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

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    , Volume 17 Issue 3 Previous Issue    Next Issue
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    EFFECTS OF RARE EARTH ON PREFERRED ORIENTATION IN OXIDE SCALE O FA Fe-Cr-Al ALLOY
    by Zhang Lixin; Luo Jixun; Yin Yaode and Li Liguang (Institute of Metal Research; Academia Sinica) Zhao Qi and Zhang Jiayun
    Acta Metall Sin, 1981, 17 (3): 233-242. 
    Abstract   PDF (820KB) ( 538 )
    The effects of RE additions, 0.5% Y or 0.15% (La+Ce), on the prefe ed orientation of oxide scale formed at 1200℃ in a Fe-Cr-Al alloy have been studied by inverse-pole-figure method. It was found that the addition of RE element affects the types of preferred orientation to a limited extent.The main preferred orientation in the oxide scale on three tested alloys are identical as (0118);whereas some differences are shown among their minor ones with (1129)and (10110) for alloys containing Y or La+Ce, and (0001) and (10110) for an alloy without RE. RE can play an important part in conserving and enhancing the preferred orientations in the scale, among which Y has a more remarkable effect than La+Ce.The oxidation process of the alloys was discribed by the shortcircuit dislocation path model. This model makes the variation curve of P_1011 parameter of the oxide scale in good agreement with the variation curves of oxidation dynamics. This accounts for the fact that RE elements improve the oxidation resistance of the alloy through their effect on modifying the preferred orientation of the oxide scale.
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    EFFECT OF Al ON THE MAGNETIC PROPERTIES OF GRAIN-ORIENTED 3%Si-Fe
    by Luo Yang; Li Weili; Li Yufeng; Chen Yizhi and Chen Minqin (Central Iron and Steel Research Institute; Ministry of Metallurgical Industry)
    Acta Metall Sin, 1981, 17 (3): 243-364. 
    Abstract   PDF (4197KB) ( 724 )
    Studies were made of the effect of A1 on the magnetic properties of grainoriented 3%Si-Fe containing about 0.007 wt-% N and 0.001—0.0088 wt-% A1. The nitrogen content, both soluted and combined in steels were determined by hydrogen extracting method. It is shown that every optimum range of A1 content in steels is available to its own soaking temperature for the purpose of obtaining proper magnetic properties as B_(10)≥1.8T and P15/50≤1.05W/kg, such as 0.008—0.018, 0.005—0.022, 0.004—0.03 and 0.05 wt-% A1 correspond 1200, 1250, 1300 and 1350℃ respectively. If any A1 content was beyond the optimum range, their magnetic properties would be steeply fallen to such extent even as a value of the non-oriented steel. It is also found that the A1 content influences markedly upon the proportion of A1N which is an effective inhibitor to normal grain growth.Most effective A1N may be precipitated while the acid soluble A1 is within 0.005—0.02%. Owing to the aforementioned results together with that of electron microscope observation and thermodynamical consideration of A1N and MnS, an approach about the behaviour of A1 on magnetic properties of grain-oriented 3%Si-Fe was proposed, namely, the Al is associated with N to form AlN, and then A1N exists as an effective inhibitor.
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    RELATIONSHIP BETWEEN MECHANICAL PROPERTY OF METALS AND CRITICAL FRACTURE ANGLE OF A SLANTED CRACK
    by Long Qiwei (Lung Chi-wei) (Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1981, 17 (3): 253-258. 
    Abstract   PDF (470KB) ( 580 )
    New concept of two critical angles was suggested to fracture analysis of a slanted crack. A discussion was especially made of the material choice for small slant angle experiment. It is shown that all the metallic materials which used to be conventionally employed in such experiments seem to be not most satisfactory.
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    FRACTURE-MECHANICS ANALYSIS OF COLD-DRAWN Si-Cr VALVE STEEL
    by Yin Jiang and Xu Jingfeng (Shanghai No. 5 Steel Works)
    Acta Metall Sin, 1981, 17 (3): 259-365. 
    Abstract   PDF (989KB) ( 687 )
    A fracture-mechanics approach was used in studying the cold-drawn splitting in Si-Cr valve steel. It seems that the cold deformation fracture toughness, K_(Ic),the peak value of cold-drawn tangential residual tensile stress, σ_(tm), and the depth of surface blemish, α, are the three main factors affected the splitting. An expression to determine the growth of split in cold-drawn rod may be as follows:K_(Ic)=σ_(tm)(πα)~(1/2)(K_I/K_0)The exact value of K_(Ic) is easily given by cold-heading specimen after cold deformation. Thus, the cold-drawing process makes possible to control the blemish depth. This process allows the steel to withstand a single cold drawing reduction of 20—30% or more at room temperature without splitting or recrystallized granular fracture and to give superior performance that can ever be obtained previously by hot drawing.
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    LAMELLAR FRACTURE CHARACTERISTICS OF MEDIUM-CARBON CrNiMoV STEEL FORGINGS
    by Zhang Jushui (Research Institute of Daye Steel Works)
    Acta Metall Sin, 1981, 17 (3): 266-369. 
    Abstract   PDF (3981KB) ( 728 )
    The lamellar fracture with streaky matt facets found in cracked surface of medium-carbon CrNiMov steel forgings has been observed by TEM. Various extracted second phases in carbon replicas from the fracture surface were identified by selected-area electron diffraction technique and EPMA. The results indicate that the fine globular α-MnS, the type-Ⅰ MnS inclusion and the thin platelet or dentritic VC were appeared, as well as the flaky complex oxides of Si and Mn, mainly as SiO_2,distributed along the direction of hot forging. The lamellar fracture characteristics relating to intercrystalline cracking is due to various second phase precipitates at its primary austenite grain boundaries. It seems that the lamellar fracture is similar to the "rocky-rock candy" one in cast steel substantially, thus,it may decrease remarkaly the transverse tensile ductility and lower moderately the impact toughness of the steel.
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    CORRELATION BETWEEN NUMERAL FRACTURE CHAR-ACTERISTICS AND FRACTURE TOUGHNESS OF MEDIUM-CARBON CrNiMo STEEL
    by Zhang Zhenfang; Zhang Tianyi and Liu Minzhi(Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1981, 17 (3): 271-372. 
    Abstract   PDF (3151KB) ( 743 )
    An investigation was conducted to observe the microstructure and macro-or micro-fracture surface, and to determine the fracture toughness and impact toughness of fatigue precracked specimens of four different types of structure of a medium-carbon CrNiMo steel. Some primary results were shown that its highest fracture toughness was evaluated by the specimens of sorbitie structure tempered at 600℃, but the lowest up to about 300℃. An identical variation is noted between the impact toughness of the fatigue precracked specimens and the fracture toughness from tri-point bending tests. Moreover, the numeral estimation for the various fractured surface characteristics with relation to fracture toughness has been attempted.
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    A CRITERION OF THE FORMATION OF AMORPHOUS STATE BY MELT QUENCHING
    by Ning Yuantao and Zhou Xinming (Institute of Precious Metals Research)
    Acta Metall Sin, 1981, 17 (3): 278-284. 
    Abstract   PDF (521KB) ( 597 )
    A criterion of the formation of amorphous state alloys by melt quenching has been proposed as I/ΔS<0.032 and (Ⅰ—0.1)/Δ>0.0044, where Ⅰ=1—T_m/T_m and S=1/100C_B((?)_m-T_m), T_m=melting point of the alloy, (?)_m=weighted average melting points of its components and C_B=at% of solute B. However, this criterion seems to be more accurate since special account has been taken of the effects of alloy composition and intermediate phase. All 127 alloys with one exception only checked up well with the criterion. Furthermore, the concentration distribution of the amorphous alloys and the characteristics of the allied constitution diagrams have been discussed.
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    0412-1961
    EFFECT OF SIZE FACTOR ON THE FORMATION OF AMORPHOUS ALLOYS
    Acta Metall Sin, 1981, 17 (3): 285-292. 
    Abstract   PDF (647KB) ( 554 )
    by Zhang Bangwei (Hunan University)
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    EXPERIMENTAL STUDIES ON LOW TEMPERATURE BRITTLENESS OF PHOSPHORUS CONTAINING STEELS AND IRON-PHOSPHORUS ALLOYS
    by Ji Jingwen; Li Maohua; Xiao Lianfang and Gao Huaisun (Baotou Institute of Metallurgy)
    Acta Metall Sin, 1981, 17 (3): 293-373. 
    Abstract   PDF (1536KB) ( 618 )
    A fractographic study on 10MnP and 15MnP steels with or without RE additions,as well as on Iron-phosphorus alloys under normalized or annealed and then reheated at 700℃ W. C. conditions has been carried out by SEM. The electrode potentials on fracture or polished surface of the RE free steels have been determined, and further investigations on their fractures have also been made by AES and ion-probe analysis.It was found that no intergranular fracture occurs in all the specimens ruptured at room temperature till—100℃. Most of the fractures are brittle cleavage in nature, except that a little ductile fracture appeared on fractures of the specimens ruptured at the interval from room temperature to—25℃. It seems that the cleavage fractures are enriched with phosphorus.
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    SELECTION OF FILLER METAL FOR ALUMINUM BRAZING AND ITS REACTION WITH BASE METAL
    by Zhang Qiyun and Liu Shuqi (Dept. of Chemistry; Beijing University)
    Acta Metall Sin, 1981, 17 (3): 300-377. 
    Abstract   PDF (2818KB) ( 825 )
    The influence of 28 element additions on the melting point, flowability, corrosion resistance and fillet bending ability of A1-Si type filler metal has been investigated. Among these systems, filler 6M, i. e.A1-Si(13.0)-Be(0.4—0.8)-Sr (0.03—0.06)-La (0.03—0.06) is regarded as the optimum. The erosion mechanism of molten filler metal on base metal has been also studied. In addition to the influences of brazing temperature and the composition of filler metal, the rate of solution of base metal into molten filler and the spreading out of molten filler along the fillet are other of importance in affecting the erosion of base metal during brazing. The fillets were annealed for different time intervals and only a little improvement of their strength and bending capacity was observed.
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    RECENT PROGRESS IN HVEM AND ITS APPLI-CATIONS TO THE STUDY OF PROPERTIES OF METALLIC MATERIALS
    Taoka Tadami (Institute of Vocational Training; Sagamihara; Kanagawa; Japan)
    Acta Metall Sin, 1981, 17 (3): 307-351. 
    Abstract   PDF (15499KB) ( 606 )
    Ⅰ. IntroductionⅡ. Advantages of HVEM2.1 Enhancement of resolution for thicker specimen2.2 Improvement of penetrating power2.3 Broadening the scope of thicker specimen observation2.4 Improvement of visibility and contrast of crystal defects and dislocation image2.5 Accuracy of selected area diffraction2.6 Irradiation damge, bombardment damage in metals and ionization damage in organic substances2.7 Critical voltage effects2.8 Special imaging techniques to improve contrastr in HVEM2.9 High voltage scanning transmission electron microscope2.10 In-situ observation of dynamic processⅢ.Specimen, its treatment and observation conditions 3.1 Specimen3.2 Orientation control of specimen3.3 Condition of specimen treatingⅣ. Identification of crystal defects and their fundamental properties4.1 Point defects and their migration4.2 Dislocation4.3 Dislocation loop4.4 Stacking fault4.5 Small angle grain boundary and coincidence grain boundary4.6 precipitates and inclusionⅤ.Relationship between microdtructure and macro-properties5.1 Mechanical properties5.2 Recovery and recrystallization5.3 Phase transformation, nucleation and growth of precipitates5.4 Magnetic domain, structure of domain wall and its temperature dependence5.5 Property of semiconducting grains and crystal defects5.6 Electron irradiation damage5.7 Application of critical voltage effect to the study of material properties5.8 Illustration of in-situ observation Concluding remarks
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    CHANGE OF CARBON CONTAMINATION DURING URANIUM REFINING
    by Zhang Yonggang; Qi Zhenzhong; Li Shuling and Li Xun
    Acta Metall Sin, 1981, 17 (3): 352-354. 
    Abstract   PDF (194KB) ( 424 )
    An investigation was undertaken to obtain a better understanding of the increase of carbon contamination in uranium during refining with graphite crucible. The results,indicate that the increasing rate of carbon content, c, in uranium melt with respect to refining time, t, may be proposed as:dc/dt=ks(1-c/c_s) where k—constant, s—specific contact surface between melt and graphite crucible,c_s—solubility of carbon in uranium melt.
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    STRUCTURAL AND MAGNETIC PROPERTIES OF Y (Mn_(1—x)Fe_x)_(12)
    by Yang Yingchang (Dept. of Physics; Beijing University)
    Acta Metall Sin, 1981, 17 (3): 355-358. 
    Abstract   PDF (278KB) ( 552 )
    The new ternary intermetallic compounds on the iron rich side Y(Mn_(1-x)Fe_x)_(12) have been prepared and their magnetic properties investigated. Their structure was found to be of the ThMn_(12) type with x=0.8 after appropriate annealing. The field dependence of magnetization was measured under range of 4.2 K to room temperature. The results indicate that Y(Mn_(1-x)Fe_x)_(12) appears antiferromagnetic when x=0.0, 0.2 or 0.4, in a spontaneous magnetization when x=0.6 and to become ferromagnetic or ferrimagnetic when x=0.8. The Curie point is above room temperature.
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    DETERMINATION OF SURFACE TENSION AND ITS TEMPERATURE COEFFICIENT OF MOLTEN URANIUM
    by Wang Jingtang; Bian Maoshou and Zeng Mengcang (Institute of Metal Research; Academia Sinica)
    Acta Metall Sin, 1981, 17 (3): 359-361. 
    Abstract   PDF (176KB) ( 461 )
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