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Comparison of Ferrite Refinement Mechanisms by Different Processing Schedules in 08 and 20Mn Steels

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Journal of university of science and Technology beijing 2001年第3期8卷 218-223页

作者： Ping Yang Feng’e Gui, Shicai Ma Material science and engineering school, {3. of science and Technology beijing, beijing 100083. china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by deformation at above A(r3., in two-phase region of (alpha + gamma) and at below A(t) in clean 08 and 20Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above A(r3. is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below A(r3. is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.

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

Refinement of packet size in low carbon bainitic steel by special thermo-mechanical control process

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Journal of university of science and Technology beijing 2004年第3期11卷 221-224页

作者： Chengjia Shang Xuemin Wang Shanwu Yang Xinlai He Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The packet size of bainitic steel can be refined by a specialrelaxation-precipitation-control phase transformation (RFC) technology. When processed by RPCprocess, the low carbon bainitic steel composes of two kinds of main intermediate transformationphases. One is ultra-fine lath-like bainitic ferrite and the lath is less than 1μm in width andabout 6 μm in length; the alignment of laths forms a refined packet, and the size of packets isabout 5-7 μm in length and about 3.4μm in width. The other is acicular structure. The morphologyand distribution of these acicular structures are influenced by relaxation process, the thin andshort acicular structures cut the prior austenite grain and refine the bainitic packet size. For theoptimum relaxation time, the packet size can be refined to the finest. The mechanical propertiesare influenced by relaxation time and the 800 MPa grade low carbon bainitic steel with excellenttoughness can be obtained by RPC process.

关键词： packet size refinement bainitic steel RPC process

Magnetic properties and structure of very thin permalloy films

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Journal of university of science and Technology beijing 2004年第3期11卷 225-229页

作者： Guanghua Yu Haifeng Li Tao Yang Fengwu Zhu Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

In order to study the magnetic properties and structure of very thinpermalloy films, Ni_(81)Fe_(19) films of 12 nm in thickness were prepared by different instrumentsat an ultrahigh base vacuum and a lower base vacuum. The anisotropic magnetoresistance coefficients(ΔR/R) of Ni_(81)Fe_(19) (12 nm) films reached 1.6 % and 0.6 %, and the coercivities were 127 and3.4 A/m, respectively. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were usedto study the structure and surface chemical state. The experimental results show that the filmsprepared at the ultrahigh base vacuum have a smoother surface, a bigger grain size and a denserstructure with fewer defects than those prepared at the lower base vacuum.

关键词： NiFe film anisotropic magnetoresistance (AMR) coercivity structure

Sintering Mechanism of Stainless Steel in Powder Injection Molding

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 51-54页

作者： Chengchang Jia Shimin Fan ying Peng Xiaojie Zhao Xiaosen lu Material science and engineering {3., university of science and Technology beijing, beijing 100083. china beijing Tungsten and Molybdenum Factory, beijing 102206, china beijing Hard Me Material science and engineering school University of Science and Technology Beijing Beijing 100083 China beijing Tungsten and Molybdenum Factory Beijing 102206 China beijing Hard Metal Factory Beijing 100055 China

Stainless steel samples were made by Powder injection Molding (PIM) process with-400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debin- ding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.

关键词： sintering mechanism powder injection molding stainless steel, volume diffusion

Fractal image compression based on fuzzy theory

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Journal of university of science and Technology beijing 2002年第3期9卷 228-232页

作者： Berthe Kya and Yang YangInformation engineering school, university of {3. and Technology beijing, beijing 100083. china (Received 2001-11-13. Information engineering school University of Science and Technology Beijing Beijing 10083 China ***

Though progress has been made in fractal compression techniques, the longencoding times still remain the main drawback of this technique, which results from the need ofperforming a large number of range-domain matches. The total encoding time is the sum of the timerequired to perform each match. In order to make this method more efficient in practical use, thefuzzy theory based on feature extraction of the projection and normalized codebook method has beenprovided to optimize the encoding time, based on the c-means clustering approach. The results of theimplementation of Rate Mean Square (RMS), Peak signal noise ratio (PSNR) and the encoding time ofthis proposed method have been compared to other methods like the Feature Extraction andSelf-orgarnization methods to show its efficiency.

关键词： fractal compression fractal optimization fuzzy logic c-mean clusteringalgorithm hybrid fractal-fuzzy compression

Metal deformation in skew rolling step-shaft

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Journal of university of science and Technology beijing 2003年第5期10卷 59-63页

作者： Yongqiang Kang, Jinping Liu, Cuiping Yang, and Zhenghuan HuMechanical engineering school, university of {3. and Technology beijing, beijing 100083. china Mech. Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The process of rolling step-shaft was simulated with the help of the FEM(Finite-Element Model) software-DEFORM^(TM) 3.. The characteristics of metal flow in differentperiods were analyzed, and the curve of variety in non-round area at different cross-sections of therolled piece, the curve of variety in bulge volume and the curve of variety in non-column volumewere obtained. On this base the method of tool design is worked out and validated by experiment.

关键词： skew rolling FEM metal deformation non-column volume bulge volume

Interactive graphics mechanical optimum design

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 54-56页

作者： WANG Guobiao (Resources engineering school, university of {3. and Technology beijing, beijing 100083. china)

Virtually all conventional optimizations are Performed in a batch computer environment. No graphic information during the optimization process is provided. The research tactics and implementation procedure of interactivegraphics in mechanical optimum design are presented. An interactive Graphics Mechanical Optimum Design Program(IGMODP) for microcomputers is developed. The example of wheeled loader' s working device optimum design usingIGMODP is carried out.

关键词： interactive graphics mechanical optimum design computer program

Electrochemical Study of Hypophosphite

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International Journal of Minerals,Metallurgy and Materials 1998年第1期12卷 23-25页

作者： Yuguo Yang Dongbai Sun Dongbai Sun Dejun Yang (Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china) Materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no corresponding cathodic peaks were obtained. The one at - 0.44 V wits ascribed to the oxidation oftautomeric form of hypophosphite, the other at - 0.59 V was due to the oxidation of absorbed form of hypophosphite. The two oxidation reactions were believed to be the electron source of nickel ion reduction in electrolessnickel processes.

关键词： cyclic voltammogram electroless nickel plating gold electrode hypophosphite

In Situ Studies of Deformation and Fracture in Sputtering Copper Film

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International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 38-41页

作者： Jinxu Li Yimin Zeng Yanbin Wang Wuyang Chu Materials science and engineering school, {3. of science and Technology beijing, beijing 100083. china Materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline copper films were prepared by sputtering and then in situ straining experiments were performed using a trans- mission electron microscope. Macroscopically, these copper films exhibited very low ductili... 详细信息

关键词： in situ straining, deformation fracture nanocrystalline copper film