钢铁钒钛

Development and Application of Cyclic Metallurgy Process

Wang Xuewen, Ge Qi, Yang Ming'e, Wang Mingyu, Wang Xingming, Meng Yuqi, Gao Daxiong, Liu Biao

2019, 40(2): 1-7. doi: 10.7513/j.issn.1004-7638.2019.02.001

Abstract(26) PDF(2)

Abstract:
The cyclic metallurgy process refers to a metallurgical process that can economically and efficiently extract valuable metals and realize the recycling of the chemical raw materials and water used in the process,and can reduce or avoid the generation of waste water,waste gas and waste residue.With the economic transformation and development of the country,the ecological civilization construction and environmental protection work in depth,the smelting industry faces severe challenges,and many traditional metallurgical processes have to be transformed and upgraded.In this paper,the recovery of vanadium,chromium and sodium carbonate from the leach solution of roasted vanadium slag,the separation of copper and nitric acid from nitric acid deplating solution,and the removal of arsenic,antimony and bismuth from copper electrolyte were taken as examples to introduce the development and application of cyclic metallurgy process.

Leaching of Vanadium and Chromium from High Chromium Vanadium Slag

Peng Hao, Wu Qian, Wang Lilian, Li Gang, Zhou Yuju, Cheng Qinzhe, Liu Zuohua, Tao Changyuan

2019, 40(2): 8-12. doi: 10.7513/j.issn.1004-7638.2019.02.002

Abstract(29) PDF(2)

Abstract:
Vanadium and chromium are hard to be leached out directly from the high chromium vanadium slag since they co-exist in spinel in the slag.CaF₂ and MnO₂ were applied to intensify the leaching process of vanadium and chromium from high chromium vanadium slag.The dosage of CaF₂,the dosage of MnO₂ and reaction time on the leaching efficiency of vanadium and chromium were investigated.The results indicate that the vanadium and chromium in low valence are hard to be leached out in acid condition,with the leaching efficiency of vanadium and chromium at 38.47% and 14.72%,respectively.The addition of CaF₂ could destroy the Si-O structure and the vanadium and chromium in low valence can be released out,and then oxidized by MnO₂.The leaching efficiency of vanadium and chromium increase with increase of the reaction time.The leaching efficiency of vanadium and chromium can be respectively increased to 62.08% and 29.56% with CaF₂ and MnO₂ intensifying the leaching process.

Study on Heat Treatment Process of Nano Titanium Dioxide

Wu Jianchun

2019, 40(2): 13-17. doi: 10.7513/j.issn.1004-7638.2019.02.003

Abstract(58) PDF(6)

Abstract:
Titanium tetrachloride was used as raw material to prepare hydrated titanium dioxide by alkali neutralization method,and then anatase nano-TiO₂ and rutile nano-TiO₂ were prepared by heat treatment at different temperatures.The effects of heat treatment on the crystal structure,specific surface area,pore volume and UV absorption spectrum of the sample were analyzed by Raman spectroscopy,XRD and UV-visible spectroscopy,respectively.The experimental results show that the unheated samples have oxygen vacancy defects and have large lattice strain.With increase of the heat treatment temperature,the grain size of the samples grows from 6 nm to 70 nm with the specific surface area decreased from 186 m²·g^-1 to 5.6 m²·g^-1 and the total pore volume decreased from 0.085 cm³·g^-1 to 0.001 3 cm³·g^-1,respectively.Meanwhile,the crystal structure gradually transforms from amorphous phase into anatase and rutile phases accompanying gradual decrease of the lattice strain.The samples are composed of anatase phase with heat treatment temperature below 600 ℃,mixture of anatase and rutile phase at 600～650 ℃,and rutile phase with heat treatment temperature higher than 800 ℃.At 680～750 ℃,sodium hexatitanate is formed.

Application Study on the Grey Point Determination of Hydrolysis by On-line Instrument

Lu Ruifang, Liu Chan

2019, 40(2): 18-24. doi: 10.7513/j.issn.1004-7638.2019.02.004

Abstract(21) PDF(1)

Abstract:
In this work,spectrophotometry was used to characterize the grey point of hydrolysis during titanium dioxide preparation via sulphate process.Employing the self-developed on-line grey point determination instrument,the effects of scanning wavelength at a certain range and dilution ratio on the transmittance at gray point were studied for the hydrolysis process within adding external seeds,and the optimum scanning wavelength and dilution ratio were determined.Furthermore,the influences of two methods of grey point judgement,the on-line determination by the instrument and artificial observation,on the control level and process capability of hydrolysis process were compared.The results show that the control level and process ability of hydrolysis process could be improved significantly by using the self-developed grey point detector instead of artificial observation.

Study on Scar-formation Mechanism and Scar Removal for Oxidation Reactor of TiO₂ by Chlorination Process

Zhou Airan

2019, 40(2): 25-30. doi: 10.7513/j.issn.1004-7638.2019.02.005

Abstract(49) PDF(3)

Abstract:
The oxidation reaction is the key process of titanium dioxide preparation by chlorination process,while scarring is a bottleneck restricting long-term operation of oxidation reactor.Therefore,grasping the crux of scar formation is the foundation and key to extend the operation period of oxidation reactor.Accordingly,on the basis of detection results of scarring materials of rutile TiO₂ prepared in oxidation reactor by gas phase oxidation method in the production site,this thesis analyzed the reasons for scarring in oxidation reactor through simulation calculations and scarring simulation tests.And this work also proposed the optimization measures for scarring prevention in oxidation reactor,combining with the design structure of existing large-scale oxidation reactor in China.

Market Analysis of Vanadium and Progress on Technologies of Vanadium Extraction from Stone Coal

Hu Yibo, Ye Guohua, Wang Heng, Zuo Qi, Xie Yu

2019, 40(2): 31-40. doi: 10.7513/j.issn.1004-7638.2019.02.006

Abstract(45) PDF(3)

Abstract:
Vanadium production of China ranks the first in the world,and the market prospect will be more optimistic due to the rising price of vanadium in recent years,which will be expected to greatly promote the development for the industry of vanadium extraction from stone coal.As a kind of advantageous vanadium resource in China,stone coal has not been fully exploited and utilized,and the researches and developments of advanced technologies are needed to provide support for this industry.In view of the shortcomings of the traditional vanadium extraction processes,the advanced processes for extracting vanadium from stone coal were analyzed and summarized.Calcification roasting can achieve green production,while the disadvantage is poor selectivity;Blank roasting has the lowest pollution and production cost,but it has high acid consumption,long leaching time and high impurity content in leaching solution;Direct acid leaching has the advantages of low energy consumption,low pollution,and high leaching index,unfortunately,the consumption of sulphuric acid is too large,and it has the disadvantages of long leaching time and high requirement for corrosion resistance of equipment;Low-temperature sulfation roasting has the advantages of low energy consumption,low pollution and high efficiency,but the technology is still immature.Other advanced processes（such as ultrasonic and microwave technology,circulating fluidization process,microbial treatment technology,etc.） are limited by the development level of technology and equipment,so there is still a long way before their industrial application.

Vacuum Magnetic Levitation Refining for Titanium Aluminum Alloy Prepared by Electro-thermal Reduction

Li Jun, Wu Enhui, Yang Shaoli, Hou Jing, Xu Zhong, Huang Ping, Ma Lan, Jiang Yan, Liu Qianshu

2019, 40(2): 41-49. doi: 10.7513/j.issn.1004-7638.2019.02.007

Abstract(38) PDF(1)

Abstract:
The theory and experiment results for vacuum magnetic levitation refining of titanium aluminum alloy（TiAl alloy） indicate that increasing the vacuum degree and heating current can help to decrease the oxygen content in the alloy,while it suffers from Al volatilization with a drastic process which is adverse to composition control and inclusion removal for the alloy.At heating current of 60 A,vacuum degree of 400 Pa with Ar and refining time of 30 min,the slag inclusions of coarse particle can be effectively removed.After two times of refining at the same conditions,the oxygen and nitrogen content of the alloy can be decreased to 0.50% and 0.55%,respectively.The microstructure of TiAl alloy after two times of refining is near layer tissue composed of γ and α₂ structures,with TiAl,Ti₂AlN and Ti₂Al as the main phases.Brittle fracture at room temperature can be attributed to the obtained alloy,with bending strength of 258 MPa and vickers hardness of 486.

Preparation and Electrode Formulations of Lithium Titanate

Li Wang, Liu Jiali

2019, 40(2): 50-54. doi: 10.7513/j.issn.1004-7638.2019.02.008

Abstract(63) PDF(8)

Abstract:
In this paper,lithium titanate anode materials were prepared by high temperature solid state synthesis.The phase and morphology of the obtained lithium titanate were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）,respectively.Three different electrode formulations were used to assemble coin cells,for measuring the capacity,ratio,cycle and AC impedance of the anode materials.The electrochemical performances of LTO-1 electrode were found to be the best,with 97.7% of capacity retention after 100 cycles at 1C of ratio and 147.7 mAh/g of discharge capacity at 8C of ratio.

Research on Slurry Viscosity of Zinc Salt Initial Titanium Dioxide

Wang Haibo, Li Li, Luo Zhiqiang, Wu Xiaoping, Liu Yong

2019, 40(2): 61-65. doi: 10.7513/j.issn.1004-7638.2019.02.010

Abstract(9) PDF(1)

Abstract:
According to the problem of high viscosity with high concentration of zinc salt initial titanium dioxide slurry,factors such as the amount of salt treatment agent,the S content of the initial titanium dioxide,surfactant,slurry temperature and pH were systematically studied.The results show that with the increase of potassium salt amount,the viscosity of the slurry increases first and then decreases.As the amount of zinc salt increases,the viscosity of the slurry gradually decreases.With the increase of phosphate amount,the viscosity of the slurry increases.The lower the S content in the initial titanium dioxide,the lower the slurry viscosity.The initial titanium dioxide slurry with polymer surfactants has a lower viscosity than the slurry with small-molecule surfactants.The slurry by Raymond mill grinding has a slightly lower viscosity than that by the roller-grinding.The more the amount of surfactants,the lower the slurry viscosity.Higher slurry concentration leads to a higher viscosity of the slurry,while a higher slurry temperature results in a lower viscosity of the slurry.With pH increases,the viscosity of the slurry decreases first and then increases.This study provides technical guidance for reducing the viscosity of the slurry of zinc salt initial titanium dioxide.

Microstructure and Properties of Magnesium Alloy for Titanium-containing Mechanical Shell Forged at High Strain Rate

Tong Yilin

2019, 40(2): 66-70,78. doi: 10.7513/j.issn.1004-7638.2019.02.011

Abstract(9) PDF(1)

Abstract:
High strain rate forging tests for AZ80 Ti titanium-containing mechanical shell magnesium alloy specimens were carried out,and the microstructure and mechanical properties were compared and analyzed.The results show that the content of titanium,forging temperature and strain rate have important effects on the microstructures and mechanical properties of the specimens.With the increase of titanium content from 0.4% to 1.2% and strain rate from 50 s^-1 to 125 s^-1,the average grain size of the sample decreases first and then remains basically unchanged,while the mechanical properties of the sample increase first and then remain basically unchanged.With the forging temperature increasing from 300 ℃ to 340 ℃,the average grain size of the sample decreases first and then increases,and the mechanical properties increase first and then decrease.Compared with the sample with 0.4% titanium content,the tensile strength and yield strength of the specimens with 0.8% titanium increase by 31 MPa and 29 MPa,respectively.Compared with the sample with forging temperature of 300 ℃,the tensile strength and yield strength of the specimens forged at 320 ℃ increase by 38 MPa and 39 MPa,respectively.Compared with the sample with strain rate of 50 s^-1,the tensile strength and yield strength of the specimens respectively increase by 19 MPa and 21 MPa at 100 s^-1 of strain rate.

Research on Corrosion Behaviors of Electron Beam Welded Joints of TC4 Titanium Alloy in Hydrochloric Acid

Jiang Rui, Ao Jinqing

2019, 40(2): 71-78. doi: 10.7513/j.issn.1004-7638.2019.02.012

Abstract(8) PDF(1)

Abstract:
Electron beam welding is more suitable for titanium alloy than traditional methods,but the corrosion behaviors of the welded joints have been rarely reported for electron beam welding,which restricts its development and applications.In this paper,the microstructure of welded joints was analyzed by metallography,electron microscopy and X-ray diffraction.Meanwhile,the corrosion resistance and corrosive behaviors of the overall welded joint,welding bead and base metal in 1 mol/L HCl medium were investigated by electrochemical method.The results show that the base material of the welded joint consists of the equiaxed α phase and the β phase in the gap,and the heat affected zone is composed of the original α phase,β phase and α’ phase,while the weld bead is under the structure of α’ phase only.The corrosion resistance of the weld bead is better than that of the base metal,and the corrosion resistance of the overall welded joint is worse than that of the base metal.With immersion time increasing,all samples undergo active dissolution,passivation film generation and destruction processes.After immersion,the surface of the samples is etched,the corrosion resistance decreases sharply.

Experimental Study on Preparation of Cr-containing Ti-Al Based Alloys by Aluminothermic Reduction-remelting of Waste SCR Ti-based Denitration Catalyst

Piao Rongxun, Ma Lan, Yang Shaoli, Cao Daipeng

2019, 40(2): 79-86. doi: 10.7513/j.issn.1004-7638.2019.02.013

Abstract(13) PDF(1)

Abstract:
Ti-Al based alloys were prepared for the first time by aluminothermic reduction-remelting method using scrap selective catalytic reduction（SCR） catalyst as raw material.The effects of Cr on the microstructure,phase compositions and properties of the alloys were also studied by adding different contents of Cr.X-ray diffraction（XRD） and energy dispersive spectroscopy（EDS） analysis show that the phases observed in the alloys without adding Cr element are mainly composed of Ti_0.8V_0.2Al₃,TiAl₂,Ti₃Al,TiAl,Ti₅Si₃,TiSi₂,CaAl₄O₇,Ca₂AlSiO_5.5 and so on.Adding Cr element can reduce the formation of Al-rich titanium aluminide compounds,and reduce the content of Ca-Al oxides.It can also form Ti_0.25Cr_0.08Al_0.67 phase,and increases the formation of Ti₃Al and TiAl phases.The phase evolution calculation by Pandat thermochemical software shows that the addition of Cr can significantly reduce the phase ratio of Al₃（Ti,V） and decrease a certain amount of（Ti,Cr）₅Si₃,and can increase the formation of TiAl phase.The hardness test results show that the hardness of the alloy increases with the increase of Cr content.This may be due to the uniform distribution of equiaxed TiAl-like phases and the decrease of（Ti,W）₅Si₃ phase.

Thermodynamic Calculations and Kinetics Study on Direct Alloying Process of Abandoned Denitration Catalyst

Chen Guangyu, Kang Jialong, Wu Shijie, Peng Jun, Liu Lixia, Zhang Fang, An Shengli

2019, 40(2): 87-91. doi: 10.7513/j.issn.1004-7638.2019.02.014

Abstract(14) PDF(2)

Abstract:
The thermodynamic software Factsage 7.1 was used to calculate the effects of reduction temperature and aluminum amount of the TiO₂-CaO-CaF₂-Na₂O-SiO₂ slag system during the direct alloying process of the abandoned denitration catalyst.When the reduction temperature reaches 1 550 ℃,titanium in the steel almost no longer rises,but the content of titanium oxides continues to increase with the increase of temperature.At 1 600 ℃,titanium content in the steel increases with increase of the amount of aluminum.When the ratio of aluminum to slag is about 0.4,the titanium content can reach to maximum 4.25%.The reaction for reduction of the abandoned denitration catalyst by aluminum occurs at around 923 ℃ and belongs to a liquid-solid reaction.The kinetics parameters of the direct alloying reduction process were calculated by Freeman-Carroll method,with the obtained apparent activation energy E=243.33 kJ/mol and the reaction order n=0.13.

Titanium Recovery from Baima Crude Residue

Bao Binli

2019, 40(2): 92-96. doi: 10.7513/j.issn.1004-7638.2019.02.015

Abstract(4) PDF(1)

Abstract:
The annual output of Baima crude residue is 1.3 million tons,with average 3.09% of TiO₂ content.At present,the residue is directly discharged into tailing pond,resulting in waste of titanium resources.In order to recover ilmenite from the residue,the combined processes of pre-discarding the tailings by ZCLA,then grinding for iron removal-strong magnetic separation-spiral classification-grinding for iron removal-strong magnetic separation-flotation were carried out in the laboratory.The results show that ilmenite concentrate with the yield rate of 0.47%,TiO₂ grade of 46.06% and recovery rate of 7.18% can be obtained through the combined processes,which provides a technical foundation for ilmenite recovery from Baima crude residue.

Titanium Flotation Dynamics Analysis for Vanadium-titanium Magnetite

Fan Xuesai, Chen Jun, Shi Shuaixing, Wang Wenchao, Liu Wanfeng

2019, 40(2): 97-101. doi: 10.7513/j.issn.1004-7638.2019.02.016

Abstract(13) PDF(2)

Abstract:
Strong magnetic separation-flotation becomes the best separation circuit for vanadium-titanium magnetite.The feeding of titanium flotation is the tailing of iron separation.The titanium flotation process is featured by high input TiO₂ content,high solid content（50%～65%）,high specific gravity of ore and coarse mineral particles,all those presents a challenge for air dispersion.In this paper,the dynamics characteristics of flotation cells in Sichuan Lomon had been studied.The measurement result shows good axial and radial dispersion in flotation cell.As the grade of titanium is high and the size of mineral particles is coarse,the coarse mineral particle is liable to collide and attached with the bubbles,but it is easy to detach during the transportation towards the lip.In the cell there is a significant gradient in slurry concentration. The slurry concentration of the 3 levels（1 700 mm,2 200 mm,2 700 mm） is about 55%,but the slurry concentration decreases from 55% to 25% towards the lip.

Reduction Behavior of Bituminous Coal Coated Magnetite Powder

Hao Suju, Sun Tianhao, Jiang Wufeng, Zhang Yuzhu, Lan Jiran

2019, 40(2): 102-106. doi: 10.7513/j.issn.1004-7638.2019.02.017

Abstract(10) PDF(1)

Abstract:
In order to restrain the agglomeration and loss of flow of iron ore powder in fluidized reduction process,the method of bituminous coal coated magnetite powder was adopted.The reduction behavior of bituminous coal coated magnetite powder was studied the morphology based on ore powder during reduction.The reduction samples of bituminous coal coated magnetite powder at different temperatures were characterized by SEM,EDS and XRD,and the results were compared and analyzed.It is concluded that the reaction process between solid carbon and iron ore powder can be effectively improved by increasing temperature,and the formation of iron whiskers can be effectively inhibited by coating magnetite powder with bituminous coal carbon.

Calculation Model of Optimal Basicity for the Refining Slag of Bearing Steel Based on IMCT Theory

Lei Jialiu, Li Desheng, Zhu Hangyu

2019, 40(2): 107-111. doi: 10.7513/j.issn.1004-7638.2019.02.018

Abstract(8) PDF(1)

Abstract:
The fatigue life of bearing steel is closely related to the total oxygen content in the steel.Aimming at the control of T[O]in the bearing steel during refining process,a calculation model of optimal basicity for the refining slag CaO-SiO₂-MgO-Al₂O₃-FeO at 1 853 K is established,based on the ion and molecule coexistence theory（IMCT）.And the influence factors on optimal basicity for the slag system are discussed and analyzed.The results show that:①For different FeO content,the maximum value of N_FeO occured when the basicity are all around 3,the optimal basicity basically does not change with the variation of FeO content.②The content of MgO has a great influence on the optimal basicity,with the increase of MgO content,the optimal basicity decreased.③The effect of Al₂O₃ content on the optimal basicity is opposite to that of MgO.With the increase of Al₂O₃ content,the optimal basicity increases significantly.

Experimental Study on Effect of Absorbing Rods on Removal of Inclusions in Molten Steel Port with Different Deoxidation Methods

Zhao Dingguo, Zhang Fujun, Wang Yufei, Wang Shuhuan

2019, 40(2): 112-116. doi: 10.7513/j.issn.1004-7638.2019.02.019

Abstract(8) PDF(1)

Abstract:
The adsorption of impurities in molten steel under deoxidation conditions of aluminum and titanium was studied by thermal experiments.The experimental results show that the magnesia-calcium adsorption rod has strong adsorption capacity for inclusions in different deoxidation steels from the three aspects of the number of inclusions per unit area,area ratio and adsorption rate.The area ratio of inclusions in titanium deoxidized steel liquid decreased significantly.The number of inclusions per unit area in the middle and side of the sample was reduced by 27.10% and 32.55%,respectively, compared with the original deoxidized steel ingot and area ratio decreased by 51.58% and 54.97%,respectively.

Mathematical Model of Microsegregation of Grain-oriented Silicon Steel during Solidification of Continuous Casting

Liu Lei, Qiao Jialong, Guo Feihu, Xiang Li, Qiu Shengtao

2019, 40(2): 117-120. doi: 10.7513/j.issn.1004-7638.2019.02.020

Abstract(14) PDF(3)

Abstract:
Based on CLYNE-Kurz model,segregation model of grain-oriented silicon steel during solidification of continuous casting was established,segregation of Mn and S elements in liquid phase during solidification of continuous casting was calculated,and the relationship between actual concentration product and equilibrium concentration product of Mn and S during solidification of continuous casting was compared.The results show that the secondary dendrite spacing decreases with the increase of cooling rate.The secondary dendrite spacing in columnar region is 191.3 μm.The degree of segregation increases with the decrease of the distribution coefficient of elements.The degree of solute segregation increases with the increase of solid fraction.When the solidification fraction reaches 0.997,MnS begins to precipitate.

Effects of M-EMS Stirring Intensity on Homogeneity and Dendritic Structure of Rail Steel

Li Hongguang, Chen Tianming, Yang Wenzhong, Chen Liang, Chen Xiong, Zeng Wu

2019, 40(2): 121-126. doi: 10.7513/j.issn.1004-7638.2019.02.021

Abstract(7) PDF(1)

Abstract:
Comparison experiments were carried out to find out the effects of M-EMS stirring intensity on the homogeneity of rail steel.The results show that homogeneity of bloom which produced without stirring is the best,the range value of carbon segregation degree is 0.13～0.20,the mean square deviation of carbon segregation degree is 0.027～0.048,the range value of manganese segregation degree is 0.04～0.06,the mean square deviation of manganese segregation degree is 0.012～0.014,the alternation of negative and positive segregation is non obvious,the maximum positive segregation area mainly gathered at center area,and columnar crystal is well developed,ratio of equiaxial crystal in bloom is higher which produced with strong stirring intensity(380×10^-4 T) ,the size of grain is small,the alternation of negative and positive segregation is obvious.The range value of carbon segregation degree in railhead which rolled from bloom that produced with strong stirring intensity(380×10^-4 T) is 0.08,and weak stirring intensity(220×10^-4 T) is 0.05,but non-stirring is 0.03 and it’s the best.The value of positive segregation degree for carbon in rail web which rolled from bloom that produced with strong stirring intensity(380×10^-4 T) is 1.01～1.03 and it’s the best,but weak stirring intensity(220×10^-4 T) is 1.03～1.05,and non-stirring is 1.02～1.06.Based the results,made suggestion to cancel M-EMS and equip F（S）-EMS combine with soft reduction to improve the homogeneity of rail steel,also spotting the install potion of F（S）-EMS by calculate where distance from the liquid steel level in mold is 5.0～6.0 m.

Finite Element Analysis of Influence of Vibration Asynchronism on Slab Stress in Mould

Guan Likun, Wu Yabin, Ren Xueping

2019, 40(2): 127-131. doi: 10.7513/j.issn.1004-7638.2019.02.022

Abstract(13) PDF(1)

Abstract:
Based on the measured vibration curve data of continuous casting mould,the motion characteristics of two sides of crystallizer were analyzed,and the vibration process of the crystallizer was simulated by finite element method using Ansys software,and the stress distribution of the slab was obtained.The results show that the relative rotation of the mould in the process of vibration results in relative extrusion and deviation of the slab; the narrow surface and corner area of the billet are affected by relative extrusion of the mould,and the stress increases with the increase of the distance from the meniscus; when relative extrusion occurs,the corner stress at the bottom of the slab is affected by relative displacement and rotation of the mould,and with the increase of the relative extrusion distance from the meniscus.The relative rotation angle increases and relative displacement decreases,and the stress in slab increases.

Effect of Al₂O₃ on the Composition and Microstructures of Crystal Products of CaO-Fe₂O₃ Melt

Yang Nan, Guo Xingmin

2019, 40(2): 132-136. doi: 10.7513/j.issn.1004-7638.2019.02.023

Abstract(11) PDF(1)

Abstract:
As one of major burdens of blast furnace,the metallurgical performance of high basicity iron ore sinter is highly related to the ironmaking process in blast furnace..In this study,the effect of Al₂O₃ on the composition and microstructures of crystal products of CaO-Fe₂O₃ melt was investigated by changing the Al₂O₃content in CaO-Fe₂O₃ melt.It was found out that the CaFe₂O₄ decreased with increasing Al₂O₃ content.When Al₂O₃ content reached 3%,Ca₂Fe₂O₅ and Fe-rich calcium ferrite crystallized from melt and their content increased with increasing Al₂O₃ content.The microstructure of Fe-rich calcium ferrite became thinner with increasing Al₂O₃ content.The viscosity of CaO-Fe₂O₃ melt was also increased with increasing Al₂O₃content.When the Al₂O₃ content exceeded 5%,the crystallization of calcium ferrite was depressed significantly.

Dynamic Simulation of Vanadium Extraction from Hot Metal Containing Low Carbon and High Vanadium

Zhao Zhimin, Luo Lingen, Di Jiuhai, Pang Jianming, Fang Jianfeng, Huang Xiaoli, Zhang Qiang

2019, 40(2): 137-143. doi: 10.7513/j.issn.1004-7638.2019.02.024

Abstract(13) PDF(1)

Abstract:
A coupled dynamic model is established to simulate the dynamic characteristic of vanadium extraction process in combined blown converter.The model consists of oxygen transfer model and slag-metal interfacial reaction model.The model canbe used to simulate the kinetic characteristics of hot metal containing low carbon and high vanadium.The simulation results show that the optimum addition of cold material is 50 kg/t at top blowing intensity of 2 m³/（min·t）.In this case,temperature of molten is 1 410 ℃ after 9 minutes’ smelting,and the content of vanadium in the molten iron is reduced from 1.2% to 0.04%.

Effect of Vanadium on the Precipitation Behavior and Aging Properties of Higher Yield Strength Weathering Steels

Liu Qingchun, Wu Lin, Zheng Zhiwang, Yong Qilong

2019, 40(2): 144-148,155. doi: 10.7513/j.issn.1004-7638.2019.02.025

Abstract(12) PDF(1)

Abstract:
The target-oriented researches on the Vanadium-containing weathering steels were conducted in this paper.Methods such as thermal simulation test,precipitate phase quantitative analysis,tensile test and so on were used to investigate the vanadium precipitation behavior and aging properties of higher yield strength weathering steels with different process condition.It has been found that with increasing N content the vanadium precipitation ratio in tested steels is significantly higher than that in referred steel.Increasing N content leads to a large V precipitation amount and V precipitation potential during cooling process.AI value is decreased when the V/N ratio increased,but the V/N ratio is less than 3.5 against aging performance.The critical technological parameters of 450 MPa grade higher yield strength weathering steel was confirmed,and the optimal coiling temperature of tested steel was 650 ℃,which corresponds to the combined effect of grain refinement and precipitation strengthening.Considering the effect of nitrogen on aging performance,the ratio of V/N in V＆N microalloying high strength weathering steel should be controlled to be a little higher than the ideal V/N chemical coordination ratio value（3.64）to achieve the best comprehensive properties.

Study on the Mechanism of Ferrite Precipitate Formation in the Crystallization of Magnesia-alumina Spinel Inclusion in Gr45 Steel

Xu Ying, Zhao Bo, Tian Bo, Wang Xing, Fu Jingchang

2019, 40(2): 149-155. doi: 10.7513/j.issn.1004-7638.2019.02.026

Abstract(11) PDF(1)

Abstract:
Based on the basic principles of thermodynamics and the theory of mismatch degree, the formation process of MG-Al Spinel in Gr 45 steel is calculated and analyzed.When the temperature is below liquid line,given certain oxygen activityAlO form prior to MgO.At a given elemental content,Magnesia-alumina spinel inclusions can be produced as long as there is a trace of magnesium.It is proved that the matching relationship between Mg-Al Spinel and ferrite is good,and it is easy to form a common lattice structure,which provides a good substrate for the crystallization of ferrite.

Influence of the Friction Coefficient Uniformity on the Hole Expansion Behavior

Wang Liangyun

2019, 40(2): 156-160. doi: 10.7513/j.issn.1004-7638.2019.02.027

Abstract(11) PDF(1)

Abstract:
In this paper,Dynaform was used to simulate the hole expanding test,and the influence of changingfriction coefficient of the plate surface on hole expansion behavior was studied. When the friction coefficient between plate and die increases,hole expansion ratio decreases,and finally cracks in the wall of the punch occurs.Single lubrication can reduce the forming force of the test and increase the hole expansion ratio.For single side lubrication,the hole diameter will be shifted to the small side of friction coefficient.When the friction coefficient difference between the two sides is too large,it can lead to the crack in the side with the larger friction coefficient.

Development of Fingerprint Resistant Hot Dip Galvanized Steel Sheet for High-end Household Appliances

Hu Huadong, Li Hongcui, Gao Guangzhou, Zha Kai, Zhang Lei, Wang Le

2019, 40(2): 161-165. doi: 10.7513/j.issn.1004-7638.2019.02.028

Abstract(21) PDF(1)

Abstract:
By adopting suitablefinishing,roller coating and drying process,and combining the film-forming mechanism of passivation solution and feature of steel plate,we developed galvanized fingerprint resistant steel sheet for high-end home appliances which meet the corrosion resistance,high temperature resistant yellow degeneration,skim phosphating resistance,alkali degreasing,solvent resistance,fingerprint resistance,good adhesion of coating performance and the membrane of.By experiment design,the relationship amont substrate roughness,film thickness and corrosion resistance has been established.As a result,these three indicators of corrosion resistance,electrical conductivity and high temperature resistant yellow degeneration can meet the technical requirements.And the developed sheet are widely used in the production of computer chassis,server,film and television sound,plating of high-end home appliance parts for automatic office system.

Improving the Properties of 50WG470 High Magnetic Induction Electrical Steel by Elevating Si Content and Reducing Mn Content

Pan Zhendong, Lin Yuan, Gu Xiangyu, Zhang Wenkang

2019, 40(2): 166-170. doi: 10.7513/j.issn.1004-7638.2019.02.029

Abstract(13) PDF(1)

Abstract:
The experiment was conducted to improve the properties of the high magnetic induction 50 WG470 grade electrical steel by using the chemical composition design of elevating Si content and reducing Mn content based on the original composition 1.4%Si-0.3%Al-0.8%Mn.The composition of the experimental steel is 1.8%Si-0.3%Al-0.2%Mn.The same processing schedule was used for both steels.The results show that the magnetic induction B₅₀ of the experimental 50 WG470 is improved by about 0.003 T,the iron loss P_1.5/50 decreases by about 0.15 W/kg,the yield strength and tensile strength increase about 20 MPa.The grain size of experimental steel in normalizing coil is bigger than that of the comparative steel.The density of the experimental steel’s γ fibre texture is lower than that of the comparative steel.And the density of the experimental steel’s Goss texture is higher than that of the comparative steel.For non-oriented electrical steel,the grain size of the normalizing coil steel has little influence on the grain size of the final product.The grain size difference of the final product between the experimental steel and the comparative steel is not obvious.The solid solution enhancement effect of element Si oo non-oriented electrical steel is much bigger than that of element Mn.

2019 Vol. 40, No. 2