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

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    , Volume 13 Issue 4 Previous Issue    Next Issue
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    THE DISTRIBUTION OF BORON IN STEEL
    Ho Hsin-lai;Chu Yu-yi;Chang Hsiu-lin;Yu Tsung-sen;Li Chiu-ping (student);Yin Hsi-kuang (student) Peking Institute of Iron and Steel Technology
    Acta Metall Sin, 1977, 13 (4): 235-356. 
    Abstract   PDF (16575KB) ( 551 )
    The distribution of boron and its effect on the hardenability of a 25Mn-TiBR steel have been investigated by means of modified particle-tracking auto-radiography. The results indicate that boron exists in the forms of equilibrium andnon-equilibrium segregation along grain boundaries. The equilibrium segrega-tion of boron disappeared during high temperature austenization. The non-equi-librium segregation along grain boundaries of a quenched boron steel occurredduring cooling by diffusion from their neighbouring regions. The degree of segre-gation increased and a boron depleted-zone appeared next to the boundaries asthe austenizing temperature was raised. The effect of rare earth additives on the distribution of boron in 25MnTiBRsteel has also been investigated. It was found that within a certain temperaturerange the segregation of boron to austenite grain boundaries was hindered bythe addition of 0.4% mischmetal. This was possibly caused by an equilibriumsegregation of rare earth elements along the austenite grain boundaries. It hasbeen confirmed that the simultaneous addition of boron and rare earth mischme-tal further increases the hardenability of the steel. Suggestions have been maderelating to the possible mechanism of this effect.
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    EFFECT OF RARE EARTH ADDITIVES ON THE QUALITY OF Fe-Cr-Al ELECTRIC HETING ALLOY
    Luo Chi-hsun;Yin Yao-teh;Lin Sheng-kun;Chao Chi;Wang Chien
    Acta Metall Sin, 1977, 13 (4): 263-359. 
    Abstract   PDF (3701KB) ( 682 )
    To ascertain the effect of rare earth additives on the quality of Fe-Cr-Alelectric heating alloy, the rapid heating life test and oxidation kinetics studyof three specimens: (A)-plain alloy, (B)-added 0.038% La-Ce mixture, and (C)-added 0.49% Y, have been examined. The observations of morphology andadhesivity of the oxidized layer reveal that in the interior of specimen C afterexposed for 350 hours under 1200℃, a new phase which has been identified asyttrium-aluminium-garnet (Y_3Al_5O_(12)) was present. This might have a direct in-fluence upon the adhesivity of the surface oxidized layer. In the case of the plain alloy, exposure at high temperatures gave rise tograin growth with rapid deterioration in the mechanical properties of the speci-men. The addition of rare earth, especially of yttrium, was found to be effec-tive in preventing crystal growth and therefore exerted correspondingly goodinfluence upon the mechanical properties of the specimen at high temperatures.Such may be the reason why the rapid heating life of alloys with the additionof rare earth is longer than without.
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    THERMODYNAMICAL THEORY OF IRREVERSIBLE PROCESSES FOR ELASTO-PLASTIC METAL-DISLOCATION SYSTEM AND STRESS-ACTIVATED MOTION OF DISLOCATIONS
    Liu Shu-I University of Science and Technology of China
    Acta Metall Sin, 1977, 13 (4): 273-281. 
    Abstract   PDF (539KB) ( 715 )
    Thermodynamical functions of metal-dislocation system are defined in phy-sico-chemical space of states by taking P=(1/3)σ_(kk) in connection with plastic in-compressibility. Irreversible shear deformation of this system is treated by the-rmodynamical laws of irreversible processes. In a way equivalent to the introduction of entropy production from theclassical second law for irreversible processes, the free energy change ΔZ_(T.P) isexpressed in terms of dissipations Δ' and Δ_Z, ΔZ_(T.P)= -A'_(iR)-Δ_Z when distor-sion work A'_(iR) is done by the system, and ΔZ_(T.R)= A'_(iR)-Δ', when work is doneto the system by applied deviational stress field, S_(jk). In a way parallel to the derivation of Nernst equation for reversible cells,the above ΔZ_(T.P) expressions, together with reaction isotherm, ΔZ_(T.P)=ΔZ_0~≠+kTln (γ~≠x~≠/γx), give the concentration x~≠ of activated dislocations, and simple kin-etic arguments lead to the rate of movement v, of dislocations under applieddeviational stress field S_(jk):wherein Δ' and Δz are taken to be equal for the case of symmetrical barrier,Δ'=Δ_z=Δ~≠ which is the monotonous internal friction of irreversible stress acti-vation; Δe_(mn)~≠ is the deviational increment of activation, and v_0, the volume ofeach dislocation. Other results are given in the Chinese text.
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    AN INVESTIGATON OF THE SUBSTITUTED AMIDETYPE A-101 EXTRACTANT AND ITS APPLICATIONS
    Res. GP. of Solvent Extraction; Changsha Institute of Mining and Metallurgy Research
    Acta Metall Sin, 1977, 13 (4): 282-288. 
    Abstract   PDF (473KB) ( 440 )
    Under the guidance of the principle of independence and self-reliance, thesubstituted amide-type A-101 extractant has been successfully synthesized. Thistype extractant showed easy synthesis, better physico-chemical properties andhigher selectivity. Dialkylacetamide is one of weakly basic extractant with car-bonyl as functional group. Examples are given in which A-101 type extractanthas been used to extract and separate rare metals from ore concentrates, e.g.niobium-tantalum separation, thallium extraction, molybdenum-rhenium separa-tion, gallium extraction etc., in every case satisfactory results on industrial scalehave been obtained.
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    AN INVESTICATION OF A MARAGING STEEL WITH LOWER Ni AND Co CONTENTS
    Tsai Chi-kung;Chu Ching;Ho Chung-chih;Shen Hui-wang;Luo Li-keng;Sung Wei-shun;Yu Wei-le Peking Institute of Iron and Steel Research
    Acta Metall Sin, 1977, 13 (4): 289-365. 
    Abstract   PDF (3584KB) ( 651 )
    It is shown that Cr and Mn bearing 12Ni maraging steels with lower Niand Co contents are of high strength and toughness, Precipitates after aging,dislocation configurations and easy cross-slip behavior of dislocations have beenexamined. The results are discussed on the assumption that the hexagonal close-packed phases were precipitated along the stacking fault zone of the dislocationlines. In order to predict the stability and solubility of high-temperature austenitein maraging steels, a criterion has been suggested from the point of view ofaverage electron concentration per atom of the alloy. The criterion is helpful forrational alloying of maraging steels with lower Ni and Co contents.
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    THE STRESS INTESITY FACTORS OF A SINGLEEDGE CRACKED BAR LOADED BY IN-PLANE TRANSVERSE FORCES
    Pan Hao
    Acta Metall Sin, 1977, 13 (4): 301-307. 
    Abstract   PDF (416KB) ( 600 )
    The stress intensity factors of a single-edge cracked bar loaded by in-planetransverse forces are calculated with the application of the principle of superposition, and St. Venant's Principle. Simple formulae for K_Ⅰ and K_Ⅱ are derivedand the appropriate conditions under which these formulae are applicable havebeen discussed.
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    THE GENERAL TREATMENT OF DIFFRACTION GEOMETRY OF AMPLITUDE-MODULATED STRUCTURE
    Li Po-tsang Peking Institute of Metallurgical Research
    Acta Metall Sin, 1977, 13 (4): 308-315. 
    Abstract   PDF (578KB) ( 597 )
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    A SUPERSONIC FLAME CUTTING TORCH
    Precision Cutting Group of Great Wall Industrial Company
    Acta Metall Sin, 1977, 13 (4): 316-369. 
    Abstract   PDF (2213KB) ( 509 )
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    METALLURGICAL AND TECHNOLOGICAL FEATURES OF RARE EARTH-MAGNESIUM NODULAR CAST IRON AND ITS APPLICATIONS IN CHINA
    Luo Kan
    Acta Metall Sin, 1977, 13 (4): 320-372. 
    Abstract   PDF (2802KB) ( 572 )
    A description is given of the metallurgical and technological features of ahigh quality nodular cast iron using rare earth-magnesium master alloy as itscomposited graphite spheroidizer. Special attention is given on the mechanical pro-perties of three varieties of this new material. Owing to its certain distinguish-ing properties, this nodular cast iron has found a wide-spread application inChina.
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    Discussion on "Improvement of Certain Properties of Alloy Fe-16% Al"
    No Author
    Acta Metall Sin, 1977, 13 (4): 335-335. 
    Abstract   PDF (78KB) ( 509 )
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    ACTA METALLURGICA SINICA Volume 13 1977 CONTENTS
    No Author
    Acta Metall Sin, 1977, 13 (4): 374-383. 
    Abstract   PDF (572KB) ( 382 )
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