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

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    ON THE IMPROVEMENT OF THE QUALITY OF BALL-BEARING STEEL L THE EFFECT OF SMELTING AND CASTING PRACTICE ON NON-METALLIC INCLUSIONS IN BALL-BEARING STEEL
    SIH TSON-YOW;HSING CHUNG-SHU;CHENG SHU-TANG;LEE CHIN-YUAN;CHANG WEN-PO;LI HER-SHENG Institute of Metal Research; Academia Sinica
    Acta Metall Sin, 1959, 4 (3): 177-194. 
    Abstract   PDF (3700KB) ( 637 )
    The present paper is the first part of a study on the improvement of the quality of ball-bearing steel made in basic electric furnace. The effect of deoxidation and casting practice onnon-metallic inclusions in steel during the steel-making process was studied. It was found that the non-metallic inclusions in ball-bearing steel could be markedly reducedwith the adoption of the following practice: On slagging off before the reducing period, silico-manganese was added for preliminary deoxidation; addition of crushed calcium carbide was thenmade to speed up the formation of carbide slag, which should be kept not less than 40 minutes;after this, ferro-silicon powders or crushed calcium carbide were added for slag deoxidation; slagmust be white before tapping; it is advisable to tap the slag first and then the liquid steel torender them thoroughly mixed in the ladle to facilitate further elimination of non-metallic in-clusions in steel; final addition was carried out by adding not less than 1/2 kilogram of aluminiumper ton of steel. Good-quality ladle linning and runners should be tar-soaked in order to decrease the amountof exogenous inclusions. It was noticed that titanium nitride inclusions in the steel were due tothe presence of titanium in ferro-alloys, the making of high-quality ball-bearing steel calls forthe use of titanium-free ferro-alloys.
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    THE EFFECT OF THE THICKNESS AND THE THERMAL CONDUCTIVITIES OF THE REFRACTORY LININGS IN THE BLAST FURNACE BOTTOM ON THE TEMPERATURE FIELD OF THE BOTTOM
    WAN SHU-MING Institute of Chemical Metallurgy; Academia Sinica
    Acta Metall Sin, 1959, 4 (3): 195-205. 
    Abstract   PDF (888KB) ( 512 )
    The effect of the thickness and thermal conductivities of the bottom linings, cooling condi-tions and hearth temperature on the temperature field of the bottom had been studied by FiniteHankel Transform, and the results were shown by Curves. It is pointed out that in a bottomwith multiple lining layers, the lower the thermal conductivity of the most inner lining andthe higher the thermal conductivity of the more outer lining, the sharper the temperature gradientof the bottom and the smaller the heat loss. Cooling conditions and hearth temperature havegreat effect on the temperature field in the bottom. The author pointed out that the dependence of the position of 1150℃ on the inner andouter diameter of the hearth and the thickness of its lining layers should be investigated furtherthe effect of the depth of the salamander on the temperature field, especially on the position of1150℃ and the temperature of the top of the foundation, should also be studied further. The author presumes that when the lining material with higher thermal conductivity is usedas the most inner lining layer, it may have a "critical thickness". Under this thickness, it obeysthe principle that the lower the thermal conductivity of the most inner lining layer, the sharperthe temperature gradient; above this critical thickness, it is just opposite to the former case. In a bottom with multiple lining layers, the lower layer with higher thermal conductivitythan the upper one displays a "transitional" cooling effect, for which the layer has an effectivethickness. This thickness may be a decreasing function of the ratio of the thermal conductivityof the lower layer to that of the upper layer.
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    SOME PROBLEMS OF THE HEAT FLOW THROUGH THE BLAST FURNACE HEARTH WITH CARBON LINING
    WAN SHU-MING Institute of Chemical Metallurgy; Academia Sinica
    Acta Metall Sin, 1959, 4 (3): 206-216. 
    Abstract   PDF (1174KB) ( 413 )
    The effect of the thermal conductivities, proportion and distribution of some refractory liningmaterials in the hearth, cooling and salamander on the temperature distribution and heat loss hasbeen reviewed critically. The temperatures of the bottom with all ceramic lining can be decreasedby substituting carbon lining from its periphery, and the carbon lining displays a "transitional"cooling effect. It is justly the advantage of the high thermal conductivity of the carbon lining.Furthermore this effect has a certain effective limit. It is pointed out that the more the tem-perature of the bottom to be decreased, the lower the thermal conductivity of the most innerlining material and the higher the thermal conductivity of the more outer lining layer. This isa very important principle in this problem. By this principle, we can see that the transitionalcooling effect of the carbon lining can appear only when it is not used as the most inner lining.By the same reason, it is obvious that the layer with higher thermal conductivity, like graphitelayer, under the bottom behaves as a underhearth cooling. It is suggested that the new approach to decrease the heat loss is using the material as themost inner lining with its thermal conductivity as small as possible. A new cooling method,called cascade cooling, was described; it is using several lining layers under the bottom, of whichthe inner one has higher thermal conductivity than the outer one. It is pointed out that in theexisting thermal model for the hearth the salamander formed actually was not taken into account,thus it is very inadequate to describe the actual state of the hearth. This is a great defect of theexisting thermal model experiment. Its improvement was described. It is proposed that the de-pendence of the heat flow on the inner and outer diameter of the hearth and the thickness ofits various linings should be studied; that the effect of the thermal conductivity of lining on theheat flow and the graphitizing of the carbon lining ought to investigate further.
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    A RESEARCH ON THE CHANGE OF MECHANICAL PROPERTIES IN THE ROLLING OF HEAVY RAILS
    CHANG TSO-MEI;GAU TZE-MING;LEI MING-FOO Institute of Mechanical Engineering; Academia Sinica
    Acta Metall Sin, 1959, 4 (3): 222-234. 
    Abstract   PDF (1813KB) ( 426 )
    The effects of roll pass design on the mechanical properties of rails and the changes inmechanical properties in the processes of rolling and the causes for these changes have beeninvestigated. The height and the angle of the wedge in the trapezoidal passes have also been stu-died. The results show that in the trapezoidal passes a change in the height and the angle of thecutting-in wedge has little effect on the mechanical properties at the foot of the rails; hence itis better to use wedges with a smaller height and a greater angle. It is found that the effect ofinhomogeneous deformation on mechanical properties is also small; hence the question of using2 or 4 trapezoidal passes may be settled by consideration of the mill construction and the condi-tions of production only. The mechanical properties of the bloom undergo considerable changes when it is rolledthrough the successive passes. After the second or the third pass, a lowering in mechanical pro-perties has been recorded; but after the sixth pass the changes in mechanical properties becomesmall. When the rate of cooling is great, the temperature of rolling has little effect on themechanical properties; hence, it is possible under this condition to increase the temperature ofrolling, the amount of reduction and the speed of rolling in order to achieve a reduction in thenumber of passes used.
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    ВЛИЯНИЕ НАКЛЕПА НА ЖАРОПОЧНОСТЬ ЖАРОПРОЧНЫХ АУСТЕНИТНЫХ СТАЛЕЙ
    Чжу Жи-чжан;М. Л. Бернштейн
    Acta Metall Sin, 1959, 4 (3): 235-244. 
    Abstract   PDF (2468KB) ( 442 )
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    SOME STRUCTURAL CHANGES IN THE TEXTURE OF THE COLD-DRAWN COPPER WIRE
    YANG SIEN-MIN;YANG BING-CHI;CHENG KUAN-HSI;LUI CHENG-HWAN;Koo CHUAN-PAN Institute of Mechanical Engincering; Academia Sinica
    Acta Metall Sin, 1959, 4 (3): 245-254. 
    Abstract   PDF (3429KB) ( 532 )
    Diffraction patterns of W radiation of the cold-drawn copper wire are investigated. Theexpansion of interplanar spacing, the half-peak width of spot, the ratio of peak values of densityof spots corresponding to (111) and (100) fibre axes etc. are correlated to the amount of reduc-tion of cross-sectional areas. The difference of yield-strengths of wires of same total percentageof reduction of area and different number of drawings may be accounted for by the structuralchanges as shown by the difference in the textures. By the graph plotted, it is shown that the distribution of densities of spots correspondingto (111) and (100) fibre axes approximately follows the distribution law of Boltzmann type;i.e. f(hkl) ∝ e~(-KE)(hkl), and E_(hkl) ∝ △A/A (the fraction of the reduction of the cross-sectional area of wire).
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    МЕТОД ТОРЦОВОЙ ЗАКАЛКИ ДЛЯ ОПРЕДЕЛЕНИЯ ПРОКАЛИВАЕМОСТИ И МЕХАНИЧЕСКОГО СВОЙСТВА
    Фан Чжи-чжун Цeнmральная завобская лабораmорuя мащuносмроumельно?о завоба Чзн-Гуань
    Acta Metall Sin, 1959, 4 (3): 255-261. 
    Abstract   PDF (562KB) ( 471 )
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    THE TEMPER-BRITTLENESS OF BAINITIC STEELS
    TAN YU-HUA Anshan Institute of Iron and Steel Technology
    Acta Metall Sin, 1959, 4 (3): 262-269. 
    Abstract   PDF (715KB) ( 429 )
    A study of the occurrence of temper-brittleness in bainitic structure has been made. It wasfound that the tendency of temper-embrittlement in the lower bainite was slightly less than thatin the tempered martensite whik the temper-embrittlement in the upper bainite was slightly greaterthan that in pearlitic structure, and the tendency of temper embrittlement of the temperedmartensite was much greater than that of the pearlite. The temperature range of temper-brittleness was 460—580℃ for upper bainite, 430—620℃ for tempered martensite, and the tem-perature of maximum temper-embrittlement appeared to be about 530℃ for both. It was sug-gested that the mechanism of temper-brittleness is the same for both structures.
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    DESULFURIZATION OF CAST IRON BY ELECTROLYZING SLAG
    Northeast Institute of Technology; The Institute of Foundry Practice
    Acta Metall Sin, 1959, 4 (3): 270-281. 
    Abstract   PDF (1220KB) ( 440 )
    In the present communication, a method for desulfurizing cast iron by electrolyzing slag wasdescribed. Experimental results obtained with this method warranted the following conclusions: (1) Among the various methods used for desulfurization of cast iron, the method describedin the present communication is the most effective and cheap one, especially for cast iron withsulfur content higher than one percent. (2) The percentage of sulfur reduction increases with the basicity (CaO/SiO_2) of the slag.For example, for slag with basicity of 0.5, the percentage of sulfur reduction is 72; while for slagwith basicity of 1.4, the percentage of sulfur reduction is 97.5. (3) The initial sulfur and carbon content of cast iron has an obvious effect on the processof desulfurization. As the sulfur and carbon content increases, the process of desulfurization pro-ceeds more completely. (4) There is a critical current density of the cathode (molten cast iron). At the criticalpoint, the percentage of sulfur reduction is the highest. As the current density exceeds the criticalvalue, the percentage of desulfurization decreases. (5) The percentage of desulfurization increases with the voltage of electrolysis. (6) If it is possible to prolong the process of electrolysis, the percentage of sulfur reductionincreases with the time of electrolysis. The mechanism of desulfurization by electrolyzing slag was also briefly discussed.
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