Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 46, Issue 1
Displaying 1-9 of 9 articles from this issue
  • Arihiro Tominaga, Takeo Yatsuzuka, Shiro Shono
    1960 Volume 46 Issue 1 Pages 7-11
    Published: 1960
    Released on J-STAGE: July 12, 2012
    To measure the wearing state of a blast-furnace brick-work during its operation, a test method using a radioactive isotope (Co60) was investigated. In this report, some basic investigations which include the measurement of absorption coefficients of the blast furnace construction materials, determination of the burying amounts of Co60, and experiments with a brick-work model are described.
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  • Takehiko Fujii
    1960 Volume 46 Issue 1 Pages 12-19
    Published: 1960
    Released on J-STAGE: July 12, 2012
    Using a high-frequency induction furnace in which atmosphere could be controlled, effect of temperature, area in contact with crucible wall, area of free surface and rotation on the rate of decarbonization was studied. The following results were obtained.
    (1) The rate of decarbonization (this rate is difference between the total rate of decarbonization which is measured and the rate of decarbonization by crucible wall (MgO), and the following rates are the same.) increases linear to temperature (1550-1650°C), and the activation energy calculated from this results is 34·6 kcal/mol.. This value is greater than the values of other investigators, because calculating the activation energy, they do not subtract the rate of decarbonization by reaction of crucible wall (MgO) from total rate of decarbonization.
    (2) The rate of decarbonization is constant on condition that the area of free surface of molten steel is constant, and have no connection with the area in contact with crucible wall. By calculating from this results, it becomes clear that in this experiments, the reaction of decarbonization occurs mainly at free surface, and the reaction in molten steel and through boundary layer between molten steel and gas phase of crevices in the crucible wall is extremely small.
    (3) The rate of decarbonization increases linear to the area of free surface. This fact indicates that the reaction of decarbonization occurs mainly at free surface.
    (4) The rate of decarbonization in case of rotation increases linearly to the area of free surface of paraboloid of revolution. But this inclination of the straight line is smaller than the inclination by increase of free surface in case of rest, because the condition of stir by high-frequency induction power is changed by rotation.
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  • Kichizo Niwa, Mitsuo Shimoji
    1960 Volume 46 Issue 1 Pages 19-24
    Published: 1960
    Released on J-STAGE: July 12, 2012
    The reaction of carbon oxidation in liquid iron,
    should be rapid in true terms of homogeneous chemical reaction. This can be confirmed by the theoretical reason of the absolute reaction rate theory. The most reasonable view for the rate determining step of the above reaction may be obtained from “diffusion film theory”.
    1) The thickness of the diffusion layer is briefly discussed in terms of Reynolds'. number of liquid iron. The nucleation and growth of CO gaseous bubbles are explained from the point of view of the “theory of heterogeneous phase transformation” and the “theory of diffusion film.”
    2) If the rate of carbon-oxygen reaction in liquid iron were controlled by the process of “homogeneous one”, the rate of this reaction energetically leads to too very large value compared to observed one.
    3) The most reasonable process determining CO formation would be a transport of the dissolved carbon (C) and oxygen (O) to the existing surface of CO bubbles.
    4) The favorable place of nucleation for CO bubble formation would be in the solid-metal interfaces such as the hearth-metal interfaes.
    5) The rate of carbon oxidation in the open hearth has a weak tendency to diminish with decrease of carbon concentration.
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  • Katsuyosi Kajiyama
    1960 Volume 46 Issue 1 Pages 25-29
    Published: 1960
    Released on J-STAGE: July 12, 2012
    It is considered that surface defects of steel products such as round bars and sections have been depended on the skin blowholes of ingots originating from steel making and teeming process.
    There are some kinds of the steel products on which seamy defects appear easily during rolling operation while others do not, and in the case of each steel products, there are specific. parts on which seamy defects appear easily.
    In order to solve such practical problems, the author pursued the relation between surface defects of ingot and that of various steel products by means of artificial blowholes.
    The results were as follows:
    The seamy defects on various round bars and sections tended to appear severely on the parts which correspond to the wider side of the rectangular cross section of the ingot and their development was much affected by the initial roughing conditions.
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  • Tadashi Ohtake, Koichi Aoki, Hisashi Gondoh, Yukito Sasaki
    1960 Volume 46 Issue 1 Pages 29-34
    Published: 1960
    Released on J-STAGE: July 12, 2012
    The extent of internal defects, which lay at the top of the semikilled mild steel plate, was measured by ultrasonic testing of the liquid-holding method. Samples were selected from plates of the same size which were rolled from ingots of the same type.
    The extent (area) of the defects seemed to have some relation to manufacturing conditions.
    Studying the relation, the following results were obtained:
    (1) The extent of defects is low for the first and last poured ingots, but is high for those poured between.
    (2) The extent of defects has a linear relation to the pouring temperature, i. e. the higher the temperature, the higher the extent of defects.
    (3) Pouring speed does not affect the extent of defects.
    (4) Ingots, charged into a soaking pit inversely, show the same tendency as (1) as to extent of defects, however, except for the first poured, the extent of defects is lower than. for usual charging.
    (5) Too large cropping of slabs after slabbing greatly increases the extent of defects.. This is caused by the oxidation of the shrinkage pipe.
    (6) Too short track time disturbs the relation shown in (1) and increases the average extent of defects.
    (7) These defects seem to be caused by the scum remaining near the top surface of the ingot.
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  • Toshio Saito, Tatsuo Fujiwara
    1960 Volume 46 Issue 1 Pages 34-38
    Published: 1960
    Released on J-STAGE: July 12, 2012
    The influence of various alloing elements on the low temperature transition properties of low-manganese high-strength steel, standard composition of,0·28% C. 2·00% Mn,0·50% Cr, and 0·30% Mo, tempered sorbitic structure of HRC 32±1 hardness, were tested by V-notch Charpy inpact test.
    Result obtained were as follows:
    1. Transition temperature in this steel became very lower when carbon content fell below 0·15%, but in carbon content range of 0·20-0·35% steel, it did not follow that transition properties were always improved as carbon content lowering.
    2. Addition of such elements, silicon, chromium, tungsten, titanium, titanium-boron, and copper in this steel, were harmful to low-temperature transition properties. Especially, it was desired that such elements, silicon, chromium and copper in this steel were as fall as possible.
    3. Both elements, molybdenum and vanadium were effective, additional elements for lowtemperature transition properties. Most effective content of these elements were 0·5-0·6%. molybdenum and about 0·1% vanadium in this steel.
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  • Mamoru Nishihara, Hiroshi Hirano, Shunji Yamamoto, Kiyoshi Yoshida
    1960 Volume 46 Issue 1 Pages 39-42
    Published: 1960
    Released on J-STAGE: July 12, 2012
    As evident on the data given in our first report, the heat treatment before creep-rupture test of type 321 stainless steel presented some remarkable results on the creep rupture strength.
    In this study carbide changes observed in specimens before and after creep-rupture test were studied by various kinds of testing methods such as high-resolution electron-diffraction and select electron-diffracttion, etc. Carbides extracted from each specimen by chemical procedures were tested by X-ray diffraction.
    Carbides precipitated in all the specimens quenched from the temperature range of 1300-800°C before creep-rupture test were identified as titanium carbide and carbides of other kinds. The lattice constants of titanium carbide extracted had different values depending upon each different quenching temperature.
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  • Takeshi Akutagawa, Iku Uchiyama
    1960 Volume 46 Issue 1 Pages 43-53
    Published: 1960
    Released on J-STAGE: July 12, 2012
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  • M. Allard
    1960 Volume 46 Issue 1 Pages 54-59
    Published: 1960
    Released on J-STAGE: July 12, 2012
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