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

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    AN INVESTIGATION ON STRATIFIED INCLUSIONS IN MILD STEEL PLATES
    LEE HSUN;CHEN CHI-TSE;LEE CHE-POW;YAN SHO AND HAN YAO-WEN Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 301-415. 
    Abstract   PDF (3676KB) ( 596 )
    Certain defects associated with the presence of stratified inclusions in mildsteel plates of medium thickness manufactured by Anshan steel works were inves-tigated.It has been found that the nature and the appearance of such inclusionscan be classified into three different types in accordance with the different positionsof the rimming ingots from which the plates were being made.The origin of thedifferent types of inclusions has been discussed in the light of the works data andcertain suggestions have been put forward with a view to minimizing the occurren-ce of such inclusions.
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    ON THE SHORTENING OF REDUCING PERIOD IN THE ELECTRIC FURNACE SMELTING
    FANG BING;SUENG I-KWANG;HOO CHWANG-CHI;HO CHEIN-CHU;LIU CHENG-CHI;WANG CHING-TANG AND HSING CHUNG-SHU Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 311-324. 
    Abstract   PDF (959KB) ( 497 )
    Experiments were carried out with the purpose of shortening the reducingperiod in small basic electric furnace for carbon steels of various carbon content.In some of the experimental heats reducing period was shortened by 20 mi-nutes and the others were made according to the normal procedure of the works.For some of the low carbon steel heats,the amount of ferro-silicon powder wasincreased by 20% and added in advance.The results,obtained from heats of shorterreducing period,show that the deoxidation and desulphurization appear to be ascomplete as that of a normal heat,the content of nitrogen and non-metallic in-clusions being much less.In addition,the results on mechanical properties showthat in the case of medium carbon steel,the impact value is higher,and in thecase of low carbon steel the percentage of elongation and the rate of reductionof area are also slightly superior although the yield strength becomes somewhatlower.Such a shortening of reducing period also results in a 7% increase ofthe rate of production.It is suggested that in electric steel smelting process theappropriate deoxidation procedure and the length of reducing period should varyin accordance with different carbon content of the steel.A relationship of[S]/[O]=1.2—2.2 at the end of reducing period was ob-served,and the possibility of further shortening of the reducing period in makingmedium and high carbon steel was also pointed out.
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    AN INVESTIGATION OF CHEMICAL EQUILIBRIA IN THE BLAST-FURNACE HEARTH Ⅰ.THE MANGANESE-SULFUR EQUILIBRIUM
    CHOU YUAN-HSI Institute of Metallurgy and Ceramics;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 325-335. 
    Abstract   PDF (835KB) ( 529 )
    This paper presents an analysis of slag-metal data of 122 tests collected fromthree blast-furnace plants in China by plotting[Mn][S]against(MnO)(S).Itis shown that the manganese-sulfur equilibrium is approached in the blast-furnacehearth in agreement with the conclusions of some recent publications.The threesets of data may be represented by straight lines of different slopes obtained bythe least square method.The manganese-sulfur equilibrium constant is shown to be related to theactivities of CaO,MnO and CaS.By using the activity values derived previouslyby the author,some preliminary results have been obtained concerning the effectof basicity and(S)on the manganese-sulfur equilibrium.The temperature-depen-dence of the manganese-sulfur equilibrium constant has been recalculated fromFiler and Darken's data on the distribution of manganese and sulfur betweenblast-furnace metal and slags.The blast-furnace practice of the three different plants is discussed in the lightof the present calculations.
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    THE DECOMPOSITION OF δ-FERRITE IN A Cr-Ni-Mo-Ti STAINLESS STEEL
    CHUANG YU-CHIH AND LIU CHIA-LO Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 337-421. 
    Abstract   PDF (6166KB) ( 589 )
    The decomposition of δ-ferrite at 750°,850° and 950℃ in quenched 18/8/3/1Cr-Ni-Mo-Ti stainless steel specimens has been studied microscopically,thetransformation products being electrolytically extracted and identified by X-raydiffraction method.At early stages of decomposition accicular austenite forms along certaincrystallographic planes of δ-ferrite.As a result,the remaining ferrite becomesenriched in Cr,Mo and impoverished in C,Ni,Mn,and was found to transformsubsequently to sigma which begins after heating for 5-6 minutes at 850℃.Precipitation of titanium carbide first occurs in the ferrite grains,later itmakes appearance along the ferrite-austenite interphase boundaries and along thetwinning planes within the austenite grain.The precipitation of titanium carbideseems to have no appreciable effect on the sequence of decomposition of δ-ferrite.The impact value of the steel was found to decrease very markedly before thecommencement of the δ→σ transformation and it is considered that this mightbe associated with the titanium carbide precipitation.
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    NATURE OF ISOTHERMAL TRANSFORMATION BETWEEN ROOM TEMPERATURE AND MARTENSITE POINT IN A BALL-BEARING STEEL
    CHANG PEI-LIN AND HSU TSUI-CHANG Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 347-366. 
    Abstract   PDF (1909KB) ( 513 )
    The isothermal transformation of austenite in a ball-bearing steel within thetemperature range between martensite point M and room temperature has been investigated by electrical resistance measurements.The steel employed was ofcommercial production containing 1.43% Cr and 1.02% C and its martensite pointis 159℃ when quenched from 1100℃.The specimen was first quenched toroom temperature(in which state it contained 17% retained austenite),and thenupquenched to isothermal bath in which its transformation was followed.Theeffect of tempering of martensite was eliminated by employing two specimens ofdifferent martensite contents.1)By comparing the kinetics of isothermal transformation below and abovemartensite point,it was concluded that isothermal transformation below M pointtakes place by the martensite process and not by intermediate transformation(bainitic),in.spite of the presence of large amount of martensite and relativelyhigh temperature at which the transformation takes place.2)From kinetics considerations it appears that isothermal transformationof retained austenite to martensite takes place not by the formation of new nuc-lei but mainly by the growth of already existing martensite.This would alsoinfer that coherency between martensite and austenite is not destroyed(or notcompletely destroyed)during quenching transformation.3)The tempering of martensite appears to be the controlling process forthe isothermal transformation of retained austenite to martensite,such that theelastic strain energy relaxed by tempering of martensite exceeds the difference offree energies between the two phases.The activation energy of tempering ofmartensite within the temperature range considered(below 150℃)was found tobe 13,300 cal/mol,which compares favourably well with the value of 16,000 cal/molas given by Averbach and Cohen in 1953.4)The results show that isothermal keeping for prolonged duration at theneighbourhood of 100℃ brings about maximum amount of transformation of re-tained austenite.That is,at either higher or lower temperatures and for a speci-fied time,the amount of austenite-martensite transformation is less.This is signifi-cant for practical heat-treating of precision gauges and tools for which dimen-sional stability is important and high temperature tempering may not be de-sirable for hardness consideration.
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    ВЛИЯНИЕ ВАНАДИЯ НА СВОЙСТВА КРЕМНЕМАРΓАНЦОВИСТОЙ СТАЛН
    МА Жу-чжАн Пекцнскцǚ цнсмцмум черноǚ мемаддур(?)цц
    Acta Metall Sin, 1956, 1 (4): 367-382. 
    Abstract   PDF (1156KB) ( 479 )
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    KINETICS OF DECOMPOSITION OF RETAINED AUSTENITE DURING TEMPERING IN SOME HIGH STRENGTH STEELS
    SHIH CHANG-HSU Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 383-393. 
    Abstract   PDF (715KB) ( 490 )
    The kinetics of decomposition of retained austenite in AISI 4325,AISI 4340and their silicon modified steels has been studied by precision length measurement.It is found that the internal stresses play a very important role in the first instantof transformation.In steels with normal silicon content(0.2—0.3%),the activation energy of thedecomposition of retained austenite is about 35,000 cal/mole,comparable to thatrequired for the diffusion of carbon in γ-Fe.In general,high silicon content(1.5% Si)retards the transformation of retain-ed austenite in these steels.Based upon the isothermal transformation curvesand rate equation the activation energy for this transformation has been deter-mined to be about 44,000 cal/mole,and it is therefore suggested that the diffusionof silicon in γ-Fe surrounding the growing carbide particles is possibly the ratecontrolling factor.
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    THE EFFECT OF FURNACE ATMOSPHERE DUE TO COMBUSTION UPON HYDROGEN CONTENT IN LIQUID STEEL
    LEE HSUN AND YANG WEI-SHEN Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 395-400. 
    Abstract   PDF (416KB) ( 476 )
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    DETERMINATION OF MULLITE IN CLAY REFRACTORY PRODUCTS
    YEH FU-HAN Institute of Metal Research;Academia Sinica
    Acta Metall Sin, 1956, 1 (4): 401-405. 
    Abstract   PDF (417KB) ( 517 )
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