Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 67 , Issue 9
Showing 1-24 articles out of 24 articles from the selected issue
  • Tetsuo KATO, Shozo ABEYAMA, Norioki UYEHARA
    1981 Volume 67 Issue 9 Pages 1409-1419
    Published: July 01, 1981
    Released: January 19, 2010
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  • Kichinosuke HIROKAWA
    1981 Volume 67 Issue 9 Pages 1420-1430
    Published: July 01, 1981
    Released: June 19, 2009
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  • Nobuyasu KAWAI, Hisashi TAKADA, Toru YUKAWA
    1981 Volume 67 Issue 9 Pages 1431-1438
    Published: July 01, 1981
    Released: June 19, 2009
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  • Munetsugu MATSUO
    1981 Volume 67 Issue 9 Pages 1439-1446
    Published: July 01, 1981
    Released: June 19, 2009
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  • Hiroshi TAMURA
    1981 Volume 67 Issue 9 Pages 1447-1459
    Published: July 01, 1981
    Released: June 19, 2009
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  • Shoji SHIMAMURA
    1981 Volume 67 Issue 9 Pages 1460-1470
    Published: July 01, 1981
    Released: June 19, 2009
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  • Takaaki NOHARA
    1981 Volume 67 Issue 9 Pages 1471-1477
    Published: July 01, 1981
    Released: June 19, 2009
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  • Takeaki MURAYAMA, Yoichi ONO
    1981 Volume 67 Issue 9 Pages 1478-1484
    Published: July 01, 1981
    Released: June 19, 2009
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    To determine rate parameters for the gaseous reduction of an iron oxide pellet, mixed-control plot proposed by T. YAGI and Y. ONO (Trans. ISIJ, 8 (1968), 377.) has been widely used. The method, however, can not be properly applied to the case where the reduction is retarded at the beginning. In this paper, a modified method to avoid any influence of the initial delay of reduction on the mixed-control plot is proposed. In this method a straight line representing the mixed-control plot is drawn to pass through an observed data point (t=t1, F=F1) other than the initial point. The point (t=t1, F=F1) is selected so that the value of F1 may be relatively low and the mean relative residual of the calculated reaction time from the observed time, Δtr, can be minimum.
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  • Tadashi CHIDA, Noboru SAKAI, Teiriki TADAKI
    1981 Volume 67 Issue 9 Pages 1485-1490
    Published: July 01, 1981
    Released: January 19, 2010
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    An approximate and simple mathematical model is proposed in order to analyze the reduction behavior of a metallic oxide pellet with gas mixtures of hydrogen and carbon monoxide. The model used is the (single interface) unreacted-core shrinking model, and the following assumptions are made : the gas mixture of hydrogen and carbon monoxide is considered to be as a single-component gas so that oxide pellets are reduced with this imaginary gas, and the apparent reaction rate constant ka is proportional to the real constant k. The correction factor α(=ka/k) can be evaluated approximately by the assumption that the reaction rate at the reaction surface is calculated by summing the reduction rates due to hydrogen and carbon monoxide. The evaluated values of α are in a relatively good agreement with the experimental results. These facts show that the simple model proposed can be applied to the reduction processes with mixtures of hydrogen and carbon monoxide.
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  • Takahisa KOSHIDA, Takeshi OGASAWARA, Hisashi KISHIDAKA
    1981 Volume 67 Issue 9 Pages 1491-1497
    Published: July 01, 1981
    Released: June 19, 2009
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    Viscosity, surface tension, and density of blast furnace slag and synthetic slags which had nearly the same composition as that of the blast furnace slag were measured below the smelting temperature. The following results were obtained:
    (1) Viscosity of synthetic CaO-SiO2-Al2O3-MgO slags increases with increasing SiO2 and Al2O3 contents, and decreases with increasing CaO and MgO contents. Small amounts of another compounds contained in the blast furnace slag cause the decrease of vicosity, and the extent of effect of these compounds on viscosity is similar to that of MgO.
    (2) Surface tension of quaternary CaO-SiO2-Al2O3-MgO system is not influenced by the interchange of Al2O3 and MgO but increases markedly with increasing (CaO/SiO2) mol. The surface tension of the blast furnace slag is 472 to 498 dyn/cm in the temperature range 1 380° to 1 500°C, and sulfur has a great influence on the decrease of surface tension. The surface tension of all the systems studied here decreases with increasing temperature.
    (3) Great increase of viscosity of blast furnace slag occurs when cooled below 1 405°C to 1 375°C, and it is made clear that this temperature range corresponds to the upper limit of the operation temperature to produce hard granulated slag in the factory.
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  • Yasuhiro HABU, Seiji ITOYAMA, Toshihiko EMI, Kenichi SORIMACHI, Hideak ...
    1981 Volume 67 Issue 9 Pages 1498-1507
    Published: July 01, 1981
    Released: June 19, 2009
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    A method has been developed which increases the fraction of equiaxed crystals and results in decreasing centerline segregation in continuously cast slab by adding steel strip into mold. The effect of shape, liquidus temperature, feeding speed of the strip and superheat of melt in mold on the melting behavior of the strip in crater has been evaluated by a mathematical model. Then, the effect of the amount of the strip addition on the ratio of the equiaxed zone and the centerline segregation has experimentally been investigated by use of strip with low liquidus temperature. The equiaxed zone of 50 to 75% has been obtained and the centerline segregation has disappeared by adding 6 to 8 kg/t of the strip at 15 to 30°C of superheat. A countermeasure to prevent the contamination of molten steel caused by adding the strip is established. The mechanism for the increase in the fraction of equiaxed crystals has also been discussed.
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  • Yasuo SUGITANI, Masanobu NAKAMURA, Tadao WATANABE
    1981 Volume 67 Issue 9 Pages 1508-1514
    Published: July 01, 1981
    Released: June 19, 2009
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    The influence of rate of heat removal on uneven solidification in a continuous casting mould has been investigated by changing thickness of a steel plate which is closely set on a surface of sand mould. The steel plate has a heat capacity corresponding to its thickness, and the rate of heat removal in initial stage of solidification decreases with the thickness decrease.
    As a result, Al-killed steel containing about 0.12%C, whose shell is formed quite unevenly in water-cooled copper plate mould, has been observed to solidify evenly under some low rate of heat removal. This critical rate is about 0.8×106 kcal/m2·h by heat transfer analysis.
    This fact can be explained as follows. When the rate of heat removal is lowered, temperature of shell on mould side gets to drop more slowly and the difference of cooling rate between mould and liquid steel sides of shell becomes smaller, which makes the difference of shrinkage smaller. In this way, the bending force towards liquid steel, which is potentially exerted at upper part of shell by the difference of shrinkage, gets weakened. Moreover, strength of shell becomes weak due to a rise of temperature level of shell. Consequently, the bending force cannot overcome the static pressure and air gap is not formed between the shell and mould, which results in even solidification.
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  • Katsuhiro KAWASHIMA, Yukio NAKAMORI, Shoji MUROTA, Hiromu SOGA
    1981 Volume 67 Issue 9 Pages 1515-1522
    Published: July 01, 1981
    Released: June 19, 2009
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    It is very important to measure solidification shell thickness of C.C. slabs for a good and fast control system of a production line. There have been so far only destructive methods and theoretical calculation for the shell thickness estimation.
    We have developed the method of nondestructive, real time and quasi-contionuous measurement of the shell thickness utilizing the technique of electromagnetic generation and detection of ultrasonic waves and successfully tested it in our C.C. production line.
    The measurement system was installed about six meters below the molten steel level and measurements were done every one to two minutes for long time, during that time casting speed was changed. The measured results showed that this method could be applied to measure the shell thickness not only for stable casting conditions but also for dynamically changing casting conditions.
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  • Toshimitsu W-FUJII, Koichi YAMAMOTO, Masakatsu UENO
    1981 Volume 67 Issue 9 Pages 1523-1532
    Published: July 01, 1981
    Released: June 19, 2009
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    Stress-annealing tests (constant load, or constant displacement) on smooth bars which were given a prior treatment to simulate a heat-affected zone in a welded joint were used to characterize the susceptibility to intergranular fracture at about 600°C of various heats of a pressure vessel steel, SA 508-2.
    Micro-alloying to cerium or zirconium in the steel proved to have the effect of suppressing the intergranular fracture, whereas phosphorus, arsenic, antimony, or copper did not have any substantial effect on the susceptibility. Remarkable enrichment of sulfur was found on the intergranular facets with an Auger spectrometer, which is quite dissimilar to the grain boundary segregation in temper-embrittle low alloy steels. The extent of the sulfur enrichment proved to reduce with lowering of the quenching temperature in a prior treatment (two step austenitizing), corresponding to the decrease in the susceptibility to the intergranular fracture.
    On the basis of these results, a new model is proposed to explain the mechanism that the intergranular fracture is promoted by the enriched sulfur in cavity surfaces.
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  • Minoru NISHIDA, Toshiyuki KATO, Tomo TANAKA
    1981 Volume 67 Issue 9 Pages 1533-1541
    Published: July 01, 1981
    Released: June 19, 2009
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    Spheroidization behavior of manganese sulfide inclusions and associate decrease in hydrogen induced cracking were investigated in a hot rolled commercial API-X60 grade steel coil during various heat treatment.
    MnS inclusions which were elongated like ribbons in the hot rolled state began to spheroidize at such a low heating temperature as 600°C, and the extent of spheroidization was remarkable above 900°C. At an early stage of spheroidization, thin edges of elongated MnS became blunt to have a dog-bone shape, and subsequently the part was broken into very small particles. At high temperatures at or above 900°C, even the central part was broken into several spheres in the later heating stages.
    The hydrogen induced cracking was not much reduced by heating below 900°C, but it was decreased remarkably as the temperature exceeded 1000°C. The cracking initiated preferentially at large inclusions, and the width rather than the length of the inclusions was correlated more closely with the cracking susceptibility ; occurrence of cracking increased with the increase in the width.
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  • Masaki UEKADO, Kuniyasu SAKAI, Masanori KIYOSHIGE
    1981 Volume 67 Issue 9 Pages 1542-1550
    Published: July 01, 1981
    Released: June 19, 2009
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    The effects of gas composition, alloying elements, cold working and heat treatment on the susceptibility of stress corrosion cracking of mild steels, low alloy steels and austenitic stainless steel in CO-CO2-H2O environments have been investigated.
    The results obtained are summerized as follows:
    (1) The transgranular stress corrosion cracking occured in CO-CO2 environments which are consisted of both vapor and liquid phase. Stress corrosion cracks initiated from pits on the surface of specimens in liquid phase.
    (2) The resistance of the killed SS41 steel to stress corrosion cracking is superior to the rimmed SS41 steel. The Cr-Mo steels containing Cr more than 9% did not suffer from stress corrosion cracking in CO-CO2 environments.
    (3) The susceptibility of these steels to stress corrosion cracking was increased with increase of hardness due to heat treatment.
    (4) Mild steels are more susceptible to stress corrosion cracking at 5% cold working than at other cold working conditions.
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  • Yoshikuni KAWABE, Seiichi MUNEKI, Junji TAKAHASHI
    1981 Volume 67 Issue 9 Pages 1551-1556
    Published: July 01, 1981
    Released: June 19, 2009
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    The prior austenite (γ) grain sizes have been controlled in the range of 780 μm using cold working recrystallization treatment, and these effects on tensile properties and fracture toughness have been in vestigated for a 2 750 MPa grade 17Ni-20Co-6Mo-1.5Ti maraging steel.
    Tensile properties were strongly dependent on the prior γ grain size. Tensile strength and reduction of area mainly exhibited a linear function of the reciprocal of the square root of the prior γ grain size, but the unstable fracture in a low stress level occurred without showing reduction of area when the prior γ grain sizes were coarser than a critical size. Fracture toughness was almost independent of the prior γ grain size and the fracture mode was quasi-cleavage type. Thus, it was concluded that the prior γ grain size had the pronounced influence on crack initiation but no or only a small effect on crack propergation.
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  • Hisashi TAKADA, Hiroshi HATO, Yuichi SEKI, Katsumi TSUJI, Shigeru KAWA ...
    1981 Volume 67 Issue 9 Pages 1557-1566
    Published: July 01, 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    An attempt has been made to survey the effect of Ni, Cr and Mn in the matrix on the precipitation strengthening of austenitic hot work die steels containing 0.5%C and 2%V. The materials tested are a Fe-Cr-Ni austenitic steel with 15%Cr and 15%Ni and two kinds of Fe-Cr-Ni-Mn austenitic steels in which some of Ni is replased by 13% and 25% Mn respectively. Cr is decreased with the increase of Mn in order to suppress the precipitation of σ-phase.
    The maximum hardness of Fe-Cr-Ni-Mn steels are much higher than that of Fe-Cr-Ni steel, while the maximum hardness decreases slightly when Mn increases from 13% to 25%.
    The hardness in the early aging stage rises more rapidly with the increase of Mn content. This is probably attributed to the difference of the amount of C and V in matrix when solution treated and the difference of the coherency between the matrix and VC carbide which precipitates during aging. The elongation and reduction in area of aged steels decrease markedly with the increase of Mn content, because the fracture occurs on the grain boundary. But, it is possible to improve them by hot rolling at about 1 200°C before aging without the decrease of the strength.
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  • Tetsuya YAMAMOTO, Michiharu HARIKI, Michiya YAMASHITA, Tateo KAWASAWA, ...
    1981 Volume 67 Issue 9 Pages 1567-1573
    Published: July 01, 1981
    Released: June 19, 2009
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  • [in Japanese]
    1981 Volume 67 Issue 9 Pages 1573-1573,1581
    Published: July 01, 1981
    Released: June 19, 2009
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  • Junsaku KURIHARA
    1981 Volume 67 Issue 9 Pages 1574-1581
    Published: July 01, 1981
    Released: June 19, 2009
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  • Hiroyoshi MATSUBARA, Toshiharu IRIE, Satoshi HIROSE, Keiji TAKAKI
    1981 Volume 67 Issue 9 Pages 1582-1585
    Published: July 01, 1981
    Released: June 19, 2009
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  • [in Japanese]
    1981 Volume 67 Issue 9 Pages 1589-1590
    Published: July 01, 1981
    Released: June 19, 2009
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1981 Volume 67 Issue 9 Pages 1593-1599
    Published: July 01, 1981
    Released: June 19, 2009
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