Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
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Volume 88, Issue 3
Displaying 1-8 of 8 articles from this issue
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  • Overview of Near-net-shape Continuous Casting for Steel Sheet
    Tadao WATANABE
    2002 Volume 88 Issue 3 Pages 107-116
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_107
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    Current status and technologies on the near-net-shape continuous casting for steel sheet are reviewed. Thin slab continuous casting and compact rolling process is economically acceptable and has become pretty popular for the last 10 years. High quality applications will be the key to further expansion of this process. The twin-roll strip continuous casting process for austenitic stainless steels has been commercialized recently. The key process parameters determining the casting regurality and the product quality have been assessed. However it will take some time to expand the strip casting process, because it remains to be seen if the technology is economically feasible.
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  • Fundamental Properties of Cementite and Their Present Understanding
    Minoru UMEMOTO, Koichi TSUCHIYA
    2002 Volume 88 Issue 3 Pages 117-128
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_117
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    The fundamental properties of cementite (Fe3C) in the literatures have been reviewed. The nonisotropic crystal structure of cementite and its effect on the mechanical and physical properties were presented. The effect of annealing temperature and alloying content on the lattice parameters has been summarized. The thermodynamics of cementite such as specific heat, formation free energy were discussed to show the metastability of cementite. The engineering importance and thermodynamical stability of alloyed cementite was discussed. Finally the mechanical properties (elastic constants, hardness and strength), thermal properties (thermal expansion) and electrical and magnetic properties (electrical resistivity and saturation magnetization) of cementite have been presented.
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  • The Effect of Pressure in the Atmosphere on Desulfurization of Hot Metal and Reaction Mechanism with Magnesium
    Seiji HOSOHARA, Yoshiei KATO, Hakaru NAKATO, Ken-ichi SORIMACHI
    2002 Volume 88 Issue 3 Pages 129-135
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_129
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    Experimental and theoretical studies were carried out to clarify the effect of pressure in the atmosphere on desulfurization of hot metal and reaction mechanism with magnesium (Mg). Desulfurization rate and the efficiency of Mg supplied for desulfurization were increased with the increase in the pressure. The pressurization from 0.098 MPa to 0.294 MPa improves the efficiency of Mg supplied for desulfurization by 13%.
    The rate determining steps for desulfurization were theoretically analyzed and compared with the experimental data. At the early stage of treatment in the region of low [Mg] and high [S], desulfurization rate is controlled by diffusion of Mg. At the final stage of treatment in the region of high [Mg] and low [S], the rate determining step for desulfurization changes to the diffusion of sulfur in hot metal.
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  • Reaction between Iron and Solid Zinc through Thin Fe-Al Alloy Layer
    Yoshinori WAKAMATSU, Daisaku TOMITA, Yasushi KAJI, Masahiro YAMANE, Fu ...
    2002 Volume 88 Issue 3 Pages 136-141
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_136
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    Fe/FeAl/Zn diffusion couples having a thin Fe-Al alloy layer composed of Fe2Al5, FeAl2 and α phases between Fe and Zn specimens were annealed at 673K for various time. Formation and growth kinetics of Fe-Zn alloy layer were investigated. ζ(FeZn13) phase formed between Zn specimen and the Fe-Al alloy layer after a certain incubation period, the length of which increased with increasing thickness of the Fe-Al alloy layer. The Fe-Al alloy layer was consumed and penetrated by ζ phase and then δ1(FeZn7) phase appeared between ζ phase and Fe specimen after disappearance of the Fe-Al alloy layer. It appears that Fe-Zn alloy layer is formed by reaction of Zn atoms with Fe atoms supplied through the Fe-Al alloy layer from Fe specimen.
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  • Influence of Thermal History on Surface Hot-shortness of Cu-Sn Bearing Steel
    Masaharu HATANO, Kazutoshi KUNISHIGE, Yuichi KOMIZO
    2002 Volume 88 Issue 3 Pages 142-147
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_142
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    The influence of thermal history on the surface hot-shortness of 0.3%Cu-0.05%Sn bearing steel was investigated in this paper. Surface hot-shortness was assessed by measuring the number of surface cracks occurring in the specimens which were held at 950 to 1200°C for 5 to 30 min after 1250°C heating in air, which were given 40% tensile-deformation at 1100°C in Ar gas atmosphere. The microstructure at the scale/steel interface was closely observed and the effect of Cu(Sn) on the surface hot-shortness was discussed.
    Surface cracks occurred in the specimens which were held at 1200°C for 5 min and the number of surface cracks decreased in the specimens which were held for 10 to 30 min. At 1100°C, however, the number of surface cracks increased in the specimens which were held for 10 to 30 min. Cu(Sn) enriched alloy was observed at the scale/steel interface in the specimens where the number of surface cracks increased. In addition, Cu(Sn) concentrated film was observed at austenite grain boundaries.
    The hot shortness is estimated to result from the liquid film of Cu(Sn) being precipitated at grain boundaries and its growth during cooling along with Fe-Cu phase diagram. The effect of holding temperature and time on the hot shortness was explained in terms of ξwhich was introduced as a parameter indicating the severity of cracking caused by Cu(Sn) enriched liquid film at grain boundaries.
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  • Relationship between Thickness of Pancake Austenite and Thickness of Grain Boundary Ferrite
    Shiro TORIZUKA, Kotobu NAGAI
    2002 Volume 88 Issue 3 Pages 148-154
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_148
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    The grain boundary of the pancake austenite (γ) is a predominant nucleation site for ferrite (α). If the thickness of the pancake γ becomes small through deformation, the thickness of the α grains that are formed at the γ grain boundaries is also expected to become as small as the thickness of the pancake γ. On this basis, the relationship between the thickness of the pancake γ (THγ) and that of the grain boundary α (THα) is studied both experimentally and theoretically for a 0.16C-0.4Si-1.5Mn steel. When THγ is in the range of 30 to 300 μm, THα is 6-7 μm and independent of THγ. However, when THγ is less than 20 μm, THα decreases linearly with a decrease in THγ. Since the volume fraction of the pearlite is assumed to be 0.25, THα is expected to follow the relation THα<0.75THγ. The obtained relation was near THα= 0.375 THγ. The geometrical soft impingement is attributed to the decrease of THα.
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  • Effects of Cold Rolling Reduction on Secondary Recrystallization of Fe-3%Si Alloy
    Takahide SHIMAZU, Satoshi ARAI, Tomohiko SAKAI, Harushige TSUBAKINO
    2002 Volume 88 Issue 3 Pages 155-162
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_155
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    The principal subjects discussed in this paper are the effects of cold rolling reduction on secondary recrystallization and magnetic properties of Fe-3%Si alloy. One-stage cold rolling process, which is known as a production method of high permeability grain-oriented silicon steel containing AlN precipitates, induced very unstable secondary recrystallization with too high cold reduction above 87%. Sharp deterioration of magnetic properties because of high reduction is related to the presence of fine grains, which mean poorly oriented grains deviating widely from the {110}<001>grains. This incomplete secondary recrystallization is supposed to be caused by the steps as follows: The higher cold rolling reduction causes the weaker {110}<001> orientation in primary recrystallized texture, and the secondary recrystallization temperature increases. The surface grains coarsen prior to secondary recrystallization. The larger surface grains, which are poorly oriented, consume the subsurface grains of the {110}<001> nuclei. Therefore the more fine grains were observed in the finally annealed structure with the higher reduction.
    The two-stage cold rolling process was studied to clarify the effects of the first and second cold rolling reduction on secondary recrystallization. The second cold rolling affected magnetic properties rather than the first cold rolling in the two-stage cold rolling process.
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  • Development and Production of 10Cr1.5MoVNb Steel for Gas Turbine Compressor Disk
    Yoshikuni KADOYA, Ryotaro MAGOSHI, Yoshihiro OKAMOTO, Kazuhiro NAKATA
    2002 Volume 88 Issue 3 Pages 163-167
    Published: March 01, 2002
    Released on J-STAGE: June 19, 2009
    DOIhttps://doi.org/10.2355/tetsutohagane1955.88.3_163
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    Recently, gas turbine inlet temperature has been raised in order to improve thermal efficiency of power plant. The turbine inlet temperature of 1500°C has already been attained in the newly developed gas turbine. In case of the combined cycle power plant, optimization of compressor pressure ratio corresponding to the increase of turbine inlet temperature is required to improve the thermal efficiency. Development of higher creep strength material for disk, therefore, is needed to actualize higher thermal efficiency gas turbine. Alloy design based on 12% Cr steels indicated that the high purity 10Cr1.5Mo0.75NiVNbN steel is suitable to the compressor disks required to the advanced type gas turbine. A trial disk has successfully been manufactured with this steel from 800 mm dia. electroslag remelting (ESR) ingot. Several evaluation tests revealed good material properties which meet the requirements of advanced type gas turbine compressor disk, especially in toughness and creep rupture strength.
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