ISSN 0412-1961
CN 21-1139/TG
Started in 1956

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    , Volume 33 Issue 2 Previous Issue    Next Issue
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    MATERIALS DESIGN AGAINST FRACTURE
    XIAO Jimei (HSIAO Chimei) (University of Science and Technology Beijing; Beiing 100083)
    Acta Metall Sin, 1997, 33 (2): 113-125. 
    Abstract   PDF (1229KB) ( 990 )
    From methodological point of view, the concepts of failure, property and structure are clarified, their relationship and methods of analyses discussed. The design of materials against the following three types of fracture are elucidated: (1) Creep ruptureSystematic development of new alloy systems, establishment of phenomenalogical equations about property, structure and their relationship for design purpose; (2) Intergranular fracture-Phenomenalogical equation between the grain boundary concentration of impurity and the solid solubility of the impurity is obtained by induction method; the effect of grain boundary impurity on the work of intergranular fracture is derived with quasichemical theory; and the expert system is established; (3) Environmental cracking-The results of mechanism research are used to set up the guide lines for improvement and design of materials.
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    NEW GENERATION SOLUTION GEOMETRICAL MODEL AND ITS FURTHER DEVELOPMENT
    ZHOU Guozhi(Kuo-Chih Chou) (University of Science and Technology Beijing;Beiing 100083)
    Acta Metall Sin, 1997, 33 (2): 126-132. 
    Abstract   PDF (659KB) ( 634 )
    Geometrical model is a kind of solution model that has been used extensively in predicting thermodynamic properties and calculating phase diagrams for ternary and multicomponent systems. However, all current geometrical models have their inherent defects since they have improperly assumed that the models are independent of the system treated. In order to overcome these inherent defects that lasted for almost 30 years, a complete new assumption has been given, that is, the selected model should be closely related to the systems considered. After a new conception "similarity coefficient" has been introduced, a new geometrical model has been established that can overcome all defects appearing in the current models. We call this kind of models as a new generation model. In this paper the problems for this kind of model and the possible development have also been discussed.
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    PROGRESS IN MODERN TEXTURE ANALYSIS
    LIANG Zhide (Northeastern University; Shenyang 110006)
    Acta Metall Sin, 1997, 33 (2): 133-142. 
    Abstract   PDF (819KB) ( 798 )
    The progress in modern texture analysis was systematically elucidated in this paper.
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    EFFECT OF NaOH CONCENTRATION AND AlO_2~- SPECIES ON CAUSTIC STRESS CORROSION CRACKING OF A LOW ALLOY STEEL AT 260℃
    LIU Su'e; ZHU Ziyong; KE Wei (State Key Laboratory for Corrosion and Metals;Institute of Corrosion and Protection of Metals; Chinese Academy of Sciences;Shenyang 110015)
    Acta Metall Sin, 1997, 33 (2): 143-149. 
    Abstract   PDF (1950KB) ( 554 )
    The effects of NaOH concentration and AlO2 species on caustic stress corrosion cracking (SCC) for steel 16MnR at 260℃ were studied by using the sl0w strain ratetechnique (SSRT), cyclic voltammetry technique, and X-ray diffraction analysis. The results indicate that OH- promotes and AlO2 inhibits the caustic SCC susceptibility. The presence of aluminate anions (AlO2) in caustic solusions also makes the corrosion film more stable and protective and the repassivasion rate more rapid, leading to a less crack propagation. The X-ray diffraction analysis indicated that the film for simple caustic solution was Fe3O4 and for the aluminate solution was Fe3-xAlxO4(x≤2) and a littIe (Fe, Mn)3-x AlxO4(x≤2), which was not an amorphous film.
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    INTERFACES IN PHASE TRANSFORMATIONS
    J.W.Christian FRS(Department of Materials; Oxford University; Parks Road; Oxford OX1 3PH; UK)
    Acta Metall Sin, 1997, 33 (2): 150-156. 
    Abstract   PDF (1249KB) ( 720 )
    The classification of interfaces in various kinds of phase transformation is discussed.Reconstructive phase transformations have incoherent interfaces and there is no systematic change of shape of the product region. Displacive phase transformations have fully coherent or partly coherent interfaces and are detectable by the change of shape.Fully coherent interfaces include martensitic types in which there is no change of composition and diffusional displacive interfaces in which a change of composition occurs.Both types of interface migrate by the motion of steps or ledges which are also called transformation dislocations in the martensite case. Partly coherent interfaces are also martensitic or diffusional. although examples of the latter type are rare.
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    THE HISTORY OF PHYSICAL METALLURGY AND OF MATERIALS SCIENCE
    R. W. Cahn(Department of Materials Science & Metallurgy; University of Cambridge;Cambridge CB2 3QZ; UK)
    Acta Metall Sin, 1997, 33 (2): 157-164. 
    Abstract   PDF (811KB) ( 2099 )
    The first half of the paper examines current ideas of what a historian of science should be and whether it is acceptable for someone trained as a scientist to write the hisotry of a science The second half looks more specifically at the problems of writing about the history of physical metallurgy or its descendant, materials science, and concludes with a brief sketch of what has been published in this field.
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    NANOSTRUCTURED MATERIALS
    H.Gleiter(Forschungszentrum Karlsruhe; 76021 Karlsruhe; Germany)
    Acta Metall Sin, 1997, 33 (2): 165-174. 
    Abstract   PDF (2428KB) ( 1346 )
    Nanostructured materials (NsM) are solids composed of structural elements-mostly crvstaltites-with a characteristic size (in at least one direction) of a few nanometers.NsM may be classified into twelve groups according to the shape and chemical com-position of their constituent structural elements. The atomic structu re and properties of NsM deviate from the ones of a single crystal and / or glass with the same chemical composition. This deviation results from the reduced size of the crystallites.dlmensionality effects due to the shape of the crystallites (thin plates. needles or equiaxed shape). and the reduced densitV and / or modified coordination numbers in the interfaces between the structural elements. Some of the experimental observations supporting these ideas are discussed. Technological applications of metallic .macromolecular and semiconducting NsM are described,
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    SAFETY ANALYSIS OF RIVETED BRIDGES BASED ON FRACTURE MECHANICS
    W. Dahl and P. Langenberg(Institute of Ferrous Metallurgy; RWTH Aachen; Germany)
    Acta Metall Sin, 1997, 33 (2): 175-186. 
    Abstract   PDF (874KB) ( 638 )
    A simplified method of safety analysis of riveted bridges based on fracture mechanics is presented in this paper First a new formula for the calculation of the fracture load of a brjdge member with an assumed crack. has been derived from new FEM-calculations.Second. a population of more than 400 experimental strength and fracture mechanic values derived from material taken from riveted bridges build between 1890 and 1930has been evaluated statistically to derive characteristic distributions as a basis for the material input data of the fracture mechanic concept. Third, large scale tests with oldbridge plates using the plane plate geometries described above bearing artificially pro-duced cracks have been carried out to verify the proposed method by comparing pre-dicted with experimental results. Fourth the new formula has been applied for modern structural steels with yield strength from 350 t0 890 MPa and large scale tests per-formed on the large sale testing machine at the Institute of Ferrous Metallurgy in sever-al research projects have re-evaluated to find out the quality of this approach.
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    PHYSICAL FUNDAMENTALS OF MESOMECHANICS OF PLASTIC DEFORMATION AND FRACTURE OF SOLIDS
    V.E.Panin(The Institute of Strength Physics and Materials Sciences; Russian Academy of Sciences;Siberian Branch; Tomsk; 634048; Russia)
    Acta Metall Sin, 1997, 33 (2): 187-197. 
    Abstract   PDF (4379KB) ( 884 )
    The research review on plastic deformation and fracture of solids based on phvsicalmesomechanics is presented. A solid under loading is considered in physicalmesomechanics as multilevel self-consistent system. where the plastic flows atmicro-meso- and macrolevels are natrually interrelated according to the principle ofscaIe invarlance.Bulk mesovolumes are moved at the mesoscale level according toscheme "shear+rotation". Plastic deformation and fracture of solids are considered astwo stages of the same process.
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    INVESTIGATION OF THE DISLOCATION STRUCTURE IN HCP SINGLE CRYSTALS BY MEANS OF THE ROCKING CRYSTAL METHOD
    Y.Hao and G.Petzow (Max-Planck-Institut fur Metallforschung; Institut fur Werkstoffwissenschaft; Pulverme-tallurgisches Laboratiorium; Heisenbergstr. 5; 70569 Stuttgart; Germany)F.Mucklich (Institute fur Werkstoffwissenschaftern Universitat des Saarlandes; 66041 Saarbrucken)
    Acta Metall Sin, 1997, 33 (2): 198-206. 
    Abstract   PDF (1202KB) ( 598 )
    A single crystal contains a large number of dislocations after its growth, which can give rise to deflection and distortion of the crystal lattice. In this study the disloctaion struc-ture of hcp single crystals was investigated by means of the rocking crystal method.The theoretical calculation is based on the Krivoglaz model which was developed fromthe kinematic diffraction theory. Beryllium single crystals. due to their excellent opticalproperties as X-ray monochromators. were chosen as a specimen and their rockingcurves were investigated. The dislocations generated on different glide systems- for ex-ample basal and prismatic dislocations. contribute differently to each reflection. There-fore by studying the rocking curves of different reflections it is possible to determinethe dislocation structure within the crystal This is of great imprortance in developingthe crystal monochromators. which usually require tailored dislocation structures byoptimising the growth and heat treatment conditions.
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    THE IMPACT OF THE ENVIRONMENTAL CONCERNS ON THE DEVELOPMENT OF IRONMAKING TECHNOLOGY
    W-K.LU (McMaster University; Hamilton; Ontario; Canada)
    Acta Metall Sin, 1997, 33 (2): 207-212. 
    Abstract   PDF (548KB) ( 798 )
    The steel industry consumes large amounts of energy and raw materials and produces industrial wastes, Most of the waste is produced in ironmaking. therefore, forsustainable development new processes will have to observe environmental regula-tions anywhere in this global village, in view of the situation in Chian. the characteris-tics of three types of ironmaking technology. i.e.. blast furnace. HBI / DRI in EAF androtary hearth / smelting reduction are reviewed for the country's furture needs.
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    Al_2Ni_3 PRECIPITATION INDUCED BY ELECTRON BEAM IRRADIATION
    D.L.Li.(Department of Materials Physics; University of Science and Technology Beijing; Beijing100083; China)H.Hashimoto(Department of Mechanical Engineering; Okayama University of Science; Japan)
    Acta Metall Sin, 1997, 33 (2): 213-221. 
    Abstract   PDF (5117KB) ( 833 )
    An as-quenched Cu-11 .2%(wt)%Al-2.9 (wt)%Ni alloy specimen. which consists ofordered N9R and 2H structure martensites, was examined by a 400 kV TEM. Largenumbers of dispersive precipitates in the specimen are induced by the electron beam irradiation, These fine particles are identlfied as AI2Ni3 phase by electron diffraction.The stereoscopic measurement of the dark field TEM images combined with HREMstudy showed that this irradiation induced precipitation is not only a surface reaction.AIzNi3 particles precipitate preferentially at crystalline defects and interfaces of themartensitic matrix. When duration of the electron beam irradiation lengthens. growthand coarsening of the precipitates are also observed.
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    RARE METALS IN CHINA
    L.Zhou and W.H. Yin (Northwest Institute for Nonferrous Metal Research; Xi'an 710016)
    Acta Metall Sin, 1997, 33 (2): 222-224. 
    Abstract   PDF (266KB) ( 661 )
    A brief account of the development of rare metals research and production in China.
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