Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 78 , Issue 8
Showing 1-16 articles out of 16 articles from the selected issue
  • Hirosi SANO
    1992 Volume 78 Issue 8 Pages 1275-1280
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
  • Jun-ichiro YAGI, Shinichi INABA
    1992 Volume 78 Issue 8 Pages 1281-1293
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
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  • Hajime KITAGAWA
    1992 Volume 78 Issue 8 Pages 1294-1304
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
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  • Takakazu SHINTOMI, Hajime ISHIMARU, Yoshinobu UNNO, Yasuo ARAI, Yoshiy ...
    1992 Volume 78 Issue 8 Pages 1305-1313
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
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  • Haruhisa IWAKIRI
    1992 Volume 78 Issue 8 Pages 1314-1321
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    Properties of coke which was carbonized at lower temperatures than in the conventional process were examined experimentally, and the possibility of its use in a blast furnace was discussed.
    The following results were obtained:
    (1) When coke was carbonized under the conditions of final coke temperature higher than 800°C and higher heating rate, the same level of coke strength as that of conventional coke was obtained.
    (2) The heating rate in the coal bed between 400°C and 500°C and the bulk density of charged coal controlled the pore structure, and were also important factors in determining coke qualities.
    (3) It was noticed that the coke qualities might be improved by heat treatment in a blast furnace before the occurrence of coke degradation by solution-loss reaction.
    (4) In order to obtain a higher heating rate in the coal bed, it was required that the chamber wall was constructed by the materials with high thermal-conductivity or that the thickness of chamber wall became thinner.
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  • Reiji ONO, Tetsuya GOTO, Junpei KIGUCHI, Ryuichi HORI, Keiji KUWANO
    1992 Volume 78 Issue 8 Pages 1322-1329
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    At Kakogawa Works of Kobe Steel, Ltd. a sinter plant and a pelletizing plant have been operated for pretreatment of ores and the ore are used for source of pellets or sinter according to the brand, grain size and chemical composition. This builds an extension to the variety of raw material. In future, as the ratio of fine ore in raw material increases, the importance of pelletizing is considered to increase. Therefore, to establish the predominance of pellets over sinter, advantages of not only cost but also applicability is needed.
    From this point of view, test operation was conducted for raising the mixing ratio of pellets from the conventional 35% to 70% at Kakogawa No. 2 blast furnace, where pulverized coal is continuously injected at 120 kg/t. By means of adjustment of burden distribution and mixing small coke into ore, the stable operation was continued with no conspicuous changes in the furnace condition.
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  • Ryuichi HORI, Hitoshi MIYATANI, Tetsuya GOTO, Reiji ONO, Yoshiyuki MAT ...
    1992 Volume 78 Issue 8 Pages 1330-1336
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    Use of small size sinter ore was investigated by the control of particle size distribution. Ore was divided in O I and O II, and particle size distribution was controled by each movable armor position.
    Pressure drop and temperature distribution in the furnace was evaluated by the mathematical model. Control of particle size distribution enables to keep good permeability as same as that of large size sinter by the calculation.
    At Kakogawa works, sinter plant screen and blast furnace ore bin screen was decreased from 5.0 mm to 3.0 mm. Movable armor was used in order to control particle size distribution and Blast furnace operation was kept stable.
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  • Toshirou SAWADA, Toshio UETANI, Shuichi TANIYOSHI, Masaharu MIYAGAWA, ...
    1992 Volume 78 Issue 8 Pages 1337-1344
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    No. 3 blast furnace (3rd campaign) equipped with 3 parallel bunker bell-less top, first in Japan, was blown in June 19th, 1990 at Mizushima Works, after revamping for 111 days.
    The characteristics of the charging system which strengthens the behavior discharging fine materials first and coarse materials later, are the segregation control plates to control burden surface profile in the bunkers, the multi batch charging facilities, and the two size fraction charging equipment for sinter.
    The new burden distribution control technique are described as follows.
    (1)The dynamic control of material flow rate during charging.
    (2)The two size fraction charging of sinter with short terrace.
    (3)The coke vertical charging aimed at simple control of ore/coke at central region.
    With the adaptions of improvements, the increase in the consumption of small size materials recycled from fines under screens was performed keeping high productivity.
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  • Michinori HATTORI, Bungo IINO, Akio SHIMOMURA, Hideaki TSUKIJI, Tatsur ...
    1992 Volume 78 Issue 8 Pages 1345-1352
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    The burden distribution model was indispensable so as to ensure smooth blow-in and stable operation with high productivity of Keihin No. 1 blast furnace, which is one of the largest blast furnaces with bell-less top. On the basis of the full scale model and 1/10 scale model experiments, the effect of enlargement of throw diameter on burden profile was analyzed. The behavior of the discharged material from the lower banker was also investigated. Considering these influences, the burden distribution model for Keihin No. 1 blast furnace was constructed. It has been successfully applied for the operation of Keihin No. 1 blast furnace with high productivity.
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  • Hiroyuki KATAYAMA, Takafumi KAWAMURA, Hiroshi HIRATA, Takamasa OHNO, K ...
    1992 Volume 78 Issue 8 Pages 1353-1360
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    One of the problems with the direct use of coals containing a high level of volatile matter (high VM coal) in a smelting reduction furnace is fragmentation. This leads to an increase of the amount of carbonaceous material which becomes dust when a high VM coal is used, to a level higher than 5% of the added fixed carbon, or a few times that when coke is used. In this paper, the simulation method of fragmentation and the influence of heating conditions on fragmentation were investigated and a pretreatment process for coal was considered.
    (1) The fragmentation of coal in a smelting reduction furnace could be simulated by a series in which there was the heating of coal, rotating it in a drum tester and calculating the consumption by reaction.
    (2) The influence of the heating condition on fragmentation was investigated by the simulation test. When high VM coal was heated at the temperature of 800-900°C, the volatile matter could be removed, as well as keeping fragmentation at a low level.
    (3) Based on above results, the char, which was produced by preheating a high VM coal in a rotary kiln, in which the highest temperature was 850°C, was used in 5 ton smelting reduction furnace. The amount of carbonaceous dust was decreased to almost the same level as with coke.
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  • Pan WEI, Ken-ichiro UEMURA, Shinji KOYAMA
    1992 Volume 78 Issue 8 Pages 1361-1368
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    Cold model experiments have been done on entrapment of inclusions in steel by inert gas bubbles. A water-air system has been adopted and the teflon, polystyrene, polyethylene, polypropylene and polycarbonate particles( dia.= 100800 μm, ρp= 0.892.2 g/cm3) were used in the experiments. The collision-trapping rates V(np/cm3s) of various particles with bubbles were measured, and the effects of water-particle contact angle, φ, the particle diameter, dp, the bubble diameter, db, the particle density, ρp and the frequency of bubble which passed through a unit volume of water have been investigated.
    It is found that V increased with increasing φ, and there is a critical φc above which the V is independent of φ, and in this case the bubble surface resistance can be neglected in the collision-trapping process.
    The particle mass transfer coefficients k (cm/s) have been measured under the condition that the surface resistance could be neglected, and an equation of the relation between k and db, dp and ρp has been obtained.
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  • Hideo MIZUKAMI, Toshio SUZUKI, Takateru UMEDA
    1992 Volume 78 Issue 8 Pages 1369-1376
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    Initial solidification structure of stainless steel droplets has been investigated in relation to mold temperature and pouring temperature. Results of present experiments are compared with the previous ones which are related to surface roughness and surface materials of subtrates and pouring temperature. On the onset of the solidification, undercooling is observed under various casting conditions. The undercooling at the initial solidification depends only on cooling rate, and has a linear dependence on cooling rate. Initial solidification length which corresponds to the region of cellular structure increases, but primary arm spacing and surface grain size decreases with increasing cooling rate. There exists the critical cooling rate at which a primary phase changed from δ phase to γ phase, and the value of the critical cooling rate is estimated to be about 0.5 × 104 Ks-1. The morphology of solidification structure is cellular for primary γ phase and dendritic for primary δ phase. The results indicate that the initial solidification structure is controllable by changing the cooling rate.
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  • Hisakazu EZAKI, Masahiko MORINAGA, Katsunori KUSUNOKI, Yutaka TSUCHIDA
    1992 Volume 78 Issue 8 Pages 1377-1382
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    A new method has been proposed for predicting the phase stability of Cr-Mo-(V-Nb) ferritic steels on the basis of an electron theory. In this method, employed is a parameter Md which is the d-orbital energy level of a transition metal element in the steel obtained by the molecular orbital calculation of bcc Fe cluster. By defining the compositional average of the parameter as Md, the trend of formation is predicted of the δ ferrite and the Laves phase (Fe2Mo) in ferritic steels. These second phases are found to be formed in the steels if the Md exceeds a certain critical value. This prediction method is useful for the design and development of ferritic steels.
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  • Shinji FUSHIMI, Saburo SHIMAMURA
    1992 Volume 78 Issue 8 Pages 1383-1390
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    In the previous report, basic tests conducted on test pieces revealed the possibility of improvement of bevel gear strength through the combined application of carburizing and forge-quenching.
    A study was then made of suitable manufacturing conditions including the blank shape, die shape and forging temperature, and metallurgical structures and mechanical properties were examined.
    The following results were obtained in carburized, forge-quenched gears and bevel gears that were by conventional process. (1) Bevel gear strength was reduced due to increased surface roughness as a result of oxidation when gears were forged at temperatures over 1050°C. (2) Low cycle fatigue life of the gear corner R of tooth root was 100 times longer at a forging temperature of 1050°C, but 40 times longer at forging temperatures of 850 or 950°C. (3) The bending fatigue limit of the corner R of tooth root was 40% higher at a forging temperature of 850°C, but 20% higher at 1050°C. (4) Gear accuracy was nearly equal to that of gears manufactured by a conventional machining process.
    The results of these tests have led to the development of higher fatigue strength bevel gears.
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  • Kenichi USAMI, Hiroshi TAKAYASU, Kohji SATO, Yutaka FUKUI, Joshiro SAT ...
    1992 Volume 78 Issue 8 Pages 1391-1397
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    Metallography, hardness, cavitation erosion weight loss, and silt erosion weight loss were examined for austenitic steel and SiC powder prepared by the plasma welding method, SiC content powder varied from 0 to 15 wt%. The resistance was improved with an increase of SiC content. According to EDX analysis, Si, Ni, and Co were found in matrix and Cr, Mo, and Fe were found in precipitates. It is suggested that SiC is decomposed during melting and C forms new carbide with Cr, Mo, Fe. The reaction may cause the improvement of cavitation and silt erosion resistance.
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  • Manabu NISHIMOTO, Wataru TAKAHASHI, Yoshiaki SHIDA
    1992 Volume 78 Issue 8 Pages 1398-1405
    Published: August 01, 1992
    Released: May 29, 2009
    JOURNALS FREE ACCESS
    High temperature deformation of pure titanium, (α+β) and β titanium alloys were studied by means of compression tests over the range of strain rate from 10-1s-1to 10-3 s-1 and at temperatures between 973 K and 1473 K, and the results obtained were analysed by using Zener-Hollomon parameter (Z).
    The following results were obtained ;
    (1) Maximum flow stress, σmax, was correlated with working temperature, T, and strain rate, ε, approximately by the following deformation equation;
    Z(=ε exp(Q/RT))=A(sin h(ασmax))n
    whereQ: hot-working activation energy, n: stress exponent, R: gas constant, A and a: constants.
    (2)The value of Q in α+β phase was much larger than that in β phase. So the deformation mechanism in α+β phase must be different from that in β phase. The value of Q in β Ti was almost the same as the activation energy for the self-diffusion of Ti.
    (3) Deformation structure became to equiaxed microstructure by continuous recrystallization in the range of Z less than the critical value, Zc. The recrystallized grain size was determined only by the deformation condition Z, and did not depend on the initial grain size.
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