钢铁钒钛

Preparation of Doped Porous Titania from Industrial Titanyl Sulfate and its Catalytic Activities

Tian Congxue, Yang Ying, Pu Hong

2011, 32(3): 1-6.

Abstract(16) PDF(1)

Abstract:
Doped porous titania with anatase phase was prepared via thermal hydrolysis of industrial titanyl sulfate solution as titanium source,by adjusting the index of the titanium solution and the volume ratio of titanium solution to water.The as-prepared samples were characterized by XRD,particle size distribution,nitrogen absorption-desorption method and XRF determinations.Different volume ratio of titanium solution to water has great effects on the crystal structure,particle size,specific surface area and pore structure of the porous titania.Improving of crystallite of anantase phase,increase of specific surface area and impure ion dopant can all promote the photocatalytic activity of porous titania.At the volume ratio of titanium solution to water of 100:35,the porous titania was prepared with the biggest specific surface area,the S_BET of 215.4 m²/g,which had a narrow pore size distribution and doped with a small amount of oxides.And it showed high photocatalytic activity on degradation of methylene blue,with degradation rate of 92.8%.

Preparation and Photocatalytic Activity of the N-Fe co-doped TiO₂ by Hydrothermal Method

Cao Yan

2011, 32(3): 7-11.

Abstract(25) PDF(1)

Abstract:
Using tetra-4-butyl titanate as precursor,NH₄NO₃ and Fe(NO₃)₃·9H₂O as dopants,the N-Fe co-doped TiO₂ were synthesized through hydrothermal method.The size,appearance,structure and property of TiO₂ were characterized by XRD,FE-SEM,UV-VIS,BET and FT-IR.The results showed that the co-doped TiO₂ powders were anatase,spherality,possessed specific surface area of 201 m²/g and grain size of 9.2 nm.The experiment results of methyl orange solution degradation show that the degradation rate of methyl orange was 96.4% under Xe-lamp(350 W) irradiation 1 hour,and the photocatalytic activity was higher than P25.Under the sunlight irradiation 4 hour,the degradation rate of methyl orange was 84.5%.

Study on the Ultra High Cycle Bending Vibration Fatigue Test of Titanium Alloys

Shen Jingsheng, Li Quantong, Wu Xiaofeng, Gao Chao, Liu Qingchuan

2011, 32(3): 12-15.

Abstract(22) PDF(2)

Abstract:
Based on the three-point bending method,an ultra high cycle bending vibration fatigue system is developed and the design method of fatigue test specimens is introduced too.The S-N curve of titanium alloy TC17 is determined by the ultra high cycle dissymmetrical bending fatigue system(20 kHz).The result shows that when stress ratio(R) is-1,the S-N curve of titanium alloy TC17 is a continuously declining curve,The specimens continue to fail over 10⁷ stress cycles.In 10⁷ weeks time,the samples don't happen the fatigue damage,so it does not exist in the traditional sense fatigue limit.

Influence of Vanadium on Thermal Healing of the Inner Cracks in Q235 Steels

Zhao Zhongli, Wu Daming, Zhang Yajun

2011, 32(3): 16-20.

Abstract(18) PDF(1)

Abstract:
Thermal healing experiment of inner cracks made by compressing a drilled hole on samples of Q235 steel with various vanadium addition was carried out.The effects of vanadium on inner cracks thermal healing and morphology evolution were investigated.SEM analysis results displayed that inner crack samples have apparent healing at 800℃ and the healing is best with 0.1% vanadium addition.After vanadium added to the matrix partial of it is soluted in the matrix.The soluted vanadium reduces the activation energy for diffusion of Fe atoms,accelerates the self-diffusion of Fe atoms.The primary mechanism of inner crack healing in metals is diffusion thermal healing and the recrystallization.It requires the systemic method to research the microstructure both of the crack zone and the matrix of internal cracks healing in the steel.

Effect of Micro-Ti Treatment on Microstructure and Mechanical Properties of V Microalloyed Steel

Guo Fuxing, Zhang Junfen, Zhao Yingli, Wang Baohua, Liang Jingzhao

2011, 32(3): 21-24.

Abstract(27) PDF(3)

Abstract:
V and Ti-V microalloyed steels were produced in Chenggang 1780 hot rolling line.The effect of micro-Ti treatment on microstructure and mechanical properties of vanadium microalloyed steels has been studied in this paper.The experimental results demonstrate that a little amount of TiN precipitation can be obtained after micro-Ti treatment and its quantity is less,can not effectively refine ferrite grains in V microalloyed steels;the amount of precipitation of vanadium reduced because of the priority of titanium and nitrogen combined,then tensile and yield strength values of vanadium microalloyed steels can decrease about 54 MPa,45 MPa respectively,and the elongation was up slightly.

Thermodynamic Analysis of Ca²⁺ and Mg²⁺ Curing Process in Molten Chlorides

Ju Dianchun, Qing Yang, Yan Dingliu, Chen Zhiyong, Li Xiangyang

2011, 32(3): 25-29.

Abstract(17) PDF(2)

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The reasons of deterioration of physical and chemical properties of molten chlorides during molten-salt chlorination of titania-rich slag were discussed,and a process of curing of Ca²⁺ and Mg²⁺ in molten chlorides was proposed which can improve the properties of molten chlorides,also the feasibility of the Ca²⁺ and Mg²⁺ curing process was verified by thermodynamics.The Gibbs free energy of curing reactions is less than zero,thus they can spontaneous reaction.When Na₂SO₄ as a curing agent and the temperature is below 1 073 K,both of k_p=[Ca²⁺] [SO₄^2-] and k_p=[Mg²⁺] [SO₄^2-] are less than 2.5×10^-3;when Na₃PO₄ as a curing agent and the temperature is below 1 173 K,k_p=[Ca²⁺] [PO₄^3-]^2/3<2.5×10^-6,k_p=[Mg²⁺] [PO₄^3-]^2/3<1×10^-7.

Research on Reasonable Selecting Rail in the Line with Notable Damage of Contact Fatigue

Deng Jianhui, Chen Chaoyang, Xu Quan

2011, 32(3): 30-33.

Abstract(30) PDF(1)

Abstract:
In the main line transporting both passenger and freight with notable damage of contact fatigue,the paving trial of 1 100 MPa heat treated rail,U75V rail,and U71Mn rail have been carried out.The result indicates that the 1 100 MPa heat treated rail's contact fatigue resistance properties are better than the U75V and U71Mn rail's.Selecting 1 100 MPa heat treated rail in the sweeping curve or line of the main line transporting both passenger and freight with notable damage of contact fatigue,the rail's contact fatigue damage can decrease obviously,and the trail gains good integral effectiveness.

Formation Mechanism of a Sliver-type Defect on the Surface of Hot Rolled Plate

Yang Wen, Wang Xinhua, Wang Wanjun, Xue Yongqiang, Dan Qinglin

2011, 32(3): 34-39.

Abstract(16) PDF(1)

Abstract:
A sliver-type lineal defect on the surface of hot-rolled Q345B plate was investigated.The morphology,structure and component of the defect's cross and longitudinal sections were analyzed by using optical microscope and SEM-EDS.The results showed that the defect with concavity is a wrinkle type defect,which is derived from the transverse corner crack of the slab and formed during the rolling process.Accordingly,a formation mechanism of the defect is proposed,and it is supposed that in order to eliminate the defect,the formation of the transverse corner crack should be prevented.

Effect of Coiling Temperatue and Cold-rolling Reduction on the Properties of High Strength IF Steel

Zheng Zhiwang, Wang Minli, Li Xusheng

2011, 32(3): 40-45,50.

Abstract(20) PDF(1)

Abstract:
Two industrial produced hot-rolled high strength IF steel strips were cold rolled in laboratory cold rolling mill,and then annealed in salt bath according to the process of a continuous hot-dip galvanizing line.Optical microscopy and tensile tests were used to study the effect of coiling temperature(670℃ and 710℃,respectively) and cold-rolling reduction(55%,65%,75% and 85%,respectively)on their properties.The results showed that,lower coiling temperature refines the grain size of the hot-rolled strip,but the grain size of the cold-rolled and annealed steel is relatively coaser and the r_m value is also relatively lower.the ferrite grain size of the cold-rolled and annealed steel remains fine.However,the cold-rolled and annealed steel has much lower yield strength as a result of scavenging of interstitial carbon atoms by means of NbC ripening during annealing.The coiling temperature has little effect on the strength,elongation and n_m value of the cold-rolled and annealed steels.An increase of cold rolling reduction from 55% to 75% almost doesn't affect the ferrite grain size of the annealed steel.A further increase of cold rolling rduction to 85% only refines the ferrite grain a little.The cold rolling reduction has no obvious effect on strength and elongation and has no effect on n_m value.But r_m value increases when the cold-rolling reduction increases.

Control of Inclusions of Non-oriented Silicon Steel Sheets by RE Treatment

Zhang Feng, Lü Xuejun, Wang Bo, Ma Zhigang, Zhang Yi, Li Guangqiang

2011, 32(3): 46-50.

Abstract(29) PDF(1)

Abstract:
Based on the industrial production of non-oriented silicon steel,the experiment on RE treatment during the RH refining process was studied.The morphology and the size distribution were observed for the steel specimens treated with different RE treatment conditions.Further more,the formation and change of inclusions of final steel sheets after RE treatment were discussed.The results show that the suitable RE added amount was 0.6~0.9 kg/t.After the suitable RE treatment,the formation of AlN and MnS irregular inclusions were restrained,and the aggregating,floating of micro inclusions were promoted efficiently,the cleanliness of liquid steel increased obviously.Meanwhile,the total oxygen content reached the minimum value and the desulfurization effect was optimal,and the type of main inclusions was approximate spherical or elliptical spherical RE radicle inclusions whose size was relative large.

Research on the Microstructure and Anti-corrosion Property of Magnesium Chromate Insulation Coating on Non-oriented Silicon Steel

Kong Xianghua, Sun Ruihong, Tang Jin, Li Wenhao, Wang Gengchao, Wang Yuanji

2011, 32(3): 51-54.

Abstract(17) PDF(1)

Abstract:
In this paper,the microstructure and anti-corrosion property of magnesium chromate coating on non-oriented silicon steel were studied.The microstructure was observed by SEM and AFM.The anti-corrosion properties were evaluated by polarization curves.The results show that the thickness of coating is several microns and the polymer particles were scattered on the surface of inorganic coating,which is the guarantee for lamination property.The corrosion resistance of the magnesium chromate film was equal to that of the zinc chromate film.

Microstructure and Corrosion Resistance of Hot Dip Zn-Sn-Ni Alloy Coatings

Gui Yan

2011, 32(3): 55-58.

Abstract(14) PDF(1)

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In this paper,0.36% silicon-containing steels were used and the growth dynamics and microstructure of hot dip galvanized Zn-Sn-Ni(w_Ni ≤ 0.12%,w_Sn=1%) coating of those steels at 450℃ were studied in a series of galvanizing experiments and by various of testing methods such as SEM,electrochemical polarization and XRD.The results showed that the Zn-Sn-Ni alloy bath method can effectively restrain the over-growth of galvanized coatings of reactive steels and gain eligible coatings with proper thickness,and compact microstructure.The corrosion rate of Zn-Sn-Ni coating is less than that of pure zinc coating in 5% NaCl solution.Zn-Sn-Ni coating shows lower corrosion current,the increasing polarization resistance,and presents the better corrosion resistance than pure zinc coating.The corrosion products of Zn-Sn-Ni and pure zinc coating are both composed of Zn₅(OH)₈Cl₂·H₂O and ZnO.

Segregation of Boron in Ultra Low Carbon Microalloyed Steels Containing Copper during Continuous Cooling

Zhao Shoutian, Wu Ping, Chen Sen, Zhao Xin

2011, 32(3): 59-63.

Abstract(12) PDF(1)

Abstract:
By means of particle tracking autoradiography(PTA),the segregation of boron to grain boundaries in ultra low carbon microalloyed steels during cooling from 1 150℃ to 850℃ at 5℃/s was investigated.The enrichment factors and widths of boron depletion zone were measured at different temperatures,and the effect of copper on the segregation of boron was analyzed.It is found that the concentration of boron on the grain boundary increases in the beginning cooling stage and reaches its maximum at about 1 090℃;after that,it decreases gradually to a minimum with temperatures decreasing to 940℃;and then,it increases again.

Analysis of Mechanical Properties and Microstructure of Q235 H-beam Steel after Hot Rolling and Fast Cooling

Lu Huaimin, Wang Kaizhong, Wu Shengfu, Huang Zhenyi

2011, 32(3): 64-69.

Abstract(27) PDF(1)

Abstract:
Ferrite grain size and mechanical properties of Q235 H-beam steel after hot rolling and fast cooling were concerned with austenite grain size and cooling rate.Under experimental conditions of the Masteel's built cooling system and common rolling process and constant water pressure and flow density,different cooling rate,ferrite grain size,mechanical properties and its distribution of Q235 H-beam steel were obtained by changing fast cooling time.At the same time,the result proved the correctness of the Hall-Petch formula and provided the basis of set down resonable cooling process.

Production Practice of Clean Steel in Pangang

Yang Senxiang

2011, 32(3): 70-75.

Abstract(15) PDF(1)

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The equipment and technical level of steelmaking plant in PISCO(Panzhihua Iron & Steel Co.) have been introduced briefly.To achieve the production of clean steel in recent years,some effective technologies in hot metal pretreatment,converter smelting,desulfurization,deoxidation and dephosphorization in the process of refining,and inclusion control have been developed and applied.In addition,the applications of these technologies in some steel grades such as 350 km/h high speed rail steel and H₂S corrosion resistance steel for petroleum tube blank have been shown as well.On this basis,it achieves the production of clean steel whose w_T[O] ≤ 0.001 5%,w_[S] ≤ 0.005%,w_[P] ≤ 0.010% and level of oxide inclusions is not more than 1.0.

Analysis of Surface Sliver Defect on Cold Rolled and Cold Rolled Galvanizing Sheet

Zhang Hejia, Chen Liansheng

2011, 32(3): 76-81.

Abstract(18) PDF(1)

Abstract:
The reason on the surface sliver defect of the cold rolled steel sheet and galvanized steel sheet was analyzed with optical microscopy,scanning electron microscopy and energy disperse spectrometer.Comprehensively,the bubble,inclusion in the continuous cast slab and oxide scale are the main reason of surface sliver defect formation of cold rolled sheet,meanwhile the principal morphology characteristics were indicated respectively.

Drawing Brittle Fracture Causes Analysis of Large Gauge High Carbon Steel 82B Wire Rod

Zhang Jidong, Zhi Jianguo, Lü Gang, Su Cheng

2011, 32(3): 82-86.

Abstract(63) PDF(6)

Abstract:
The causes of drawing cleavage brittle fracture of large gauge high carbon steel 82B wire rod are analyzed by carrying out metallographic structure inspection and analysis.They are found out as the result of Mn,Cr central segregation causing formation of martensite in the centre of the wire rod,and the center martensite fracture becomes one of the sources of crack in the process of drawing because of the difference of deformation rate between the central part and the other area.There are some defects of scar and scratches near the fracture surface.It is manifested,through deeper analyzing,the main cause of drawing cleavage brittle fracture is the combined action of central martensite and surface defect.The incidence rate of cleavage brittle fracture defect has been reduced effectively through optimizing the content of Mn and Cr and improving the technics of steelmaking,rolling and drawing.

Research Progress of the Application of Microwave Heating in the Metallurgy Field of Vanadium and Titanium Magnetite

Yu Wenhua

2011, 32(3): 87-96.

Abstract(30) PDF(1)

Abstract:
The mirowave heating characteristics of vanadium and titanium magetite and application satus of microwave heating technology in vanadium and titanium magnetite metallurgy are summarized.According to the reality of rich vanadium-titanium magnetite in Panzhihua-Xichang erea unrealized iron,vanadium,titanium effective recovery at the same,and combined with the characteristics of microwave heating such as selective heating,internal heating,strengthening leaching,and the exist problem on equipment in small scale,it is pointed out that the key research direction on microwave heating technology is microwave heating reducing the vanadium-titanium magnetite and ilmenite,microwave strengthening leaching preparing rich-titanium material and other metallurgy operation about preparing high value-added products.

2011, 32(3): 97-98.

Abstract(19) PDF(1)

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2011 Vol. 32, No. 3