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The precipitation and effect of nano nitrides in HSLC steel

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science china(Technological sciences) 2008年第7期51卷 989-998页

作者： FU Jie1, LIU YangChun1,2.& WU HuaJie1,3 1 sch.ol of met.llurgical and {2. engineering, university of science and technology beijing, beijing 100083, china 2.Shougang technology Research Institute, Shougang (Group) Corporation, beijing 100041, china 3 met.llurgical engineering Research Institute, university of science and technology beijing, beijing 100083, china sch.ol of met.llurgical and {2. engineering University of Science and Technology Beijing Beijing China Shougang technology Research Institute Shougang (Group) Corporation Beijing China met.llurgical engineering Research Institute University of Science and Technology Beijing Beijing China

The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

关键词： thin slab casting and rolling high strength low carbon steel AlN nano nitride precipitation strengthening

Molar heat capacities of La2.o2.9 and La1.9Sr0.1Mo2.9-δ

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International Journal of Minerals,metallurgy and Materials 2007年第5期14卷 395-398页

作者： Baijun Yan, Jianhua Liu, Yunduo Dai, Qifeng Shu, and Zhihua Ren met.llurgical and ecological {2. sch.ol, university of science and technology beijing, beijing 100083, china met.llurgical and ecological {2. sch.ol University of Science and Technology Beijing Beijing 100083 China

The molar heat capacities of La2.o2.9 and La1.9Sr0.1Mo2.9-δ were obtained using the differential scanning calorimetry (DSC) technique in a temperature range from 2.8 to 1473 K. The DSC curve of La2.o2.9 showed an endothermal peak around 834 K corresponding to a first-order monoclinic-cubic phase transition, and the enthalpy change accompanying this phase transition is 5.99 kJ/mol. No evident endothermal peak existed in the DSC curve of La1.9Sr0.1Mo2.9-δ, but a broad thermal anomaly existed in its heat capacity curve at around 832.K. In addition, the heat capacity values of La2.o2.9 and La1.9Sr0.1Mo2.9-δ began to decrease at 1196 and 1330 K, respectively. The non-transitional heat capacity values of La2.o2.9 and La1.9Sr0.1Mo2.9-δ were formulated using multiple regression analysis in two temperature ranges.

关键词： heat capacity phase transition La2.o2.9 La1.9Sr0.1Mo2.9-δ DSC

Mass transfer coefficients in met.llurgical reactors

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Journal of university of science and technology beijing 2003年第2期10卷 1-9页

作者： Ying Qumet.llurgical engineering {2., university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Met Engn Sch Beijing 100083 Peoples R China

An overview on the application and achievements of physico-mathematicalmodeling of met.llurgical processes in china is briefly declared. The important role of coefficientsin model formulation is shown from our experience. The mass transfer coefficients of the slag-{2.alreactions and the gas-{2.al reactions are discussed referring to the flow conditions near theinterface. The influence of the surface-active species on the mass transfer and the interfacialreaction is also discussed briefly.

关键词： mass transfer modeling pyrometallurgy reaction engineering interfacial flow stirring power

Preparation of titanium oxycarbide from various titanium raw materials:Part *** reduction

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Rare metals 2010年第6期29卷 547-551页

作者： GAO Chengjun,JIANG Bo,CAO Zhanmin,HUANG Kai,and ZHU Hongmin sch.ol of met.llurgical and {2. engineering,university of science and technology beijing,beijing 100083,china sch.ol of met.llurgical and {2. engineering University of Science and Technology Beijing Beijing China

Carbothermal reduction was performed at temperatures up to 1600°C for vanadium-bearing titanomagnetite,ilmenite concentrate,and high titania *** possibility of selective carbothermal reduction was discussed in detail from the viewpoint of thermodynamics,and also *** products were analyzed by X-ray diffraction,scanning electron microscopy,and chemical *** results show that it is possible to reduce all iron oxide to metallic iron,and titania to oxycarbide（TiCxOy）,without the reduction of other oxides like silica and magnesia.

关键词： titanium carbothermal reduction oxycarbide ilmenite

Electrochemical studies of nickel deposition from aqueous solution in super-gravity field

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science china(Technological sciences) 2007年第1期50卷 39-50页

作者： GUO ZhanCheng1,2. GONG YingPeng2.& LU WeiChang2.1 met.llurgical & ecological {2., university of science and technology, beijing 100083, china 2.Institute of Process engineering, Chinese Academy of sciences, beijing 100080, china met.llurgical & ecological {2. University of Science and Technology Beijing China Institute of Process engineering Chinese Academy of Sciences Beijing China

The effect of super-gravity on electrochemical deposition of nickel from aqueous solution was studied. The SEM pictures show that the microstructure of nickel film deposited under the super-gravity condition is finer and more uniform compared with that obtained in normal gravity condition, and the crystal grains diminish with the increase of super-gravity coefficient. The XRD patterns indicate that the arrangement of crystalline grains of nickel film deposited under the super-gravity field is more regular, and the crystalline grain sizes decrease with the increase of super-gravity coefficient. Toughness, tensile stress and hardness of the nickel film are markedly raised with the increase of super-gravity coefficient, and hydrogen content in the nickel film decreases with the increase of super-gravity coefficient. From the polarization curves of hydrogen evolution reaction under the super-gravity condition, a significant reduction of over-potential on electrode was found when current density increased. The process of hydrogen evolution reaction was enhanced under the super-gravity condition. The electro-deposition rate, the microstructure and properties of deposited nickel film under super-gravity condition were still affected by the relative orientation between inertia force and depositing surface. It is favorable to gain the nickel film with better mechanic properties when inertia force orientates vertically towards depositing surface. Keywords super-gravity - electrochemistry - electro-deposition - nickel film Supported by the Notional Natural science Foundation of china (Grant No. 50674011)

关键词： super-gravity electrochemistry electro-deposition nickel film

A COMPUTERIZED SYSTEM ON KINETIC ANALYSIS AND EVALUATION OF GAS/SolID REACTIONS

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Acta metallurgica Sinica(English Letters) 2003年第6期16卷 495-506页

作者： J.H. Liu, J. Y. Zhang and S.K. Weisch.ol of met.llurgical and {2. engineering, university of science & technology beijing, beijing 100083, china sch. of metall. and {2. Eng. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.

关键词： gas/solid reaction kinetics computer system evaluation anal-ysis

Effect of Nb-V Microalloying on Microstructures and Mechanical Properties of Medium Carbon Non-Quenched and Tempered Steel

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Journal of Iron and Steel Research International 2011年第S1期18卷 779-784页

作者： CHENG Hui-jing 1,WANG Fu-ming 1,LI Chang-rong 2.ZHANG Bo 1,XIA Yun-jin 1 (1.sch.ol of met.llurgical and {2. engineering,university of science and technology beijing,beijing 100083 2.sch.ol of Materials science and engineering,university of science and technology beijing,beijing 100083) Univ Sci & Technol beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

Based on optical microscope(OM),transmission electron microscope(TEM) and mechanical performance measurement,the microstructures and mechanical properties of Nb-V micro-alloying non-quenched and tempered steels have been *** results showed that the microstructure consists of ferrite and pearlite,in which there exists a lot of intragranular *** carbide is the main form of carbonitrides,Nb-enriched carbonitrides refine grains,V-enriched carbonitrides have precipitation strengthening effect,which promotes the toughness of the studied *** mechanical properties for steels 1,2.and 3 have met the standards required by high load automobile crankshaft,in which the comprehensive property for No.2.is the best.

关键词： non-quenched and tempered steel Nb-V microalloying strength and toughness-enhanced mechanism

An improvement to the data processing course of electrochemical impedance technique

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Journal of university of science and technology beijing 2003年第6期10卷 57-60页

作者： Yinglv Jiang, Yinshun Wu, and Hong ChuCorrosion and Protection Center, university of science and technology beijing, beijing 100083, {2. Corrosion and Protection Ctr. Univ. of Sci. and Technol. Beijing Beijing 100083 China

For some electrochemical systems the traditional data processing methods cannot be met, so it is necessary to develop a new method to deal with these problems. When processingthe electrochemical AC impedance data of titanium alloy TA12.in 3 percent NaCl solution (at freecorrosion potential, room temperature) a new method is developed which can detach the information ofthe interface resistance demonstrably from the interface capacitance. The results show that theinterface resistance and capacitance are all functions of frequency. And the AC impedance of theresistance and capacitance obey the following relations: C(f) = 10^(4.01982. f^(-0.92.2., R(f)=10^(4.80011) (f+0.008)^(-0.90897), which is completely different from the traditional conceptionthat the interface resistance and capacitance are constants. And this phenomenon is ubiquitous intitanium alloys according to the study. So perhaps it is an innate characteristic of interface.

关键词： titanium alloy electrochemical impedance corrosion

Study on Solidification Microstructure of Slab by Numerical Simulation

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Journal of Iron and Steel Research International 2011年第S2期18卷 371-376页

作者： LIU Zhi-ming, ZHANG Jiong-ming, LUO Yan-zhao, WU Lian (sch.ol of met.llurgical and {2. engineering, university of science and technology beijing, beijing 100083, china) Univ Sci & Technol beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China

The solidification structure was simulated by the commercial software CALCOSOFT under the real cooling condition during the continuous casting processes in this paper. The cellular automation-finite element model (CA-FE) was applied to simulate the microstructure of the slab, and the results were compared with the actual macrostructure. The results of microstructure simulated were in good agreement with that detected in the slabs. In addition, the solidification structure under different secondary cooling intensity was simulated. The results show that when specific water flows increase, the average grain surface area reduces, and columnar grains have the tendency to be longer.

关键词： numerical simulation continuous casting solidification structure