Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 73 , Issue 6
Showing 1-21 articles out of 21 articles from the selected issue
  • Kazuhiro Sylvester GOTO
    1987 Volume 73 Issue 6 Pages 585-595
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Hiroshi TAMURA, Noboru KATOH
    1987 Volume 73 Issue 6 Pages 596-608
    Published: April 01, 1987
    Released: June 19, 2009
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  • Akira KOJIMA, Sugio OTANI
    1987 Volume 73 Issue 6 Pages 609-615
    Published: April 01, 1987
    Released: June 19, 2009
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  • Keiji IBA
    1987 Volume 73 Issue 6 Pages 616-628
    Published: April 01, 1987
    Released: June 19, 2009
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  • Jun FUKAI, Takatoshi MIURA, Shigemori OHTANI
    1987 Volume 73 Issue 6 Pages 629-636
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    A heat transfer model of the coke oven chamber is proposed considering the radiation within the macro fissures in the coke and the convection of the product gas.Contributions of the radiation and convection to the temperature distribution in the coke oven chamber are numerically observed under the various conditions concerning the fissure width and the direction of the gas flow. As a result, it is found that both of them cannot be neglected in the heat transfer analysis in the coke oven chamber since they have the significant effects on the temperature distribution.
    By using a newly proposed thermal property estimation method, the thermal conductivity and the heat capacity of coal are estimated from temperature distribution computed by the model mentioned above.Thermal properties of coal which are estimated from the temperature history in the coke oven chamber are suggested to be much different from the true values and to have no generality.
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  • Chisato YAMAGATA, Yoshimasa KAJIWARA, Shinichi SUYAMA
    1987 Volume 73 Issue 6 Pages 637-644
    Published: April 01, 1987
    Released: June 19, 2009
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    In order to clarify the mechanism of the transformation reaction of SiO2 in coke ash under operating conditions in blast furnace, fundamental experiments were performed with single coke particle as sample under gas flowing condition by the use of a pressurized high frequency furnace.Based on the experimental results, an unsteady state mathematical simulation model with consideration of the radial distribution was developed and applied to the quantitative evaluation of the transformation reaction of SiO2 in coke ash.
    The following knowledge was obtained.
    1) Reaction rate constants for both SiO gas generation reaction (k1) and SiC formation reaction (k2) were obtained in the temperature range of 1350-1650°C.
    2) The influences of total pressure, CO gas partial pressure and coke size on the transformation reaction can be quantitatively evaluated by the use of the simulation model.
    3) In the actual operation, both the decrease of coke temperature, in other words, flame temperature, and the increase of coke size in the lower part of blast furnace are effective for the restraint of SiO gas generation reaction.
    4) The behavior of SiO2 in coke ash in the lower part of blast furnace was estimated.
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  • Mitsuhiko NISHIMURA, Masamichi KOJIMA, Morikatsu SAKURADA, Hideki ISHI ...
    1987 Volume 73 Issue 6 Pages 645-652
    Published: April 01, 1987
    Released: May 07, 2010
    JOURNALS FREE ACCESS
    Decarburization of pretreated hot metal with less slag was studied by use of a 10 t ladle type travelling furnace based on a new idea. The characteristics of refining and the mechanism of post combustion of off gas were discussed.
    (1) In spite of deep bath (L0/D= 1.0) in the furnace, molten steel was not overoxidized in the case that the flow rate of argon blown from the bottom was more than 0.05 Nm3/min·t with super soft oxygen top blowing (L≅100 mm).
    (2) In this method, the post combustion ratio (CO2/(CO+CO2)) was very high, so the high temperature rising, almost 200°C/%C, was obtained.This decarburization furnace had large flexibility for heat balance.
    (3) On post combustion, the parameter K (=(ΣiSi+αΣjSj')×3600/(FO2+ FO2')) was proposed and the mechanism could be explained by this parameter K on this ladle type furnace and the conventional top and bottom blowing converter.
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  • Hidetake ISHIKAWA, Chikara SAITO, Kenichi BABA, Mitsuhiko NISHIMURA, Y ...
    1987 Volume 73 Issue 6 Pages 653-660
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Charactristics of post-combustion and heat transfer both into the iron bath and into the furnace wall during the decarburization were studied using a 10 T ladle-type test furnace.
    From the results of heat balances, It was made clear that about 2030% of the heat of CO to CO2 combustion was not efficient for heating the bath and results in raising the exhaust gas temperature.
    The amount of heat transfered into the wall from the high temperature gas was estimated both by the measurement of refractory temperature and by the mathematical calculations.As for the obvious increase in the transfered heat at higher post-combustion ratio, the observed value coincided well with calculated one.
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  • Masahiro KAWAKAMI, Koin ITO, Masaru OKUYAMA, Takuzo KIKUCHI, Shyunji S ...
    1987 Volume 73 Issue 6 Pages 661-668
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Argon and/or nitrogen was injected into molten pig iron through the bottom orifice.The experimental conditions are as follows : gas flow rate, 10-25Nl/min ; melt depth, 9-28cm temperature, 1400-1600°C.
    The absorption rate from pure nitrogen was controlled by the mass transfer in metal phase.When Ar-N2 gas mixture was injected, however, the absorption rate was controlled by the mass transfer in gas phase.The desorption rate of nitrogen by pure argon was controlled by the gaseous mass transfer.
    The volumetric rate constant, which is defined as the mass transfer coefficient multiplied by the total interfacial area between bubbles and molten iron, was obtained in different conditions.The rate constant for the gaseous mass transfer, Akg, increased linearly with the gas flow rate and the melt depth.The apparent activation energy was 64kcal/mol.The rate constant for the mass transfer in metal phase, Akm, increased proportionally to 0.65 power of the gas flow rate, and linearly with the melt depth.The apparent activation energy was 43kcal/mol.Akm/H obtained in the present work was compared with the published data, including not only those of nitrogen transfer, but also of oxygen transfer between bubbles and molten copper and silver.
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  • Ikuo SAWADA, Tetsuro OHASHI
    1987 Volume 73 Issue 6 Pages 669-676
    Published: April 01, 1987
    Released: June 19, 2009
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    The numerical simulation of the fluid flow in the bottom-gas blowing ladle was conducted by the use of the two phase model.In the model not only the balances of mass, momentum and turbulent characteristics k and ε in metal phase but also those of mass and momentum in gas phase are taken into account.
    The accuracy of the calculation was confirmed by the comparison of the flow velocities and turbulent kinetic energies between the calculation and the measurement in a water model test using the laser doppler anemometer.
    The mean velocities in the plume zone where both metal and gas went up were expressed as a function of Froude number and the aspect ratio of molten bath.
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  • Shin-ya KITAMURA, Ko MIYAMURA, Isahiro FUKUOKA
    1987 Volume 73 Issue 6 Pages 677-683
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Distribution of Ca-oxide, Ca-sulfide and MnS in Ca-added CC slabs has been investigated by new X-ray microanalyser (CMA).Although the relation between the amount of MnS and ACR and ESSP which had been proposed as parameters indicating the degree of shape control was found, it was not quite satisfactory since MnS formation was observed to be suppressed by Ca addition even in the slab in which oxygen content was too high to form CaS according to the ACR or ESSP concept.
    On the other hand, calcium-aluminate inclusions were found to be classified into the following two types:
    i) Ca+O type ; Calcium-aluminate covered by thin S enriched zone.
    ii) Ca+S type ; Calcium-aluminate enriched by S in the whole region.
    The Ca+S type inclusions were mainly observed in the segregated area.
    A thermodynamical consideration as well as the above experimental results revealed that the desulfurization by calcium-aluminate during the solidification had the dominent importance in the shape controlling mechanism.This desulfurization mechanism by calcium-aluminate inclusions qualitatively explains the above descrived deviation of the experimental results from the prediction by ACR or ESSP concept.
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  • Tadayoshi WADA, Masaji HONDA
    1987 Volume 73 Issue 6 Pages 684-690
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    This work was carried out to obtain the information on the function of mould coatings most necessary to reduce surface defects in ingots.
    Thermobalance and differential thermal analyses and small scale casting experiments were carried out so that splash boxes and splash like scabs could be related to the thermal decomposition temperature of mould coatings.
    It is concluded that water soluble resin coatings cause so called rolling reaction of hot metal at the first stage of pouring and promote a smooth hot metal rise in the moulds and ingot surfaces appear to be the best.Coal tar and graphite of low and high thermal decomposition temperature are the causes of many surface defects in ingots.
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  • Yoshihiro OHKOMORI, Ikuziro KITAGAWA, Keigo SHINOZUKA, Ritsuzo MIYAMOT ...
    1987 Volume 73 Issue 6 Pages 691-698
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Spalling phenomena of backup roll of a hot strip mill and their prevention are discussed.Most of spalling phenomena are attributable to either of the following two causes.
    1) Excessive fatigue, which occurs mainly at barrel edges due to an increased contact stress resulting from uneven local wear of a roll barrel.
    2) A surface crack which is caused by a thermal shock resulting from a mill accident or roll-slip and by propagation of still remaining cracks after dressing.
    Accordingly, prevention of spalling should be achieved by both of improved roll property and proper maintenance.The results of the experiments in laboratory and the actual mill operation showed that wear resistance and fatigue property were improved by increasing C and Cr contents and hardness of roll.And it was revealed that reduction of undissolved carbide was effective to improve thermal shock resistance, KIC and fatigue property.Backup roll specifications, however, should be made with consideration of the mill conditions such as operating condition, material and hardness of work roll.Roll maintenance also is important.Detection and perfect removal of a surface crack is essential, in addition to proper dressing depending on the mill conditions.
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  • Nobuo SHIKANAI, Hisatoshi TAGAWA, Junichi TANAKA
    1987 Volume 73 Issue 6 Pages 699-706
    Published: April 01, 1987
    Released: June 19, 2009
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    The influence of grain size on the yield strength at moderate temperature in ferrite-pearlite steels was studied with paying attention to the ky value in the Petch equation.The lower yield stress of a ferrite-pearlite steel has been considered to depend on the grain size, and is estimated by the Petch equation.The ky value in the Petch equation is considered as the value which ralates with the dislocation mobility and the Pierce-force.The ky value is reported to be constant as 2.2kgf/mm2/mm-1/2 below the room temperature.On the other hand, the investigation on ky above the room temperature has not been reported.The authors have verified that the ky value decreased with the increase in temperature above the room temperature.The temperature dependence of ky is clasified to four ranges between 25°C and 550°C.The dependence can be explained by the decrease in pinning force of dislocations by carbon and nitrogen, the active multification of dislocations, and I.S.(Interstitial-Substitutional) effect.
    The ky value becomes negative, when the grain boundary sliding occurs because of the creep phenomenon under the lower strain rate at relatively high temperatures.The ky value can not become negative without the creep phenomenon, but the ky value approaches to zero.
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  • Saburo MATSUOKA, Masuo SHIMODAIRA, Hiroyuki MASUDA, Etsuo TAKEUCHI, Sa ...
    1987 Volume 73 Issue 6 Pages 707-714
    Published: April 01, 1987
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    Low-rate fatigue crack propagation properties in sodium chloride solution were investigated for carbon steel S45C, high-strength steels SM 50B and HT 80 and stainless steels SUS 403 and SUS 304.Tests were conducted under the condition of decreasing ΔK where maximum load was kept constant and minimum load was increased with the increase of crack length.This constant Pmax test was confirmed to be a method free from crack closure, although the load ratio increased from 0.5 to 0.97.Low-rate fatigue crack propagation properties, obtained under closure-free condition, are summarized as follows.
    1) In air, fatigue crack propagation properties including the threshold, ΔKth, air, were independent of the kind of materials.The ΔKth, air values for the five steels were around 2.8MPa·m1, 2.
    2) In 3% sodium chloride solution under freely corroding condition at a frequency of 30Hz, fatigue crack propagation rates were also independent of the kind of materials and coincided with those in air when ΔKKth, air, When ΔKKth, air, the crack propagated at such low region of ΔK<1MPa·m1/2 that the threshold, ΔKth, corr, did not exist in practical sense for carbon and high-strength steels.ΔKth, corr, which was 70% of ΔKth, air, existed for stainless steels under the experimental conditions.
    3) Fatigue crack propagation properties including the threshold values for all the steels coupled with zinc anode in sodium chloride solution were coincident with those in air.
    4) Decreasing in frequency from 30 to 0.03Hz resulted in a sixfold acceleration of crack propagation rate regardless of materials and ΔK levels under freely corroding condition.
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  • Ritsu MIURA, Keizo OHNISHI, Hideo NAKAJIMA, Susumu SHIMAMOTO
    1987 Volume 73 Issue 6 Pages 715-722
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Effects of C and N contents on the tensile properties and deformation behaviors at low temperatures have been investigated to obtain an alloy design basis on SUS 304 and 316 austenitic stainless steels for cryogenic application.
    Increase in C and N contents led to the increase in temperature dependency of 0.2% yield strength for both SUS 304 and 316 steels. However, SUS 316 steel showed larger temperature dependency than SUS 304 at the same level of (C + N) content, probably due to the solution strengthening effect of Mo.
    The results of multiple regression analyses on the effects of C and N contents on the 0.2% yield strength at each temperature indicated that the contributions of both C and N increase with decreasing temperature and that the contribution of N is larger than that of C at low temperatures.
    The deformation behavior of metastable austenitic steels could be comprehensively explained in relation to austenite stability. Increase in austenite stability resulted in increase in onset strain at which strain-induced martensitic transformation occurred. And increase in austenite stability also led to the decrease in transformation rate which in turn gave rise to lowering strain-hardening exponent. It has been also found that tensile elongation shows maximum at around Md30 temperature.
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  • Koji SHIBATA, Toshio FUJITA
    1987 Volume 73 Issue 6 Pages 723-730
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Computer simulation of serrated plastic flow at very low temperatures has been investigated by comparing it with the deformation curves of Fe-Ni binary alloys obtained in some coolants such as liquid helium.Simulation was carried out by dividing a specimen into small elements and calculating repeatedly some equations concerning the amount of deformation and the temperature change of each element during a short period of time.The equations were derived basically from the thermally activated dislocation motion and from the heat balance among heats converted from mechanical work, conducted in a specimen and exchanged with the coolant.It was concluded that the behavior of the serration and the accompanied phenomena could be reproduced fairly well by the simulation which did not have unreasonable assumption, whereas details of dislocation motion at cryogenic temperatures has not been clarified.The effects of some factors on the serration were discussed by using the simulation.
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  • Yasuo FUJIOKA, Saburo OSHIMA, Hiroshi MURO
    1987 Volume 73 Issue 6 Pages 731-738
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    A new machining process, called auscutting, has been developed in which the cutting operation is performed in supercooled austenitic state during quenching.In order to realize a new manufacturing process for bearing races with auscutting, it is desired to obtain the satisfactory tool life.In this paper, from the viewpoint of the improvement on the tool life many factors which influence the tool life are examined and the methods for stabilizing and lengthening the tool life are considered.
    The results obtained are summarized as follows :
    1) The short-lived factors in auscutting are the vibration caused by the saw-toothed chip formation, a drop of the deflective strength of the tool material by high cutting temperature and the adhesion failure of the work material.The methods for improving the tool life are the improvement on the stiffness of machine parts such as the tool holder, the suitable cutting speed of about 100m/min and the increase of the nose radius of the tool.
    2) As the frequency of the saw-toothed chip formation is increased after the tool failed in auscutting, it is possible to detect the tool failure by the change of the vibration frequency.
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  • [in Japanese]
    1987 Volume 73 Issue 6 Pages 739-741
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1987 Volume 73 Issue 6 Pages 744-749
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese]
    1987 Volume 73 Issue 6 Pages 749-750
    Published: April 01, 1987
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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