Transactions of the Iron and Steel Institute of Japan
Online ISSN : 1881-1183
Print ISSN : 0021-1583
Volume 21, Issue 7
Displaying 1-9 of 9 articles from this issue
  • Yoshihiro INAYAMA
    1981 Volume 21 Issue 7 Pages 459-463
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
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  • Motoaki OSAWA, Masayoshi HASEGAWA
    1981 Volume 21 Issue 7 Pages 464-468
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    Stress corrosion cracking (SCC) of hydrogen-containing austenitic stainless steels was investigated in H2SO4-NaCl solution. The specimens used were exposed to 28MPa hydrogen at 673K (400°C) for 16hr. The time-to-fracture of hydrogen-containing Type 304 steel was shorter than that of hydrogen-free one in weak corrosive solution, but was longer in strong corrosive solution. And the time-to-fracture of hydrogen-containing Type 316 steel was shorter than that of hydrogen-free one even in strong corrosive solution. The susceptibility to SCC of hydrogen containing Type 304 steel decreased under the cathodic hydrogen charging. This suggests that the stress corrosion process of this steel is active path corrosion. The self-activation time of Type 304 and 316 steels in H2SO4 solution became shorter by hydrogenation, and deformation promoted this tendency. In an immersion test in FeCl3 solution, Type 304 and 316 steels increased the susceptibility to pitting corrosion by hydrogenation. From these results, the change of SCC susceptibility of hydrogen-containing austenitic stainless steels might be caused by the passive film destabilization and the anodic activation of stress induced martensite.
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  • Ko SOENO
    1981 Volume 21 Issue 7 Pages 469-476
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    Tensile properties and resistivity changes during isothermal aging have been investigated mainly on a 13Ni-15Co-10Mo-0.2Ti maraging steel aged in the range from 400° to 575°C. A crosshead speed has been varied from 1mm/min to 0.005mm/mim, in order to investigate the effect of strain rate on the tensile properties.
    The embrittlement caused by the decrease in strain rate is found in the tensile properties of the maraging steel containing fine and coherent precipitates. The ductility of the overaged 13Ni-15Co-10Mo-0.2Ti maraging steel is also decreased at a lower strain rate. When this steel is averaged after cold rolling to 40%, the ductility parallel to the rolling direction is not decreased by the decrease in strain rate. Tensile properties insensitive to strain rate are obtainable after aging for about 10-100min in the range from 525° to 575°C.
    Investigation carried out on 14Ni-10Co-10Mo and 14Ni-15Co-7Mo maraging steels is included in order to consider the effect of chemical composition on the strain rate sensitivity. The maraging steels containing fine and coherent precipitates are also embrittled by the decrease in strain rate. The 14Ni-15Co-7Mo maraging steel continues to precipitate coherent precipitates for longer times at a certain aging temperature than does the 14Ni-10Co-10Mo one.
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  • Yoichi ITO, Noriyuki MASUMITSU, Kaichi MATSUBARA
    1981 Volume 21 Issue 7 Pages 477-484
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    Manganese sulfides in low carbon steel were grouped into a colony type (type II according to Sims' classification) and non-colony type (type I, type III and type X). The formation mechanisms of both types were investigated on the basis of the experimental results with the effects of sulfur content and cooling rate on the morphology of sulfides, the relation between the solidification structure and the distribution of sulfides, and the observation of formation process of sulfides in steels quenched from various temperatures.
    Though the colony type sulfide was increased with the sulfur content and cooling rate, the non-colony type sulfide was hardly affected by the sulfur content but decreased with an increase of cooling rate. The former was observed mostly in interdendritic space and formed in contact with a melt at a final period of solidification, while the latter was observed mainly around a dendrite and increased remarkably after solidification.
    These results can rationally be explained by the mechanisms that the colony type sulfide is formed by the eutectic reaction and the non-colony type sulfide is formed as a precipitate from the solid steel.
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  • Itsuo OHNAKA, Tatsuichi FUKUSAKO
    1981 Volume 21 Issue 7 Pages 485-494
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    A numerical technique of solidification analysis is presented, which is based on “Inner Nodal Point Method” and takes account of fluid flow induced by solidification shrinkage and variable fluid density. First, the effects of the coupling of heat and fluid f lows and the permeability in the mushy zone on the solidification have been analyzed for columnar steel ingots. The solidification was affected considerably by the permeability. A step-by-step method with a proper time step, where the equations for the heat and fluid flows are solved alternately, can be available instead of solving the equations simultaneously. Second, as numerical examples, the solidification process in tapered steel ingots has been analyzed. The experimental results about macrosegregations and porosity have been explained in terms of the ingot taper, the negative pressure, the velocity field, the fraction solid contour line and the movement of solid phase. Although the more precise analysis may request to consider the movement of solid phase and to use an accurate permeability, the proposed technique which can handle complicated boundary shape may be more useful for the determination of ingot shape and casting conditions than conventional ones.
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  • Hidesato MABUCHI, Hitoji NAKAO
    1981 Volume 21 Issue 7 Pages 495-501
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    Low-temperature toughness has been studied through the changes of Al and N contents in A302C steels for reactor vessels by means of Charpy V-notch and press-notch impact tests. The results show that the low-temperature toughness was improved significantly by the elimination of excess Al.
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  • Kenji CHIJIIWA, Yotaro HATAMURA, Tetsuro SUZUKI
    1981 Volume 21 Issue 7 Pages 502-511
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    A new experimental method for stress analysis of a steel slab in hot rolling or continuously cast slab by Plasticine is developed. When Plasticine is used for a simulation of steel in high temperature, it is thought that not only the simulation of deformation, which has been made conventionally, but also the simulation of stress and force is possible. First, different kinds of stress detectors-miniature pressure cell, miniature frictional stress cell and internal stress cell-are developed with success. Then an apparatus for the simulation with 2-stand rolls equipped with these detectors is made, and it is possible to measure the following items:
    (i) Distribution of stresses (pressure, circular frictional stress and axial frictional stress) on the surface of a roll.
    (ii) Distribution of internal stress (direction and magnitude of principal stress) in a workpiece.
    (iii) Deformation of workpiece and load or torque acting on a roll. Finally an experiment of rolling by single stand is made as an example. Deformation, load and torque, distributions of many kinds of stresses are clarified and the precision of the experimental method is confirmed.
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  • Yoshimoto WANIBE, Kohji SAWADA, Toshiharu FUJISAWA, Hiroshi SAKAO
    1981 Volume 21 Issue 7 Pages 512-517
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    Since the co-existence of a small amount of tellurium can be expected to improve the practical deoxidation of steel, three kinds of experimental examinations were carried out to eliminate the residual tellurium out of steel as the subsequent treatment. The results are
    (1) Tellurium evaporates fairy fast out of the molten iron into Ar stream.
    (2) Rare earth metal is the best substance to be added for the elimination of tellurium at a low oxygen potential of molten iron.
    (3) CaF2-CaGN2 composite flux is also applicable, especially one with a composition ratio of 1:1 which has succeeded in reducing the residual concentration of tellurium to rd. 20ppm (about 90% reduction performance) during 20min treatment.
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  • Yoshiaki MIURA, Toshiaki OKUHARA, Tetsu NISHI, Tokuji YAMAGUCHI, Hiros ...
    1981 Volume 21 Issue 7 Pages 518-529
    Published: 1981
    Released on J-STAGE: September 08, 2006
    JOURNAL FREE ACCESS
    This paper summarizes a series of experimental studies conducted by the author et al., on coal blending theory which is a basic condition for the production of coke. A brief history is given of the condition of coking coal supply and past studies undertaken in Japan ranging from the establishment of basic concepts of coal blending in the period immediately after World War II to recent trends in the search for blending standards aiming at the improvement of hot properties of coke. The essential point in coal blending is to obtain uniform, strong-textured coke as a composite material by an optimum combination of various grades of coal having different heating properties, i.e., thermal transformation temperatures. With the above-mentioned in mind, the paper describes the classification of single coal on the basis of the blending theory, the estimation of coke strength, and the theory for size control of coal charge. Finally, the relation among coal blending, coke texture, reactivity with CO2, and strength after the reaction with CO2 is described, indicating the importance of future efforts for the improvement of hot properties of coke by the addition of caking additive.
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