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

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    FORMATION OF (γ+γ') EUTECTIC AND CONTROL OF σ-PHASE IN A HIGH Al-Ti CAST Ni-BASE SUPERALLOY
    ZHU Yaoxiao; XU Leying; ZHAO Hong'en; TONG Yingjie; SHI Changxu (Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1986, 22 (2): 5-143. 
    Abstract   PDF (3382KB) ( 936 )
    An investigation was made of the various phases formed in what order and composed under different temperatures during the process of solidification and segregation of alloying elements in a high Al-Ti cast Ni-base superalloy. The formarion of (γ+γ') eutectic and the control of σ-phase precipitation have been discussed. During solidification of the alloy, the dendritic segregation of Al and V is almost unespied, and of Ti, Cr and Mo is positive, especially, Ti being the most serious. This may impel the formation of segregation zone at eutectic reaction and the enrichment with σ- phase forming elements, e.g. Cr, Mo and Co, in the remainder liquid. Thus the increasing of σ-phase transformation may be tended. However, the σ-phase may be avoided either by adjusting the ratio Al/Ti taking the advantage of the difference of the segregation behaviour of Al and Ti, or by controlling the cooling rate after casting.
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    RELATIONSHIP BETWEEN γ→εTRANSFORMATION TEMPERATURE M_(εs) AND COMPOSITION OF METASTABLE AUSTENITE REGION IN Fe-Mn-Al-Cr SYSTEM
    TIAN Xing; ZHANG Yansheng; SHI Changxu (Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1986, 22 (2): 13-20. 
    Abstract   PDF (1566KB) ( 782 )
    The γ→ε martensite transformation temperature M_(εs) of 40 metastable austenitic alloys in an Fe-Mn-Al-Cr system was determined by dilatometry. Resulting from the multicomponent linear regression an experience formula for a linear relationship between M_(εs) and alloy composition has been developed that each wt-% or Al, C and Cr may decrease 51, 339 and 8℃ of M_(εs) of Fe-Mn alloy respectively. It is in agreement with those of either previous allied works and Ishida's calculation for the influence of alloying elements on driving force of γ→ε transformation in Fe-Mn alloy. A brief discussion about the effect of Al, C or Cr on M_(εs) was also made referring to the mechanism of stacking fault for γ→ε martensite transformation.
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    UNUSUAL DISLOCATION SUBSTRUCTURES IN Zr BY HYDROSTATIC EXTRUSION
    LIN Yijian; LIU Ansheng; SANG jimei (General Research Institute of Non-ferrous Metals; Beijing); KE Jun (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 21-145. 
    Abstract   PDF (2622KB) ( 490 )
    A TEM study was made of the dislocation substructures in Zr extruded under a high hydrostatic pressure. It was found in 10% extruded Zr that the dislocations densely assembled in certain regions on the primary active slip planes with a configuration of complicate tangling in two dimensions. Only after 30% extrusion, the cell-subgrains in a laminar structure with distinct interfaces appeared as a result of the development of special mentioned dislocation configuration. After heavily extruded under 12000 atm, the subgrains of less than 0.5μm width and apparent misorientation became extensive, which could be crystallographically divided into two types. The first is the developed subgrains parallel to (1010), occurring previously in earlier stage of deformation, the other, being more in quantity and thinner than the former, has the interfaces lying on the basal plane with typical twisting misorientation. The mentioned substructures have not been seen in conventionally drawn Zr used for comparison. Its formation can be interpreted from the point of view of the effect of high hydrostatic pressure on the thermal activation movement of dislocations.
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    EFFECT OF HYDROGEN ON CREEP IN AUSTENITIC STAINLESS STEEL
    CHU Wuyang; DING Wei; XIAO Jimei (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 27-30. 
    Abstract   PDF (304KB) ( 539 )
    The dynamic charging does not influence on the creep rate of type 321 austenitic stainless steel if the initial strain was less than 2%, in which the amounts evolving hydrogen after test were below 1.5 ppm (by wt). However, the creep rate increased markedly when the initial strain was larger then 8% or the specimen was precharged for a long time. In the case the corresponding amount evolving hydrogen was 5 to 12 ppm (by wt).
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    BEHAVIOUR OF Hf IN SOLIDIFICATION OF CAST Ni-BASE SUPERALLOYS
    ZHENG Yunrong (Institute of Aeronautical Materials; Beijing)
    Acta Metall Sin, 1986, 22 (2): 31-148. 
    Abstract   PDF (3075KB) ( 940 )
    Results of quantitative metallography, SEM, EDAX and EMPA studies of Hf on the solidification of cast Ni-base superalloys are presented. The Hf is found to lower the liquidus temperature of the superalloys even the final solidification temperature to drop to 1130℃. The Hf may narrow down the range between temperature lost the interdendritic capillary feeding action and solidus, as well as may decrease the liquid content necessary for linking the interdendritic pools in the late solidification. The Hf-rich melts have superior fluidity, wettability and skin effect. These are the factors in increasing castability of Hf-containing superalloys. The Hf is not found in the dendritic arms of the superalloys, but is exceedingly concentrated in the narrow interdendritic zones usually in the form of Hf-rich phases. The Hf content in primary Hf-rich phases may be arranged in decreasing order of MC_(2), (Hf, Ti)_2 SC, Ni_5Hf, MC_(1) and eutectic γ'. The Hf may depress the formation temperature of primary phases. The solidification temperatures of all Hf-rich phases are lower than 1250℃. These phases may precipitate from the molten pools with Hf concentration over 13 wt-% at the late solidification and may have an intergrowth feature.
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    ON THE RAPIDLY SOLIDIFIED Cu-Zn-Al SHAPE MEMORY ALLOY
    JIN Jialing; SHAO Zichang (Shanghai Institute of Iron and Steel Research)
    Acta Metall Sin, 1986, 22 (2): 37-150. 
    Abstract   PDF (2134KB) ( 557 )
    The shape memory properties, microstructure and the influence of heat treament on them of Cu-24.9wt-%Zn-4.5wt-%Al alloy ribbon of different sizes prepared by rapid solidification technique have been investigated by means of σ-εand R-T curves, optical metallography, X-ray diffraction, SEM and TEM. The results showed that the alloy ribbon is of a fine-grained β structure, about 20 μn, originally, and grows up to about 100μm after water quenching from 720℃ for 10 rain. For the alloy with a β+M structure at room temperature, its optimum shape memory properties may be obtained and the embrittlement by grain coarsening may be avoided. The complete memory recovery may be realized with the strain no more than 8%. The formation of granular relief and martensite on the specimen surface seems to be reversible during deformation under loading.
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    CALCULATION OF α/γ EQUILIBRIUM PHASE BOUNDARY IN LOW ALLOY STEELS
    ZHAO Yuxin; LI Pengxing; XU Zuyao (T. Y. Hsu) (Shanghai Jiaotong University)
    Acta Metall Sin, 1986, 22 (2): 42-50. 
    Abstract   PDF (589KB) ( 462 )
    The α/γ phase boundary, relative proportion of the two phases and A temperature have been calculated by extending the Sharma et al. 's regular solution model to multicomponent commercial steels 20Cr, 30Cr, 40Cr, 40Mn2, 20CrMn, 35CrMn2, 38CrSi and 30CrMnSi with the thermodynamical data taken from available literatures. The calculated A are in good agreement with the experimental data.
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    EQUILIBRIA OF Ce-Al-O AND Nd-Al-O IN MOLTEN IRON
    DIAO Shusheng; HAN Qiyong; LIN Gang; CHEN Dong (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 51-60. 
    Abstract   PDF (745KB) ( 641 )
    Equilibrium of Ce-Al-O or Nd-Al-O system in molten iron was studied by separately smelting the radioactive isotope of ~(141)Ce or ~(147)Nd in an Al_2O_3 crucible filled with pure iron to form ~(141)CeAlO_3 or ~(147)NdAlO_3 around its inner wall. The content of dissolved Ce or Nd in iron was determined by means of radioassay and electrolysis in organic electrolyte. The analysis of dissolved Al in iron was obtained by colorimetry and followed by calculation. The activity of oxygen as dissolved state in liquid iron was directly measured by solid electrolyte sensors made of ZrO_2(MgO) tube. By extrapolation of data obtained, the temperature dependence of equilibrium constant of RE-Al-O in molten iron, K_(REAlO_3) or of interaction coefficient, e_(RE)~(Al), may be described as: For reaction CeAlO_(3(s)=[Ce]+[Al]+3[O] lg K_(CeAlO_3)=-37900/T+5.84 △G_(CeAlO_3)~0=175400-26.7T cal/mol e_(Ce)~(Al)=20500/T-13.53 For reaction NdAlO_(3(s)) =[Nd]+[Al]+3[O] lg K_(NdAlO_3)=-24700/T+0.69 △G_(NdAlO_3)~0=113030-3.16T cal/mol e_(Nd)~(Al)=13500/T-9.33
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    THE PRECIPITATION DIAGRAM OF [Ce]-[O]-[S] IN LIQUID IRON AND ITS APPLICATION
    DONG Yuanchi; HAN Qiyong (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 61-67. 
    Abstract   PDF (503KB) ( 502 )
    A space precipitation diagram of [Ce]-[O]-[S] in pure liquid iron has been constructed by proper selection of the recent and correct experimental thermodynamical data collected from allied equilibrium systems of RE-O, RE-S and RE-O-S. The quantitative correlation between the activity of oxygen or sulphur and the constitution of RE inclusions formed has been evaluated theoretically by thermodynamical calculation. This was verified well by the experimental facts from which the correlation between the initial activities of oxygen and sulphur in liquid iron and the constitution of RE inclusions formed was also determined.
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    EQUILIBRIUM OF Fe-La-O-S SYSTEM
    CHEN Dong; HAN Qiyong; WANG Tao; XIANG Changxiang (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 68-74. 
    Abstract   PDF (535KB) ( 556 )
    A study was made of the equilibrium of Fe-La-O-S system. The oxygen activity was directly measured by the solid electrolyte sensors made of ZrO_2(MgO) tube. The stability of La_2O_2S in the electrolytic separation and the content of La as dissolved state in liquid iron were examined by means of radioassay and electrolytic isolation of inclusion in organic electrolyte under low temperature. By extrapolation of data obtained, the equilibrium constant of La_2O_2S may be described as: 1550℃ K_(La_2O_2S)=3.81×10~(-19) e_s~(La)=-4.1 1600℃ K_(La_2O_2S)=6.45×10~(-19) e_s~(La)=-4.8 1650℃ K_(La_2O_2S)=7.41×10~(-19) e_s~(La)=-4.2 La(1)=[La] △G_(sol)~0=-136700+59.82T, γ_(La)~0=0.33 (1873 K) It seems that the deoxysulphurizing effect of La is more intense than that of Co, Nd and Y.
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    EFFECT OF CARBON CONTENT ON AXI-CORED INTERGRANULAR CRACKS OF STEEL INGOT
    QI Shangming; ZHENG Guoxue (Institute of Xining Steel Works); SHI Naili (Ma' anshan Institute of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 75-154. 
    Abstract   PDF (3850KB) ( 678 )
    An account was discussed of the nature of intergranular cracks appeared in the axial core of ingot of low carbon alloy steels, such as Cr5Mo, 12CrMoV and steel 10 on the basis of informations of industrial production and laboratory test. The experimental steel ingots weighing about 25 kg were examined under macroscopic observation, fractography, metallography and EMPA. It showed that the intergranular crack in axial core is true crack which seems to be related to the carbon content in steel owing to the high temperature δ→γ transformation on the solidification of ingot.
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    FATIGUE STRIATION AND MACROCRACK PROPAGATION IN Cr12Ni2WMoV STEEL
    CHEN Chuanyao; DAI Shujuan; GAO Daxing (Huazhong University of Science and Technology; Wuhan)
    Acta Metall Sin, 1986, 22 (2): 81-86. 
    Abstract   PDF (1271KB) ( 631 )
    TEM microfractography of the fatigue striation formation was further analyzed resulting from investigation of the fatigue crack propagation in Cr12Ni2WMoV steel, and the data for quantitative evaluation of striation interval was developed. The relationship between the rate of fatigue macrocrack propagation, da/dN, and microstriation interval, α, has been discussed. On the assumption to explain the phenomena observed and by interoducing an areacorrecting function: F(△K,R)=A(△K)~m/(1-R)K_c-△K the relation of (dα/dN)vs α may be expressed as dα/dN=F(△K,R)α(△K) The value F for Cr12Ni2WMoV steel is given.
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    ESTIMATION OF FRACTURE TOUGHNESS FOR POLYCOMPONENT COMPOSITE MATERIALS
    LI Zhonghua (Xi' an jiaotong University)
    Acta Metall Sin, 1986, 22 (2): 87-92. 
    Abstract   PDF (453KB) ( 452 )
    The expressions for estimating fracture toughness of the polycomponent composite materials have been derived in terms of the fracture toughnesses and the volume fractions of individual component each is included. The expression, conformed to mixed rule, of upper (n→) or lower (n=1) bound value was also derived on the basis of limit analysis.
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    KINETICS OF COMBUSTION OF PULVERIZED COAL IN RACEWAY BEFORE TUYERE OF BLAST FURNACE
    YANG Yongyi; YANG Yanhui (Beijing University of Iron and Steel Technology)
    Acta Metall Sin, 1986, 22 (2): 93-106. 
    Abstract   PDF (3175KB) ( 824 )
    The combustion efficiency study was made of the partially burnt Purverizeb coal, sampled from the raceway before the tuyere of blast furnace either No.9 of AISC or No.2 of SISC. Results showed that the injected coal started to volatilize and burn just it has entered the blowpipe where seems to be an important preheating and precombustion space before the raceway, however, it could not be completely burnt out there in front of tuyere. In order to replace more coke by injecting more coal, the laboratory simulation test on the combustion kinetics of the pulverized coal used by the above-mentioned two blast furnaces under conditions prior to tuyeres indicated technically possible by: pulverizing the coal down to 40 μm; enriching the blast with oxygen up to 30-40%; further raising the blast temperature; improving the injected coal distribution early in blowpipe; consistently injecting the coal at all tuyeres and selecting the variaty of coal of better combustibility, e.g., bituminous coal being superior to anthracite. Petrographic observation on coal samples prior to injection and after being partially burnt revealed that the bituminous coal burns violently and simultaneously not only on the surface but also in the interior of its particles, while the anthracite, especially, of SISC, mostly on the surface. Based on the theory of heat-transfer and mass-transfer, a set of mathematical model for combustion of pulverized coal has been derived. By substituting the combustion conditions of both above-mentioned two blast furnaces and laboratory test furnace into the model and with the aid of computer, a close approximation to the practice was obtained.
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    LIQUIDUS AND INTERMETALLIC COMPOUND IN Al-RICH REGION OF Al-Mg-Ce SYSTEM
    ZHENG Chaogui; WU Youyu; QIAN Jiuxin; YE Yupu (Department of Chemistry; Peking University)
    Acta Metall Sin, 1986, 22 (2): 107-155. 
    Abstract   PDF (1238KB) ( 550 )
    The liquidus of the Al-rich corner in Al-Mg-Ce phase diagram and the intermetallic compound, if any, formed in this region have been studied by themal, EMPA, chemical analysis, metallography and X-ray examination. An intermetallic compound in the solid phase was observed to form solid solution with rather extensive range. The pseudo-ternary system Al-Mg_5Al_8-CeAl_4 is of the ternary eutectie type. Three surfaces corresponding to primary crystallization of α-Al, Mg_5Al_8 and CeAl_4 respectively, three univariant curves associated with secondary crystallization and a ternary eutectic with composition about 12.6 wt-%C e and 26.0wt-%Mg at 446℃ were detected.
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    COMPUTERIZED SIMULATION OF STRUCTURE OF CRYOLITE MELT
    XU Chi; CHEN Nianyi (Shanghai Institute of Metallurgy; Academia Sinica); JIANG Naixiong; LI Qingzhi (Shanghai Institute of Computational Technology); SHEN Shiying (Northeast Institute of Technology; Shenyang)
    Acta Metall Sin, 1986, 22 (2): 112-118. 
    Abstract   PDF (531KB) ( 696 )
    The structure of molten cryolite has been investigated by computerized simulation using Monte Carlo method. The radial distribution functions and some parameters describing the local structure of 3NaF·AlF_3 melt at 1283K have been calculated. It is concluded that a part of F~- ions in AlF_6~3-moves away from Al~(3+) ions after the melting of cryolite, forming xNa~+·yF~- clusters with Na~+ ions. The removal of a part of F~- from AlF_6~(3-) makes it disintegrated into some local structures like AlF_4~- or AlF_5~(2-). Some Al~(3+) ions are connected to each other by AlF-Al bridges, forming ionic clusters like Al_2F_7~-, etc. It is also concluded that the distribution of the free space in molten cryolite is not uniform. There are more fissures and holes in xNa~+·yF~- clusters and between AlF_4~- and xNa~+·yF~- clusters.
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    ON THE CRYSTALLIZATION OF AMORPHOUS Ni-BASE ALLOY
    WANG Yuming; MENG Zhaofu; WANG Zhao (Jilin University; Changchun)
    Acta Metall Sin, 1986, 22 (2): 119-156. 
    Abstract   PDF (1593KB) ( 436 )
    The crystallization of amorphous Ni_(83)Cr_7Fe_3Si_4B_3 alloy was investigated under dynamic heating and isothermal annealing conditions. An identical crystallization and unaltered phases are revealed under both treatments. However, the initial crystallization is mainly due to the nucleation of crystals under dynamic heating, while the crystal growth plays a major role under isothermal annealing. It has also been measured that the microhardness approached its highest value just before the specimen being totally crystallized.
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    CORRELATION BETWEEN STRUCTURE OF ELECTROCHEMICALLY DEPOSITED (Fe,Co,Ni)-P LAYERS AND PROCESS CONDITIONS
    JIANG Xiaoxia; ZHANG Xuan; LIN Shuzhi (Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1986, 22 (2): 124-133. 
    Abstract   PDF (2999KB) ( 797 )
    A study has been made of the structure of the electrochemically deposited amorphous (Fe, Co, Ni)-P layers with relation to the process conditions, e.g. pH value, current density, metallic salt concentration, etc., by means of X-ray analysis, SEM and EPMA. Results showed that the effect of the process on the structure is realized by changing the P content of the layer. While P contained over 8%, below 3% or between 3 and 8%, a layer may be constructed as amorphous alloy, supersaturated solution or mixed structures respectively. The major factors affecting the structure of the deposited layer are found to be the concentration of NaH_2PO_2 and pH value of the bath. The structure of the layer may be also influenced by the potential of electro-deposition. The Fe-P, Co-P or Ni-P system is similar in amorphous structure of which the highest thickness of stack of the atomic face is 2.0, 2.5 or 6.5nm respectively.
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    A NEW METHOD FOR MEASURING DENSITY OF HIGH TEMPERATURE MELT
    BIAN Maoshu; MA Luming; WANG Jingtang (Institute of Metal Research; Academia Sinica; Shenyang)
    Acta Metall Sin, 1986, 22 (2): 134-140. 
    Abstract   PDF (583KB) ( 823 )
    According to Archimedes principle, a method, so called couple weighing method, for measuring the density of the high temperature melt was proposed in which a new-designed sinker, corresponding measuring regime and calculating formula are presented. Examples of the simultaneous measurement under similar conditions are shown that the data collected by this method with more accuracy and precision than that by both methods of Archimedes correction and bi-sinker.
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