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

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    THE DESULFURIZATION AND MANGANESESULFUR EQUILIBRIA IN THE OPEN-HEARTH PROCESS
    CHOU YUAN-HSI;MENG SHIEN-TZE;PAN HONG-FANG;WANG WEI-JI Institute of Metallurgy and Ceramics; Academia Sinica
    Acta Metall Sin, 1957, 2 (4): 321-333. 
    Abstract   PDF (941KB) ( 609 )
    Based on a family of (S)/[S] basicity curves of Chipman et al., a new basicityexpression for basic open-hearth slags has been evaluated and correlated with thesulfur-distribution ratio. Another method is to plot the sulfur-oxygen ratio (S)/[S][O]against Σα=N_(SiO_2)+4/3 N_(P_2O_5)+4/3 N_(Al_2O_3), a parameter suggested by the authors onthe basis of the ionic constitution of slags to replace the mole per cent SiO_2 used byChipman et al. A modified Turkdogan's method is also used for correlating works'desulfurization data, in which the ratio (S)/[S] (Σ Fe), called the sulfur-iron ratio bythe present authors, is plotted against the paramters (%SiO_2)+0.563 (%P_2O_5)+ 0.784 (%Al_2O_3), (%SiO_2)+0.5 (%P_2O_5)+0.2 (%Al_2O_3), (%SiO_2)+0.5 (%P_2O_5), orsimply (%SiO_2). It is found that all the three methods can be used with reasonablesuccess, although the last method is probably the simplest for practical slag-controlpurpose. Of the four parameters used in the last method, the second appears to bethe best. The manganese-sulfur equilibrium has been treated in a similar manner by plot-ting the manganese-sulfur ratio ((βMnO)(S))/([Mn][S]) against Σα. The curve obtained is similarto the sulfur-oxygen ratio curve of Chipman et al. This similarity suggests that ourmethod of treatment is sound and that the ratio (αMnO)/[Mn] is a correct measure of thedegree of oxidation of the bath as far as desulfurization is concerned. The sulfur-oxygen ratio curve of Chipman et al. has been extended to the regionof acid slags by incorporation of and data. The shape of thiscurve in the basic range is briefly discussed from an ionic point of view. Withcertain assumptions, we have also been able to estimate the concentration of (O~=)in silica-saturated 'FeO'—SiO_2 slags from the extension of the curve of Chipman et al.
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    ON THE STICKING OF THIN STEEL SHEETS DURING PACK ROLLING
    CHANG TSO-MEI;LEE HUI-CHEN Institute of Metal Research; Academia Sinica
    Acta Metall Sin, 1957, 2 (4): 335-348. 
    Abstract   PDF (3763KB) ( 559 )
    Results of a comprehensive investigation on the sticking of thin steel sheetsduring pack rolling reveal that it is a very complicated problem, so that it is neces-sary to have a good control of the conditions of the materials under working aswell as the heating, tool surface and rolling conditions before sticking can be effec-tively reduced. Experimental results also point out that rolling temperature is one of the mainfactors affecting sticking, since sticking increases with the rise in rolling temperature.Increase in reduction also increases sticking; while a rise in rolling speed reducesit. The way in which rolled sheets are cooled has also considerable influence onsticking, so that it is best to cool the sheets down rapidly and it is undesirable topile up too many sheets together during cooling. The oxide film on the surface of sheets is also an importan factor affectingsticking. When there is no oxide film on the surface, the sheets stick togetherfirmly as a solid whole during pack rolling. Both heating and rolling change thedistribution of phosphorus in the sheet with a tendency to increase the phosphoruscontent on the surface, thus reducing the degree of sticking. The microstructure of the stuck surface has been examined and has been foundto show five different forms revealing the complicated nature of sticking.
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    THEORETICAL AND EXPERIMENTAL INVESTIGATION ON FRICTION-LINES OF ELLIPTIC PLATES IN PLASTIC COMPRESSION
    LIU SHU-I;WANG MING-TZONG Institute of Metallurgy and Ceramics; Academia Sinica
    Acta Metall Sin, 1957, 2 (4): 349-365. 
    Abstract   PDF (6424KB) ( 516 )
    This paper is one of the developments of our previous investigations (forexample,). In a recent paper a set of general plane differential equations forfriction-lines and for pressure contours were obtained as:θ=angle (x, second principal stress);τ=unit frictional force. As shown in the chinese text, these two equations and the general curvilineardifferential equation (C) for pressure distribution all hold for any case of plasticfriction: P=unit pressure; h=thickness of the plate; f_2(ε)=strain function (see[2]); K=uniaxial yielding point; s=arc length of the complete friction-line.For the case of elliptical plates a set of solutions were obtained as shown in Fig1 of the chinese text, by taking θ as defined by the tangents of concentric ellipses.In this paper, we show that a second set of solutions can be deduced by taking θas defined by regular elliptic coordinates. As shown in Fig. 2 and Fig. 3, the new solutions for friction-lines and pressure contours are radii and circles, the pressuredistribution has a finite peak at the center. To check the validity of these theoretical results, experimental determinationof friction-lines was made for lubricated plates of lead and plastic mass by photo-graphic and isoclinic methods. The methods are obvious in the Fig. 4 to 17, andneed not be elabourated here. As Liu Shu-i has pointed out in a paper to be published soon, the surfacestream-lines and the instantaneous friction-lines are two different families of curvesobeying different laws-the rule of gradient for instantaneous friction-lines andLiu's rule of isoclinic gradient for stream-lines called long-rang friction-lines. Fig. 9 to 11 are surface stream-lines from which the instantaneous friction-lines were deduced by isoclinic method as shown in Fig. 12 to 17. Each figure forfriction-lines consists of two families: the isoclinics and the friction-lines (witharrows). Fig. 18 provides an indication of a no-slip point at the center of the plate. It appears that the theoretical solution of the last paper yields friction-lineswith curvatures greater than the experimental curves and the solution given in thispaper is close to the experimental curves only for ellipses with axial ratio not too farfrom unity. However, the solution of last paper mathematically holds, if the axialratio is replaced by an arbitrary constant. This will allow us to interpret moreexperimental facts on the basis of that solution. The case of bipolar plate is under investigation, we have obtained the dif-ferential equation for friction-lines as equation (D), its solution will be published inanother paper.tanφ={(y/x)([(a~2+y~2-x~2)~2-4x~2y~2](a~2+y~2+x~2)-4x~2(a~2+y~2-x~2)(a~2-y~2-x~2))/(4y~2(a~2+y~2-x~2)(a~2+y~2+x~2)+[(a~2+y~2-x~2)-4x~2y~2](a~2-y~2-x~2)); (y/x)(a~2+y~2+x~2)/(a~2-y~2-x~2); when(a~2+y~2-x~2)>0. when(a~2+y~2-x~2)=0. (y/x)([(a~2+y~2-x~2)-4x~2y~2](a~2+y~2+x~2)+4x~2(a~2+y~2-x~2)(a~2-y~2-x~2))/(-4y~2(a~2+y~2-x~2)(a~2+y~2+x~2)+[(a~2+y~2-x~2)~2-4x~2y~2](a~2-y~2-x~2));}(D) when(a~2+y~2-x~2)<0.α=constant in the equation of bipolar coordinates.
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    PROCESS OF CARBIDE PORMATION DURING AUSTENITEPEARLITE TRANSFORMATION IN CHROMIUM STEELS
    CHANG PEI-LIN;LIANG TZE-TEH Institute of Metal Research; Academia Sinica North-East Engineering College
    Acta Metall Sin, 1957, 2 (4): 367-375. 
    Abstract   PDF (739KB) ( 444 )
    The process of carbide formation during isothermal decomposition of austeniteinto pearlite in four chromium steels has been investigated by X-ray method. Theexperimental results are analysed and compared with results obtained by otherauthors on chromium steels of various compositions, and unified conclusions aredrawn. 1) Depending upon the composition of steels, the initial carbide formed duringisothermal formation of pearlite may be cementite, (Cr, Fe)_7C_3 or (Cr, Fe)_(23)C_6.That is, special carbides can be formed directly from austenite, and they are notalways products of secondary process as some authors believe. 2) Type of carbides to be formed directly from austenite is not determined bythe requirements of equilibrium diagram, but depends upon Cr: C ratio in austenite.When the atom ratio Cr: C is smaller than 2, the initial carbide is cementite; whenthe ratio lies between 2 and 13, the initial carbide is (Cr, Fe)_7C_3; when the ratiois larger than 13, it is (Cr, Fe)_(23)C_6. It seems that the Cr:C ratio in austenite hasdecided influence on the kinetics of nucleation of different carbides. 3) When the type of carbides formed directly from austenite is not that re-quired by the equilibrium diagram, carbide transformation takes place as a secondaryprocess. 4) When the directly formed carbide is an alloy carbide, i. e. (Cr, Fe)_7C_3 or(Cr, Fe)_23C_6, diffusion of chromium in austenite immediately in front of the growingnodules of pearlite is a necessary process during transformation.
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    THE DECOMPOSITION OF δ-FERRITE IN A 18/8 STAINLESS STEEL CONTAINING 0.34% Ti AND 0.24% Mo
    CHUANG YU-CHIH;LI YOU-KO;CHANG YENG-LIN Institute of Metal Research; Academia Sinica
    Acta Metall Sin, 1957, 2 (4): 377-385. 
    Abstract   PDF (2752KB) ( 644 )
    The decomposition of δ-ferrite between 550°—900℃ in quenched 18/8 stainlesssteel specimens containing 0.34% Ti and 0.24% Mo has been studied microsco-pically. The mechanism of decomposition of δ-ferrite was found to be dependenton the reheating temperature. No sigma phase was found on prolonged heating inthe temperature range studied. Above 750℃, accicular austenite forms first, followedby general precipitation of TiC in the untransformed ferrite. Below 650℃, the se-quence of precipitation in ferrite is reversed, carbide precipitation precedes the for-mation of austenite. Between 650°—750℃, δ-ferrite decomposes into carbide andaustenite in an eutectoid manner. The eutectoid decomposition does not carry to itscompletion; part of the remaining ferrite then transforms into austenite which soonalso stops on account of the enrichment of δ-forming elements in the remainingferrite. Upheaved martensite plates were found in the electrolytically polished surface ofspecimens containing undissolved carbide and also in specimens in which the decompo-sition of ferrite has started when prepared in the same way. However, when allcarbide is dissolved, no martensite is found in the surface of the specimens whetherit is prepared electrolytically or mechanically. It is believed that the formation ofmartensite in this particular steel is a surface effect associated with electrolytic poli-shing, but its formation is also closely related to the carbon content of the auste-nitic matrix.
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