempering temperature are 860 ℃,850 ℃ and 580 ℃,respectively.

Effect of Co-permeation of Vanadium-titanium-cerium on Properties of Hot Work Die Steel

Ji Chengmei, Zhao Hui, Lu Jianhui

2017, 38(6): 59-63. doi: 10.7513/j.issn.1004-7638.2017.06.011

Abstract(30) PDF(1)

Abstract:
Vanadium,titanium and cerium were infiltrated into the 5 CrNiMo hot work die steel with different processing temperatures and processing time,and the thermal fatigue property and wear resistance were tested and analyzed.The results show that with processing temperature from 875 ℃ to 975 ℃ and processing time from 2 h to 8 h,both of the thermal fatigue property and wear resistance of hot work die steel first increase and then decline.The optimized processing temperature and time are 950 ℃ and 6 h,respectively.

Extrusion Process Optimization of Novel Automobile Radiator with Magnesium Alloy Containing Titanium

Li Shizeng, Li Anmin

2017, 38(6): 64-68. doi: 10.7513/j.issn.1004-7638.2017.06.012

Abstract(41) PDF(1)

Abstract:
Novel automobile radiator containing titanium-magnesium alloy was produced with different extrusion temperatures,extrusion speeds and extrusion ratios,and the mechanical properties were tested and analyzed.The results show that with extrusion temperature from 320 ℃ to 420 ℃,extrusion speed from 1.5 m/min to 3.5 m/min and extrusion ratio from 12 to 24,the tensile strength of the radiator first increases and then decreases,and the elongation after fracture changes slightly. The optimized extrusion temperature,extrusion speed and extrusion ratio are 380 ℃,2.5 m/min and 20,respectively.

Experimental Research on Sintering Liquid Phase Fluidity Behavior of Imported Iron Ore

Wang Zhe, An Gang, Wei Hongqi, Cheng Zhengming, Liu Boyang, Pei Yuandong, Qi Chenglin, Chen Shaoguo

2017, 38(6): 69-73. doi: 10.7513/j.issn.1004-7638.2017.06.013

Abstract(47) PDF(1)

Abstract:
In iron ore sintering process,iron ore liquid fluidity property has a critical impact on sinter quality.Liquid phase fluidity experiments of imported iron ore are carried out by using high temperature characteristic apparatus for iron ore.Influencing factors that affect liquid phase fluidity are elucidated and the characteristic of pore microstructure is also investigated.Results show that liquid phase fluidity of imported iron ore was mainly influenced by SiO₂,Al₂O₃ content of iron ore and added CaO content.Based on this finding,chemical composition factor of liquid phase fluidity was put forward.Furthermore,microstructure observation on pore in the liquid phase indicates that withthe increase of liquid phase fluidity,pore shows a higher degree of coalescing,and the roundness of pore structure is also improved.

Acetic Acid Leaching of Calcium-based Active Components from Converter Steel Slag

Chen Lin, Liu Bingguo, Zhang Libo, Jiang Yonglin

2017, 38(6): 74-80. doi: 10.7513/j.issn.1004-7638.2017.06.014

Abstract(77) PDF(4)

Abstract:
On the basis of thermodynamic study,with converter steel slag as the leaching object and acetic acid as leaching agent,the effects of leaching temperature,leaching time,concentration of acetic acid and the ratio of solid to liquid on the leaching rate of calcium in converter steel slag having different particle sizes were investigated.The results show that the Gibbs free energy change for leaching reaction of CaO and Ca₂SiO₄ phase is negative while it’s positive for the leaching reaction of the CaTiO₃ phase in the converter steel slag with temperature range of 273.15~373.15 K.The leaching rate of calcium-based active components in the slag are very rapid.The smaller the particle size and the solid-liquid ratio,the higher the leaching rate of the calcium-based active components. Meanwhile,a higher leaching rate of calcium can be obtained at higher concentration of acetic acid.The leaching rate of calcium ion reaches to 87.52% at 1 mol/L of acetic acid,1 ∶ 20 of solid to liquid ratio,70 °C of leaching temperature for 60 min.XRD and SEM analysis shows that the active calcium oxide in the converter steel slag is completely leached with irregular pores formed on the surface of the slag,while calcium titanate （CaTiO₃） stays in the slag.

Discussion on the Process Feasibility of Granulation for High-titanium Slag by Water Quenching

Liu Xianghai, Gou Zhiyuan

2017, 38(6): 81-84. doi: 10.7513/j.issn.1004-7638.2017.06.015

Abstract(65) PDF(6)

Abstract:
In order to reduce the crush times and grinding cost of high titanium slag,an attempt was carried out to apply the water quenching process of blast furnace slag to the production of high titanium slag.The physical properties of the blast furnace slag and high titanium slag were contrasted and the water quenching tests of high titanium slag were conducted.The problems and feasibility of the process were also discussed.The possible reasons for the rutile transition of high titanium slag during water quenching were analyzed by thermodynamics calculations for the oxidation process of high titanium slag. Through comprehensive analysis,it is proposed that the high titanium slag cannot be treated by water quenching.

Thermodynamics Analysis for Carbon Thermal Reduction of Titanium-containing Slag

Wang Dongsheng

2017, 38(6): 85-90. doi: 10.7513/j.issn.1004-7638.2017.06.016

Abstract(65) PDF(2)

Abstract:
In this paper,the thermodynamics of carbon thermal reduction process of titanium-containing slag was analyzed.The results show that during the carbon thermal reduction process of titanium-containing slag,TiO₂ is reduced to a series of low-valence titanium oxides.TiO₂ begins to transform into Ti₃O₅ at 1359K then it probably forms Ti₂O₃ and TiC_xO_y which are finally reduced to TiC.CaO,MgO and Al₂O₃ in the slag could not react with carbon,while Fe₂O₃,V₂O₅,MnO and SiO₂can be reduced by carbon with the preference of Fe₂O₃＞V₂O₅＞MnO＞SiO₂.TiC formed in the early stage could react with TiO₂ to generate low-valence titanium oxides such as Ti₃O₅.Solid CaTiO₃ cannot directly react with carbon but the molten CaTiO₃ is reduced to TiC by carbon.The thermodynamic calculations provide important references for understanding transformation of minerals in titanium-containing slag during carbon thermal reduction process.

Effects of Specific Surface Area on Granulation Behavior of Vanadium Titano-magnetite Concentrate

Zhang Jianliang, Liu Donghui, Liu Zhengjian, Wang Guangwei, Wang Yaozu, Kang Qingfeng

2017, 38(6): 91-97. doi: 10.7513/j.issn.1004-7638.2017.06.017

Abstract(51) PDF(4)

Abstract:
Effects of specific surface area on the granulation behavior of the vanadium titano-magnetite concentrate（VTM） were investigated using micro-drum granulation equipment. The results show that the particle morphology of the VTM mainly present irregular shape,part of them are lamellar and globular structure.Their specific surface area and average particle size have a negative correlation,but there exist great difference in the particle surface roughness of different kinds of VTM. When the particle size of the VTM is small,there is no evident relationship between the specific surface area and uniformity index（UI）,and the effects of the particle morphology on granulation index （GI）,resistance index of the thermal disintegration（KI） and damage index（DI） are greater than the specific surface area.At this moment,the restrictive link for the VTM granulation are the compact structure and smooth morphology of the iron ore particles.The main reason is that the adhesion among VTM granules is relatively week,when the quasi-particles are subjected to the mechanical shock and hot air flow,the adhering layer of the quasi-particles is easy to fall off,leading to the destruction of the quasi-particle structure.In order to increase the adhesive capacity of iron particles,and improve the strength and thermal stability of the quasi-particles,the iron-bearing materials with relatively rough and good hydrophilicity or some kinds of additives should be added in the VTM granulation process.

Impact of Magnesium Oxide on the Green Ball Quality and Cruslring Strength of Pellets

Yan Zhaozhao, Lu Jianguang, Lü Qing, Zhang Shuhui, Liu Xiaojie

2017, 38(6): 98-103. doi: 10.7513/j.issn.1004-7638.2017.06.018

Abstract(78) PDF(3)

Abstract:
Magnesium oxide plays a crucial role in the progress of blast furnace production. In this paper the effect of magnesium oxide on the green ball quality and cruslring strength of acid pellets had been investigated through changing the content of magnesium oxide by adoption of A fine powder,B fine powder and light burned dolomite. It was found out that with the increase of magnesium oxide content,the compressive strength and falling strength of the green ball firstly decreases and then increases,and its thermal explosion temperature firstly increases and then decreases,the change of the green ball quality is mainly related to mineral powder foundation properties such assurface area. The compressive strength of pellets after roasting reduces with the increase of the magnesium oxide content since a portion of the Mg atoms move into hematite and replaces the Fe atoms in crystal,and the strength of Mg-O bond is lower than the strength of Fe-O bond. At the same time,a few magnesium oxide get into the slag phase and destroy the silicate network structure,which improve the liquidity of the slag phase. Parts of the slag phases are dispersed into hematite between grains,other slag phases gather together,the gap between slag phase and hematite becomes more border with the decrease of temperature,resulting in the decrease of compressive strength of the pellets.

Comparative Study on Low-temperature Reduction and Powdered Properties of Vanadium Titanium Sinter and Ordinary Sinter

Yang Wenkang, Yang Guangqing, Li Xiaosong, Yin Sibo, Zhou Ziqing

2017, 38(6): 104-107,120. doi: 10.7513/j.issn.1004-7638.2017.06.019

Abstract(74) PDF(2)

Abstract:
The experimental results show that the pulverization of vanadium and titanium sintered ore and ordinary sintered ore at low temperature is analyzed. The results show that ordinary sinter At 500 ℃,the pulverization rate was 83.80%. Vanadium and titanium sintered ore at 700 ℃ low temperature reduction pulverization reached a minimum value of 41.94%,the lowest temperature reduction powder performance.The low-temperature reduction and pulverization index RDI_+3.15 of vanadium-titanium sintered ore is less than half of the ordinary sintered ore,and the low-temperature reduction pulverization performance of vanadium-titanium sintered ore is worse than that of ordinary sinter. Adjust the composition of the chemical composition of vanadium titanium sinter,so that the MgO content can be increased to about 5%,as well as spray chloride dilute solution to improve the low temperature of vanadium titanium sinter.

Effect of Slag Splashing on Gasification Dephosphorization in Converter

Yao Hongyong

2017, 38(6): 108-112. doi: 10.7513/j.issn.1004-7638.2017.06.020

Abstract(36) PDF(1)

Abstract:
The effect of nitrogen supplying intensity and ratio of coke powder and bottom blowing gas flow rate on gasification dephosphorization are studied,in combination with thermodynamic analysis of gasification dephosphorization for top and bottom combined blowing converter in this paper.The result shows that it is feasible to use carbon-based dephosphorizer to reduce P₂O₅ in slag at steelmaking temperature.and it is more reasonable to choose coke powder as reducing agent.In order to achieve the gasification dephosphorization rate more than 36%,the nitrogen supplying intensity,ratio of coke powder and bottom blowing gas flow rate should be controlled at 4.5~6.5 m³/ （t·min）,8%~12% and 280~400 m³/h respectively.

Study on the Collision of Inclusions on Refractory Wall

Zhao Dingguo, Wang Yufei, Wang Shuhuan, Zhang Fujun

2017, 38(6): 113-120. doi: 10.7513/j.issn.1004-7638.2017.06.021

Abstract(50) PDF(2)

Abstract:
In this paper the behavior of collision between inclusions in molten steel and refractory wall when the molten steel flows through the continuous casting nozzle had been investigated and thenthe model of collision between inclusions had been developed.It is found out that when the coefficient of restitution is constant,inclusions of same sizes collide with the wall. the greater the velocity of inclusion on the vertical wall direction,the greater the maximum compression distance and the greater the springback distance,and the inclusions easily rebound into molten steel after the collision.When the coefficient of restitution and the initial velocity of inclusions are constant,inclusions of different sizes collide with the wall,,maximum compression distance and t the springback distance decrease with the size of the inclusion decreasing,therefore,inclusions are easily attached to the refractory wall after the collision. When Al₂O₃ inclusions with a radius of 20 μm collides with inclusions attachingwith a smooth wall,and the velocity of inclusions are constant,critical contact size of the inclusion attached to the refractory wall increases with the compression distance,resulting in high frequency of falling off or rolling of the inclusion are attached to the refractory wall.These inclusions collides with inclusions attached with a rough wall,when the angle between the direction of inclusions and the direction of the parallel wall is greater than 0.51°,the inclusion attached to the refractory wall will not fall off and roll.The results of the analysis are of significance to the study of adsorption of inclusions in molten steel by refractory wall in the continuous casting nozzle.

Numerical Simulation on Microstructure of GCr15 Bearing Steel Bloom

Wang Dejiong, Jiao Shuai, Yin Hao, Sun Yanhui, Zhao Yong, Li Xiaobin

2017, 38(6): 121-127. doi: 10.7513/j.issn.1004-7638.2017.06.022

Abstract(44) PDF(1)

Abstract:
The solidification mathematical model was established by ProCAST software on a GCr15 steel bloom and then the CAFE model was used to simulate the solidification structure of the bloom.The effects of superheat,casting speed and secondary cooling intensity on the solidification structure of bloom were studied.The results showed that superheat had great influence on solidification structure of bloom.With the increase of superheat degree,the average grain radius increased at the same position of the columnar zone,the columnar region increased,the equiaxial crystal ratio decreased and the CET transition was delayed.When the superheat degree decreased from 40 ℃ to 10 ℃,the equiaxial crystal ratio increased by 21.14%.The casting speed and the secondary cooling intensity had little influence on the solidification structure of the bloom.With the increase of the casting speed or the decrease of the secondary cooling intensity,the columnar region decreased,the equiaxial crystal ratio increased,and the CET transition ahead of time,but the changes were not obvious.In the actual production process,the grain size of the solidification structure of the billet can be refined by reducing superheat.

Analysis of Thermo-mechanical Coupling in the Beam Blank Mould Based on Inherited Stress

Chen Wei, Guo Gaoxiang, Yu Xingwang, Wang Jiaqi, Chen Ying, Yang Gaiyan

2017, 38(6): 128-133. doi: 10.7513/j.issn.1004-7638.2017.06.023

Abstract(51) PDF(2)

Abstract:
In order to control surface cracks in beam blank via continuous casting process,a thermo-mechanical coupling model considering the taper and air gap was established to compute the temperature and stress in the mold based on stress genetic characteristics of the slab shell and multiple load step way.From the modeling resultthe location where longitudinal surface cracks easily occurred is on the fillet at the central part of the mould.This finding will help to control longitudinal surface cracks initiation and growth.

Analysis on Heat Transfer and Optimization for Cooling Structure of Mould Narrow Face Copper Plate for Thin Slab Continuous Casting

Liu Qilong, Liu Guoping, Fan Mancang, Zhang Hui, Qiu Shengtao, Liu Heping

2017, 38(6): 134-141. doi: 10.7513/j.issn.1004-7638.2017.06.024

Abstract(84) PDF(3)

Abstract:
In oder to address the problem that narrow face of mould copper plate of thin slab continuous casting process present server wear and low service life,the effect of cooling structure of narrow face copper plate on heat transfer had been analyzed. A new copper plate used for improving cooling ability of mould narrow face was designed.The copper plate was cooled using five round tube shaped inner gullets whose inner diameter was 11 mm.When the amount of water was 230 L/min,the velocity of water could be increased from 6.23 m/s to 8.07 m/s,the convective heat transfer coefficient of water could be increased from 22 000 W/（m²·℃） to 29 000 W/（m²·℃）,and the hot side temperature of narrow face copper plate could be reduced about 25 ℃.Lots of industrial experiments had been made using this copper plate.The results showed that the maximum wear amount at the bottom of copper plate had been reduced from 4.5 mm to 1.3 mm,which made the service life of the narrow face copper plate equal to that of wide-face galvanized copper plate.In a general way,this narrow-face copper plate cooled by five round tube shaped inner gullets had many advantages including low additional taper,high heat flux,low hot face temperature and high wear resistance.

Study on Inclusion Behavior of Low Carbon and Low Silicon Al-killed Steel During Refining Process

Xu Xiaomei, Sun Yaping, Jia Jihua, Wang Chunfeng

2017, 38(6): 142-146. doi: 10.7513/j.issn.1004-7638.2017.06.025

Abstract(85) PDF(5)

Abstract:
The main source,quantity,size distribution,composition and type evolution rule of non-metallic inclusions in SPHC steel were analyzed and studied through the castig sampling of Tangsteel FTSR cold rolling base material （SPHC） steel,and the inclusions was scanned and detected automatically by ASPEX.The results showed that the inclusions were mainly Al₂O₃ after feeding aluminum line,and MgO-Al₂O₃ type inclusions were formed in molten steel during the refining process.The inclusions whose length larger than 5μm were about 15% after feeding aluminum line and inclusions floatation. After calcium treatment,the Al₂O₃ and MgO-Al₂O₃ inclusions had better deformation effect,and the inclusions were changed into CaOCaS-Al₂O₃ compound inclusions,the inclusions less than 5 μm were more than 95%. Based on these findings,The countermeasure such as optimizing slag-making and argon blowing system,optimizing production organization mode and raising the level of protection casting had been utilized,and achieved the purpose of reducing the inclusion content,shortening refining cycle,reducing the production cost.

Effects of Bending Deformation on the Domain Structure and Magnetic Properties of Non-oriented Silicon Steel

Song Shouxu, Liu Tao, Wang Wenzhe

2017, 38(6): 147-152. doi: 10.7513/j.issn.1004-7638.2017.06.026

Abstract(80) PDF(4)

Abstract:
The evolution of magnetic domain and magnetic properties of B35 AV1900 non-oriented silicon silicon steel had been studied under the condition of small deformation amplitude in this paper.Soft magnetic ac/dc tester,bitter pattern,residual stresses the X-ray detector and hardness tester had been used to acquire the variation characteristics of magnetic domain structure,bending stress,hardness and the effect laws of magnetic properties.The results show that the ac/dc performances of the silicon steel have been significantly worsen as the bending angle increases.When the bending angle is increased from 0° to 18°,iron loss of silicon steel deteriorates by 23.2%,coercive force increases,magnetic permeability and residual magnetic induction intensity decreases.The bending stress increases with the angle,hardness of the silicon steel also shows a slight increase.At the same time,when the deformation increases,the kinds of magnetic domain increases,magnetic wall width and the spacing between adjacent magnetic wall become narrow as well.

Cause of Transverse Fracture on U75V 60kg/m Heat-treated Rail

Deng Yong, Yang Bin, Yuan Jun

2017, 38(6): 153-157. doi: 10.7513/j.issn.1004-7638.2017.06.027

Abstract(54) PDF(1)

Abstract:
By detecting the macro morphology,microstructure,microhardness and chemical composition of broken rail from Central South Railway,a metal layer of high manganese steel were found being welded to the running surface of rail,which caused occurrence of brittle structure consisting of martensite and bainite formed in the base metal under weld layerdue to rapid cooling after welding.And rapid cooling resulted in thermal crack.The crack grew towards head,web and foot under the effect of 30 tons of axle load.In the end,the broken rail accident happened.

Analyzing of Titanium Patents at Home and Abroad

Zhang Tao

2017, 38(6): 158-164. doi: 10.7513/j.issn.1004-7638.2017.06.028

Abstract(55) PDF(2)

Abstract:
The statistical analysis for rolled titanium’s the overall trend,technique construction and technological tendency over the whole world has been processed combining with patent analyzing methods of quantitative analysis and qualitative analysis.The number of rolled titanium’s patent application over the whole world has been increasing fast from 2005 till now,and such technology is in the growth stage. The number of Chinese rolled titanium patents takes more than half a part in the world.The patent quantity of key foreign rolled titanium production enterprises doesn’t taking the most part,implying they keep their technique secret to retain their technique advantage.The most rolled titanium patents are applied by colleges and universities in China.

2017 Vol. 38, No. 6