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

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    , Volume 15 Issue 4 Previous Issue    Next Issue
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    A FRACTOGRAPHIC STUDY OF AN OVERHEATED MEDIUM CARBON NiCrMo STEEL
    Zhao Jian;Wang Degen Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 439-572. 
    Abstract   PDF (3030KB) ( 539 )
    Fractographic examination of an overheated-medium carbon NiCrMo steel hasbeen carried out by SEM. The rock-salt fracture occurred at the original austeniticgrain boundaries of the steel showed dimples, and the morphology and size ofMnS inclusions located in such dimples varied with different facets even for asingle austenite grain. The Widmannstatten precipitates of sulphide also occurredat the rock-salt fracture surfaces at times. The probable cause and the controllingfactors in regard to the formation of sulphide inclusions in various morphologieshave been discussed.
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    THE IMMUNIZATION OF FLAKES IN A MEDIUM CARBON MANGANESE STEEL BY HOT WORKING
    Chen Lian;Liu Minzhi(Liu Min-chih);Zhang Weidou;Liu Shengyen;Yin Wanquan;Hu Kuiyi;Sun Jihong
    Acta Metall Sin, 1979, 15 (4): 446-576. 
    Abstract   PDF (4563KB) ( 556 )
    42Mn2 steel cylinders processed by hot extrusion and drawing of flake-con-taining billets have been examined by SEM and by other methods to ascertain theimmunization of flakes in the final products. All internal flakes in the billets werecompletely healed after processing into cylinders, with the exception of those origi-nally exposed to the surface of the billet owing to oxidation. From practical appli-cation point of view, however, little difference in properties has been found betweencylinders completely or incompletely immunized from flakes. Thus, in the fatiguetest of the cylinders within cyclic stress ranges of 10?150 kg/cm~2, no signalsinduced by the formation and propagation of cracks were detected by acoustic emis-sion till 30,000-60,000 cycles. Likewise, the static bursting test of all cylindersalso met the standard set up by the users.
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    AN INVESTIGATION OF TRANSFORMATION MECHANISM AND FINE STRUCTURE OF (M-A) PHASE IN 12Cr2MoWVTiB STEEL BY TEM
    Wang Yingshu;Ma Guoqian;Ai Baorui;Wang Jiansheng;Deng Xinglin Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 456-580. 
    Abstract   PDF (2948KB) ( 467 )
    Thin foil of normalized specimen of 12Cr2MoWVTiB steel has been examinedby TEM. The fine structure and crystallographic orientation relationship of the(M-A) phase in carbonless bainite were determined. In the light of the observedstructure features the transformation mechanism of (M-A) phase was also discussed.
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    EFFECTS OF RECRYSTALLIZATION TEXTURES ON THE PLASTIC STRAIN RATIO R AND DEEP-DRAWING PROPERTIES OF COLD ROLLED LOW-CARBON STEEL SHEETS CONTAINING TITANIUM
    Qiu Li;Zhang Kui;Yin Ying;Liu Yuming;Liu Jianmin Anshan Iron and Steel Company
    Acta Metall Sin, 1979, 15 (4): 462-583. 
    Abstract   PDF (2862KB) ( 622 )
    The effects of titanium 0.145-0.35% corresponding to the ratio Ti/(C+N)varied from 2.9 to 10.1 on the recrystallization textures of cold rolled low-carbonsteel sheets have been investigated in comparison with the plastic strain ratio Rand deep-drawing properties. For the ratio Ti/(C+N)>4, the main texture com-ponent of (111) [112] is beneficial to the deep-drawing ability; for the ratio Ti/(C+N)<4, that of (100) [011] is detrimental. It would appear that the deep-drawingproperties were substantially determined by the type and degree of the recrystal-lization textures, but not by their erystalline shape. The influence of fine precipi-tates of TiC phase on the recrystallization texture has been discussed.
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    PHASE TRANSFORMATION AND MECHANICAL PROPERTIES OF MARAGING STAINLESS STEELS
    Li Jianchun;Gao Anjuan;Wang Zhanyi Central South Institute of Mining and Metallurgy
    Acta Metall Sin, 1979, 15 (4): 472-481. 
    Abstract   PDF (1120KB) ( 677 )
    The volume fractions of austenite have been determined on two maragingstainless steels with respect to tempering temperature and time or quenching tem-perature. When the specimens were quenched from 850℃ and tempered under dif-ferent temperatures for 4h, the reverted austenite began to appear at a temperingtemperature of about 550℃, reached its peak value of 24% volume fraction atabout 610℃ and disappeared over 700℃. Under certain definite tempering temper-ature their volume fractions were increased as prolonging the tempering time.And the process seems to be of diffusion controlling. The minimum volume frac-tion of austenite, being near zero, was resulted by being quenched at 1000 or950℃ under same tempering temperature of 580℃ for 4h. The effect of different heat treatment on the microstrain Δα/α of the steels,closely related to phase transformation process of M?A, has also been investigatedby means of X-ray diffraction. The presence of austenite at any 10% would causeloss of strength of both steels about 10 kg/mm~2, however, their toughness mightbe actually improved by these softer austenites formed along the boundaries oflath martensite. In view of combining both strength and toughness of the steelsthe proper heat treatment process to form 5-10% stable reverted austenite wouldperhaps be desirable.
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    AN INVESTIGATION OF THE GROWTH PROCESS OF MODULATED STRUCTURE IN A NiFeNbAl ALLOY
    Xu Wenchong;Wang Junjian;Su Xiujin;Li Zhihua Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 482-586. 
    Abstract   PDF (3289KB) ( 496 )
    The formation and growth process of modulated structure in a NiFeNbAlalloy during aging have been investigated by means of TEM, X-ray diffraction andhardness measurements. The presence of Al in the alloy appears to accelerate thegrowth process of the structure. At an early stage of aging, the pre-precipitatesof γ′[Ni_3(Al,Nb)] phase in the alloy has been found to arrange in line along thethree <100> directions; and a micrograph showing parallel striations has also beenobtained under [001] and [011] zones of the electron diffraction. At this stagethe spacing of the striations was about 100A. When the aging period was pro-longed a "tweed structure" appeared. Further increase of aging time widened thespacing of parallel striations to about 200A. With 10h-aging at 550, 700 or 800℃,γ′ particles were observed at the striations of the modulated structure in the alloyand appeared to be in perfect arrangement along [100] and [010] directions. X-raydiffraction of the alloy showed that there is a side-band on the (220) main peakunder various aging conditions. Attempts have also been made to clarify the natureof hardening of the alloy during aging as well as to explain the higher hardnessin NiFeNbAl alloy than in NiFeNb alloy.
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    CALCULATION ON THE STABILITY OF THE CONSTANT PERMEABILITY ALLOY
    Yang Yingshan;Zhang Anning Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 489-497. 
    Abstract   PDF (500KB) ( 639 )
    A study was made to calculate the stability of permeability of isopermalloyrelated to the magnetocrystalline anisotropy with the aid of a computer. It wouldseem that the problem regarding the correlation of magnetization with magneticfield intensity might be solved by a non-existence of analytical form, sinβ=f(H),and of the condition of many values. Therefore, the stability of an alloy char-acterized by an evenly random crystal orientation may be much superior to thatby an arbitrary texture.
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    EFFECT OF AUSTENITIZING TEMPERATURE ON THE MICROSTRUCTURE AND FRACTURE TOUGHNESS OF A MEDIUM CARBON CrMnMo STEEL
    Lou Bingzhe;Chen Xicheng Shaanxi Mechanical Engineering Institute Institute of Physics; Academia Sinica
    Acta Metall Sin, 1979, 15 (4): 498-589. 
    Abstract   PDF (3936KB) ( 737 )
    An investigation of the effect of austenitizing temperature on the microstruc-ture, strength and fracture toughness of a quench-tempered 0.5% C CrMnMo steelhas been carried out. The fracture toughness (K_(IC)) of this steel in fully temperedcondition was improved by adequately increasing the austenitizing temperature inwhich the amount of lath martensite was increased and the rupture was mainlyductile. When the austenitizing temperature went up beyond 950℃, films of retainedaustenite began to appear at the lath boundaries. Such a distribution of retainedaustenite would seem to be liable to continuous precipitation of carbide platesaround the lath boundaries owing to its decomposition on being tempered at 500℃.Such carbide plates would seriously deteriorate the fracture toughness of the steeland enhance its tendency to intergranular fracture. After protracted tempering at500℃, spheroidization of the carbides and disappearance of the twins in acicularmartensite resulted. Both would contribute to the improvement of the fracturetoughness (K_(IC)) of the steel, as well as to an improvement of the ductile behaviouron fracturing. The effect of carbide size on the propagation behaviour of cracksare discussed tentatively. The variation of the plane strain fracture toughness (K_(IC))caused by an increase of austenitizing temperature would seem to agree well withthe Hahn-Rosenfield relation.
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    THE DISSOLUTION AND PRECIPITATION OF BORON CONSTITUENT AND THEIR EFFECTS ON THE PROPERTIES OF 40MnB STEEL
    Res. Gp. of Boron Steels; Beijing Steel Works and Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 506-591. 
    Abstract   PDF (2610KB) ( 551 )
    The effects of dissolution and precipitation of M_(23)(C,B)_6 during heating athigh temperature and cooling subsequently upon the properties of medium carbonsteel 40MnB containing different amounts of boron have been investigated by meansof quantitative phase analysis and boron-autoradiography. The volume fraction andgrain size of M_(23)(C,B)_6 precipitate may be increased with the increase of boroncontent and with the decrease of cooling rate. Although the steels contained dif-ferent amounts of boron, a same critical cooling rate may be appeared at whichM_(23)(C,B)_6 precipitate reached to saturation. The dissolution and precipitation ofM_(23)(C,B)_6 are deeply affected the hardenability and toughness of the steels. Underthe same condition, M_(23)(C,B)_6 in steels containing less boron may be precipitatedout in smaller size and easily dissolved. Thus, they exhibited better combinedproperties and less sensitivity to the change of heat history. Suggestion on stabi-lizing the properties of the steels has been made.
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    INTERACTIONS BETWEEN CREEP AND LOW CYCLE FATIOUE IN A NICKEL BASE SUPERALLOY
    Zhang Anqing;Kong Qingping;Shi Changxu(Shih Chang-hsu) Institute of Metal Research; Academia Sinica
    Acta Metall Sin, 1979, 15 (4): 518-592. 
    Abstract   PDF (1381KB) ( 605 )
    A trial of creep combined with stress controlled low cycle fatigue has beentested for a nickel base superalloy. The life of the notched specimens in the com-bined test did not always obey the linear cumulative damage law, owing to inter-acting between creep and fatigue. The strongest interactions occurred at 650℃,where the creep ductility of the alloy seemed to be minimum. If the specimens un-derwent certain heat treatment to improve their creep ductility, the interaction dis-appeared. However, no interaction was observed in plain specimens tested at 650℃.According to the fractography and creep ductility of the alloy, the probable causeof the interaction between creep and fatigue has been analyzed.
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    AN INVESTIGATION OF MECHANISM ON THE REMOVAL OF OXIDE INCLUSIONS DURING ESR PROCESS
    Fu Jie Beijing Institute of Iron and Steel Technology
    Acta Metall Sin, 1979, 15 (4): 526-539. 
    Abstract   PDF (1770KB) ( 697 )
    The mechanism on the removal of oxide inclusions during ESR process hasbeen investigated. The alumina inclusions may effectively migrate from moltenmetal into CaF_2-Al_2O_3-SiO_3 liquid slag pool contained 30% alumina and 7%silica. The oxidation of Al by SiO_2 at the slag/metal interface did not result anincrease of alumina inclusions in metal. Atmospheric oxygen was found to be de-leterious for the removal of alumina inclusions. It has been proposed that thevariation of interface energy may directly affect the behaviour of oxide inclusions inESR process. The thermodynamic requirements for removal of oxide inclusionsby the slag/metal interaction should be: ΔF=(c-σ_(m/i))2πRh+σ_(m/s)πr~2<0where σ_(s/i), σ_(m/i) and σ_(m/s)——interface energy of slag/inclusion, metal/inclusionand metal/slag interaction respectively. From viewpoint of interface enrgy, an explanation would be possible to cla-rity why the migration of the oxide inclusion clusters tends to stay along the freesurface of metal or the refractory/metal interface.
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    A STUDY ON THE CORROSION RATE OF MOLYBDENUM AND ITS ALLOYS IN MOLTEN GLASSES
    Hu Tingxian;Xu Kedian;Gong Mingying;Liu Zhichao Central Iron and Steel Research Institute; Ministry of Metallurgical Industry
    Acta Metall Sin, 1979, 15 (4): 540-593. 
    Abstract   PDF (1724KB) ( 589 )
    The free energy calculation of the interaction between molybdenum and theoxides in glasses has been correlated with the results obtained by immersing mol-ybdenum electrodes in molten glass bath in work's practice. The corrosion rateof molybdenum electrode as observed was directly proportional to the currentdensity and to the temperature of molten glass, the critical current density beingabout 0.4-0.7 A/cm~2. After one year's service in molten glass, the structure ofmolybdenum became very coarsely recrystallized, with an oxygen content of 0.04to 0.38 wt% (max). It would appear therefore, that molybdenum is sufficientlycorrosion-resistant to be adequately used as electrode or as structural materials inglass industry.
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    INFLUENCE OF CERTAIN ALLOYING ELEMENTS ON THE CREEP ACTIVATION ENERGY OF PLATINUM
    Ning Yuantao;Wang Yongli Institute of Noble Metals Research
    Acta Metall Sin, 1979, 15 (4): 548-594. 
    Abstract   PDF (1306KB) ( 548 )
    The influence of certain alloying elements such as Rh, Au, Mo, W, Zr andHf on the activation energy of creep of platinum alloys at high temperatures hasbeen investigated. The presence of Rh, Zr or/and Hf in the alloys might causean increment of their activation energy of creep but W, Mo or/and Au mightdecrease them. Based on the behaviour of these alloying elements, the mechanismof the creep rupture of the platinum alloys has been discussed.
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    EFFECT OF RARE EARTH ADDITIONS ON THE IMPACT FRACTURE OF Cr18Nil8Si2 STEEL
    Qiu Jufeng;Cheng Wanrong Baotou Metallurgical Institute
    Acta Metall Sin, 1979, 15 (4): 557-596. 
    Abstract   PDF (1791KB) ( 559 )
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    PREDICTION OF THE PROBABILITY OF SPHEROIDIZATION IN NODULAR CAST IRON BY PARAMETRIC DIAGRAM OF CHEMICAL BOND
    Wei Yongde Harbin University of Technology
    Acta Metall Sin, 1979, 15 (4): 559-562. 
    Abstract   PDF (237KB) ( 432 )
    So far the selection of a proper spheroidizing agent for nodular cast ironproduction is deduced from the experience. On the basis of the related theoriesof chemical bond an attempt was made to suggest a parametric diagram of chemi-cal bond concerning interaction between graphitic carbon and other atoms in mol-ten cast iron. Three distinguishable regions as spheroidizing, transitional and anti-spheroidizing may be designated. The element distribution in either spheroidizingor anti-spheroidizing region appears to agree fairly well with both experimentsand production practice. Furthermore, a function ρ_i has been taken as the measureof probability of spheroidization for certain elements in the spheroidizing region.
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    OXYGEN CONTAMINATION OF Ti-679 ALLOY UNDER HIGH TEMPERATURE
    Wan Xiaojing;Cao Mingzhou;Xin Gongchun Institute of Metal Research; Academia Sinica Liming Machine Works
    Acta Metall Sin, 1979, 15 (4): 563-565. 
    Abstract   PDF (159KB) ( 438 )
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    ELECTRON DIFFRACTION ANALYSIS OF Ti_3Si-PHASE IN NEAR α-Ti ALLOY
    Li Yongsen Institute of Metal Research; Academia Sinica
    Acta Metall Sin, 1979, 15 (4): 566-597. 
    Abstract   PDF (716KB) ( 402 )
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