钢铁钒钛

Calcination Time Effects on Anatase White Pigment Production via Low Concentration Industrial Titanyl Sulfate Solution Hydrolyzing

Tian Congxue, Huang Shuanghua, Yang Ying, Ren Xiaoqing, Li Hui, Yang Cheng

2012, 33(5): 1-5.

Abstract(60) PDF(1)

Abstract:
Using low concentration industrial titanyl sulphate solution as raw material,anatase titania white pigment was prepared via the sulphate process of hydrolyzing,washing,salt treatment and calcination.And the effects of calcinations holding time at the highest temperature on structure and pigment properties were investigated.The as-prepared calcined samples were characterized by XRD,particle size distribution test,SEM and pigment properties test.Calcinations conditions had great influence on the crystal structure,grain size,particle size and its distribution,as well as pigment properties of the anatase white pigment.The average particle size of all the samples maintained about 300 nm,and crystal growth was consistent with first order kinetics of growth model.Keeping temperature at 930 ℃ for 30 min was the optimized calcination condition,and the prepared titanium white pigment was with regular morphology,the narrowest particle size distribution.The achromic ability index of the sample under optimized calcination condition was of 1 450,and relative whiteness index of 100.23%,higher than standard sample PTA120.

Leaching of Water Quenched Titanium-bearing Blast Furnace Slag in Hydrochloric Acid

Zhang Peng, Liu Daijun, Mao Xuehua, Chen Jianjun

2012, 33(5): 6-9.

Abstract(50) PDF(3)

Abstract:
Following ironmaking process in BF,a great deal of titanium is brought from iron conentrate into slag.In order to recycle the titanium in water-quenched Ti-bearing blast furnace slag,hydrochloric acid is used in the leaching process.Possible influencing factors on leaching rate are investigated.The result indicates that a large amount of Ca,Mg,Al and Ti dissolves in hydrochloric acid solution in leaching process.Among the potential influencing factors investigated in experiments,raw materials size has no influence on Ti leaching rate,while hydrochloric acid concentration,reaction time,reaction temperature and ratio of liquid over solid have a pronounced impact on it.The optimum leaching conditions are thus obtained as follows: concentration of hydrochloric acid of 30% above,residence time for 120 min,ratio of liquid over solid of 7.5 above,and temperature at 90 ℃.Under the optimum leaching conditions,the leaching rate of titanium can reach 90% above.

Study on Reducing Soluble Vanadium in the Vanadium-bearing Residue

Wu Zhenxiu

2012, 33(5): 10-13.

Abstract(39) PDF(2)

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In view of too high soluble vanadium in the residue during continuous leaching and filtration of vanadium-bearing clinker using the belt filter in a vanadium plant,simulation and optimization experiments were carried out in laboratory to probe into the effects of particle size of clinker,residue washing times,washing water volume and clinker soaking time on soluble vanadium content in the residue.The results show that soluble vanadium can be lowered below 0.12% with the washing liquid to solid ratio no less than 0.65∶1,residue washing times no less than 3 and soaking period more than 25 min.It can be found from experimental results that the vanadium recovery rates are obviously improved compared with previous production（soluble vanadium percentage of 0.184%～0.324%）.

Effects of Al Content on Phase Transformation in FeV50 Alloy and Its Mechanism

Xian Yong

2012, 33(5): 14-18.

Abstract(49) PDF(2)

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FeV50 alloys with different Al contents were smelted and cooled to room temperature in the furnace,then their phases and microstructures were investigated by X-ray diffraction（XRD）and scanning electron microscope（SEM）respectively.The results showed that with the increase of Al content in FeV50,the phase transformation from σ phase to α phase was found.The 0.8% Al content was so critical that when it was below 0.8%,FeV50 was in form of σ phase,but when above 0.8%,two phases coexisted until a single α phase was obtained.It is supposed that Al affects the phase transformation in two ways.First,critical nucleus size becomes larger with the increase of Al which results in less energy available as driving force for α→σ phase transformation in the system.Second,the higher Al content,the stronger its inhibitory effect on the Fe atom diffusion,and as a result allotropic transformation of Fe is prevented,thus,α→σ phase transformation is retarded.

Studies on Photocatalyic Properties of ATP-SnO₂-TiO₂ Composite Photocatalysts

Dong Xingsheng, Si Naichao, Si Songhai, Zhou Guanghong

2012, 33(5): 19-24.

Abstract(53) PDF(1)

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Photocatalytic removal of formaldehyde under ultraviolet radiation has been studied using attapulgite base composite photocatalysts（ATP-SnO₂-TiO₂）,which were synthesized by an in situ sol-gel technique with a carrier of attapulgite.The composites were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM） and other analytical techniques.The effects of preparing conditions on the physical characterization and the photoactivity were investigated,and photoability of different composite photocatalysts were also discussed in detail.Results showed the photoability of ATP was improved significantly by loading SnO₂-TiO₂,when the proportion of TiO₂ was 50%,quality ratio of SnO₂/ TiO₂ was in 1∶4 and the sample was treated at 800 ℃,the photoability was larger.The degrationg rate on the formaldehyde of 30 mg/L can amount to 99% above after three hours,the composite photocatalyst showed excellent photocatalytic properties.

Strengthening Mechanism of Ti(C_yN_1-y) Particle on Metal Matrix Composite Layer by Laser Cladding

Qi Yongtian, Cao Zhaoxia, Cao Runping

2012, 33(5): 25-29.

Abstract(32) PDF(1)

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Fe-based composite layer with Ti（C_yN_1-y） particles was prepared on the surface of cast steel by laser cladding process using transverse CO₂ laser beam as inducing heat source.The microstructures and strengthening mechanism of laser clad layer were analyzed by means of optical microscopy（OM）,X-ray diffraction（XRD） instrument,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The microhardness of the layer was measured by using microhardness meter.The results show that the surface quality of laser clad layer which is composed of bonding metal matrix and second phase particle Ti（C_yN_1-y） homogeneously dispersed is fairly good.The newly formed particles Ti（C_0.3N_0.7）and Ti（C_0.2N_0.8）come into being by some new chemical combination reactions,and most of Ti（C_yN_1-y） particles are irregular.The microhardness of laser clad layer distributes within HV_0.2 800～900.Microanalysis of the clad layer shows that the strengthening mechanism of the layer includes fine grain strengthening,dispersing strengthening of hard particles and solid solution strengthening.

Comparative Study on Softening-melting Properties Between V/Ti-bearing magnetite pellet and Common Pellet

Yang Guangqing, Zhang Jianliang, Shao Jiugang, Wen Yongcai, Rao Jiating, Fu Weiguo

2012, 33(5): 30-34.

Abstract(59) PDF(3)

Abstract:
The softening-melting properties of the V/Ti-bearing magnetite pellet and four kinds of common pellets were researched through simulating the conditions of blast furnace in the laboratory,and the difference between V/Ti-bearing magnetite pellet and common pellet in the process of softening-melting was analyzed.The result of the experiment indicates that the softening,melting and dripping temperature of the V/Ti-bearing magnetite pellet are higher than that of common pellet,and the maximum pressure drop and characteristic value of the V-Ti magnetite concentrate pellet are lower than those of common pellet.The softening-melting properties of the V/Ti-bearing magnetite pellet are superior to the common pellets,and also the V/Ti-bearing magnetite pellet has stronger deformation resistance than common pellet.Finally,the service performance of the V/Ti-bearing magnetite pellet in blast furnace is consistent with the results of simulating experiment in the laboratory.

Course Analysis and Prediction Principle of Steel Leakage in Continuous Casting Mold

Xu Hailun, Ma Chunwu, Li Qingzhong, Xing Wei, Xu Yongbin

2012, 33(5): 35-40.

Abstract(76) PDF(1)

Abstract:
Course and characteristics of sticking leakage of molten steel in mold was introduced and appearance feature of tear position in sticking shell was unveiled in this paper.Expansion pattern of tear lines caused by sticking and characteristics of temperature transmission in the process of sticking were analyzed by geometric method.In order to improve the accuracy of prediction,horizontal and vertical temperature transmitting behavior should be detected simultaneously,and thus the thermocouple should be laid according to the rule of the equivalence of horizontal and vertical temperature transmitting time.In addition,several typical temperature changing patterns were studied and two atypical temperature patterns of sticking leakage were added,which can provide reference and basis for correct dynamic recognition of sticking leakage and surface defects of shells.Thus,a foundation has been laid for the development of advanced leakage prediction system based on temperature measurement with thermocouple.

A Method for Solving the Inverse Heat Conduction Problem During Aerosol Cooling Process

Zhao Zengwu, Zhao Lifeng, Zhang Yazhu, Zhou Liping, Zhang Mengyun, Hu Qiang

2012, 33(5): 41-45.

Abstract(48) PDF(1)

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A mathematical model was established in this paper to deduce unknown surface temperature and surface heat flux density in the process of 1-d unsteady state thermal conductivity based on the temperatures measured at each internal temperature measuring point in casting strand.Difference equation for each node was established by using heat balance method,and through the introduction of sensitivity coefficient,the initial boundary conditions was optimized through Newton iterative method.In order to verify the correctness of the mathematical model,through exerting heat flux with given density on the solid surface,it was found that the heat flux density obtained through deduction coincided with the given value.In addition,the changing rule of the heat flux density on the surface of the casting strand in the process of secondary cooling during continuous casting was analyzed.

Water Modeling Experiment on Factors of Casting Process to Intermixed Slab Length during Grade Transition

Bi Jinghan, Tang Ping, Wen Guanghua, Ding Ling, Su Gang

2012, 33(5): 46-49.

Abstract(67) PDF(2)

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Taking the No.1 continuous caster of Chongqing Iron and Steel Co.,Ltd.as a prototype,water modeling experiments were conducted to simulate continuous casting during grade transition.The dimensionless concentration profiles along slab length under different casting speed,residual steel level in tundish and casting sequence were measured.The results show that the residual steel level in tundish has a more significant impact on the length of intermixed slab than the other two factors.

Thermodynamic Analysis and Control of the Precipitation of TiN in Titanium-bearing Gear Steel

Ge Yunzong, Wang Jianjun, Yan Huicheng, Qiu Shengtao

2012, 33(5): 50-54.

Abstract(58) PDF(2)

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The themodynamic analysis on titanium nitride’s formation was carried out in order to control its precipitation in the tested steel.The results show that no TiN inclusions can be found in molten steel at temperature above liquidus;during solidification of molten steel,thanks to the enrichment of Ti and N in the two-phase region,the formation reaction of TiN proceeds.So the best way to reduce precipitation of TiN in practical production is to control Ti and N contents in steel,and quicken the molten steel through two-phase region（1 728～1 787 K） by increasing secondary cooling rate during continuous casting.Calculation suggests that the value should be controlled below 7.04×10^-5 to ensure no precipitation of TiN inclusion in the tested steel during solidification process.

Research on the Mathematical Modeling for Dynamic Recrystallization of V-N Microalloyed Steel

Zhao Baochun, Zhao Tan, Li Guiyan

2012, 33(5): 55-59.

Abstract(55) PDF(1)

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Single-pass compressing tests were performed with the Gleeble-3800 thermo-mechanical simulator at the temperature of 900 ℃ to 1 050 ℃ and strain rate of 0.1 s^-1 to 10 s^-1 to investigate the dynamic recrystallization behavior of a kind of vanadium-bearing microalloyed steel and the stress-strain curve was obtained as a result.By the regression analysis of the stress-strain data obtained from the test,the material parameters in the hyperbolic sine constitutive equation and the dynamic recrystallization activation energy,including the relationship between the critical strain and parameter Zener-Hollomon,were determined.Based on the conditions for the deformation,the dynamic recrystallization diagram of the tested steel was drawn.

Research and Application of High Temperature Deformation Resistance in Low-alloy Steel with Vanadium

LIU Yong

2012, 33(5): 60-65.

Abstract(65) PDF(1)

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By the MMS-200 testing machine for thermal simulation,researched the deformation resistance in 850~1 100 ℃ temperature for vanadium low-alloy steel whose tensile strength is 510 MPa and analyzed deformation temperature,deformation speed and deformation extent to influence the deformation resistance in the test.According to the experimental result,the mathematical model of deformation resistance in hot continuous rolling has been optimized and improved.The prediction error for rolling force is reduced from 8%~10% to below 5%.The prediction accuracy of the mathematical model for process control has been improved effectively.

Comparative Study on Precipitation Behavior and Texture Formation of Ti-IF Steel and Nb+Ti-IF Steel during Batch Annealing

Feng Yanqing, Wang Fuming

2012, 33(5): 66-69.

Abstract(32) PDF(1)

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Precipitation behavior and texture formation of the two interstitial-free steels with Nb and without Nb addition during cold rolling-batch annealing process were investigated by using metallographic microscope,scanning electron microscope（SEM）,transmission electron microscope（TEM） and X-ray diffraction（XRD） instrument.The results show that Nb does not significantly improve the recrystallization texture;however,it promotes the formation of TiN,TiC and TiS and increases the number and size of TiN precipitate by increasing the effective solid solubility of Ti in the matrix;as a good grain refiner,Nb inhibits grain growth during coiling and recrystallization annealing;the addition of Nb tends to coarsen the carbonitride precipitates and reduce the volume fraction of the {111}＜110＞ texture component in the γ fiber.

Investigation into Causes of Cracking of HP295 and Countermeasures

Chen Xingfu, Yang Tongli, Xiao Jiming, Zhu Ning, He Xiaofeng, Zhou Qiulan

2012, 33(5): 70-74.

Abstract(44) PDF(1)

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Cracks have been found during deep processing of the HP295 supplied by a hot rolling plant of an iron ＆ steel company.In order to solve this problem,based on analysis of mechanical properties and microstructure of HP295,chemical compositions and rolling processes are optimized by lowering the content of C,Mn and P,reducing the anisotropy of the strip,and applying final rolling temperature of 850～890 ℃,two-stage cooling,coiling temperature of 630～670 ℃,which may be adjusted a little with seasons.Thus,higher proportion of finer and more uniform ferrite and more dispersive pearlite with lower yield ratio are obtained.As a result,the average cracking rate of HP295 is decreased from about 1% to 0.3%.

Study on Microstructure and Properties of 590L Auto Beam Steel and Its Trial Production

Dou Zhiyong, Huang Bin, Luo Youyuan

2012, 33(5): 75-79.

Abstract(60) PDF(2)

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Through rolling simulation of 590L auto beam steel,microstructure and properties of the steel under different microalloying conditions are investigated.Research results show that microstructures of acicular ferrite and a small amount of bainite obtained from microalloying with Nb,V,Ti,and B can satisfy the strength and toughness requirements of 590L auto beam steel.According to the research results in the laboratory as well as production experience,trial production has been carried out and qualified 590L auto beam steel has been successfully developed through optimization of composition and process design.The microstructure and properties of the steel so produced can fully meet the users’ requirements.

Process Control and Defect Formation Mechanism of 321 Stainless Steel

Wang Jianze, Tang Xingchang, Hu Weihua, Kang Yonglin

2012, 33(5): 80-83.

Abstract(46) PDF(1)

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The technical features of 321 stainless steel produced by steekle mill were introduced in this paper,including its alloying design,process control and mechanical properties.Morphology of the inclusions and the surface defects of the steel were analyzed by OM and SEM.The results showed that the 321 stainless steel exhibits excellent mechanical property and good surface quality.The main surface defect is linear scale,which is caused by the mass clustering of TiN grains in the continuously cast bloom.In order to effectively improve the surface quality of the steel,some measures can be taken,including controlling contents of elements such as Ti,Al,N,and O and degree of superheat during casting,and setting reasonable parameters of argon stirring in LF.

Influence of Microstructure on Erosion Behavior of 3Cr13 Stainless Steel

Wang Haishuai, Wang Shuqi, Zhu Tao, Mao Yishu, Yu Jianping

2012, 33(5): 84-88.

Abstract(49) PDF(1)

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The liquid/solid erosion wear tests were conducted for 3Cr13 steel which had been tempered at different temperatures on the self-made jet-type erosion wear tester.The effects of microstructure on erosion behavior of 3Cr13 steel were investigated,and erosion mechanisms were also discussed.Results showed that for all the three tempered microstructures of 3Cr13 steel,maximum erosion rates were found at 45 degree angle of attack.The erosion resistance of specimens tempered at 200 ℃ and 500 ℃ exhibited no obvious difference,showing better erosion resistance than the specimen tempered at 750 ℃ which reached stable erosion stage earlier.The main erosion mechanism was characterized by micro-cutting at low angle of attack and by brittle spalling and fatigue damage at high angle of attack.

Study on Texture Evolution of 50W600 Non-oriented Silicon Steel During Grain Growth

Pu Chunlei, Xiang Li, Qiu Shengtao, Song Ning

2012, 33(5): 89-95.

Abstract(48) PDF(1)

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The mechanism of recrystallized texture evolution of non-oriented silicon steel during grain growth has been studied by using EBSD technology.The results show that texture evolution during recrystallized grain growth originates from different growth rates of texture components;grain size is not the only determinant for the grain growth,and the misorientation angle distribution of the grain and other surrounding grains has obvious influence on its growth.Thanks to grain competition between {111} ＜112＞ and {111} ＜110＞,sharpness of {111} texture’s orientation changes alternately.As the annealing time increases at 950 ℃,the {100} ＜120＞ texture and {100} ＜310＞ texture are weakened while {110} ＜001＞ is enhanced;As the annealing temperature increases with a constant annealing time for 3.5 min,all of the {110} ＜001＞,{100} ＜120＞,and {100} ＜310＞ textures are enhanced.Temperature has a great impact on misorientation angle distribution of grains with different orientations.

Comparative Research on Properties of High-strength AH32 Uncoiled and Leveled Plate and AH32 Medium Plate

Dong Zhongqi, Yuan Zhixue, Li Junsuo, Han Tiwen, Chen Jin, Ma Shuiming

2012, 33(5): 96-100.

Abstract(94) PDF(2)

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Comparative research on mechanical properties（including tensile strength,yield strength,elongation and residual stress） and the microstructure of AH32 uncoiled and leveled plates produced with new process and conventional AH32 medium plates in the thickness range of mm, mm, mm, mm was carried out.The test results show that both of the tensile strength and yield strength of AH32 uncoiled and leveled plates at the transverse direction are higher than those at longitudinal direction while its elongation is better at longitudinal direction;both of the tensile strength and yield strength of AH32 medium plate are similar at the two directions while its elongation is a little better at longitudinal direction.It can be concluded that the mechanical properties of AH32 uncoiled and leveled plate are better than those of the medium plate in the same size range.The difference in mechanical properties between longitudinal and transverse directions may be attributed to the different deformation of the plates in the two directions.

Research on Wear Behavior of 3Cr3Mo2V Cast Steel and 3Cr13 Steel

Mao Yishu, Cui Xianghong, Wang Shuqi, Li Dongsheng

2012, 33(5): 101-106.

Abstract(49) PDF(1)

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Dry sliding wear tests were performed for 3Cr3Mo2V cast steel and 3Cr13 steel at 25 ℃ and 200 ℃ on a pin-on-disk wear tester.The effect of microstructures and tribo-oxides on the wear behavior of 3Cr3Mo2V cast steel and 3Cr13 steel was probed into and the wear mechanism was also discussed.The results show that tribo-oxides exert a significant influence on wear behavior and mechanism,and the wear reducing effect of tribo-oxides depends on their amount and substrate state that is closely related with the compositions and microstructures of the steel.High Cr content impedes the formation of tribo-oxides and tempered sorbite with low hardness accelerates the stripping of tribo-oxides,thus,the wear reducing effect of tribo-oxides is destroyed or reduced.

2012, 33(5): 107-108.

Abstract(54) PDF(1)

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2012 Vol. 33, No. 5