Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 79 , Issue 2
Showing 1-17 articles out of 17 articles from the selected issue
  • Hiroshi KIMURA
    1993 Volume 79 Issue 2 Pages 131-138
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
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  • Yasuo KAMEI, Tomio MIYAZAKI, Hideyuki YAMAOKA
    1993 Volume 79 Issue 2 Pages 139-146
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Scrapmelting test was performed using an experimental melting furnace with coke packed bed injected with highly oxygen enriched air and a large quantity of pulverized coal and the following results were obtained.
    1) Scrap (100% of material) was able to be melted by using coke for blast furnace.
    2) The pig iron whose quality is equal to that of the blast furnace can be produced with high carburization and high desulfurization.
    3) The fuel rate of 240 to 290 kg/t and productivity of 14.7t/d/m3 were obtained.
    4) The fuel rate can be decreased and productivity can be increased by post combustion with air injection from the shaft wall.
    Based on the above mentioned results, the comparison of energy consumption of scrap melting process such as this process, electric furnace and basic oxygen furnace was made and a possibility was confirmed that the energy consumption of this process was the least among them.
    Therefore it is concluded that this process can be one of the attractive scrap melting methods when the scrap utilization is required in large quantities.
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  • Masanori IWASE, Hitoshi KITAGUCHI
    1993 Volume 79 Issue 2 Pages 147-151
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    The phase relation of the system ZrO2+BaO+P2O5 was investigated at 1673K. Seven compatibility triangles were detected, ( 1 ) BaO·ZrO2+3BaO·P2O5+10BaO·3P2O5, ( 2 ) ZrO2+BaO·ZrO2+3BaO·P2O5, ( 3 ) ZrO2 +3BaO·P2O5+7BaO·ZrO2·3P2O5, ( 4 ) ZrO2+7BaO·ZrO2·3P2O5+BaO·ZrO2·P2O5, ( 5 ) ZrO2+BaO·ZrO2·P2O5+BaO·4ZrO2·3P2O5, ( 6 ) ZrO2+ZrO2·2P2O5+ZrO2·P2O5, ( 7 ) ZrO2·P2O5+ZrO2·P2O5+BaO·4ZrO2·3P2O5. In addition to the phase diagram studies, the electrical conductivities of ZrO2+14.55 mol% BaO+3mol%P2O5 electrolyte were measured to find a suitable three-phase electrolyte for rapid determinations of phosphorus in hot metal.
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  • Kazuhiko IWAI, Kensuke SASSA, Shigeo ASAI
    1993 Volume 79 Issue 2 Pages 152-158
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Three dimensional magnetic field around a cold crucible system has been analysed by using the boundary element method to get the basic information for designing a cold crucible system. From the computed magnetic field distribution, heat generation rates in the charge, the crucible and the coil were calculated. The calculated magnetic field and heat generation rates in the charge, the crucible and the coil showed good agreement with the observed ones. The axial and radial components of magnetic field are dominant in comparison with the azimuthal component. The heat generation rate in the charge increases with decreasing the gap between the charge and the crucible or with increasing the diameter of the charge, under the same coil current. Energy efficiency can be improved by increasing the surface of the charge and decreasing the surface of the crucible. The distribution of heat generation rate in the charge along the axis is sensitive to the arrangement of the coil.
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  • Ikuo SAWADA, Yutaka KISHIDA, Kensuke OKAZAWA, Hiroyuki TANAKA
    1993 Volume 79 Issue 2 Pages 160-166
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    The authors developed a numerical simulator which can conduct transient calculations of molten steel turbulence in a continuous casting mold based on large eddy simulation model and compared the calculated values of fluid velocity with the measured ones in water and mercury models.
    With respect to time-averaged velocities in the upper region of mold, a qauntatively good agreement between the calculation and the measurement in a water model was obtained. The calculated turbulence energy spectrum near meniscus agreed qualitatively with the measured one in a mercury model. The turbulence fluctuation with higher frequency is generated due to the velocity fluctuation at taps of immersion nozzle which is caused by fluid instability at the inner bottom of nozzle.
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  • Akira YAMAUCHI, Kenichi SORIMACHI, Toshikazu SAKURAYA, Tetsuya FUJII
    1993 Volume 79 Issue 2 Pages 167-174
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Laboratory experiments have been performed to make clear heat transfer behavior in the mold of continuous casting of steel. The overall thermal resistance of a parallel-sided plate filled with mold flux has been measured. The interfacial thermal resistance between the mold and flux film interface and the thermal conductivity of the mold flux are analyzed quantitatively. An interfacial thermal resistance corresponding to the air gap of 20-50μm is observed in the case of solid mold flux. When the temperature of the mold surface exceeds solidification temperature of the flux, the interfacial thermal resistance disappears together with disappearance of air gaps. The crystallization of the mold flux inhibits the radiative heat transfer that is equivalent to 20% in the total heat flux. The thermal conductivity of the mold flux depends on the size of silicate ions. Large size of silicate ion promotes the conductive heat transfer.
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  • Isamu INAMOTO, Koichi CHIBA
    1993 Volume 79 Issue 2 Pages 175-179
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Isotope dilution analysis (ID) with inductively coupled plasma mass spectrometry (ICP-MS) was applied to the determination of ultra trace levels of impurities, such as Mg Cu, Zn, Ag and Pb in pure irons. Furthermore, a cation exchange method was combined with the ID as a pretreatment procedure in order to remove the iron matrix cation to preconcentrate impurities. It was found that the cation exchange method was very suitable for a pretreatment procedure for ID, because the cation exchange resin contained almost no contaminant elements after properly rinseing. Recoveries of elements by the cation exchange method were 50 to 86% for the above elements, and it was high enough to be combined with ID. Using ID-ICPM S, it was possible to measure 0.1μg/g levels of these elements with R.S.D. of less than 4%. In particular, 1ng/g of Ag was determined with R.S.D. of less than 17%.
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  • Shigeo MATSUBARA, Kazunari NAKAMOTO, Yusuke HIROSE, Iwao KATAYAMA, Tak ...
    1993 Volume 79 Issue 2 Pages 180-186
    Published: February 01, 1993
    Released: February 16, 2010
    JOURNALS FREE ACCESS
    Control of the free aluminum concentration in a hot dip galvanizing bath is of great importance for producing galvannealed steel sheets. Since aluminum has much greater affinity for oxygen than zinc, the oxygen potential of Zn-Al-O bath may be determined only by the following equilibrium reaction ;
    Al2O3(s)=2Al (in Zn)+ 3O (in Zn) when the aluminum concentration in the bath is relatively low. Aluminum sensor based on the emf method using the zirconia solid electrolyte has been deviced by utilizing the above equilibrium relation.
    In this paper, emf measurements have been carried out in Zn-Al-O baths having aluminum concentration of 0.020.50mass% under an air atmosphere by using some of the most appropriate combinations of zirconia solid electrolyte and liquid reference electrode for Zn-O baths.
    From the analysis of such emf values at temperatures between 450500°C, the following relationships between aluminum concentration and cell emf for two reference electrodes were obtained ;
    E/mV=57.19ln [Al]/mass%+506.4, 0.02≤[Al]/mass%≤0.30 (In-In2O3 as ref. electrode)
    E/mV=68.27ln [Al]/mass%+270.4, 0.05≤[Al]/mass%≤0.20 (Zn-ZnO as ref. electrode)
    The external AC voltage applied on these sensors immediately after immersion into the bath showed to be effective to their responsibility and stability. The possibility of the present aluminum sensor has been ascertained experimentally.
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  • Kazumi NISHIMURA, Hisao ODASHIMA, Koji KISHIDA, Masahiko ODA
    1993 Volume 79 Issue 2 Pages 187-193
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    The hot dip galvanizing mechanism of hot rolled Al killed steel sheets with various surface conditions were investigated.It was found that various factors of steel surface conditions affected the galvanizing reaction. The appearance of Zn coatings was improved in adequate pickling time. This pickling time affected the residual scale, smudge and surface roughness. Surface roughness of hot rolled steel sheets varied with pickling time and pretreatment methods affected the galvanizing reaction. The appearance and adhesion of Zn coating became better in a small range of surface roughness. More ramarkable result was that reactivity of substrate in molten zinc depended on the pretreatment methods. Mechanical polishing and skinpass rolling of steel sheets increased the reactivity of substrate in molten zinc more than just pickling and electropolising. Increase of residual strain and stress on the steel surface by mechanical pretreatment was observed by X-ray diffraction method. It seemed that active sites such as the lattice deffects of substrate increased by mechanical pretreatments, and therefore Zn-Fe reaction increased.
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  • Takehide SENUMA, Shiro SANAGI, Kaoru KAWASAKI, Satoshi AKAMATSU, Teruk ...
    1993 Volume 79 Issue 2 Pages 194-200
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Although thin slab-direct hot rolling process is expected as a future process of steel sheet production, its metallurgy has not been investigated thoroughly. In this paper, the metallurgy of mild steel in thin slab-direct hot rolling process has been discussed with special attention to the precipitation behavior of MnS and its influence on the hot-cracking at the edge of hot bands and the mechanical properties of cold rolled low carbon steel sheets. The following results are obtained :
    1. The hot-cracking resistance and mechanical properties of cold rolled sheets produced through thin slab-direct hot rolling process are not inferior to those produced through a conventional process, if S content is reduced and/or proper heat treatment prior hot rolling is carried out.
    2. The experimental findings indicate that MnS precipitates under a condition of the local equilibrium at the MnS/γ interface.
    3. The hot-cracking is probably caused by the remelting reaction of austenite at grain boundaries occupied by sulfur. For explaining the experimental findings, not only the equilibrium but also the kinetics of the diffusional reaction must be considered for the remelting process.
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  • Ichiro TSUKATANI, Tsuyoshi INOUE, Masatoshi SUDO
    1993 Volume 79 Issue 2 Pages 201-208
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    In order to clarify the effect of carbon and manganese on the recrystallization texture formation of low carbon steel sheets, the change in texture and microstructure during cold-rolling and annealing have been investigated. A strong{111} recrystallization texture component forms in interstitial atom-free steels being nearly independent of manganese content, the grain size of hot bands, and the heating rate of annealing. However, in a 0.21% manganese steel containing solute carbon prior to cold-rolling, the {111} recrystallization texture component is seriousely decreased with increases in the grain size of hot bands and the heating rate of annealing. By measurement of the electrical resistivity, the solute carbons making complex with manganese atoms are found to be almost absent during the recovery process between 400 and 480°C in a 0.21% manganese steel. During cold rolling, the slip rotations into the end stable {211} <011> +5°orientations, which are assumed to form the near {111} recrystallization texture component, are suppressed by the solute carbon coexisting with manganese atom as C-Mn complex and increment of hot bands grain size. Therefore, nuclei of {110} <001> are considered to grow more preferentially than those of {554} <225> in the steel containing solute carbon and manganese.
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  • Osamu MATSUMURA, Tetsuro OHUE, Tatsuo AMAIKE
    1993 Volume 79 Issue 2 Pages 209-211
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
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  • Kozo FUKUDA, Tsunemi WADA, Ichiro NAKAUCHI, Masahiro UEDA
    1993 Volume 79 Issue 2 Pages 212-218
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    To shorten treatment time, heat treatment conditions were investigated, taking into account the possible high toughness of the web and base portions of rails by means of continuous quenching and tempering.
    The investigation on the relations between fracture toughness and heat treatment conditions led to the following optimum conditions ; namely, finishing temperatures in quenching from 100 to 150°C, rapid heating at heating rates of 10°C/sec or less for tempering, and tempering temperatures from 650 to 700°C.
    In continuous quenching and tempering where heating rate is fast, when martensite volume fraction after quenching exceeds 40%, fracture toughness is not affected and remains nearly constant. This may be because the microstructure formed under the above-mentioned conditions consist of tempered fine bainite-martensite mixture having a microstructure similar to that of tempered martensite, and thus, shows nearly the same fracture toughness as that of tempered martensite.
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  • Kouichi MARUYAMA
    1993 Volume 79 Issue 2 Pages 219-226
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    Creep deformation and fracture mechanisms are known to change with stress and temperature, as indicated in the deformation and fracture mechanism maps. When creep rupture data are evaluated with a time-temperature parameter (TTP), the data should be divided into several mechanism fields. This idea was applied to creep rupture data difficult to be described by a simple TTP and stress function. It was suggested that, by dividing rupture data, all data can be described by a TTP having only one arbitrary constant and a linear stress function. Within the same field, rupture lives hundred times longer than the longest test duration could be predicted without introducing any appreciable error. Extrapolation across a field boundary, however, caused serious error ; one may not correctly predict a rupture life two times longer than the test duration. Information about field boundaries is necessary for correct extrapolation.
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  • Nobukazu SUZUKI, Nobuyuki ISHII, Toshio MIYAGAWA, Hiroaki HARADA
    1993 Volume 79 Issue 2 Pages 227-232
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
    A new testing method was developed which enables to quantify minute amount of hydrogen in steel and measure resistance of steel to delayed fracture. This method clarified a steel had critical hydrogen level (HT) for delayed fracture under a constant applied load. Based on this testing method, a new approach for estimating delayed fracture of steel in service was proposed. From the value of HT obtained by this testing method, together with amount of hydrogen absorbed in the steel in a service environment, which is measured by a hydrogen monitoring device, delayed fracture of steel in service can be estimated.
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  • Takahiko TANAHASHI
    1993 Volume 79 Issue 2 Pages N91-N102
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
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  • Katsuhiro IMAZU
    1993 Volume 79 Issue 2 Pages N103-N110
    Published: February 01, 1993
    Released: June 30, 2009
    JOURNALS FREE ACCESS
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