Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 66 , Issue 1
Showing 1-16 articles out of 16 articles from the selected issue
  • [in Japanese], Tsuneyo IKI
    1980 Volume 66 Issue 1 Pages 1-22
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Shin-ichi KUROZU, Reijiro TAKAHASHI, Yoshikazu TAKAHASHI
    1980 Volume 66 Issue 1 Pages 23-32
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    In order to obtain the reduction rate equation and the rate parameters of iron oxide pellet at high pressure, a single iron oxide pellet was reduced with hydrogen at pressure up to 13 atomospheres in the temperature range of 800 to 1000°C. The reduction rate equation was derived from the three-interface core model.
    The reduction rate increased by a pressure increase, but was found to be constant at about 5 atomospheres. The various rate parameters were determined by the method of data fitting based on the observed data. The calculated reduction curves based on the rate equation almost coincided with observed data under various temperatures and pressures. And also, the reaction interfaces observed from the partially reduced pellets were nearly consistent with the caluculated values. It was found from these results that the reduction rate equation in this paper could be applied to the analysis of the rate of reduction with mixtures of hydrogen and carbon monoxide at high pressures.
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  • Hakaru NAKATO, Iwao MUCHI
    1980 Volume 66 Issue 1 Pages 33-42
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Mathematical model for predicting the temperature field in the continuous casting mold is developed by taking account of the properties of casting powder.
    Heat flux in the mold calculated with the aid of this model is found to be similar to the observed result except in the vicinity of the meniscus and at the lower part of the mold.
    Calculated values of the average heat flux are in good agreement with the data observed at the various withdrawal speeds ranging from 0.8 to 1.5 m/min and by use of the various kinds of powder.
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  • Kantaro SASAKI, Yasuo SUGITANI, Susumu ISHIMURA
    1980 Volume 66 Issue 1 Pages 43-52
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The major factors affecting the formation of the centerline segregation in continuously cast slabs (CC slabs) and slab-shaped ingots were investigated.
    The results obtained are summarized as follows.
    (1) The centerline segregation in a regular CC slab is much remarkable than that of a slab-shaped ingot; the latter has the solidification structures analogous to those of the former. This result shows that the effect of the solidification shrinkage on the centerline segregation of CC slabs is small.
    (2) The centerline segregation of CC slabs becomes more remarkable as the crater becomes deeper.
    (3) The centerline segregation of CC slabs solidified stationarily in the secondary cooling zone is much slighter than that of the regular CC slabs.
    (4) The segregation band of CC slabs consists of a lot of small segregated spots with microporosities and Mn-sulfides, where the microsegregation is much remarkable than that of the columnar dentritic zones and both the clear dentrites with the smaller secondary arm spacing and the obscure dendrites are recognized.
    (5) The major factor affecting the centerline segregation of CC slab is believed to be the mechanical deformation (bulging of slab by the miss alignment etc.) at the final stage of the solidification where only the mashy zone remains.
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  • Kantaro SASAKI, Yasuo SUGITANI, Susumu ISHIMURA
    1980 Volume 66 Issue 1 Pages 53-62
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The influence of the bulging on the formation of the centerline segregation in continuously cast slabs (CC slabs) was investigated with the following experimental method. Experimental continuously cast slabs (experimental CC slabs) with a section of 130 mm×400 mm were cast continuously to the length of 2.5 m and bulged during solidification by compressed nitrogen gas from the meniscus under various conditions.
    The results obtained are summarized as follows.
    (1) The centerline segregation of the experimental CC slabs without bulging is very slight.
    (2) The degree of the centerline segregation is significantly influenced by the bulging conditions.
    (a) The centerline segregation, nearly equal to that of the regular CC slabs, is generated by the bulging of 45 mm at the final stage of the solidification, where only the mashy zone remains, even if the experimental CC slab is bulged once.
    (b) The remarkable centerline segregation is not recognized even if the bulging of 46 mm is repeated when the enough residual liquid remains.
    (c) Even if the equiaxed zone is thick, the centerline segregation is generated remarkably in the case of the condition as in (a) above.
    (3) The centerline segregation, nearly equal to that of the regular CC slabs, is the result of the accumulation of the enriched interdendritic liquid with the solid fraction from zero to 0.5. The accumulation is generated by the absorption effect formed by bulging at the final stage of the soldification where only the mashy zone remains.
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  • Kazutoshi KUNISHIGE, Tamotsu HASHIMOTO, Teruo YUKITOSHI
    1980 Volume 66 Issue 1 Pages 63-72
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The purpose of the present study is to investigate the effect of precipitation hardening on the properties of HSLA (high strength low alloy) controlled rolled steels containing vanadium and/or niobium.
    Laboratory tests were carried out under various conditions of controlled rolling and heat treatment. Also, thermomechanical treatments such as direct quenching and tempering, rolling and tempering in conjunction with rolling conditions were studied.
    The results revealed that there were two types of precipitation hardening. That is, the one which is called "secondary hardening" is accompanied by a large loss in toughness and the other called "dispersion hardening" is accompanied by little loss in toughness. The secondary hardening is attributable to fine coherent precipitates formed in the lower temperature range of ferrite region. On the other hand, the dispersion hardening is attributable to fine incoherent precipitates induced by strain in the lower temperature range of austenite region and/or in the high temperature range of ferrite region. The controlled rolling is supposed to accelerate the latter, while suppressing the former.
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  • Chuzo SUDO, Toshio NAKAMORI, Minoru NISHIHARA
    1980 Volume 66 Issue 1 Pages 73-81
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The behavior of coating films during the press forming are investigated on some kinds of surface treated steel sheets for autobody panels. It is observed that the plastic deformation causes the damages of the film such as the cracking or the flaking and the corrosion resistance decreases. The mechanisms of these phenomena are also systematically investigated.
    It has been found that the flaking depends on the deformation modes such as a stretch forming or a shrink flanging and its dependency is unique to the type of the coating. "Flaking Limit-Strain Diagram" was presented for a expression of coating characteristics.
    The decrease of corrosion resistance after forming is generally due to the loss of coating weight or the surface damage during the deformation. In the galvanized coating which has the sacrificial corrosion effect, the lowering of corrosion resistance is dominated by the loss of coating weight, and it is concluded that the severity of the forming can be evaluated by the reduction in thickness. In the paint coating, that lowering is mainly dominated by the cracking or the flaking of the film. In the material for this experiment, the severity is evaluated by the equivalent strain occurring on the surface.
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  • Ik-min PARK, Kentaro ASAKURA, Toshio FUJITA, Juro WATANABE
    1980 Volume 66 Issue 1 Pages 82-91
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The beneficial characteristic of vacuum carbon deoxidized low-Si steels, in which macro-segregation in large ingots was hardly observed, was applied to a 12Cr heat resisting steel. The studies on the microstructures and creep rupture properties for a low Si-12Cr-1.5Mo-0.2V-0.05Nb steel after various heat treatments were carried out. The creep recovery process, the precipitation characteristics of M23C6, and the dissolution and agglomeration of the fine precipitates was investigated by the aid of transmission electron microscope. Furthermore, the effects of prior tempering temperature and creep stress on the microstructures and mechanical properties were also investigated.
    This steel exhibits a creep rupture strength 1.4 times higher than that of the conventional super 12Cr rotor steels. The austenitizing temperature effective for the long term creep strength was found to be in the range of 1050°C-1100°C and optimum prior tempering temperature was about 700°C.
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  • Ei-ichi FURUBAYASHI, Masato ENOMOTO
    1980 Volume 66 Issue 1 Pages 92-101
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    An Fe-16%Ni-4%Si alloy having a large hardenability due to a maraging mechanism was used to study the effect of microstructures prior to aging upon the strength properties under a tensile test. In contrast to the conventional solution treatment for maraging steels in the γ field, the present alloy was cold rolled by 80% at a martensite state (marforming) and annealed at the temperatures in the α+γ two-phase range before aging, in an attempt to obtain microduplex structures showing a good combination of strength and toughness.
    The marforming was found to increase both the tensile strength, σu, and the reduction of area, ψ, due to the formation of proper duplex structures. In case, annealing was made at the temperatures around 570°C, large uniform elongation, εu, was observed due to a transformation plasticity of austenite which was formed on the annealing and would be rich in Ni, but the strength, σu=120 kg/mm2, was rather low. In case, annealing was carried out at the temperatures from 600 to 650°C (still in the two-phase field), the reverted austenite was transformed on cooling into martensite which in turn was strengthened by aging proportionally to the martensite fraction; the resultant duplex structure had a strength of σu=158 kg/mm2, and a plasticity of ψ=27% and εu =1%, which were better than thd combination, σu=132 kg/mm2, ψ=25% and εu=1% in the same alloy that was conventionally age-hardened without marforming and annealing.
    The marforming had a dominant effect on the reduction of transgranular brittle fracture as well as intergranular fracture associated with large austenite grains which had been present prior to the annealing in the two-phase range.
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  • Osamu HASHIMOTO, Susumu SATOH, Tomo TANAKA
    1980 Volume 66 Issue 1 Pages 102-111
    Published: January 01, 1980
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    For the purpose of investigating the formation mechanism of the texture which is developed by ferrite (α)→austenite (γ)→ferrite (α) transformation, the effects of heating and cooling rates during phase transformation and specimen thickness on the transformation texture have been studied by using extra low carbon sheet steel with the initial texture of {111}.
    The results obtained are summarized in the following: (1) Rapid heating and rapid cooling produced weak {100} and {111} texture. (2) Rapid heating and slow cooling exhibited both {110} texture and the orientation shifted 2030 degrees away from {100}. (3) Slow heating and slow cooling produced distinct {100} texture. (4) There was much difference in texture between surface and midsection of thick specimen: In the midsection, the texture similar to (1) was formed, independent of heating and cooling rates. While, specimen surface exhibited such textures as (1) to (3). (5) Those results were reasonably and consistently explained on the assumptions that the orientation relationship between bcc and fcc follows the Kurdjumov-Sachs relation, and that during α→γ→α transformation with slow rate such variants preferentially operate that undergo larger elastic work in normal direction of sheet.
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  • Osamu HASHIMOTO, Susumu SATOH, Tomo TANAKA
    1980 Volume 66 Issue 1 Pages 112-121
    Published: January 01, 1980
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    By using low and extra low carbon sheet steels with the initial texture of {111}, {110}, or {100}, the effect of transformation condition has been investigated on the texture developed by ferrite (α)→austenite (γ)→ferrite (α) transformation. (1) In specimens with the {111} texture, slow heating to transformation temperature produced {100} texture, whereas rapid heating gave the texture consisting of {110} and orientations shifted away 20 to 30 degrees from {100}. (2) Rapid heating gave {100} texture as far as transformation was performed for long-duration of time as high temperature. (3) The before-mentioned results did not change with variation in annealing atomosphere. (4) In specimens with the {100} texture, slow heating and rapid heating produced respectively {100} texture and the texture consisting of {110} orientation and that shifted away 20 to 30 degrees from {100}. (5) In specimens with the {110} texture, slow heating produced {110} texture, while rapid heating gave {100} texture. (6) To explain these experimental results explicitly and consistently, the new theory on the transformation texture was proposed: Such variants with the Kurdjumov-Sachs relation that undergo larger elastic work in normal direction of sheet tend to operate preferentially with decreasing rate of traransformation.
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  • Taro TAKEYAMA, Soumei OHNUKI, Heishichiro TAKAHASHI
    1980 Volume 66 Issue 1 Pages 122-128
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The interaction between solute atoms and defects was studied by means of tensile test and transmission electron microscopy. The defects were produced by neutron irradiation at 200°C to a fluence of 6.4×1018 n/cm2 (En>1 MeV) and electron irradiation at 650 kV electron microscope to a fluence of 7×1021 e/cm2.
    Radiation hardening and radiation embrittlement occured by neutron irradiation. The yield stress increased and the total elongation decreased with the increase of manganese content. Dislocation loops were observed on iron, but they were not detected on manganese alloys. Therefore, it will be considered that the defects would be trapped by manganese atoms and then formed complex with carbon atoms. On electron irradiation defects were not observed also on the manganese alloys, however, the defect clusters, presumably interstitial type, appeared above 325°C and grew during post-irradiation annealing. The annealing behavior was similar for the neutron and electron irradiated specimens.
    The radiation hardening could be explained as that manganese atoms trap carbon atoms and interstitial atoms during irradiation and then form fine complexes, which would act as the obstacles for dislocation motion.
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  • [in Japanese], [in Japanese]
    1980 Volume 66 Issue 1 Pages 129
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Tsugi KOIKE
    1980 Volume 66 Issue 1 Pages 130-137
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • W-K. Lu, [in Japanese]
    1980 Volume 66 Issue 1 Pages 138-145
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1980 Volume 66 Issue 1 Pages 153-161
    Published: January 01, 1980
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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