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

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    , Volume 32 Issue 6 Previous Issue    Next Issue
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    AN ANALYSIS OF VALENCE ELECTRON STRUCTURE OF Fe-C-Mn ALLOYING AUSTENITE
    ZHU Ruifu; LU Yupeng; CHEN Chuanzhong; LI Shitong; WANG Shiqing (Shandong University of Technology; Jinan 250061) ZHANG Fucheng (Yanshan University; Qinhuangdao 066004)
    Acta Metall Sin, 1996, 32 (6): 561-564. 
    Abstract   PDF (286KB) ( 519 )
    The valence electron structure of Fe-C-Mn alloying austenite containing 1.6% C(mass fraction) has been established by using bond length difference (BLD) method of the empirical electron theory of solids and molecules. The experimental results show that in unit cell containing C and Mn atoms, Fe~c, Fe~f and Mn atoms are on the 16th, 18th and 10th hybrid levels of B-type hybridization states respectively, and the carbon atom is on its 6th hybrid level. The simultaneous increase in C and Mn content will increase the number of the strongest C-Mn bond, thus lead to the increase in austenitic stability and work hardening capacity.
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    SNOEK-KOSTER RELAXATION IN Ta-O SOLID SOLUTIONS
    FANG Qianfeng (Laboratory of Internal Friction and Defects in Solids; Institute of Solid State Physics; Chinese Academy of Sciences; Hefei 230031)
    Acta Metall Sin, 1996, 32 (6): 565-572. 
    Abstract   PDF (563KB) ( 628 )
    After coating the specimen with a thin Ti layer, the Snoek-Koster relaxation is systematically investigated without the effect of oxygen pick up. Two relatively stable internal friction peaks, SK1 at lower temperature and SK2 at higher temperature, are observed in deformed Ta-O samples. The changes of their peak shape and stability with annealing at different oxygen content are experimentally studied. The activation energies of SK1 and SK2 are measured to be 1 .4 and 2.1 eV respectively. It is suggested that the SK1 corresponds to the geometrical kink migration on screw dislocations and the SK2 corresponds to the formation and migration of kink-pairs on screw dislocations. From experimental results it is estimated that the energy of kink pair formation is about 0.9 eV and the binding energy of screw dislocation with oxygen atom is about 0.3 eV. It is additionally found that the height of the Snoek peak does not change after further deformation.
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    DETERMINATION OF DISLOCATION DENSITY AND ITS INFLUENTIAL FACTORS IN BAINITE DUCTILE IRON
    WEI Bingqing; LIANG Ji; GAO Zhidong; WU Dehai (Tsinghua University; Beijing 100084)
    Acta Metall Sin, 1996, 32 (6): 573-577. 
    Abstract   PDF (369KB) ( 707 )
    Dislocation densities in ductile iron under different processing conditions were determined exactly by X-ray diffraction method and a new profile analysis theory. The relations of dislocation density to chemical composition,austempering temperature, tempering treatment and deformation treatment were analysed. Experimental results indicated that the increase in dislocation density was accompanied by the fining of bainite grain.
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    CHANGES OF ATOMIC ORDER IN Cu-Al-Ni-Mn-Ti SHAPE MEMORY ALLOY DURING AGING
    WEI Zhongguo; YANG Dazhi (Dalian University of Technology; Dalian 116024)
    Acta Metall Sin, 1996, 32 (6): 578-584. 
    Abstract   PDF (459KB) ( 476 )
    The changes of atomic order state during aging of the parent phase and martensite in an as-quenched Cu-Al-Ni-Mn-Ti shape memory alloy were investigated by X-ray diffraction and in situ electrical resistivity measurements. It was shown that the aging mechanisms of the parent phase and martensite are different. During parent phase aging, DO_3 atomic reordering occurs, leading to an increase in the degree of long range order. During martensite aging, however, short range atomic disordering takes place, resulting in the stabilization of martensite.
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    ON THE PRECIPITATE IN Fe-28Al ALLOY
    ZHAO Zhongtao; LIU Tao; MA Ruzhang (University of Scicnce and Technology Beijing; Beijing 100083); MA Changying (Central Iron and Steel Research Institute; Ministry of Metallurgical Industry; Beijing 100081 )
    Acta Metall Sin, 1996, 32 (6): 585-588. 
    Abstract   PDF (270KB) ( 496 )
    The structure of the quenched Fe-28Al alloy was investigated by means of magnetic measurements, microstructure observation and X-ray diffraction. The results showed that the second phase could precipitate at grain boundaries of the alloy quenched from B2 region. It has been recognized to be Fe_3AlC_x (k-phase), the carbide of Fe and Al.
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    TEM STUDY OF PRECIPITATED PHASES IN P/M INCONEL 718 ALLOY UNDER LONG TIME EXPOSURE
    XIAO Sufen; CHEN Mengzhe; WANG Hing; DONG Jianxin; XIE Xishan (University of Science and Technology Beijing; Beijing 100083)
    Acta Metall Sin, 1996, 32 (6): 589-593. 
    Abstract   PDF (468KB) ( 588 )
    The precipitation and coarsening behaviours of γ", γ' and δ phases in powder manufactured modified 718 alloy with variation of chemical composition and heat treatment at 650 ℃ aging, up to 10000 h as well as 750℃, 1000 h, have been studied in comparison with that in conventional 718 alloy by TEM. Experimental results show that the precipitation behaviour of γ" and γ' phase in the modified alloy is different from that in conventional one. In the former, γ" and γ' phases precipitate in compact morphology and composite structure and in the later, γ" phase andγ' phase precipitate independently. The coarsening rate of γ" phase in the modified alloy at 650 ℃ aging is slower than that in conventional one. The structure of modified alloy is more stable than coventional alloy. Large plates of δ phase precipitate in γ' matrix of both alloys at 750℃, however the morphology and the amount of δ phases in two alloys are different.
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    A STRUCTURAL OBSERVATION ON IONIZED RE METALLIZING LAYER OF PURE IRON
    WU Yaqiao; YANG Lin; ZHAO Zhongjian; GAO Lifeng XU Yongbo; LU Zhenjia(Shenyang Polytechnic University; Shenyang 110023) (Laboratory; of Atomic Imaging of Solids; Institute of Metal Research; Chinese Academy; of Sciences; Shenyang 110015)(State Key Laborutory for Fatigue and Fracture of Materials; Institute of MetalResearch; Chinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1996, 32 (6): 594-598. 
    Abstract   PDF (413KB) ( 590 )
    Ce and La atoms were successfully metallized on pure iron by using glow discharge method. The structural observation of the surface layer showed that there are three kinds of layers below surface, i.e, solid solution, penetrating and transition. Analysis by EPMA and TEM shows that RE elements exist as intermetallic compound (Ce, La)Fe_7 and solute in α-Fe solid solution. The trace carbon atoms soluted in α-Fe may diffuse towards to the surface and segregate under surface layer of the specimen. Investigations by SAED and HRLM show that a preferred orientation relationship between α-Fe and (Ce,La)Fe7 is as follows: (011)α-Fe∥(110)CeFe7,[111] α-Fe∥[001]CeFe7.
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    MICROSTRUCTURE AND HARDNESS OF ADIABATIC SHEAR BANDS IN HIGH STRENGTH STEELS
    DONG Han; LI Guifen (Central Iron and Steel Research Institute; Ministry of Metallurgical Industry.;Beijing 100081)CHEN Nanping(Tsinghua University; Beijing 100084)
    Acta Metall Sin, 1996, 32 (6): 599-604. 
    Abstract   PDF (494KB) ( 636 )
    Microstructure survey and hardness measurement were performed on the adiabatic shear band presented in high strength steels. The effects of carbon equivalent and hardness of matrix on microstructure and hardness features of adiabatic shear band were investigated. It was shown by the results that adiabatic shear band is inclined to form in high hardness steels, but its hardness is not influenced by the hardness of matrix, only depends on carbon equivalent of the steels. The white-etched adiabatic shear band presented in the steel can be named as transformed band because of its hardness characteristics and undeformed feature of microstructure.
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    MECHANICAL PROPERTIES OF SHOT PEENED SURFACE FOR STEEL 60Mn
    GAI Hiuying; LI Jiabao; KANG Zengqiao; WANG Zhongguang (State Key Laboratory for Fatigue and Fracture of Materials;Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110015)ZHU Yongping; LI Chao (Shenyang Polytechnical University; Shenyang 110023)
    Acta Metall Sin, 1996, 32 (6): 605-610. 
    Abstract   PDF (402KB) ( 784 )
    The yield strengths of shot peened and unpeened surfaces of a quenched and low temperature tempered steel 60Mn have been detected by using the X-ray stress analyses and strain gauge methods. The results show that shot peening raised the surface yield stresses although it apparently decreases the half width value of X-ray diffraction profile. This discovery proves that the shot peened surface has been work hardened, rather than work softened. On the other hand, it implies that half width value could not correctly characterize the superficial mechanical features for some material states.
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    CRACK INITIATION OF A537 STEEL IN 3.5%NaCl SOLUTION DURING LOW CYCLE FATIGUE
    WANG Jianqiu; LI Jin; KE Wei(State Key Laboratory of Corrosion and Protection; Institute of Corrosion and Protection of Metals; Chinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1996, 32 (6): 611-616. 
    Abstract   PDF (499KB) ( 719 )
    The behaviour of crack initiation of A537 steel in 3.5%NaCl active system during low cyclic corrosion fatigue was studied by using three-electrode technique. Especially the effects of strain rate, strain amplitude and polarization were researched. The results showed that the crack initiation life decreased with the decrease in strain rate and the increase in strain amplitude. The anodic and high cathodic polarization decreased greatly the crack initiation life. The crack initiation life under the cathodic protection condition was nearly same as that in air. Crack foimed mainly in the soft ferritic phase, and then connected together through pearlite. The intensive anodic dissolution cleared the surface deformation morpohology. The cathodic hydrogen reduction induced the small crack formation at the deformed surface.
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    HYDROGEN-INDUCED FAILURE OF OIL-WELL TUBULAR STEEL C90
    YU Guanghua; CHENG Yihuan; CHEN Hongxing; NIU Xuejun; QIAO Lijie; CHU Wuyang (University of Science and Technology Beijing; Beijing 100083)(Baoshan Corporation of Iron and Steel; Shanghai 201900)
    Acta Metall Sin, 1996, 32 (6): 617-623. 
    Abstract   PDF (550KB) ( 776 )
    Hydrogen-induced failure properties of three oil-well tubular steels(C90, SM90 and SM95) have been compared. The threshold diffusible hydrogen contents of steel SM90, SM95 and C90 for hydogen blistering are 1 .76, 4.3, and 8.38×10-6, respectively, and the total hydrogen contents 4.24, 6.35 and 10.22 × 10-6 respectively. The threshold stresses of hydrogen-induced fracture corresponding to SM90, SM95 and C90 in NACE solution are σ_(th) /σ_s = 0.64, 0.80 and 0.85, respectively. The threshold stress intensity of hydrogen- induced fracture for C90 decreases with the increase in the diffusible hydrogen content w_o and the experimental result which is consistant with theoretical analysis is as follows: K_(IH) = 46- 1 2. 5lnw_0.
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    KINETICS OF HYDROGEN ABSORPTION IN ML-Ni-Co-Mn-Al ALLOYS
    LIN Qin; LI Rong; YE Wen; CHEN Hing (University of Science and Technology Beijing Beijing;Beijing 100083)LIU Renmin (General Research Institute of Non-Ferrous Metals Beijing; Beijing 100088)
    Acta Metall Sin, 1996, 32 (6): 624-628. 
    Abstract   PDF (344KB) ( 617 )
    Hydrogenation kinetics of ML-Ni-Co-Mn-Al and ML-Ni-Co-Mn-Al-Cu alloys in α+β phase region at the temperature range of 303-343 K has been studied.The kinetic mechanism of hydrogen absorption is not affected by initial hydrogen pressure.Temperature does not influnce the rate of hydrogen absooption obviously. In the prior and later period of hydrogen absorption the rate-controlling steps are the chemical reaction and the hydrogen diffusion in the hydride phase in ML-Ni-Co-Mn-Al alloy respectively. Adding Cu, the mechanism of hydrogen absorption changes from chemical reaction to the nucleation and growth of β-phase in the prior period, and the process of hydrogen absorption is still controlled by the diffusion in the later period.
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    KINETICS AND MATHEMATICAL MODEL FOR REDUCTION PROCESS OF IRON ORE BRIQUETTE CONTAINING CARBON
    HUANG Dianbing; YANG Xuemin; YANG Tianjun; KONG Lingtan (University of Science and Technology Beijing; Beijing 100083)
    Acta Metall Sin, 1996, 32 (6): 629-636. 
    Abstract   PDF (526KB) ( 689 )
    The reduction process of iron ore briquette containing C(ICB) was investigated under different conditions in nitrogen atmosphere. It was found that the reduction rate in the center part of ICB was faster than that in the rim. According to this phenomenon, it can be believed that the solid reaction of Fe_xOy+yC =xFe+yCO is not the main reduction process and the previous model described process could not explain the real process exactly. In this paper, a new opinion on the reduction process was put forward and a new mathematical model was established for ICB reduction process. It was proved by experiments that the new model fits the reduction process quite well.
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    EFFECT OF COMPOSITION OF B_2O_3-MgO-SiO_2-Al_2O_3-CaO SLAG SYSTEM ON PHYSICAL PROPERTIES OF MELT
    CUI Chuanmeng; XU Xiuguang; ZHANG Xianpeng; WANG Kuihan; HAN Weiru (Northeastern University; Shenyang 110006)
    Acta Metall Sin, 1996, 32 (6): 637-641. 
    Abstract   PDF (299KB) ( 615 )
    The viscosity and the transition temperature (when the viscosity of slag changes sharply) of melting boron-magnesium-rich slag system of B_2O_3-MgO-SiO_2-Al_2O_3-CaO, as well as the density and the surface tension, were measured by using the spin-cylinder and double-cylinder continuous methods respectively. The results showed that the viscosity and the transition temperature decrease with the increase in the content of B_2O_3 in slags, and increase with the increase in MgO and basicity in slags when B_2O_3 content is constant. The density and the surface tension of the melt increase with increasing MgO or decreasing SiO_2 in slags. The density changes in the range of (2.5 ± 0.5) t·m~(-3), while the surface tension is in 0.4-0.6 N . m~(-1) .
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    LEVITATION BEHAVIOUR OF METAL IN HORIZONTAL ELECTROMAGNETIC CONTINUOUS CASTING
    REN Zhongming; ZHOU Yueming; ZHANG Chunyuan; JIANG Guochang (Shanghai University; Shanghai Enhanced Laboratory of Ferroumetallurgy; Shanghai 200072)
    Acta Metall Sin, 1996, 32 (6): 642-646. 
    Abstract   PDF (316KB) ( 594 )
    The levitative and lateral forces of A.C. electromagnetic field on metal in horizontal electromagnetic continuous casting have been investigated experimentally. It is found that the levitative force increases significantly with the increase in electric current intensity and width of the screen. and reduces obviously with the electric resistance of the screen-metal sheet loop. The lateral force decreases sharply with increasing the distance from the side block .
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    NUCLEATION MECHANISM OF 8090 Al-Li ALLOY WELD METAL
    HAO Chuanyong; YU Erjing; YING Huiyun; SHI Chenggen (Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110015)
    Acta Metall Sin, 1996, 32 (6): 647-652. 
    Abstract   PDF (602KB) ( 735 )
    A kind of very fine equiaxed non- dendrite, besides the equiaxed dendrites and the columnar dendrites, exists in the 8090 aluminum-lithium alloy welds. The equiaxed non-dendrites are mainly distributed at the edge of the fusion zone; occasionally they can appear in the intermediate section of weld in the form of banding. The nuclei of equiaxed dendrites and columnar dendrites are the equilibrium tetragonal Al_3Zr particles, while the nuclei of equiaxed non -dendrite are demonstrated to be metastable cubic Al_3Zr particles.
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    APPLICATION OF H08Mn2SiA STEEL WELDING WIRE TO JOIN OF COPPER AND STEEL
    WANG Kehong; XU Yuelan; WANG Jianping; LI Hongmou (Nanjing University of Science and Technology; Nanjing 210094)
    Acta Metall Sin, 1996, 32 (6): 653-657. 
    Abstract   PDF (449KB) ( 686 )
    H08Mn2SiA welding wire was successfully used to joint pure Cu and low carbon steel. Energy dispersive X-ray analysis shows that there is a Fe containing transitional zone of which the width is about few hundreds micron. No thermal cracks and other defects were observed in seam and the tensile strength of seam reached 200 MPa.
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    NANOMETRE SIZED SiC PARTICULATES REINFORCED Al BASE COMPOSITE MATERIAL
    XIAO Yongliang; LI Yali; LIANG Yong; LU Ke; ZHOU Benlian (Institute of Metal Restearch; Chinese Academy of Sciences; Shenyang 110015) (State Key Laboratory of Rapid Solidificatin and Non-Equilibrium Alloys; Institute of Metal Research. Chinese A cademy of Sciences; Shenyang 110015)(International Centre of Materials Physics; Chinese Academy; of Sciences; Shenyang 110015)
    Acta Metall Sin, 1996, 32 (6): 658-662. 
    Abstract   PDF (411KB) ( 642 )
    An Al base composite material reinforced by nanometre sized SiC particulates has been prepared by using powder metallurgy technique. Its microstructure and properties were examined in comparison with similar composite reinforced by SiC particulates sized in micrometre. The composite material reinforced by the nanometre sized SiC particulates is more homogeneous and fine in microstructure and its hardness and electrical resistance are superior to the composite made of micrometre sized SiC to a great extent.
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    CHANGE OF TEXTURE IN A SiC_w/LD2 COMPOSITE DURING SUPERPLASTIC DEFORMATION
    GU Wanli; WANG Dezun; YAO Zhongkai (Harbin Institute of Technology; Harbin 150001)
    Acta Metall Sin, 1996, 32 (6): 663-668. 
    Abstract   PDF (390KB) ( 557 )
    SiC_2 / LD_2 compoiste has been fabricated by using squeeze casting method and then hot extruded at 743 K and the estruded ratio is 1:22. The superplastic tensile tests were carried out in the temperature range from 773 K to 853 K and in the strain rate range from 8.33×10~(-4) s~(-1) to 8.33×10~(-3)s~(-1) A maximum elongation of 280% occured at a strain rate of 2×10~(-3) s~(-1) at 843 K. The texture of the composite has been studied in two directions by means of anti-pole figure. The results manifest that the texture of metal matrix diffuses during the superplastic deformation and the new recrystallized texture emerges at the beginning of deformation. The recrystallized texture diffuses with the progress of elongation and is similar to the original texture. This is related to the confused rotation of grains. The whiskers will rotate by the means of θrotation
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    DETERMINATION OF ENTHALPY AND MASSIC HEAT CAPACITY OF SELF-BAKING CARBON BLOCK
    XUE Xiangxin; CHE Yinchang (Northeastern University; Shenyang 110006)DU Yingmin (Institute of Metal Research; Chinese Academy of Sciences; Shenyang 110015)HUANG Hiaoyu (Ironmaking Works; Anshan Iron and Steel Company; Anshan 114012)
    Acta Metall Sin, 1996, 32 (6): 669-672. 
    Abstract   PDF (238KB) ( 476 )
    Enthalpy change, △H, of partially graphitized self-baking carbon block with different graphitization degree has been determined by means of copper calorimeter in temperature range from 14 to 1000℃. It seems that the graphitization degree is not influential to △H of the carbon blocks in the range of the experimental temperature. The temperature dependence of the A△ is expressed as follows:△H=-33.31+1.11T+3.69×10~(-4)T~2+9.85×10~2Ta~(-1) By differential the temperature dependence of the massic heat capacity c_p is repesented as follows:c_P=1.11+7.38×10~(-4)-9.85×10~2T~(-2)
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