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

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    , Volume 17 Issue 5 Previous Issue    Next Issue
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    NUMERICAL SOLUTION OF ELASTIC ENERGY OF ELLIPTIC INCLUSIONS ORIENTED IN <100>,<110>AND <111> DIRECTIONS IN CUBIC CRYSTALS
    by Yah Benda; Wu Jiansheng and Lin Dongliang (T. L. Lin) (Shanghai Jiaotong University) and Y. T. Chou (Department of Metallurgy and Materials Science; Leihigh University; U. S. A.; Adjunct Professor in Shanghai Jiaotong University; China)
    Acta Metall Sin, 1981, 17 (5): 489-505. 
    Abstract   PDF (1270KB) ( 482 )
    The elastic inclusion problem, that is the calculation of the stress-strain field and the elastic energy of an anisotropic elastic medium with an elastic inclusion contained in it, is one of the important problems in materials science.Especially, the variation of the elastic energy of the system with the orientations of the inclusion in the medium (i. e. the orientational dependence of the elastic energy), and the orientation of the inclusion corresponding to the minimum of the elastic energy of the system are of great theoretical land practical significance in the investigations of the habit orientations of the phase transformations and precipitate particles, the prediction of the microcracking direction as well as the optimum distribution of the reinforcement fibers in the composites.Based on the "Point Force-Line Force Method" given by H. Y. Yang and Y.T. Chou in 1976, a general computer program is compiled, which is applicable to the numerical calculation of the elastic energy of the elliptical inclusion oriented in any direction of the anisotropic medium for the generalized plane problem. The values of the elastic energy of the elliptic inclusions with their cylinder axes along the <100>, <110> and <111> directions in cubic metals Fe, Nb and Al were computed, and the dependence of elastic energies on the orientation of cross elliptic sections, which was rotating around their cylindcr axes, has been illustrated explicitly in graphic charts.The following conclusions arc deduced from the calculation results:1. The system has its elastic energy when the inclusion is lying on the crystal planes and oriented along the crystal directions of low indexes.2. The elastic energy of the system with the inclusion subjected to pure shear strain is 1/3-1/2 of that with the inclusion subjected to principal strain.3. The elastic energy of the anisotropic system with thin plate inclusions is very small. As the elliptic index e=b/a→0 the elastic energy of the system approaches nil.4. If the boundary energy could be neglected, the new phase and the precipitate with the lowest elastic energy would take the thin plate shape and shear mode in phase transformations and precipitation.
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    STUDIES OF CARBIDES IN 6Cr4Mo3Ni2WV STEEL
    by Liu Wenxi; Wang Binghui; Chong Keduan and Zhang Cunxin
    Acta Metall Sin, 1981, 17 (5): 513-600. 
    Abstract   PDF (4663KB) ( 578 )
    The carbides in 6Cr4Mo3Ni2WV steel have been studied by TEM, electrolytic extraction phase analysis, X-ray diffraction and EMPA. It was confirmed that the M_2C with long-range ordered carbon distribution and V_4C_3 with short-range ordered vacancy distribution are present in the residual carbides of the steel quenched from 1120℃. The nucleation of V_4C_3 with concomitant M_2C was observed during the tempering precipitation.The distribution of alloying elements partitioned between steel matrix and carbides is thus ascertained.
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    SOLUTION AND TRANSFORMATION OF Ni_5Zr IN CAST NICKEL-BASE SUPERALLOY
    by Ma Shuqin; Zheng Yunrong and Cai Yulin(Institute of Aeronautical Materials)
    Acta Metall Sin, 1981, 17 (5): 522-602. 
    Abstract   PDF (2255KB) ( 804 )
    Studies were made of the solution and transformation of intermetallic compound Ni_5Zr in Zr-bearing cast Ni-base superalloy and of effect of the Zr addition on the microstructure by DTA together with metallographic observation. The occurrence of Ni_5Zr in the superalloy may markedly decrease the incipient melting temperature and induce the solution of γ+γ′eutectic. Under high temperature exposure above 850℃, Ni_5Zr with γ (C) is transformed into ZrC and γ, which is bound to be reflected in DTA.
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    AN XPS STUDY OF ANODIC OXIDE FILM ON 1Cr18Ni9 STAINLESS STEEL
    by Zhang Yongfu; Bao Weiguo; Jiang Shaoyou and ü Guoliang (Institute of Shanghai General Petrochemical Works); Lin Rongfu; Dai Daoxuan and Dong Shuzhong (Physics Dept.; Fudan University); Huang Guozhu and Xu Kexun (Shanghai Institute of Material Research)
    Acta Metall Sin, 1981, 17 (5): 529-540. 
    Abstract   PDF (1187KB) ( 847 )
    The XPS has been used to study the composition and structure of the oxide film on stainless steel. The film was formed in the transpassive region during the anodic polarization in H_2SO_4 and after a treatment with Na_2MoO_4. It has been found that the ratio of Cr to Fe in the film is about three times higher than that in the bulk. The analysis of the valence states showed that the distribution of each constituent in the film is not uniform. The film has a three-layer structure.The outer layer is rich in OH~- and the middle layer consists mainly of Cr_2O_3 and Fe_2O_3, while the rest of the layer up to the interface contains the Fe~(2+) and Fe~0. The Mo ions have been found throughout the film. The possible mechanism for passivation of the anodic polarization in the transpassive region was discussed and a comparison was made with other oxide films.
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    A STUDY OF HYDROGEN EFFECT ON DEFORMATION AND FRACTURE MICROPROCESS IN PURE IRON
    by Chen Lian; Liu Minzhi; Su Huihe; Yin wanquan and Li Cuiping (Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1981, 17 (5): 541-606. 
    Abstract   PDF (3386KB) ( 711 )
    The effect of hydrogen on the deformation and fracture microprocess in pure iron has been studied by means of the tensile test and observation in S4-10 SEM using cathodic charged specimens. The main results are as following:1. With the increase of hydrogen content, namely, from 5.4 up to 31.0 cm~3/100g, the yield strength increases slightly, the flow stress and the fracture strength increase obviously, but the fracture strain decreases remarkably. The lower yield point and Luders band disappear when the hydrogen content exceeds 18.7cm~3/100g.2. The nucleation of a microcrack is predominately on the slip plane and the microcrack propagates along subboundaries when hydrogen content is below 10 cm~3/100g. The nucleation of a microcrack is on the grain boundaries and the microcrack propagates in a zigzag way when hydrogen content exceeds 16 cm~3/100 g, The former is transgranular fracture and the latter is a mixed fracture of transgranular and intergranular.3. The characteristics of the hydrogen embrittlement in pure iron are: (1)the slip lines on the specimen surface decrease obviously, and (2) the microfracture of brittle feature is formed and increased. This seems due to that the dissolved hydrogen in pure iron decreases the plasitc deformation.
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    ON THE LONGITUDINAL CRACKS IN 30CrMnSiNi2A ELECTROSLAG INGOT
    by Jiang Jinwen (Institute of № 1 Steel works; Benxi Iron and Steel Company); Liu Xingzhi and Tian Jifeng (Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1981, 17 (5): 549-608. 
    Abstract   PDF (3140KB) ( 609 )
    The cause and remedy of the longitudinal cracking in 30CrMnSiNi2A electroslag ingot have been investigated. Results showed that the cracks are initiated by the microsegregated C, P, S, Si, etc. along the primary austenite boundaries which become fragile and cracking under higher thermal stress. Al is injurious owing to promoting the microsegregation of elements and brittle fracture of grain boundaries rather than formation of the AlN. An effectual remedy for longitudinal cracks in 30CrMnSiNi2A electroslag ingot is to keep the residual amount of Al under control if the heat-retaining condition is restricted after stripping the ingot.
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    CRACK-TIP FRACTURE STRESS UNDER GENERAL YIELDING OF LIGAMENT
    by Deng Zhisheng and Wang Degen (Central Iron and Steel Research Institute; Ministry of Metallurgical Industry)
    Acta Metall Sin, 1981, 17 (5): 558-564. 
    Abstract   PDF (546KB) ( 560 )
    The criterion of maximum shear stress for crack extension, namely, the critical fracture stress at the crack tip,(σ_(yy))_c=σ_F was verified to be applicable to the ductile fracture in the range between—100℃ up to room temperature.Considering the independence of this criterion and the critical fracture stress at crack tip upon temperature, the observed phenomena of which J_c decreases with decreasing temperature may be qualitatively explained. The specimen geometry and the curvature radii of notch root are not affected with the average fracture strength, but affected with the true fracture strain. Thereby, the fracture strength is probably an important descriptive parameter of mechanical properties of materials.
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    IDEAL ECP MAPS FOR DIFFERENT CUBIC CRYSTALS AND THEIR RAPID INDEXING METHOD
    by Liao Qianchu and Lan Fenlan (Central Iron and Steel Research Institute; Ministry of Metallurgical Industry)
    Acta Metall Sin, 1981, 17 (5): 565-577. 
    Abstract   PDF (808KB) ( 634 )
    A set of ideal ECP maps for different cubic crystals was theoretically delineated by using the sterographical projection method of crystal planes. The data given by the maps are tabulated as a new convenient chart for rapidly indexing the ECP of cubic crystals experimentally obtained. This method saved wasting time from the indexing already. The error analysis shows that the present indexing method seems to be available to the cases of the zone axis both parallel and inclined to the optical axis of SEM.
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    ON THE ELIMINATION OF POLYMORPHISM OF OXIDE SOLID SOLUTIONS
    by Yu Guocheng (Luoyang Institute of Refractory Research)
    Acta Metall Sin, 1981, 17 (5): 578-582. 
    Abstract   PDF (389KB) ( 477 )
    A thermodynamical study was made of the problem concerning elimination of polymorphism of oxide solid solutions. The understandings on the elimination of polymorphism of ZrO_2 or SiO_2 given by various authors in recent five decades were reviewed, and yet these were contradictory. Derivation on elimination of polymorphism has been performed as:x_h(G_l~0—G_h~0)>(ΔG_(mh)—ΔG_(ml)) where x_h—-the tool % of solvent in high temperature modification of the solid solution, G_l~0 or G_h~0—the free energy of solvent under standard conditions for lower or higher temperature modification respectively and ΔG_(mh) or ΔG_(ml)—the free energy of mixing of the solid solution for higher or lower temperature modification respectively. It is only possibilty of the elimination of polymorphism that the differnce between G_l~0 and G_h~0 is much greater than that of ΔG_(mh) and ΔG_(ml). Due to the identity of the chemical bonds or coordination numbers between high and low temperature modifications of oxides, these differences are very small, thus, the polymorphism of oxide solid solutions which is possesed of polymorphism originally will be not eliminated.
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    YIELD STRENGTH OF METALS AND ALLOYS
    by Hideji Suzuki (Department of Physics; Faculty of Science; University of Tokyo; Japan)
    Acta Metall Sin, 1981, 17 (5): 583-594. 
    Abstract   PDF (811KB) ( 749 )
    A review covering the present state of yield strength of metals and alloys is presented. Emphasis is placed on slip and dislocation, multiplication of dislocations, plastic flow rate equation, Peierls stress, temperature dependence of the yield stress and effect of solute atoms.
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    AWARDED PHOTOS SELECTED FROM THE SECOND METALLOGRAPHIC EXHIBITION
    No Author
    Acta Metall Sin, 1981, 17 (5): 609-627. 
    Abstract   PDF (12808KB) ( 455 )
    The Second Metallographic Exhibition sponsored by The Chinese Society of Metals was held first in Shenyang on October 1980 and going to tour through the country. More than two thousand optical and electron photomicrographs were the preliminary choice from ninety institutes and laboratories of eighteen provinces, municipalities and autonomous regions. 813 photos were selected in the Exhibition opened to the public. The optical micrographs of them include cast iron and carbon steel, alloy, stainless steel, superalloy, non-ferrous metals, inclusions in steel, weld structure, etc.; the electron micrographs were taken by replica, metallic foil or SEM. Some colour micrographs and ones Shot by special techniques or with aesthetic microstructure are also displayed.The Judging Panel gave awards to 73 photos, they are:Optical microscopy Electron microscopy 1st award 5 2nd award 16 2 3rd award 28 22 These awarded photos will be published in two issues of the Acta Metal. lurgica Sinica, Vol. 17(1981), No. 5 and 6.The title, winner name and affiliation are classified in a list. And also a brief record of the treatment of specimen, etchant used and remark on observation is made for each photo.
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