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Two-Sublattice Thermodynamic Model on Carbonitride Precipitation in Microalloyed Steels Bearing Nb-V-Ti

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Two-Sublattice Thermodynamic Model on Carbonitride Precipita...

第六届国际低合金高强度钢会议

作者： XIANG Song~(1,3),LIU Guo-quan~2 (1.school of materials and Metallurgy,Guizhou university,Guiyang 550003,Guizhou,china 2.school of materials science and engineering,university of science and technology,beijing,beijing 100083,china 3.The Key Laboratory for Mechanical Behavior and Microstructure of materials,Guizhou Province, Guiyang 550003,Guizhou,china)

Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon *** calculation results show that starting-temperature of the precipitation of niobium carbonitride,vanadium carbonitride and titanium carbonitride are 1100℃,920℃and 1340℃,respectively,the mole fraction of carbonitride precipitates is 8.65×10 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti- 0.029V-Fe *** the N content is from 0.0028%to 0.0056%,the starting-temperature of the precipitation of the titanium carbonitride changes from 1340℃to 1430℃.And the C content is from 0.053%to 0.07%,the starting-temperature of the precipitation of the titanium carbonitride hardly changes,but the atomic fraction of niobium in the carbonitride obviously increases.

关键词： microalloyed steel carbonitride precipitation two sublattice model thermodynamics

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高强度冷轧热镀锌用双相钢组织及性能研究

物理测试 2009年第2期27卷 9-12页

作者：李国彬罗青赵征志唐荻北京科技大学冶金工程研究院北京100083 北京科技大学材料科学与工程学院北京100083

在实验室试制了高强度冷轧热镀锌用双相钢,并且优化了模拟连续镀锌退火工艺。利用扫描电镜(SEM)、透射电镜(TEM)以及电子背散射(EBSD)观察了双相钢组织及其微观结构,探讨了不同退火温度对双相钢力学性能和组织的影响规律。研究结果表明... 详细信息

在实验室试制了高强度冷轧热镀锌用双相钢,并且优化了模拟连续镀锌退火工艺。利用扫描电镜(SEM)、透射电镜(TEM)以及电子背散射(EBSD)观察了双相钢组织及其微观结构,探讨了不同退火温度对双相钢力学性能和组织的影响规律。研究结果表明,试制的冷轧双相钢具有高的强度和良好的延伸率,其组织主要由板条马氏体和铁素体两相组成,铁素体晶粒间多为大角度晶界,有一半以上的晶粒都是{111}∥Z型取向。

关键词：双相钢显微组织性能大角度晶界

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

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Rare Metals 2010年第6期29卷 642-645页

作者： LI Sha and MAO Weimin school of materials science and engineering,university of science and technology beijing,beijing 100083,china school of materials science and engineering University of Science and Technology Beijing Beijing China

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic *** effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were *** results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be *** new technology can save energy and make the pouring process *** the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to *** the alloy melt is poured at the temperature（630°C） with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic *** the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value（1.72 kW）,the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.

关键词： aluminum alloys metal forming semisolid slurry electromagnetic stirring microstructure

Dislocation Densites of Deformed Steel Sheets Based on Positron Annihilation

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International Journal of Minerals,Metallurgy and materials 1998年第1期12卷 47-50页

作者： Yonglin Kang Xianjin Wang (materials science and engineering school, university of science and technology beijing, beijing 100083, china) materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

The variation regularity of dislocation densites of some deformed steel sheets under three kinds of strainpaths as uniaxial tension, plane strain and equal biaxial stretching was investigated by means of positron lifetimespectrum and Doppler-broadening techniques. The results show that the increasing rate of dislocation densites isrelated to the plastic strain path. A relationship between the increasing rate of micro-defects, macro-instability andforming limits during the process of steel sheet forming was got based on analyzing the mechanism of dislocationdensity increasing under different stress-strain condihons.

关键词： positron annihilation dislocation steel sheet strain path

Sol-gel Preparation and Infrared Radiation Property of Boron-substituted Cordierite Glass-ceramics

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Journal of materials science & technology 2010年第5期26卷 445-448页

作者： Shuming Wang and Fenghua Kuang school of materials science and engineering,university of science & technology beijing,beijing 100083,china [a] school of materials science and engineering university of science & technology beijing beijing 100083 china

Boron for aluminum substitution in the cordierite structure has been examined by sol-gel preparation of different samples along the compositional junction Mg2Al4-xBxSi5O18 with x=0,0.5,1,*** increasing the x value from 0 to 1.5 the crystallization behavior changed *** amount B2O3 doping can promote the sintering of amorphous cordierite gel,effectively restrain the precipitation of μ-cordierite and enhance the crystallization of α-*** substitution of B3＋ for Al3＋ in cordierite crystal structure can effectively improve the near-infrared spectral emissivity of this cordierite based glass-ceramics.

关键词： Sol-gel Glass-ceramics Infrared radiation B3+ substitution Solid solution

Microstructural Features During Strain Induced Ferrite Transformation in 08 and 20Mn Steels

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Journal of university of science and technology beijing 2001年第2期8卷 105-110页

作者： Ping Yang, Feng-e Cui, Fuming Wang (materials science and engineering school, university of science and technology beijing, beijing 100083, china) (Metallurgy school, university of science and technology beijing, beijing 100083, china) Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China

The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume fraction of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of similar to1.5 ferrite grains less than 3 mum and 2 mum can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to strain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.

关键词： clean carbon steel strain induced transformation grain refinement ferrite dynamic recrystallization

Application of the annexation principle to the study of thermodynamic properties of ternary metallic melts In-Pb-Ag and In-Bi-Sb

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Rare Metals 2002年第2期21卷 142-151页

作者： ZHANG JianMetallurgical engineering school.university of science and technology beijing, beijing 100083, china Metallurgical engineering school University of Science and Technology Beijing 北京 100083

Based on the phase diagrams, measured activities an the annexationprinciple, the calculating models of mass action concentrations forin-Pb-Ag and In-Bi-Sb ternary metallic melts have been *** results of calculation both agree with practice, and obey the lawof mass action, showing that the models formulated can reflect thestructural reality of the corresponding melts and the annexationprinciple is applicable to the them.

关键词： activity mass action concnetration th annexation principle In-PB-Ag

Effects of silver powder particle size on the microstructure and properties of Ag-Yb_2O_3 electrical contact materials prepared by spark plasma sintering

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Rare Metals 2010年第4期29卷 366-370页

作者： CHEN Xiaohua,JIA Chengchang,and LIU Xiangbing school of materials science and engineering,university of science and technology beijing,beijing 100083,china school of materials science and engineering University of Science and Technology Beijing Beijing China

mg-Yb203 electrical contact materials were fabricated by spark plasma sintefing （SPS）. The effects of silver powder particle size on the microstructure and properties of the samples were investigated. The surface morphologies of the sintered samples were examined by optical microscope （OM）, and the fracture morphologies were observed by scanning electron microscopy （SEM）. The physical and mechanical properties such as density, electrical resistivity, microhardness, and tensile strength were also tested. The results show that the silver powder particle size has evident effects on the sintered materials. Comparing with coarse silver powder （5 ktm）, homogeneous and fme microstmcture was obtained by fine silver powder （_〈0.5-1am）. At the same time, the electrical conductivity, microhardness, and tensile strength of the sin- tered samples with fine silver powder were higher than those of the samples with coarse silver powder. However, silver powder particle size has little influence on the relative densities, which of all samples （both by free and coarse silver powders） is more than 95%. The fracture characteristics are ductile.

关键词： composites electrical contact materials spark plasma sintering particle size microstructure physical properties mechanical properties

Effect of powder mixing process on the microstructure and thermal conductivity of Al/diamond composites fabricated by spark plasma sintering

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Rare Metals 2010年第1期29卷 86-91页

作者： CHU Ke, JIA Chengchang, LIANG Xuebing, and CHEN Hui school of materials science and engineering, university of science and technology beijing, beijing 100083, china school of materials science and engineering University of Science and Technology Beijing

Two powder mixing processes, mechanical mixing （MM） and mechanical alloying （MA）, were used to prepare mixed Al/diamond powders, which were subsequently consolidated using spark plasma sintering （SPS） to produce bulk Al/diamond composites. The effects of the powder mixing process on the morphologies of the mixed powders, the microstructure and the thermal conductivity of the composites were investigated. The results show that the powder mixing process can significantly affect the microstructure and the thermal conductivity of the composites. Agglomerations of the particles occurred in mixed powders using MM for 30 min, which led to high pore content and weak interfacial bonding in the composites and resulted in low relative density and low thermal conductivity for the composites. Mixed powders of homogeneous distribution of diamond particles could be obtained using MA for 10 min and MM for 2 h. The composite prepared through MA indicated a high relative density but low thermal conductivity due to its defects, such as damaged particles, Fe impurity, and local interfacial debonding, which were mainly introduced in the MA process. In contrast, the composite made by MM for 2 h demonstrated high relative density and an excellent thermal conductivity of 325 W.m^-1.K^-1, owing to its having few defects and strong inter-facial bonding.

关键词： metal matrix composites thermal properties sintering powder mixing