材料期刊网

STUDY OF THE MICROSTRUCTURE SIMULATION AND PERFORMANCE OF FUSION WELDING HAZ OF ZINC-BASED ALLOY

K.K. Zhang , D.R. Chen , J. Xue , D. W. Sun and H.C. Li( 1) Department of Materials Engineer , Xi'an Jiaotong University , Xi'an 710049 , China 2) Luoyang Institute of Technology , Luoyang 471039 , China 3) CITIC Heavy)

金属学报(英文版)

Base on a vast amount of testing and calculations for the welding thermal cycling curves of different testing points in fusion welding (TIG welding, gas welding) HAZ of zinc-based alloy with low melting points, this paper defines the welding thermal cycle parameters of microstructure stimulation of HAZ by zinc-based alloy fusion welding process. On the principle of which the microstrnct,are and harkness of the testing points in simulation specimens are basically correspondence with that of actual welding HAZ, the microstructure simulation of testing points Tm=370O℃. 305℃) of ZA12 alloy by fusion welding is carried out by the means of omhic-heating welding thermal simulation tester. The study results of the abrasion-resistance of simulation specimens HAZ by fusion welding process indicates that the abmsion-resistance is closely related to the form of eutectoid microstructure in or in the structure.

关键词: zinc-based alloy , null , null , null , null

R&D STATUS ON INTERMETALLICS IN CHINA

CHEN Guoliang(State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 , China)SHI Changxu (Academia Sinica , Beijing 100864 , China)

金属学报(英文版)

This paper briefiy introduces the R&D of intermetallics in China. R&D on intermetallics in a national scale in China began near ten years ago. The investigation in past years focused on the fundamental research and materials development. A significant progress has been made. Various components that made of Ti3Al Ni3Al, TiAl and Fe3Al have been successfully manufactured Some of them have been evaluted. It is expected that some intermetallic alloys will be produced in an industrial scale in the near future.

关键词: :intermetallic alloys , null , null , null

LOW TEMPERATURE ALUMINUM FLOATING ELECTROLYSIS IN HEAVY ELECTROLYTE Na_3AlF_6-AlF_3-BaC1_2-NaCl BATH SYSTEM

H.M. Lu and K.M. Fang Metallurgy School , University of Science and Technology Beijing , Beijing 100083 , China Z.X. Qiu Department of Nonferrous Metallurgy , Northeastern University , Shenyang 110006 , China

金属学报(英文版)

Multiple regression equations of liquidus temperature, electrical conductivity and bath density of the Na_3AlF_6-AlF_3-BaC1_2-NaCl system were obtained from experiments by using orthogonal regression method. The experiments were carried out in 100A cell with low melting point electrolyte, the influences of cathodic current density, electrolytic temperature, density differences of bath and liquid aluminum on current efficiency (CE) were studied; when the electrolyte cryolite ratio was 2.5, w(BaC1_2) and w(NaCl) were 48% and 10%, respectively, CE reached 90% and specific energy consumption was 10.97k Wb/kg/kg. Because of the fact that aluminum metal obtained floated on the surface of molten electrolyte, this electrolysis method was then defined as low temperature aluminum floating electrolysis. The results showed that the new low temperature aluminum electrolysis process in the Na_3AlF_6-AlF_3-BaC1_2-NaCl bath system was practical and promising.

关键词: low temperature aluminum floating electrolysis , null , null , null

Further development of NdFeB magnet industry in China

Yang LUO

材料科学技术（英文）

Due to continued growth in key markets, a broadening of application base and performance improvements, the market demands of NdFeB magnet increased steadily in 1998, and the global output of sintered NdFeB magnet exceeded 10,000 t, in spite of the economic recession in Asia. In 1998 China produced 3,850 t sintered NdFeB block magnet, with an annual growth rate of +22% over the output in 1997.

关键词:

Study on macrosegregation in heavy steel ingots

International Journal of Cast Metals Research

Macrosegregation in heavy steel ingots was studied through numerical and experimental studies of a 500 kg ingot. The numerical model used heat conduction coupled with thermal convection. Simulation results confirm that a small 500 kg ingot poured in a sand mould has a solidification time that is equal to that of a 10 000 kg industrial ingot cast in an iron mould. Accordingly, the sand moulded ingot exhibits more severe macrosegregation compared to the iron moulded ingot, indicating the possibility that a relatively small ingot in sand can simulate conditions in a much heavier steel ingot in a conventional iron mould. Experiment demonstrated that a 500 kg ingot exhibited all the types of macrosegregation, including A- and V-segregates and negative and positive segregation commonly found in a 65 000 kg steel ingot.

关键词: Macrosegregation;Heavy steel ingot;Numerical simulation;solidification;segregation;convection

Introduction to atmospheric corrosion research in China

Science and Technology of Advanced Materials

In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions. (C) 2007 NIMS and Elsevier Ltd. All rights reserved.

关键词: atmospheric corrosion;corrosivity;rusting evolution;weathering steels;rust;mechanism;so2;o-3;no2

Recent Advances of Laser Coating Technology in China

LIANG Yong LI Ruiguo Institute of Metal Research , Academia Sinica , Shenyang 110015 , ChinaInstitute of Corrosion and Protection of Metals , Aademia Sinica , Shenyang , 110015 , China

材料科学技术（英文）

Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.

关键词: laser , null , null , null , null

Study on Thermal Simulation of Solidification in Heavy Section Ductile Iron

Zhenhua LI , Yanxiang LI , Huiyuan GENG , Jianjun CHEN , Chunyan ZHOU , Junfa CHEN

材料科学技术（英文）

Using an artificial intelligent instrument and a computer feedback control method, a new thermal simulation system is studied. Based on numerical simulation of casting solidification, a sample in the new system successfully simulated the solidification of heavy section ductile iron. The results show that the new thermal simulation system is accurate and reliable. Not only cooling curve but also graphite in the center of the thermal sample and the heavy section ductile iron is identical. Realization of accurate thermal simulation of solidification in heavy section ductile iron will be helpful for studying formation mechanism and controlling graphite degeneration in heavy section ductile iron.

关键词: Thermal simulation , null , null

ENERGY DISTRIBUTION OF BACKSCATTERED ELECTRONS FROM HEAVY METALS

Z.J.Ding , K.Salma , Z.M.Zhang

金属学报(英文版)

The full energy distribution of backscattered electrons from the elastic peak down to the true-secondaty electron peak for heavy metals, Ta, W, Pt and Au, in Auger electron spectroscopy in the EN(E) mode has been studied with a Monte Carlo simulation method, which includes cascade-secondary-electron production. The simulation model is based on the use of a dielectric function for describing inelastic scattering and secondary excitation, and on the use of Mott cross sections for elastic scattering. A systematic comparison between the calculated and experimental spectra measured with a cylindrical mirror analyzer has been made for primary energies ranging from 1 to 5keV. Excellent agreement was obtained for these heavy metals on the backscattering background at primary energies in the keV region. A significant contribution of cascade secondary electrons to the measured spectra on the low-energy side was found.

关键词: backscattered electrons , null , null

STATISTICAL EVALUATION OF CRITICAL INCLUSION FACTOR FOR SECONDARY RECRYSTALLIZATON IN 3%Si STEEL Lecturer,Department of Materials Engineering,Southwestern Jiaotong University,Chengdu 610031,China

LI Shuchen Southwestern Jiaotong University , Chengdu , ChinaCHEN Mengzhe KE Jun University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

On the basis of statistical data of MnS in the conventional 3% Si steel sheeets after various annealing processes,the critical inclusion factor has been evaluated to be 20 mm~(-1).The inhi- bition of MnS to grain growth has been exactly described.

关键词: 3%Si steel , null , null