钢铁钒钛

Process on china titanium industry in 2017

JIA Hong, LU Fusheng, HAO Bin

2018, 39(2): 1-7.

Abstract(28) PDF(4)

Abstract:

Experiment Study of Vanadium Titano-magnetite by Full Oxygen Bath Smelting Process

Gao Jianjun, Hong Lukuo, Zhang Jun, Qi Yuanhong, Yan Dingliu

2018, 39(2): 8-13. doi: 10.7513/j.issn.1004-7638.2018.02.001

Abstract(22) PDF(1)

Abstract:
Blast furnace is the most mature way to smelt vanadium tatino-magnetite,but the smelting of vanadium titano-magnetite in blast furnace needs to be added with ordinary ore and the TiO₂ content in slag is too low to be used. In order to achieve full vanadium tatino-magnetite smelting,a new rotary kiln pre reduction and full oxygen bath smelting process is put forward in this paper. The technology has the advantages of short process flow,controllable slag oxygen potential and low energy consumption.The influence of temperature and slag basicity on the smelting is studied.The results show that the vanadium tatinomagnetite smelted by full bath smelting process is feasible when the smelting temperature is above 1 450℃ and the slag basicity is more than 0.8.The fluidity of the slag is good,and the iron is easily separated from slag.But the sulfur content of liquid iron is higher than 0.21%,which can not reach the requirements of steelmaking.It must be desulfurization before steelmaking.

Effect of Dissolved Cl₂ in Crude TiCl₄ on Vanadium Removal by Aluminum Powder

Miao Qingdong, Li Kaihua, Chen Aixiang

2018, 39(2): 14-18,31. doi: 10.7513/j.issn.1004-7638.2018.02.002

Abstract(13) PDF(2)

Abstract:
The effect of dissolved chlorine（Cl₂） in crude titanium tetrachloride（TiCl₄） on the product quality and vanadium removal process by aluminum powder was studied using the industrial devices of a titanium sponge plant as test platform.The results show that the content of dissolved Cl₂ in crude TiCl₄ has an important influence on the product quality and vanadium removal process. With the dissolved Cl₂ increased both the consumption of titanium trichloride（TiCl₃） slurry and pressure of the tower top increase.In addition,the content of vanadium oxytrichloride（VOCl₃） in product also increases（during the industrial production process,dissolved Cl₂ in TiCl₄ should be less than 0.15%）.Thus,the excess coefficient of Cl₂ for industrial chlorination process should be controlled to decrease the dissolved Cl₂ content of crude TiCl₄.For the crude TiCl₄ with high content of Cl₂,pre-distillation operation should be adopted to reduce the Cl₂ content to 0.15% or less,and then the vanadium removal can be operated.

Process and Dynamic Characteristics of Vanadium Leaching Respectively in Ultrasonic and Mechanical Field

Wang Jin, Xiong Kaiwei, Zhang Lin, Zhou Shan, Zhang Guiyi, Yan Yong

2018, 39(2): 19-24. doi: 10.7513/j.issn.1004-7638.2018.02.003

Abstract(9) PDF(1)

Abstract:
The effects of mechanical stirring intensity,ultrasonic current intensity and leaching time on acid consumption and leaching ratio for vanadium leaching process respectively in ultrasonic and mechanical field were investigated.The results show that with increase of stirring intensity,the acid consumption curve in ultrasonic field reveals well stability with a higher vanadium leaching rate.The stability of acid consumption and leaching ratio of vanadium are enhanced with increase of ultrasonic current intensity.In both of ultrasonic and mechanical field,leaching ratio of vanadium sharply increases in first 30 min then gently raises with increase of leaching time,resulting in vanadium leaching rate of more than 97% in ultrasonic field but 94% in mechanical field.The rate controlling steps of two reaction stages were comparatively analyzed using rate control equations of external diffusion,chemical reaction and internal diffusion,respectively.It is indicated that the rate in the first stage is controlled by external diffusion,with 0.020 7 min^-1 of rate constant and 1-3（1-η）^2/3+2（1-η） =0.020 7 t of rate equation for leaching in ultrasonic field while 0.018 9 min-1 of rate constant and 1-3（1-η）^2/3+2（1-η） = 0.018 9 t of rate equation for leaching in mechanical field.The rate in the second stage is of chemical reaction control.The rate constant and rate equation for leaching are separately determined as 0.005 3 min^-1 and 1-[（1-η）/（1-0.937 1） ]^1/3= 0.005 3（t-30） in ultrasonic field,but respectively 0.003 8 min^-1 and 1-[（1-η）/（1-0.919 1） ]^1/3= 0.003 8（t-30） in mechanical field.

Experimental Study on Preparation of Vanadium Carbonitride by Vanadium Pentoxide

Yang Yong, Wu Wei, Liu Liu

2018, 39(2): 25-31. doi: 10.7513/j.issn.1004-7638.2018.02.004

Abstract(24) PDF(1)

Abstract:
Vanadium carbonitride was prepared by vanadium pentoxide and carbon powder in laboratory conditions.Six temperature curves and seven different carbon contents were adopted to determine the optimum reaction temperature and carbon addition.The results show that the content of vanadium and nitrogen in the sample obtained by temperature system 5 are both higher than those of samples by other temperature systems.With the increase of carbon addition,the content of vanadium in the sample increases slightly but the content of nitrogen decreases slightly,and the residual carbon content increases in the sample.When the carbon addition is 29% and 30%,vanadium carbonitride with 76% of V and 18% of N can be obtained.According to the reaction mechanism for carbon reduction of V₂O₅ and nitrogen addition,the whole process is divided into three stages including VO₂ formation through thermal decomposition of V₂O₅,VC（VN） formation and nitriding,respectively.The more suitable temperature regime was obtained at 30 ℃/min of heating speed in the first stage,6.8 ℃/min of heating speed in the second stage,1 250℃ for 1 h of heat preservation,and 10 ℃/min of cooling rate to 800 ℃ in the third stage.

Effect of Basicity on Content and Occurrence State of Vanadium in Ferrovanadium Smelting Slag

Wang Tanglin

2018, 39(2): 32-38. doi: 10.7513/j.issn.1004-7638.2018.02.005

Abstract(11) PDF(1)

Abstract:
The composition of ferrovanadium smelting slag is mainly controlled by adjusting CaO addition during the ferrovanadium production. The addition amount of CaO will affect the physical and chemical properties of the slag at high temperatures,the occurrence state of vanadium and total vanadium（TV）content in the slag.In this work,the effect of slag composition on TV content and occurrence state of vanadium in ferrovanadium smelting slag was investigated.The results show that TV content in the slag decreases as basicity reduces,from 3.01% to 2.39% respectively at 0.22 and 0.13 of basicity.Vanadium is principally hosted in magnesia-alumina spinel of the slag with higher basicity while in corundum and magnesia-alumina spinel of the slag owning lower basicity.The main species of vanadium in ferrovanadium smelting slag is V³⁺,and Mg O content is the key factor influencing TV content in the slag.The appropriate composition for the slag is 3% ~5% of Mg O and 10% ~12% of CaO.

Separation of Magnetic Vanadium Slag and Vanadium Extraction by Calcification Roasting

He Wenyi

2018, 39(2): 39-43. doi: 10.7513/j.issn.1004-7638.2018.02.006

Abstract(22) PDF(1)

Abstract:
Using MLA mineral phase analyzer and optical microscope,the compositions and iron distribution of magnetic vanadium slag with different particle sizes,and the influence of metallic iron（MFe） on roasting-acid leaching were investigated.The results show that magnetic vanadium slag is made up of MFe and high-Fe vanadium slag,occupying 35.36% and 64.64%,respectively.The recovery of vanadium will be obviously reduced when MFe is more than 2%.A method featuring grinding and screening of the magnetic vanadium slag for separation of metallic iron used for Fe V melting,and vanadium extraction from the residual high-Fe vanadium slag via calcification roasting-acid leaching was proposed in this paper.The recovery rate of vanadium in roasting-leaching process is more than 86.16%,realizing comprehensive utilization of vanadium and iron resources.

Preparation of Na₃V₂（PO₄）₃ Cathode Material for Sodium Ion Batteries by Sol-gel Method

Chen Dong, Zhang Xianghua, Ren Neng, Rui Xianhong

2018, 39(2): 44-48. doi: 10.7513/j.issn.1004-7638.2018.02.007

Abstract(36) PDF(5)

Abstract:
In order to develop Na₃V₂（PO₄）₃（NVP） cathodes with high performance for sodium ion batteries,a modified carbon-coated NVP was synthesized by sol-gel method.The crystal structure and phase analysis of the samples were carried out by X-ray diffraction（XRD）.The spectral characteristics and group compositions,the apparent morphology and particle size,and the carbon content of the materials obtained were analyzed using Fourier transform infrared spectroscopy（FTIR）,scanning electron microscopy（SEM） and thermogravimetric analyzer（TGA）,respectively.The electrochemical properties of the samples were evaluated by charge and discharge test instrument.The results show that the NVP particles have a size of 1~3 μm with amorphous carbon coated on the surface（NVP/C）.It exhibits 110 m Ah/g of initial discharge capacity at 2.5~3.8 V of voltage range and 1 C of rate,which is 93.5% of the theoretical capacity.In addition,the NVP/C could still release a capacity of 54 m Ah/g at 50 C,indicating an excellent rate capability.

Preparation and Mechanical Properties of Porous Ti-5Ag Alloy

Zhao Chaoyong, Zhang Xuefeng, Zhang Lei, Chen Min

2018, 39(2): 49-55. doi: 10.7513/j.issn.1004-7638.2018.02.008

Abstract(13) PDF(2)

Abstract:
In this study,porous Ti-5 Ag alloy was fabricated by powder metallurgy approach with Ti and Ag powders as raw materials and different content of NH₄HCO₃ as space holder.The results show that the phase composition of the porous Ti-5 Ag alloy is α-Ti. With increase of NH₄HCO₃ addition,the density of the alloy gradually decreases,and its porosity increases.Morphological observations show that with the porosity increased the number of macropores of Ti-5 Ag alloy raises and the connectivity during pores also increases.Meanwhile,both of the elastic modulus and compressive strength of the porous Ti-5 Ag alloy are reduced with increase of porosity,according to the mechanical tests. The mechanical properties of porous Ti-5 Ag alloy could be adjusted to match with the human bones by controlling the amount of NH₄HCO₃,which has the potential to be used as a porous antimicrobial implant for orthopedics.

Discussion on Denitrification of Aerospace Grade V-Al Alloy

Chen Haijun

2018, 39(2): 56-60. doi: 10.7513/j.issn.1004-7638.2018.02.009

Abstract(12) PDF(1)

Abstract:
Nitrogen content in aerospace grade vanadium-aluminum（V-Al） alloy has an important influence on properties of the downstream titanium alloy.Nitrogen in V-Al alloy mainly exists as atoms with free state or ions with combination state,and removal for both of nitrogen atoms and ions under vacuum was explored in this paper.Denitrification during the vacuum melting process is mainly realized by nitrogen diffusion to the liquid-gas interface.Furthermore,nitrogen prefers to combine with aluminum in comparison to vanadium,and mechanical vibration can accelerate the elimination of Al N. The product obtained by the proposed method here satisfies the Gf E standards for aerospace grade V-Al alloy.

Distribution Characteristics of Alloy Elements in VC Particle Reinforced Composite Wear Resistant Alloy under Different Mn Contents

Nie Junhong, Zeng Songsheng, Chen Pinghu, Nie Huiwen

2018, 39(2): 61-68. doi: 10.7513/j.issn.1004-7638.2018.02.010

Abstract(7) PDF(1)

Abstract:
Two kinds of VCp reinforced composite wear-resistant alloys with different Mn contents were developed and the Q＆P heat treatment process was adopted in order to develop a kind of composite wear-resistant alloy with higher toughness.The effects of different Mn contents and different carbon partition time on surface distribution of the main alloy elements were largely studied.It lays a foundation for the research and development of the high toughness wear resistant alloy.The results show that most of the V and Ti elements precipitate in form of carbides with very little or none of themselves soluble in the matrix due to the strong carbides forming features of V and Ti.Cr and Mo exist in both carbides and matrix,which form eutectics with VC and Ti C or dissolve in the matrix to improve the hardenability of the alloy.Mn is mainly soluble and more evenly distributed in the matrix.The localized Mn enrichment occurs with the increase of Mn content.However,Mn element is gradually of uniform distribution with increase in the carbon partition time.This study provides a theoretical basis for the application of I＆Q＆P process to VCp reinforced composite wear-resistant alloys.

Preparation and Characterization of Ti₄O₇ by Thermal Reduction of Titanium Powder with TiO₂

Zhao Sanchao

2018, 39(2): 69-73. doi: 10.7513/j.issn.1004-7638.2018.02.011

Abstract(17) PDF(3)

Abstract:
In this paper,thermodynamic calculation and analysis are carried out for preparation Ti₄O₇.With the help of differential thermal-thermal gravimetric analysis,the technological conditions for preparing Ti₄O₇ with titanium powder as reductant are explored,the sintering temperature is 850 ℃ and the sintering time is 4 ~6 h.Testing and analyzing the thermal stability,XRD,particle size,conductivity and specific surface area of Ti₄O₇.which provided the reference and basis for the preparation of Ti₄O₇.

Effect of Vanadium and Strontium Addition on Thermal Fatigue Properties of 5CrNiMo Hot Work Die Steel

Wang Zhenguang

2018, 39(2): 74-77. doi: 10.7513/j.issn.1004-7638.2018.02.012

Abstract(7) PDF(1)

Abstract:
5 CrNiMo hot work die steel samples were produced with various amounts of vanadium（V）and strontium（Sr） as well as different adding modes of vanadium,thermal fatigue properties of the samples were tested and analyzed.The results show that both the amount of V and Sr and the adding mode of V have an effect on the thermal fatigue properties of the samples. Comparing with the sample without V and Sr,the thermal fatigue crack grade of the sample with 0.5% of V and 0.5% of Sr changes from 7 to 2,and the thermal fatigue properties have an obvious improvement. The thermal fatigue crack grade of the sample by adding pure vanadium metal changes from 3 to 2 with the thermal fatigue properties improved,in comparison to the sample by adding FeV40 alloy.The optimum addition amount for both of V and Sr is 0.5%,and it’s better to add pure vanadium metal into the 5 CrNiMo hot work die steel.

Effect on the Microstructure of Carbonized BF Slag with Different Cooling Methods

Wang Dongsheng, Huang Jiaxu

2018, 39(2): 78-84. doi: 10.7513/j.issn.1004-7638.2018.02.013

Abstract(8) PDF(4)

Abstract:
The phase compositions,microstructure and Ti C distribution of carbonized blast furnace slag（BF slag） obtained separately using air cooling and water quenching were studied by polarization microscope,SEM-EDS and MLA analysis,etc.The results show that there’s a large difference on the main mineral compositions between air cooling and water quenching slag.The air cooling slag is mainly composed of ordinary pyroxene,titanaugite,Ti C and perovskite,while the water quenching slag is principally made up of titanaugite,Ti-rich green pyroxene and Ti C.The distribution of Ti in air cooled slag is more concentrated than that of water quenching slag.Ti without forming Ti C in water quenching slag is almost distributed in the silicate phases evenly.The content of Ti and O in Ti C is 72% ~87% and 3% ~9%,respectively. It has a higher O content and lower Ti concentration for water quenching slag probably due to the counterreaction of Ti C during water quenching process.The phase microstructures of air cooling and water quenching slag are similar,mainly composed of silicates,Ti C and small amount of perovskite and Fe. The Ti C grains in water quenching slag are smaller,with about 80% of the Ti C particles having 0 ~20 μm of particle size.There’s a comparative distribution of Fe phase for both of the slags,and a spot of Ti C is concentrated at the boundary and inner of Fe phase.

Iron Recovery of a Low Grade Vanadium-titanium Magnetite and the Element Distributions in the Process

Chen Chao, Zhang Yushu, Zhang Shaoxiang, Han Yuexin

2018, 39(2): 85-91. doi: 10.7513/j.issn.1004-7638.2018.02.014

Abstract(12) PDF(1)

Abstract:
A low grade vanadium-titanium magnetite contains 17.92% of TFe（total Fe） and 6.19% of TiO₂.Using the process of tailings discarding by dry pre-concentration followed with staged grinding and concentration,an iron concentrate containing 60.57% of TFe and 7.89% of TiO₂ can be obtained,and recovery rate of Fe in the whole process is 49.34%.After tailings discarding at a coarser size,Fe,V,Ti,Cr,Sc,Co and Ni are mainly concentrated in the primary concentrate.Through wet magnetic separation,V and Cr in the iron concentrate are enriched apparently,while Co and Ni are concentrated in some degree,with Sc mainly in the weak magnetic separation tailings.S in the dry tailings is of low content but is enriched in the iron concentrate to a certain extent.

Effects of Nucleating Agents on Crystalline Phase of CaO-MgO-Al₂O₃-SiO₂ System Glass Ceramics

Gao Yang, Gui Yongliang, Hu Binsheng, Song Chunyan

2018, 39(2): 92-96. doi: 10.7513/j.issn.1004-7638.2018.02.015

Abstract(12) PDF(1)

Abstract:
Tangshan Iron and steel blast furnace slag were used to prepare CaO-MgO-Si_O2-Al₂O₃ glass ceramics by melting method.And using the differential thermal analysis,X ray diffraction,scanning electron microscopy and other means had been utilized to study the effects of nucleating agents of different types and number of microcrystalline on glass phase composition. XRD results show that the main crystal phase are augite,diopside,diopside aluminum and a small amount of Tschermark’s molecule with addition of 2%Cr₂O₃ as nucleating agent.SEM observations indicates small and irregularly massive grains and high crystallization rate.When 6%Fe₂O₃ is added as nucleating agent,the main crystalline phases are diopside、clinoenstatite and omphacite. The grains are square,triangular and rhombohedral,dispersed in the whole diagram,and the crystallization rate was low. The experimental results provide theoretical support for the preparation of different phase compositions and properties,the composition design and the composition of nucleating agents.

Study on Trend of Sulfur in Titanium Slag Smelting Process with the Boundary Titanium Concentrate

Zhao Qing'e

2018, 39(2): 97-101. doi: 10.7513/j.issn.1004-7638.2018.02.016

Abstract(9) PDF(2)

Abstract:
In this paper,the trend of sulfur in the process of titanium slag smelting and the form of sulfur in raw materials and products are studied. The results show that 27. 97% and 35. 74% of sulfur from the feedstock turned into metallic iron and slag phases,respectively; and the rest turned into precipitator dust and exhaust gas.The sulfur content of titanium slag and semi steel is 0.64% and 1.2%,Further comprehensive utilization is affected.The most of sulfur present as Fe S in raw materials and products.The desulphurization of titanium slag and semi steel is very difficult and cost high,it will also change the structure of titanium slag phase and influence the effect of subsequent application.In order to obtain low sulfur titanium slag and semi steel,the desulphurization treatment of titanium concentrate should be taken by changing process of ore dressing or oxidizing roasting before smelting of titanium slag.

Comparative Study of Microstructure Changes in Vanadium Titanium Sinter and Ordinary Sinter during Reduction Process

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

2018, 39(2): 102-109. doi: 10.7513/j.issn.1004-7638.2018.02.017

Abstract(23) PDF(2)

Abstract:
The reduction process of vanadium titanium sinter and ordinary sinter is studied in laboratory simulated blast furnace.Heating process immediately ceases when the preset temperatures reaches 500 ℃,600 ℃,700 ℃,800 ℃,900 ℃,900 ℃ isothermal holding,1 000 ℃,1 100 ℃,1 200 ℃,1 100 ℃,1 400 ℃,1 500 ℃,and then the N₂ gas flow is injected to cool the sinter down to room temperature.The microstructure of vanadium titanium sinter and ordinary sinter were observed by scanning electron microscope and optical microscope.X-ray diffractometer was used to determine the structure of the sinters obtained at different temperatures.The reducibility of vanadium titanium sinter is worse than that of ordinary sinter.The phase of vanadium titanium sinter ore is more complex,with uneven structure and low temperature reducibility.When the titanium hematite was reduced to titanomagnetite,the generated titanium ferrite and some unreducible solid solution increased the difficulty of subsequent reduction,so that the whole reduction of vanadium titanium sinter was delayed in the ordinary sinter.The liquid phase viscosity of vanadium titanium sinter is larger than that of ordinary sinter.

Theoretical and Experimental Study on Gasification Dephosphorization in High-phosphorus Iron Ore

Wang Hui, Zhang Jiansong, Sun Ruijing, Sun Caijiao, Wang Xiaoyuan, Fu Junkai

2018, 39(2): 110-114. doi: 10.7513/j.issn.1004-7638.2018.02.018

Abstract(12) PDF(2)

Abstract:
Taking high phosphorus iron ore as the research object. the feasibility of gasification dephosphorization is analyzed theoretically from the views of oxygen potential diagram,thermodynamics and advantage area map,and the influence of different carbon content and additive ratio on the rate of gasification dephosphorization was studied by mini sintering test.Theoretical analysis shows that the oxygen potential line of the phosphorus oxide is higher than iron oxide and the phosphorus oxide is difficult to be reduced.When carbon is added into the raw material,there is a partial reduction in the surrounding carbon particles,and thus P can be reduced.After adding the additive,the phosphorus in the raw material is converted into phosphorus gas,so as to achieve the purpose of dephosphorization. The experimental results show that the too low or high carbon content is not conducive to dephosphorization.The rate of dephosphorization is about 17% when the carbon content is 4% and SiO₂+CaCl₂ is added at a certain ratio.

Investigation on the Reduction Features of Carbon-containing Pellets of Bayan Obo Iron Ore Concentrate

Ding Shengli, Zhao Zengwu, Gai Shaoqun, Kang Yi, Qiao Guoping, Han Chunliang

2018, 39(2): 115-120. doi: 10.7513/j.issn.1004-7638.2018.02.019

Abstract(8) PDF(1)

Abstract:
Carbon-containing pellets of Bayan Obo iron ore concentrate and the other ordinary iron ore concentrate were used for the isothermal reduction experiments at 950 ~1 100 ℃.Under the same reduction conditions,the features of the carbon-containing pellets of Bayan Obo iron ore concentrate were obtained by comparing the reduction degree and the shrinkage rate of two kinds of pellets.Experiment results show that the reduction degree of the carbon-containing pellets of Bayan Obo iron ore concentrate is more than that of ordinary iron ore concentrate,but the difference valuebetween them decreases with increasing reduction temperature.For the two kinds of pellets,shrinkage rate of pellets and pellet’s surface cracking degree are bigger when reduction temperature increases. However,the shrinkage rate of pellets of the carbon-containing pellets of Bayan Obo iron ore concentrate is bigger than that of the ordinary iron ore concentrate.

Application of Continuous Casting Mold Fluxes in Crack Sensitive Steel

Wang Xingjuan, Tian Kuo, Zhu Liguang, Wang Haonan, Fan Yapeng

2018, 39(2): 121-126. doi: 10.7513/j.issn.1004-7638.2018.02.020

Abstract(16) PDF(1)

Abstract:
According to the solidification characteristics of crack sensitive steel,the physical and chemical properties of the mold fluxes which could be applied in the steel are analyzed,and the improvement of the crystallization rate of the mold fluxes and the control of heat transfer are the main measures to solve the defects such as the longitudinal defects,the depression and the leakage of the steel.Based on the tested performance of mould slag and experimental results,two kinds of measures have been put forward,ie,high basicity high crystallization rate（S1） and low basicity high crystallization rate（S2） With implement of S1,the crystallization rate of the mould slag has reached 80%,the surface of the billet is flat,and the ratio of longitudinal cracks is controlled to 0.87%. The crystallization rate of the mould slag used in scheme 2 reaches 80%,which well solves the problem that the low basicity slag is not easy to crystallize. The surface of the cast slab after optimization is flat,and the problems such as longitudinal cracks and pits are well controlled.

Study on the Dissolution Behavior of Al₂O₃ for CaO-Al₂O₃ Based Slag

Xu Jinzhong, Han Yihua, Bi Yanxue, Yang Fan, Zhu Liguang

2018, 39(2): 127-131. doi: 10.7513/j.issn.1004-7638.2018.02.021

Abstract(10) PDF(1)

Abstract:
The dissolution behavior of Al₂O₃ in Ca O-Al₂O₃-B₂O₃ slag system during casting high Al and Mn steel was studied by rotating cylinder method. The effects of Al₂O₃ rod diameter,temperature and the composition of protective slag on the dissolution behavior of Al₂O₃ were investigated.All results show that for the the same type of mold powder at 1 300 ℃,the amount of Al₂O₃ dissolved increases with the Al₂O₃ rod’s diameter increasing in a certain period of time.Forthe same mold powder composition and rod diameter,the amount of Al₂O₃ dissolved will be increased with the rising temperature.While the amount of Al₂O₃ dissolution are the largest in slag No.2 at a certain diameter and temperature at 1 300 ℃.In addition,the dissolution rate of Al₂O₃ is found to be the largest on the slag surface.In addition,2#slag is superior to the other three kinds of mold fluxes in terms of the ability of slag to absorb Al₂O₃ and the performance stability after absorption.

Control of Reoxidation Product in Oil Casing Steel

Fang Zhongqiang, Sun Yanhui, Zhu Wei, Wen Bang, Wang Zhen

2018, 39(2): 132-136,145. doi: 10.7513/j.issn.1004-7638.2018.02.022

Abstract(16) PDF(1)

Abstract:
The shape and composition of inclusions in samples during secondary refining process were observed.A certain number of Al₂O₃ and Mg O·Al₂O₃ spinel inclusions were found besides liquid complex inclusions in tundish samples,which is caused by reoxidation during continuous casting.Then,The calcium treatment process was optimized based on the research on mechanism of reoxidation product formation and control.After optimization,the typical inclusions are liquid complex inclusions in tundish samples,while the number of Al₂O₃ and Mg O·Al₂O₃ spinel inclusions is reduced sharply.

Influence of Coiling Temperature on Microstructure and Property of Ti-V-Mo Micro-alloying Steel

Ye Xiaoyu

2018, 39(2): 137-140. doi: 10.7513/j.issn.1004-7638.2018.02.023

Abstract(13) PDF(1)

Abstract:
Thermal simulation experiments of Ti-V-Mo micro-alloying steel under various coiling temperatures were carried out by Gleeble-3500 thermal simulated test machine to analyze the influence of coiling temperature on microstructure,precipitate and hardness. Experimental results show that: when coiling temperature ranges at 600 ~625 ℃,microstructure of tested steel is polygonal ferrite,precipitate is（Ti,V,Mo）C particles which mainly contains V,and hardness reaches peak value.

Research on Controlling Titanium Content in Bearing Steel during Secondary Refining

Wang Le, Liu Liu, Yao Tonglu, Zhao Junpu

2018, 39(2): 141-145. doi: 10.7513/j.issn.1004-7638.2018.02.024

Abstract(9) PDF(1)

Abstract:
Based on the production process characteristics and quality requirements of bearing steel,industrial test and actual production data had been compared to analyze the main metallurgy process which can bring titanium uptaking in the steel.According to thermodynamic calculation the effects of oxygen activity in steel,acid-soluble aluminum and the composition of slag on the titanium content had been investigated.LF refining stage was thought as the main process causing titanium uptaking during steelmaking process.After BOF tapping,the content of titanium can be reduced effectively by using weak deoxidization,reducing the basicity of the refining slag and decreasing the soluble aluminum content in the steel.When the content of oxygen is above 20 × 10^-6 after BOF,the titanium content could be controlled below 20 ×10^-6.When the soluble aluminum content is below 0.018%,the content of SiO₂ in slag is above 6.5%,it is beneficial to control titanium uptaking.

Hot Compression Deformation Behaviors and Microstructure Evolution of GH4169 Alloy

Jiang Shichuan

2018, 39(2): 146-152. doi: 10.7513/j.issn.1004-7638.2018.02.025

Abstract(12) PDF(2)

Abstract:
The hot deformation behavior of GH4169 alloy were investigated by single-pass isothermal compression tests with Gleeble-3500 D simulated machine. The investigated variable included the deformation temperature ranging from 900 ℃ to 1 150 ℃,strain rate ranging from 0.01 s^-1 to 10 s^-1 and the deformation degree ranging from 10 % to 70 %.By the resulted flow stress curve and microscopic observation,the influence of thermodynamic parameters on the flow stress,peak stress and dynamic recrystallization of GH4169 alloy was analyzed,and the constitutive relation model of GH4169 alloy was established.

Effect of Microstructure on Mechanical Properties of Hot Rolled Bainitic Dual-phase Steel

Yu Chong, Wu Teng

2018, 39(2): 153-156. doi: 10.7513/j.issn.1004-7638.2018.02.026

Abstract(10) PDF(1)

Abstract:
In this work the bainitic dual-phase steel with combined high strength and good toughness had been achieved through ultra-fast cooling after hot rolling.The effect of microstructure on hole expansion performance and mechanical properties had been studied.The resulted steel is mainly composed of ferrite and bainite,with tensile strength of 501 MPa and total elongation of 34%.The good mechanical property of steel is related to bainite.Excess hard phase bainite and pearlite deteriorate hole expansion performance,however,large fraction of polygonal and quasi polygonal ferrite can improve the elongation and hole expansion.

Effect of Ferrite Rolling Process on Texture of Ultra Deep Drawing Steel

Wang Jiangong, Zhou Zheng, Hao Leilei, Zhou Xun, Xia Yinfeng, Kang Yonglin

2018, 39(2): 157-164. doi: 10.7513/j.issn.1004-7638.2018.02.027

Abstract(8) PDF(1)

Abstract:
In this study,the effect of process parameters on the varieties and evolution of texture during rolling process were investigated by controlling the rough rolling temperature,finish rolling temperature and the thickness of finished products.The result shows that as the rough rolling temperature declines from 923 ℃ to 855 ℃,the intensity of { 111} ∥ND texture increases.Besides,when the finish rolling temperature declines from 810 ℃ to 791 ℃,the intensity of the unfavorable { 113} ＜ 110 ＞ texture is markedly weakened.All of these adjustments benefit to the good performance of ultimate sheet.when the thickness of finished products is reduced from 4.0 mm to 3.0 mm,the responding annealed cold-rolled sheet have a increasing r vaule with r₉₀ exceeding 3.2 and |Δr| as low as 0.08.

Analysis on Fracture Failure of Large Angle Q420 Steel for UHV Transmission Project

Huang Yao, Liu Weining, Li Feng, Fu Mingxiang, Han Junke, Wang Changzhi

2018, 39(2): 165-172. doi: 10.7513/j.issn.1004-7638.2018.02.028

Abstract(18) PDF(1)

Abstract:
The fracture behavior of large angle Q420 steel was studied by means of optical microscope,scanning electron microscope,mechanical property test and Charpy impact. The fracture behavior was analyzed mainly by metallographic structure,mechanical property,fracture analysis and inclusions analysis,in order to identify the reason of the crack and the density of the crack in the large angle.The results show that the chemical composition and mechanical properties of fractured steel meet the requirements of national standard.Fracture appearance observation indicates brittle cleavage fracture,and large inclusions particles which aremainly the protective residue composition,and the a higher intensity of transverse cracks as well.

2018 Vol. 39, No. 2