钢铁钒钛

Effect of Technological Parameters on Microstructures and Mechanical Properties of Low Carbon Steel in Thin Slab Continuous Rolling Process

Liang Xiaokai, Liu Qingyou, Zhang Jianping, Hu Xuewen

2006, 27(1): 1-5.

Abstract(28) PDF(1)

Abstract:
Combined with the technological characteristics of thin slab continuous rolling process,the effect of technological parameters,such as cooling rate,rolling temperature,and coiling temperature on microstructures and mechanical properties of low carbon Al-killed steels was studied.Optimization of technological parameters was discussed in real production.The results show that decreasing cooling rate and increasing rolling temperature and coiling temperature are beneficial to the coarsening of ferrite grain.

Effect of Process Parameters on Continuous Cooling Transformation for V-Ti Microalloyed Steel

Wu Hongyan, Du Linxiu, Xue Wenying, Shen Kaizhao, Liu Xianghua, Wang Guodong

2006, 27(1): 6-11.

Abstract(24) PDF(1)

Abstract:
The continuous cooling transformation(CCT) diagrams of austenite non-deformation and 50% compressively deformed at 950 ℃ were constructed on the Gleeble-1500 thermomechanical simulator and by means of a combined method of microhardness measurement for a microalloyed steel include V and Ti.Optical microscope and TEM were employed to investigate the influence of cooling rate,deformation process and microalloying elements on the transformation behavior and microstructure.The experimental results show that the deformation promotes the area of ferrite and pearlite move towards left,leading to the increase of critical cooling rate obtained ferrite plus pearlite.The deformation increases the transformation temperature of bainite and makes microstructure finer under high cooling rate.The stability of austenite is enhanced by the co-addition of V and Ti,which decreases transformation temperature and results the refinement of microstructure.

Heating Behavior of Blast Furnace Slag Bearing High TiO₂ Under Microwave Irradiation

Chen Yan, Bai Chenguang, He Yizhu, Noboru YOSHIKAWA, Shoji TANIGUCHI

2006, 27(1): 12-16,20.

Abstract(28) PDF(1)

Abstract:
The blast furnace（BF） slag bearing high TiO₂ was processed under microwave irradiation in order to induce micro-cracks in it and to improve the grindability of the slag.During inducing crack in the slag,it was found that the slag could be effectively heated by microwave,and thermal runaway was occurred.In order to investigate the mechanism for effectively heating of the slag and the reason of occurring thermal runaway in the slag irradiated under microwave field,different kind of synthesized slag was heated in microwave field.Experimental results showed that the existence of CaTiO₃ played a key role in heating of the slag under microwave irradiation.The permittivity of CaTiO₃ was measured with Network Analyzer.It was determined that the permittivity of CaTiO₃ was higher than general material,which quantitatively explained the role of CaTiO₃ on heating of the BF slag bearing high TiO₂ irradiated under microwave field.Furthermore,the permittivity of CaTiO₃ increased with the temperature rising,which resulted in the heating way of positive feedback.The heating way of positive feedback was one of the main reasons for the occurrence of thermal runaway in the BF slag bearing high TiO₂.

Study on Impurity-absorptivity of Basic Tundish Covering flux

Sun Yongchao, Huang Jun, Wu Yonglai, Zhao Junxue

2006, 27(1): 17-20.

Abstract(17) PDF(1)

Abstract:
A kind of basic tundish covering flux was developed according to the phase diagram of CaO-SiO₂-Al₂O₃.The absorbing ability for Al₂O₃ inclusion of the basic tundish covering flux was compared with the acid and neutral tundish covering flux,it was founded that the basic tundish covering flux was of better absorbing ability for Al₂O₃ inclusion.The industrial tests also approved that the basic tundish covering flux was of good metallurgical characters.

Study on Extraction of V₂O₅ from Vanadium Ore by Roasting and Acid Leaching Process

Bin Zhiyong

2006, 27(1): 21-26.

Abstract(19) PDF(1)

Abstract:
The recovering of V₂O₅ by roasting in air—sulfuric acid leaching—P204 extracting—precipitate separation V₂O₅ with ammonium salt from the vanadium ore was tested.The results show that about 90% of the vanadium can be leached after roasted 1.5 h in air at 800 ℃ while the rate of <1.19 mm roastedore is 84%.The acid leaching was taken out at normal temperature for 1h,and the mass ratio of liquid and solid was 1.2∶1,then a pure solution containing V₂O₅ was acquired.After been extracted with P204 and TBP dissolved in sulfonated kerosene and precipitated with ammonium water and pyrolytic decomposition,the refine V₂O₅(purity 98.74%) was acquired.The straight receive rate of V₂O₅ was over 85%.

Influence of Calcium Content on Fluidity of Ca-treated Liquid Steel

Yuan Fangming, Wang Xinhua, Yang Xuefu

2006, 27(1): 27-32.

Abstract(35) PDF(2)

Abstract:
It is found that Ca-treated liquid steel can be cast at lower superheat. In order to ascertain the reason that the castability of Ca-treated liquid steel is improved and to find optimal range of calcium content,behavior of calcium in liquid steel was studied in terms of relationship between calcium content and solid ratio of inclusions.By analyzing the composition of inclusions in Ca-treated steel samples of different calcium content,especially calcium aluminate or calcium aluminum silicate inclusions,the relationship between calcium content and solid ratio of inclusions was obtained by means of Al₂O₃-CaO-SiO₂ phase diagram.For making well effect of Ca treatment and improving fluidity or castability of Ca-treated liquid steel,the optimum calcium content should be（17～23）×10^-6.

Microstructure and Impact Toughness of High Strength Pipeline Steel

Jiang Haitao, Kang Yonglin, Liang Zhengwei

2006, 27(1): 33-37.

Abstract(16) PDF(1)

Abstract:
The Charpy impact properties of high strength pipeline steel with different microstructure were investigated.Experimental results show that the high strength pipeline steel with acicular ferrite microstructure has higher ability to prevent impact cracking than that with ferrite pearlitic microstructure.It can be concluded that the excellent impact toughness of high strength pipeline steel with acicular ferrite microstructure can be obtained by strictly controlling inclusions and producing fine,homogeneous ferrite grains,M-A structure and precipitates.

Effects of Carbon Content on Impact Wear Performance of High Vanadium High-speed Steel

Ma Zhizuo, Wei Shizhong, Long Rui, Zhang Yongzhen, Li Yan

2006, 27(1): 38-43.

Abstract(15) PDF(1)

Abstract:
Effect of carbon content,ranging from 1.76% to 3.65%,on the impact wear performance of high vanadium high-speed steel was studied using self-designing impact wear tester WM-1.The results show that when the carbon amount is lower than 2.3%,the matrix is ferrite,so the wear resistance of the high vanadium high-speed steel is very bad and the main wear mechanism is scouring and plastic deformation.After the carbon content reached 2.3%,the matrix is martensite primarily and the impact wear resistance performance enhanced largely compared with the low-carbon high vanadium high-speed steel.When the carbon content achieved 3.0%,the wear resistance achieves peak value.With the increase of carbon content,the quantity of primarily chromium and molybdenum carbide increased while the wear resistant decreased because the crack sprout in grain boundary at where the carbides formed and the flaking is the main wear mechanism in the impact process.

Study on Ultraviolet Visible Light Spectrum Characteristic of Nano- TiO₂ and Modified Polypropylene

Cao Jianjun, Guo Gang, Duan Xiaoping, Wu Jianchun, Tu Mingjing

2006, 27(1): 44-49.

Abstract(23) PDF(1)

Abstract:
The polypropylene modified by rutile type nano-TiO₂ was degraded by accelerated aging test with high pressure mercury-arc lamp.The ultraviolet and visible light spectra of some samples were analyzed with ultraviolet and visible light spectrophotometer,such as nano-TiO₂,nano-TiO₂/polypropylene composites and so on.It was noted that rutile type nano-TiO₂ had excellent ultraviolet shielding function.The capacity of shielding ultraviolet was increased by 2 times when the polypropylene was filled with 0.5wt% nano-TiO₂.The shielding ultraviolet capacity of polypropylene was increased by 9 times when modified by nano-TiO₂ cooperating with hinderd amine light stabilizer(HALS).And the capacity of shielding ultraviolet had not any loss after 14 days artificial weathering,according which can endue excellent aging resistance function to modified polypropylene for long time.

Study on Effect Factors for Antibacterial Property of TiO₂ Powder Doped with Ag⁺

Yin Xiaomin, Cheng Yongqing, Xu Jie

2006, 27(1): 50-54.

Abstract(22) PDF(1)

Abstract:
Pure TiO₂ powder and Ag⁺ doping TiO₂ powder were prepared by sol-gel process.The effect of UV illumination time,light source,Ag⁺ ratio in powder and different experimental bacteria on antibacterial property of Ag-TiO₂ powder was investigated by agar hole diffusion-inhibition zone method.The effect of Ag-TiO₂ powder dosage in agar hole on the antibacterial result was tested.It was found that the Ag-TiO₂ powder was of good antibacterial property under different light source conditions while the UV illumination time was 60～90 min and the dosage was 2～4 mg,so it could be a sort of widely used antimicrobial.

Preparation and characterization of VO₂ Nano- powder by Thermal Decomposing VOC₂O₄·H₂O

Lin Hua, Zou Jian, Li Qing

2006, 27(1): 55-58,63.

Abstract(16) PDF(1)

Abstract:
A method of synthesizing VO₂ nano-powder by decomposing VOC₂O₄·H₂O（which was made from commercial V₂O₅ powder deoxidized by oxalic acid） in vacuum oven pipe at 350 ℃ was developed.The powder was characterized by means of thermal analysis（TG-DSC）,X-ray diffraction spectroscopy（XRD）,transmission electron microscope（TEM） and resistance-thermometer.The results show that the powder is crystallized,the component is only VO₂,the average particle size is 80～120 nm,its phase transition temperature is 68.5 ℃,and its resistance abrupt change reaches three magnitudes.

Preparing VO₂ Powder using Leach Solution of Vanadium Slag

Yang Dongmei, Peng Mingfu, Zhu Shengyou, Hua Yixin

2006, 27(1): 59-63.

Abstract(18) PDF(2)

Abstract:
Based on the actual state of PZH steel, VO₂ powder was prepared using the leach solution of vanadium-bearing slag as raw material for the first time.The preparing process includes removing the impurity of leach solution, hydrolytic precipitation and calcining the precipitated material at high temperature.The optimal conditions as follows: the ratio of dechromisation agent Z to total chrome is 22.86∶1, and the desiliconisation agent X to total silica is 3.2∶1, pH=4.5~5.0, circulating wash 5 times, calcining at 1 000 ℃, the time of constant temperature is 60 min, argon gas flow is 4 L/min.Compared with other methods, this preparing method is of more widely raw materials source and lower cost.The process is also simple and easy to realize industrial turn.

Determination of Iron in Nano-TiO₂ by 1,10-phenanthrolin Spectrophotometry

Zheng Xiaomin, Wang Xuemei, Yang Ping

2006, 27(1): 64-67.

Abstract(23) PDF(1)

Abstract:
A determination method of iron content in nano-TiO₂ was presented,in which the sample was dissolved into sulfuric acid and ammonium sulfate,the titania ion was masked by ammonium tartrate.The 1,10-phenanthrolin reacted with Fe²⁺ to form a stable orange-red complex in the medium of CH₃COOH—CH₃COONa(pH 5.5).The absorbance was measured at the wavelength of 510 nm.The apparent molar absorptivity is 4.7×10⁴ and it is obeyed Beer law in the range of 0~100 μg/100 mL for iron concentration.The proposed method is of very good selectivity for determining iron in nanometer titania samples,the relative standard deviation is below 4%,and the recovery is in the range of 94.95%~105.33%.

2006 Vol. 27, No. 1