钢铁钒钛

Preparation of High Purity Metal Titanium by Iodization

Hu Zhifang, Jiang Honglin, Xu Dong, Cui Yan, Yin Yanxi

2018, 39(5): 1-4. doi: 10.7513/j.issn.1004-7638.2018.05.001

Abstract(179) PDF(9)

Abstract:
In this paper,the influences of raw material temperature and K value on the average deposition rate for iodization reaction were studied using industrial sponge titanium as raw material.The results show that the deposition rate increases with raw material temperature rising at a fixed K value,while the deposition rate increases at an obviously slow trend with raw material temperature over 600 ℃.Furthermore,the deposition rate increases with increase of K value at a certain raw material temperature.At a raw material temperature of 600 ℃ and K value of 80,multi-batch trial production results show that the diameter of the obtained crystal rods is about 23～26 mm with a total yield rate of about 98% and a deposition rate of 30 g/（h·m）.Meanwhile,the prepared forgeable high-purity metallic titanium owns a thick grain size,shining surface and a purity higher than 99.99%,showing an excellent purification effect.

Study on the Reaction of Ti⁰ and Ti³⁺ Ions in Molten Salt

Mu Hongbo

2018, 39(5): 5-8. doi: 10.7513/j.issn.1004-7638.2018.05.002

Abstract(93) PDF(1)

Abstract:
The molten salts containing titanium ions with lower valence state were prepared by the reaction of titanium sponge and TiCl₄ in NaCl-KCl molten salts（molar ratio of NaCl∶KCl=1∶1）. The average valence state of titanium ions was calculated, and then the molten salts with Ti³⁺ and Ti~0 were obtained by reaction between TiCl₄ of calculated amount and excess titanium sponge. The ion reaction of Ti and Ti³⁺ was investigated. It is indicated that the reaction at 0～210 min is of second order. The results in this paper have directive significance on titanium powder preparation by molten salts electrolysis.

Extraction of Titanium（Ⅳ）from Hydrochloric Acid Solutions by Tributylphosphate and Decanol

Mao Xuehua, Liu Daijun

2018, 39(5): 9-15. doi: 10.7513/j.issn.1004-7638.2018.05.003

Abstract(48) PDF(4)

Abstract:
The extraction of titanium（Ⅳ） from hydrochloric acid solutions by tributylphosphate（TBP） and decanol was studied. The results demonstrate that the extraction ratio of titanium（Ⅳ） increases with the increased concentration of TBP, decanol and chloride ion. Titanium（Ⅳ） exists as TiCl₄（TBP）₂ Decanol in the organic phase during the extraction of lower concentration titanium（Ⅳ）, while it changes into TiCl₄TBP（Decanol）_1/2 for the extraction of higher concentration titanium（Ⅳ）. TBP-decanol-titanium with higher concentration can aggregate into reversed micelles in the organic phase, according to the measurement of average hydrodynamic radius, electrical conductivity and IR spectra of the organic phase as well as the synergistic extraction effects investigation. It means that the extraction of titanium（Ⅳ） with higher concentration from hydrochloric acid solutions by TBP and decanol progresses as a combined mode of solvent extraction and reversed micelle extraction. The extraction rate is fast and the equilibrium can be obtained in 10 min. At the same time, calcium（Ⅱ）, magnesium（Ⅱ） and aluminum（Ⅲ） in hydrochloric acid solutions cannot be extracted. The extraction isotherm for titanium（Ⅳ） in 8 mol·L^-1 hydrochloric acid solutions was plotted with the composite extraction agents. And the stage of countercurrent extraction was explored.

Removal Techniques for Impurities in Acidic Ammonium Salt Precipitation of Vanadate

Guo Jike, Yin Zhaoqian, Jiang Lin, Fu Zibi

2018, 39(5): 16-23. doi: 10.7513/j.issn.1004-7638.2018.05.004

Abstract(86) PDF(6)

Abstract:
The impurities separation technology and the dissolution kinetics analysis of impurities in ammonium polyvanadate were studied, in order to solve the problem of high impurities content in ammonium polyvanadate prepared by acid ammonium salt precipitation from vanadium and sodium solution. The results show that ammonium polyvanadate having 50.25% of total vanadium content, 0.15% of Na₂O+K₂O and 0.13% of S can be gained by hot water immersion and washing at 5～7 of washing solution pH, 50～70 ℃ of wash temperature,（1.5～2.0）∶1 of liquid-solid ratio and 1%～2% of ammonium salt addition, with the vanadium recovery more than 99.60%. Moreover, the impurities separation process is kinetically controlled by solid film diffusion with 16.19 kJ/mol of apparent activation energy, based on the dissolution kinetics analysis of the impurities.

Structural Changes of Metatitanic Acid during Hydrolysis Process of Industrial Titanyl Sulfate Solution

CHEN Hua, TIAN Cong-xue, ZHU Yu-xuan

2018, 39(5): 24-29. doi: 10.7513/j.issn.1004-7638.2018.05.005

Abstract(148) PDF(10)

Abstract:
Using low concentration industrial titanyl sulfate solution as raw material,metatitanic acid was prepared via the self seeded thermal hydrolysis sulfate process.The structural changes of metatitanic acid during hydrolysis of industrial titanyl sulfate solution were investigated.The as-prepared samples were characterized by particle size distribution test,XRD,BET and Raman.The results show that the D₅₀ and D_AV of the metatitanic acid particles were almost the same at the early stage of hydrolysis.The metatitanic acid particles became larger and distributed wider with the crystal growth and agglomeration,and.The TiO₂ structure of anatase phase in meta titanic acid was determined by the crystal nucleus,and subsequent hydrolysis has no obvious effect on the structure of anatase phase.The metatitanic acid was TiO₂ short chain structure with many mesopores and irregular pore structure.The cell parameter c increases with the increase of hydrolysis time,and the anatase TiO₂ structure had trend of distorted to the syncline square crystal.The intensity of Raman peak increases and the corresponding wavenumber of characteristic peak decreases,which results in the increase of the content of TiO₂ and the increase of the degree of crystallization.

Temperature Control of Acid Leaching Process for Calcified Clinker of Vanadium Slag

SHEN Biao

2018, 39(5): 30-36. doi: 10.7513/j.issn.1004-7638.2018.05.006

Abstract(81) PDF(1)

Abstract:
The calcified clinker of vanadium slag is usually leached by sulfuric acid to obtain V-containing solution. During the industrial process of acid leaching, the leaching temperature increases abnormally and vanadium in the solution will be precipitated to decrease the recovery rate. In this paper, the effects of sulfuric acid concentration, sulfuric acid addition, solid-liquid ratio and the initial temperature of leaching agent on the leaching process were investigated. The results show that the sulfuric acid concentration, solid-liquid ratio and initial temperature of leaching agent influence the leaching temperature obviously. The leaching slurry temperature can be controlled to satisfy the process requirements with a higher vanadium leaching rate, at optimum conditions for leaching pH of 2.7～2.9,concentration of sulfuric acid ≤38%,solid-liquid ratio of 0.3～0.4 and leaching agent initial temperature of 25～35 ℃. Verified by industrial leaching production, the leaching temperature can be reduced by an average of 13.09 ℃,with the leaching rate of vanadium increasing by 3.45 percentage points.

Effect of Aluminum Sulfate on Abrasion Ratio of TiO₂-V₂O₅ Denitration Catalyst

Xiao Yuting

2018, 39(5): 37-42. doi: 10.7513/j.issn.1004-7638.2018.05.007

Abstract(61) PDF(3)

Abstract:
TiO₂-V₂O₅ denitration catalyst with high wear resistance was prepared using aluminum sulfate as additive.Through analyzing the wear strength,denitration activity,pore structure and specific surface area of the catalyst,effects of aluminum sulfate additive were studied,and the mechanism of wear resistance improvement for the catalyst by aluminum sulfate was discussed.The results show that aluminum sulfate in the catalyst forms a three-dimensional grid to enhance the wear resistance of the catalyst at 650 ℃ of calcination temperature.When the addition amount of aluminum sulfate is 10 %,wear ratio of the catalyst is 0.079 %/kg,decreasing by about 28% compared to that of the conventional catalyst.The denitration efficiency of the catalyst is improved by introduction of sulfate,and the denitration efficiency of catalyst with 15 % of aluminum sulfate is 3.15% higher than that of the normal catalyst.

Effect of Conductive Agent on Electrochemical Performance of Cathode Materials of Lithium Ion Batteries

Liu Tiantian, Cui Xumei, Wang Ningjun

2018, 39(5): 43-46,64. doi: 10.7513/j.issn.1004-7638.2018.05.008

Abstract(259) PDF(7)

Abstract:
The effect of conductive agent on the electrochemical performances of the cathode material of Li₃V₂（PO₄）₃ lithium ion batteries（LIBs） was studied respectively using graphene, Ketjen black and acetylene black as the conductive agent, and then the ratio of Ketjen black was adjusted to investigate its effect on the electrochemical performances of LIBs. The results show that the first specific discharge capacity of the battery is 108, 114 and 104 mAh/g respectively with graphene, Ketjen black and acetylene black, at charge and discharge voltage range of 3.0～4.3 V and discharge rate of 0.2 C. The cycling performances show that the specific discharge capacity changes slightly after 50 times of cycling. By changing the conductive agent ratio, the first specific discharge capacity of the battery is 105, 114 and 96 mAh/g respectively for LVP∶PVDF∶conductive agent=85∶10∶5, 80∶10∶10 and 75∶10∶15, at charge and discharge voltage range of 3.0～4.3 V and discharge rate of 0.2 C. It indicates that the content of conductive agent influences the electrochemical performances of LIBs as well. When the content of conductive agent is 10%, the battery has the best electrochemical properties.

Research on Relationship between Microstructures and Mechanical Properties of TA15 Bars

Tang Jing, Huang Deming, Yang Xiongfei, Liu Xibin

2018, 39(5): 47-53. doi: 10.7513/j.issn.1004-7638.2018.05.009

Abstract(75) PDF(1)

Abstract:
Lamellar and equiaxed microstructures of TA15 bar were characterized by BEI and EBSD techniques,focusing on the alloying elements distributions and their effects on the corresponding mechanical properties.Image Quality（IQ）and chemical composition analysis indicate that 20% of alloying elements in solid solution of β phase produce remarkable lattice distortion and consequent higher solid solution strengthening than α phase.The contribution of solid solution strengthening is greater than that of grain refinement strengthening,resulting in a similar yielding strength of these two microstructures.The equixed microstructure with finer grains,uniform distribution of β phase and about 29% of low angle grain boundaries（LAGB）,exhibits homogeneous deformation and then raises the tensile strength and plasticity,making comprehensive mechanical properties better than those of the lamellar structure.

Effect of Mo Addition on Microstructure and Properties of （Ti,V,Mo）C-based Cermets

Chen Min, Zhang Xuefeng, Xiao Xuan

2018, 39(5): 54-59. doi: 10.7513/j.issn.1004-7638.2018.05.010

Abstract(60) PDF(1)

Abstract:
The effects of Mo addition and sintering temperature on the microstructure and mechanical properties of（Ti,V,Mo）C-based cermets were investigated by BSE ＆ EDS,IPP,XRD and density,hardness,bending strength tests.The results show that the hard phase is constituted by black core phase and grey phase in（Ti,V,M）C-based cermets.Mo addition mainly contributes to form carbides solution in the hard phase.With increasing the sintering temperature,the proportion of black core phase decreases and the grey phase coarsens obviously,leading to the decrease of bending strength.（Ti,V,M） C-based cermet with favorable comprehensive properties can be obtained at 1 400 ℃ of sintering temperature with 6% of Mo addition.

Effect of Cooling Mode for Heat Treatment on Microstructure and Hardness of TC4 Alloy Prepared by TiH₂ Powder Metallurgy

Malan, Piao Rongxun, Yang Shaoli, Li Junhan, Fan Xingping, Fang Gongjun

2018, 39(5): 60-64. doi: 10.7513/j.issn.1004-7638.2018.05.011

Abstract(73) PDF(2)

Abstract:
TC4 alloy prepared by TiH₂ powder metallurgy was subjected to heat treatment and the effects of different cooling methods on microstructure and hardness of the TC4 alloy were studied. The results show that both solid solution treatment and aging treatment can densify the alloy. In addition, the cooling method of solid solution treatment can significantly affect the proportion of α phase and β phase in the TC4 alloy, resulting in the change of microstructure. The recrystallization in the air-cooled sample produces fine equiaxed structure with the smallest average grain diameter. Solid solution treatment can significantly increase the hardness of the alloy.

Application of Rutile Nano-TiO₂ in Automotive Paint

Wu Jianchun, Du Jianqiao, Wang Bin, Xin Huijin

2018, 39(5): 65-70. doi: 10.7513/j.issn.1004-7638.2018.05.012

Abstract(52) PDF(1)

Abstract:
Several kinds of rutile nano-TiO₂ used in automotive paint were analyzed by UV-Vis spectra,SEM,BET and CPS.On the basis of characterizations,rutile nano-TiO₂ PGNR-508 with aluminium paste was used as the raw materials to prepare the optically variable automotive paint,and the weather resistance and optically variable properties of the paint were analyzed.The results show that the nano-TiO₂ PGNR-508 has a cylindrical structure with about 10 nm of diameter and about 50～100 nm of axial direction size.It has a uniform particle size distribution and strong shielding to ultraviolet radiation.The modification of nano-TiO₂ can give the automobile paint an optically variable effect obviously and can improve the weather resistance of the paint significantly.

Research Status and Prospect of Vanadium Extraction from Vanadium Titano-magnetite

Chang Fuzeng, Zhao Beibei, Li Lanjie, Geng Litang, Zhang Zhenquan

2018, 39(5): 71-78. doi: 10.7513/j.issn.1004-7638.2018.05.013

Abstract(148) PDF(9)

Abstract:
The process of vanadium extraction from vanadium-titanomagnetite was described systematically in this paper.The methods of direct vanadium extraction,vanadium extraction from vanadium slag and steel slag were mainly introduced.The advantages and disadvantages of various methods were analyzed and discussed.The new technologies of vanadium extraction were also discussed.Finally,it is pointed out that extraction of vanadium from vanadium slag by calcium method,clean extraction of vanadium by molten salts method and vanadium-chromium co-extraction by sulfuric acid method are the focus of future researches.The technology of preparing high purity vanadium oxide by chlorination has a good application prospect because of its short and clean process,as well as the high purity of products.Seeking clean process with short procedure,large-scale,low cost,high yield rate and no pollution becomes.The development direction of vanadium extraction from vanadium-titanomagnetite in the future.

Roasting and Induration Mechanism in Magnesia Pellet

Wang Shuchao, Shi Xuefeng, Zhang Qiaorong, Zhao Kai

2018, 39(5): 79-85. doi: 10.7513/j.issn.1004-7638.2018.05.014

Abstract(104) PDF(2)

Abstract:
Magnesia pellets have become a major trend in the development of the pellets in the future due to its good metallurgical performance.However,problems such as low strength and high demands for roasting process parameters are existing for magnesia pellets.Therefore,it is of important practical significance to study roasting and induration mechanism and then improve process of magnesia pellets.The recent development of roasting and induration mechanism of magnesia pellets and effects of Mg’s source,ratio,process parameters,mineral composition and microstructure on the metallogenic mechanism and metallurgical properties of magnesium acid pellets and magnesian flux pellets were systematically reviewed in this paper,for the purpose of providing basic data and the reference for further promoting magnesia pellet.

Effect of Calcium Fluoride on Slag Cementitious Activity and Volume Stability

Xu Ying, Wang Qiaoling, Hu Chenguang, Zhang Zizi

2018, 39(5): 86-92. doi: 10.7513/j.issn.1004-7638.2018.05.015

Abstract(118) PDF(2)

Abstract:
The cementitious activity and the volume stability of reconstruction steel slag were improved by adding different proportion of calcium fluoride（CaF₂）.The cementitious activity index of the reconstructed steel slag showed a rising trend with the increase of CaF₂ content.It wass 120% when the amount of CaF₂ was 5%.At the same time,it was found out that the content of free calcium oxide（f-CaO）and free magnesium oxide（f-MgO）decreased continuously by means of EDTA chemical titration,and there dropped to 0.09 % and 0.19 % eventually.XRD and SEM observations showed that with the increase of CaF₂ content,the diffraction peak of C₂S decreased gradually,and the diffraction peak of C₃S increased gradually.The diffraction peaks of C₄AF and C₃A were observed when the content of CaF₂ was 1%.The results indicated that the addition of mineralizer（CaF₂）can promote the formation of 3 C₃S-CaF₂ and 2 C₂S-CaF₂ in the intermediate phase,in favor of reducing melting point of molten slag,increasing the liquid amount of reaction,reducing the viscosity of reconstructed steel slag,and promoting the formation of C₃S and C₂S.At the same time,CaF₂ increased the reactivity of CaO,SiO₂ and MgO,and reduced the content of f-CaO and f-MgO in slag,and promoted the formation of C₃S and C₂S.

Optimization of Dephosphorization Rate of Converter Final Slag by Gasification Dephosphorization

Xue Yuekai, Li Chenxiao, Wang Shuhuan, Zhao Dingguo, Chen Jianjun

2018, 39(5): 93-97. doi: 10.7513/j.issn.1004-7638.2018.05.016

Abstract(38) PDF(1)

Abstract:
The coke powder can be used to remove the P element in the final slag in the form of gaseous form,and the slag can be recycled after treatment.In order to further improve the gasification dephosphorization rate,the optimum industrial experiment was carried out.The results showed that the optimum amount of coke powder was 1.1 times of carbon equivalent,and resulting gasification dephosphorization rate was 42.3%.The gasification dephosphorization rate was as high as 37.9% when the bottom blown flow rate of the slag splashing furnace was controlled at 350 m~3/h.The gasification dephosphorization rate was 34% when the coke powder was 6～8 mm.Further refine of coke powder to 4～6 mm had litter effect on gasification dephosphorization rate.Adding 1/2 of coke powder before slag splash and the rest in 10 s after slag splash,the gasification dephosphorization rate can be increased to 37%.

Study on the Mineralogical Characteristics of Titano-magnetite of V-Ti Magnetite Ore in Panxi Region

Li Junhan, Sun Ning, Ma Lan, Yang Shaoli

2018, 39(5): 98-105. doi: 10.7513/j.issn.1004-7638.2018.05.017

Abstract(128) PDF(6)

Abstract:
The x-ray diffraction phase qualitative analysis,optical microscope,electron probe micro-analyzer,scanning electron microscope and linear regression analysis were employed for the mineral composition,chemical composition and the inner structural feature of the titano-magnetite of V-Ti magnetite ore in Panxi Region in this paper.The results indicated that the main mineral composition of the titano-magnetite was consisted of titano-magnetite（whose content was about 68%～90%）,ilmenite（approximate 8%～30%）,titanite（approximate 1%～5%） and the spinel（approximate 0.5%～1.5%）.The main chemical composition of the titano-magnetite was consisted of iron,titanium,vanadium,chromium and manganese,and with about 48%～63% of TFe,14%～30% of TiO₂,1.0%～1.5% of V₂O₅,0.4% of Cr₂O₃ and 0.5% of MnO contained in the titano-magnetite.In addition,there were small amounts of calcium,magnesium,aluminum and silicon,and some of which also contain traces of cobalt and nickel.The content of titanium and manganese has a significant linear negative correlation with iron content,and both of the vanadium and chromium have a closely linear positive correlation with iron.The results showed that the titano-magnetite was in forms of hedral-subhedral aggregates,whose internal structural feature was solid solution separation structure,and the dissolved mineral was mainly ilmenite with platylium,lath or lattice.The researches indicate that the titano-magnetite of the mining area has reached the content standards of industrial utilization,and could be used as industrial iron concentrate after sorting,which provide a basis for the formulation of the titano-magnetite beneficiation technology route.

Effect of Microwave-assisted Silicon Carbide on pH/COD of Coking Wastewater

Shi Yan, Zhao Ying, Zhao Xin, Kong Zheng, Feng Yingying

2018, 39(5): 106-110. doi: 10.7513/j.issn.1004-7638.2018.05.018

Abstract(43) PDF(1)

Abstract:
In this paper the effect of microwave irradiation and silicon carbide absorbing microwave on the pH and COD of coking wastewater had been studied by changing the microwave heating temperature,the type and amount of silicon carbide.When the time is fixed,the increase of microwave temperature can significantly reduce the pH of the coking wastewater.The pH of the coking wastewater after treatment is close to neutral.When the microwave temperature is 90 ℃,the pH of the coking wastewater is 7.78.Increasing microwave heating temperature helps to remove COD.The highest COD removal rate was 23% at a heating temperature of 90 ℃.The co-treatment of green silicon carbide and microwave can achieve the better effect of reducing the pH of coking wastewater.When the mass of green silicon carbide is 5 g,the pH is 7.89.Compared with green silicon carbide,black silicon carbide has achieved better effect of improving the removal rate of COD and the highest COD removal rate is 25%.

Influence of Mineral Structure of Vanadium-titanium Sinter on its Metallurgical Properties

Bai Dongdong, Han Xiuli, Li Changcun, Liu Lei, Chen Qianchong, Zhang Di, Zhao Zhe

2018, 39(5): 111-115. doi: 10.7513/j.issn.1004-7638.2018.05.019

Abstract(31) PDF(2)

Abstract:
The mineral structure of sinter with medium and high titanium content was studied quantitatively by means of polarization microscope.Observations indicates that titanium hematite and titanomagnetite are the main metallic phases in this two sinter,and the binder phases are calcium ferrite,dicalcium silicate and glassy.And perovskite appears in high titanium sinter.The presence of perovskite not only weakens the continuous crystal effect of iron oxide,but also reduces fraction of the binder phase,which results in low temperature reduction degradation of high titanium sinter.Medium titanium sinter has larger amount of titanium hematite than high titanium sinter,therefore it has better reducibility.When the whole structure of sinter is uniform,its structure type determines the strength.The drum strength of medium titanium type sinter with interwoven structure is higher than that of high titanium type sinter with granular structure.It is suggested that the sintering atmosphere should be controlled reasonably and the formation of good structure should be ensured in order to reduce the negative effect of perovskite.

Research on Directly Smelting Semi-steel by Blowing CO₂ into Blast Furnace Vanadium-bearing Molten Iron

Luo Yi, Zhang Ting'an, Niu Liping, Liu Zhuolin, Zhang Baojing

2018, 39(5): 116-121. doi: 10.7513/j.issn.1004-7638.2018.05.020

Abstract(43) PDF(2)

Abstract:
The thermodynamics analysis and experimental investigation had been conduct on the system of decarbonization and vanadium protection by blowing CO₂ to smelt vanadium-bearing hot metal.The results show that it is feasible to remove carbon and keep vanadium by CO₂ blowing.In standard state,the transformation temperature of decarbonization and vanadium protection is 1 630 K.The experimental results show that the optimum conditions are as follows: gas flow rate is 0.6 L/min,ventilation time is 80 min,smelting temperature iss 1 550 ℃,CO₂ concentration is 70%.Under these conditions the decarburization rate can reach 95.6%,and the vanadium content increases slightly..

Precipitation Behavior of Vanadium in HRB500E Steel

Wang Anren, Wang Jinnan, Li Zhaoliang, Qi Jinggang

2018, 39(5): 122-129. doi: 10.7513/j.issn.1004-7638.2018.05.021

Abstract(52) PDF(3)

Abstract:
In this study the solid solution and precipitation temperature of vanadium in steels had been experimentally determined,and the thermodynamics and kinetics of vanadium particle precipitation had been studied.For the steel with chemical compositions of 0.25%C-0.05%V-0.011%N,the V（C,N） particle begins precipitate at 1 040 ℃.The precipitation temperature rises with increasing V content,while the combination index x of VC_xN_1-x decreases as the content of N increasing.V particle is rich in nitrogen at high temperature precipitates and rich in carbon at lower temperature precipitates.A model of dislocation nucleation in a spherical grain is presented to explain its nucleation and growth mechanism.Taking the mass transfer of vanadium as a constrain factor,the calculation result indicates that the growth rate of precipitates decreases with higher interfacial vanadium concentration and bigger precipitate size.

Development of Q500q Steel Plate Via Ultra-fast Cooling and Accelerated Cooling System

Feng Lulu, Zhou Wen, Li Pingping, Wu Kaiming

2018, 39(5): 130-135. doi: 10.7513/j.issn.1004-7638.2018.05.022

Abstract(58) PDF(1)

Abstract:
After continuous cooling transformation test on Q500 q steel,a ultra-fast cooling and accelerated cooling technology had been proposed.For the new controlling rolling and cooling process,during the roughing rolling phase, start rolling temperature shall be over 1 050 ℃ and total reduction shall be greater than 60%,and the thickness of transferred bar is 2.5 times over that of finished product.For the finishing rolling phase,start rolling temperature is between 830～860 ℃and finishing rolling temperature is between 780～810 ℃.The cooling strategy of combined Ultra-fast Cooling and Accelerated Cooling System is used to achieve 630～650 ℃ of finishing cooling temperature with cooling rate of about 15 ℃/s.Microstructure observation show that microstructure of the test steel is composed of acicular ferrite and bainite,with average grain size at ASTM 13.Mechanical test results show yield strength between 538 MPa to 560 MPa,tensile strength between 538 MPa to 560 MPa,elongation≥21% and impact absorbed energy≥160 J at-40 ℃,the direction of thickness reduction of area≥75%.The tested steel has a satisfied combination of strength and toughness.

Development and Welding Thermal Simulation Test of the Normalizing Type 460 MPa Steel for Container

Dong Fujun, Wang Ruizhen, Yang Caifu

2018, 39(5): 136-139. doi: 10.7513/j.issn.1004-7638.2018.05.023

Abstract(36) PDF(1)

Abstract:
A C-Mn-Si base chemistry with Ni addition and V-N microalloying had been designed for producing low yield strength high toughness steel plate via control rolling and normalizing process.The resulted steel plate had been conducted welding thermal simulation test.Welding test results show that with the increase of t_8/5 time,ie,the increase of heat input,the hardness and impact value of HAZ decreases.Microstructure observation indicates that volume fraction and grain size of ferriteare the main reason for the deterioration of CGHAZ performance.Good CGHAZ performance can be achieved at 12.36～14.27 kJ/cm of heat input.

Effect of Bainite Isothermal Temperature on Microstructure and Mechanical Properties of Ultra-high Strength Cold Rolled Transformation Induced Plasticity Steel

Kuang Chunfu, Zhang Jinchao, Zheng Zhiwang, Zhao Juanni

2018, 39(5): 140-143. doi: 10.7513/j.issn.1004-7638.2018.05.024

Abstract(40) PDF(1)

Abstract:
In this paper,C-Si-Mn steels were soaked at 800 ℃ for 120 s,and then rapidly cooled to 350～410 ℃ and held for 600 s to simulate the bainite transformation process.The influence of bainite isothermal temperature on the microstructure and mechanical properties of ultra-high strength cold rolled transformation induced plasticity（TRIP）steel was investigated by means of scanning electron microscopy（SEM）and tensile test.The results showed that the microstructure of cold rolled TRIP steel was composed of ferrite,bainite,martensite and retained austenite.The bainite and retained austenite were formed in the isothermal stage,and the martensite island was formed in the final cooling stage after isothermal process.With an increase in the bainite isothermal temperature,the carbide precipitated fully due to the increase of diffusion coefficient.Therefore,the average solute C content in the supercooled austenite decreased due to the precipitation of solute C atoms.The martensite volume fraction increased,and the retained austenite volume fraction reduced.As a result,with an increase in the isothermal temperature from 350 ℃ to 410 ℃,the yield strength decreased from 720 MPa to 573 MPa,the tensile strength increased from 1 195 MPa to 1 312 MPa,and the elongation A₈₀decreased from 17.8% to 12.5%.Therefore,the cold rolled TRIP steel with excellent comprehensive mechanical properties(R_m×A₈₀=21 270 MPa·%)was obtained by bainite isothermal holding at 350 ℃.

Microstructures and Properties of HR800CP Multiphase High Strength Steel Welded Joints

DONG Xian-chun, ZHAO Yang, HAN Ni-dan, ZHANG Yong-qiang, GUO Zi-feng

2018, 39(5): 144-148. doi: 10.7513/j.issn.1004-7638.2018.05.025

Abstract(95) PDF(3)

Abstract:
HR800 CP multiphase high strength steel was welded with laser welding and 80%Ar+20%CO₂gas-shield welding（MAG）with CHW-60 C welding wire.Microstructures and mechanical properties of the joints were studied.The result shows that,the microstructure of the weld center and the heat affected zone withlaser weldingare martensitic and bainite,the hardness of the weld center and the heat affected zone is higher than that of the base metal,there is no cracking along the weld seam while the bending degreeis 180°,the tensile strength of the joint is 799 MPa,which is lower than the base metal,because the pit on laser welding seam.For MAG welding,the microstructure of weld center are acicular ferrite and massive ferrite,while the coarse grain zone is comprised of lath martensitic and bainite.Bainite dominates the normalizing region,there is relatively soft area near the fusion line,and the tensile strength of the joint is 755 MPa,which is lower than the base metal too.

Analysis on Temperature Field and Stress Field of T-type Long Plate Welding

Liu Jixiao, He Pengfei, Wu Aihui

2018, 39(5): 149-156. doi: 10.7513/j.issn.1004-7638.2018.05.026

Abstract(94) PDF(3)

Abstract:
The numerical simulation of 4 m T-welded joint welding process was carried out by the finite element software Ansys.Using the indirect coupling method,the temperature field was calculated and then the stress analysis was carried out to obtain the stress field.It was found out that there would be a very uneven temperature field after welding,and it would lead to large welding residual stress and residual deformation.The calculated results showed that the temperature field was good agree with the experimental results,but not for the welding residual deformation.In order to study the influence of the boundary condition on residual deformation,parameter analysis were carried out.It was found out that supporting the plate during welding could reduce the residual deformation effectively.

Development of Hot-dip Galvanized Baking Hardened H220BD + Z Steel for Automobile External Application

Hu Huadong

2018, 39(5): 157-161. doi: 10.7513/j.issn.1004-7638.2018.05.027

Abstract(60) PDF(4)

Abstract:
Considering the metallurgy characteristic of baking hardening steels,the YS220 MPa grade baking hardening steel was developed by suitable alloying design and optimizing smelting,hot-rolling and galvanizing processes.The results show the steel has 220～270 MPa yield strength,320～400 MPa tensile strength,A₈₀≥32%,r-value ≥1.5,n-value ≥0.16 and BH₂ value≥30 MPa,and excellent formability and good bake-hardening behavior.The coating layer of sheet is even..After aging 150 days,the steel still has the smooth tensile curve and constant mechanical properties except decreasing r-value.The steel is well used in automobiles for exposed panels with excellent aging behavior within room temperature.

Molecular Dynamics Study of the Structure of Titanium Carbide Nanoparticles during Cooling Process

Lü Yanan, Zhang Shunhu, Chen Dong

2018, 39(5): 162-166. doi: 10.7513/j.issn.1004-7638.2018.05.028

Abstract(58) PDF(1)

Abstract:
The variation of titanium carbide cluster structures during cooling process were studied via molecular dynamics simulation.The influence of titanium carbide cluster size varying from 80 to 5 000 atoms on cluster structure were investigated,and the influence of cooling rate on the cluster structure and solidification point was carried out.The results show that for large titanium carbide particles the NaCl-crystalline,glassy clusters and polycrystalline structure were formed at different cooling rates,respectively.The TiC cluster sturcures are NaCl-crystalline at the cooling rates of 5×10¹¹ K/s,glassy clusters at 1×10¹³ K/s,and polycrystalline structure at 1×10¹² K/s.Furthermore,the solidification point decreases with the increasing cooling rate and the decreasing particle size.

Cause Analysis of Central Cracks in SPA-H Steel

Xu Mengchun, Li Dejun, Chen Dong, Yu Fuzhi, Jin Xing

2018, 39(5): 167-172. doi: 10.7513/j.issn.1004-7638.2018.05.029

Abstract(29) PDF(1)

Abstract:
Central crack frequently occurred in the forming of a kind of SPA-H steel sheet.The cause for central crack had been investigated by analysis of the chemical composition, metallurgical structure and EDS.It is found out that ferrite segregation band exists in the center of steel sheet, and there are a lot of MnS inclusions in segregation zone, which is expected the main reason for the central crack during process steel sheet.Accordingly the counter measurement has been proposed to solve the central cracks in SPA-H steel sheet.

2018 Vol. 39, No. 5