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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 63 (1977), No. 6

  • フオス随感

    pp. 899-900

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  • Model Experiment on the Permeability of Gas in the Shaft of a Blast Furnace

    pp. 901-908

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    The pressure drops caused by the flow of gas through the various packed beds were measured in order to obtain some information on the permeability of gas in the shaft of a blast furnace. The packed beds used in this study are (a) A-type bed or a bed packed with single sized materials (glass beads, alumina pellets, Marcona pellets, or coke), (b) B-type bed or a bed packed layer by layer with different sized materials, and (c) C-type bed or a bed composed of binary mixtures of materials with different size distributions. The results obtained are as follows: (1) The pressure drops for A-type bed were correlated by the equation, ΔpgcD2p3/LμU (1-∈) (1-∈) 2=6.8φcX0.8, where X=Re/ (1-∈), Re=DpUρ/μ, Dp=diameter of materials, L=length of the bed, U=superficial velocity of gas, gc=conversion factor, ρ=density of gas, μ=viscosity of gas, ∈=fractional voidage, and Δp=pressure drop. (2) The value of φc was unity in the range 300<X<8000 for spherical glass beads with smooth surface, which consisted with the value obtained by HICKS under the similar conditions, while the value for another materials was greater than unity. From this, it was satisfactory to consider the coefficient φc as the parameter due to the degree of surface roughness and the degree of distortion. (3) The pressure drops for both B-type and C-type beds could be estimated by means of the above equation, in which Dp and φc were calculated by the equations W/Dp=nΣi=1Wi/Dp, i, and W/φc=nΣi=1Wic, i, respectively, where W=weight of packing materials and i=number of layers or component of mixtures.
  • Influence of Pressure in Surrounding Atmosphere on the Cavity Formation by Gas Jet

    pp. 909-916

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    Through the modification of gas jet theory by BRADSHAW et al, a mathematical representation that is capable of expressing the influence of pressure in atmosphere has been proposed for the dynamic characteristic of gas jet. Experimental model tests gave also been conducted for the confirmation of the proposed model.
    The results are summarized as follows:
    (1) The mathematical model is found to give semi-quantitative agreement with results of experimental model tests.
    (2) The results of the model tests indicate that the gas jet under the reduced pressure transports the momentum to the liquid surface with less energy loss than that under the atmospheric pressure. The cavity gets, with the decrease of pressure in atmosphere, accordingly.
    (3) The approach outlined here seems to indicate an attractive suggestion for the understanding of the mass transfer in gas jet/liquid reaction.
  • Galvanostatic Polarization Measurements on a Soid Platinum-Alkali Silicate Melts

    pp. 917-925

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    Galvanostatic polarization measurements were made at 1350°C on a solid platinum-molten alkali silicate interface. From the analysis of the initial dccay up to 80μsec of the overpotential-time curves, the exchange current density has been determined as a function of the M2O/SiO2 molar ratio (M=Li, Na and K) and the oxygen partial pressure. (PO2=1, 0.21 and 0.03atm) The exchange current density has been found to increase with increasing the M2O/SiO2 molar ratio and the oxygen partial pressure. Subsequent decay up to 1msec, 10msec, 100msec, 1sec and 5sec- of the overpotential curves has been studied on the assumption that mass-transfer controls the rate of the oxygen discharge reaction. At the constant M2O/SiO2 molar ratio, the slope in the overpotential-square root of time plots has been shown to be inversely proportional to the square root of an oxygen pressure. It was also found that the product of the solubility of and the square root of the diffusivity of soluble oxygen and oxygen ion increases with the increase of the M2O/SiO2 molar ratio. The product also increases with changing M2O from Li2O to Na2O to K2O in this order at a constant M2O/SiO2 molar ratio.
  • Interdiffusion and Reaction Diffusion in the Fe-Mo System

    pp. 926-935

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    Interdiffusion and reaction diffusion in the Fe-Mo system were studied in the temperature range between 800 and 1400°C with diffusion couples of pure Fe/pure Mo and pure Fe/Mo alloy.
    Formation of three intermediate phases, ∈, R, and σ, were observed in the diffusion zone. However, the Laves phase, λ, could not be found. The layers of three intermediate phases were found to grow according to the parabolic law showing that the growth was by a diffusion process. The interdiffusion coefficients in the intermediate phases were also determined applying Heumann's method. Quantitative correlation between the activation energy for the layer growth determined by the temperature dependence of the rate constant and that of the interdiffusion was found in each phase.
    The interdiffusion coefficient in the α phase determined by the Matano analysis was found to decrease with increasing Mo content, at each temperature. The interdiffusion coefficient in the γ phase, Dγ, could be estimated from the interdiffusion coefficient in the α phase and the growth rate of the α phase and it was found that the temperature dependence of Dγ showed the Arrhenius relationship.
    The Kirkendall effect was observed in the diffusion couple of Fe-3.0at%Mo and Fe-7.0at%Mo alloys in the temperature range between 1100 and 1300°C, and it was found that the markers moved toward the Mo rich side. Deviation of the γ-loop determined by the concentration distribution in the diffusion couple from that in the equilibrium phase diagram was observed and turned out difficult to be quantitatively investigated at the present stage.
  • Dendrite Arm Spacing in Iron-Carbon-Chromium Alloys

    pp. 936-942

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    Dendrite arm spacings in unidirectionally solidified iron-carbon-chromium alloys with chromium and carbon less than 15% and 2%, respectively, were measured and discussed on the basis of the results for ironbase binary alloy described in the previous paper. The results obtained are as follows:
    1) Primary and secondary arm spacings in the iron-carbon-chromium alloys are inversely proportional to the square root and the cube one, respectively, of cooling rate in similar way as those in iron-base binary alloys.
    2) Primary arm spacings in the alloys which form γ-iron as the primary phase decrease with increasing the chromium content or with decreasing the carbon content, With the carbon content of the alloys less than the critical value below which the primary phase becomes δ-iron, the arm spacing becomes much larger than not would be expected from the extrapolation of data above the critical value.
    3) Secondary arm spacings decrease with increasing the carbon content or chromium content. They arc discontinuously varied by the change from δ-iron to γ-iron in the primary phase.
    4) It is shown that a parameter proposed in iron-base binary alloys as expressing the effect of alloying elements on dendrite arm spacings is determined from the ternary phase diagram and is also applicable to the ternary alloy.
  • Sulfur Equilibria in Molten Fe-La-S, Fe-Ti-S and Fe-Zr-S Systems

    pp. 943-952

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    Sulfur equilibria in molten Fe-La-S, Fe-Ti-S and Fe-Zr-S systems are determined by melting Fe-S alloy in an induction furnace with subsequent addition of desulfurizing element, La, Ti, and Zr under deoxidized argon. The possible reaction betweem the desulfurizing element in liquid iron and crucible material was prevented by lining of equilibrium sulfide (3mm thick) on alumina crucible in which the melt was contained. Activity of oxygen in the melt and total oxygen content were lowered by adding about 0.3% Al prior to the addition of the desulfurizing element, so that oxysulfide formation in the melt might be suppressed.
    The results obtained are summarized as follows:
    1) Equilibrium constants for desulfurizing reactions with LaS (s), TiS (s), or Zr3S4 (s) as the equilibrium phase are determined to be
    log KLa=-26000/T+8.98
    log KTi=-8000/T+4.02
    log KZr=-44100/T+19.5
    for T from 1818 to 1923K.
    2) Interaction parameters between the desulfurizing element and S are given by
    e (La) s=-18.3 (1883K), e (Ti) s=-0, 18 (1873K), e (Zr) s=-0.22 (1873K)
    3) Standard free energy change, ΔG°, for the reaction; La (1) =La is derived as
    ΔG°=30100-22.6T
    and that for TiS (s) and Zr3S4 (s) formation is also determined at 1873K to be -57 and -227kcal/mol, respectively.
    4) Applicability of the equation, given by SAKANO and SANO for the evaluation of ∈ (j) O, to that of ∈ (j) s in molten iron is examined, using the values of ∈ (La) s, ∈ (Ti) s, ∈ (Zr) s and ∈ (Ce) s determined by the authors, and verified to be valid even in the case of ∈ (J) s.
  • A Calorimetric Study of Heats of Mixing of Nickel or Cobalt Alloys

    pp. 953-961

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    The isothermal calorimeter previously reported was improved particularly by changing the heating system to the molybdenum winding heater. These improvements made it possible to measure the heats of mixing of nickel or cobalt alloys at 1450 to 1550°C under a controlled gas atmosphere.
    It was also observed that so called “Newton's law of cooling” was applicable to the calibration of the calorimeter at such higher temperature.
    The maximum heats of mixing of the Ni-Cu and the Co-Cu systems were 1035 and 2310 cal/g·atom, respectively. And the Ni-Cu system is considered to be the regular solution. The heats of mixing of theNi-Co system were very small, and this system could be treated as an ideal solution.
    The errors of those heats of mixing were estimated approximately as ±15%.
  • Fatigue Strength of Steels Composed of Two Phases

    pp. 962-970

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    Fatigue strength of two-uctile-phase steels is studied in order to clarify the effects of volume fraction of the harder phase (f), C*-value (=0.2% proof stress of the harder phase /0.2% proof stress of the softer phase), and shape of the harder phase grains on the fatigue strength. The alloys used are classified into three groups with various values of f: Fe-Cr-Ni alloys composed of austenite and ferrite (A), Fe-C steels composed of ferrite and martensite (C), and Fe-Cr-Ni alloys composed of austenite and martensite (D). The C*-value is changed by aging (A) or tempering (C). The mean grain size (d) of each alloy is adjusted to be nearly the same by heat treatment. The main results obtained are as follows:
    (1) When the shapes of grains (both of the harder phase and of the softer phase) are nearly spherical, the effects of f, C*-value, and d are as follows.
    (a) Effects of f when d is constant; Three regions are observed in the relation of the endurance limit (σW) vs f. Namely, according to an increase in f, σW hardly changes at first (lst region), then increases rapidly (2nd region) and again hardly changes (3rd region).
    (b) Effect of C*-value; When alloys belong to the 1st region, σW is independent of C*-value in the case of an alloy of the 2nd or 3rd region.
    (c) Effect of d; σW is estimated to increase with decreasing d, which plays an important role to obtain a two-phase alloy with excellent fatigue strength.
    (2) In case of thin plate-like grains of the harder phase, σW increases with an increase in f even if f is small. That is, the range of each region mentianed above changes by the shape of the harder phase.
    (3) The above conclusions (1) and (2) are explained qualitatively by the observed preferential path of fatigue crack growth.
  • Precipitation of Carbides and Nitrides Observed by Thermoelectric Power Measurement in Low Carbon Aluminum Killed Steel

    pp. 971-979

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    Ghanges in thermoelectric power and electrical resistivity during 10min/20°C isochranal annealing were observed in several quenched or cold rolled specimens of low carbon aluminum-killed steel. Annealing stages corresponding to the precipitation of metastable carbide, cementite, iron-nitride and aluminum-nitride could be followed by the thermoelectric power measurement with fairly good accuracy. In the quench-aging of the steel, a weak unidentified peak was detected around 380°C, which could not be found by the resistivity measurement. From a discussion on the abnormally high value of the ratio of thermoelectric power increment to resistivity decrement (-dS/dρ), it was postulated that the aging on heating from room temperature to-100°C immediately after cold rolling (70% reduction) was associated with dissociation of point defectnitrogen complexes to form AlN molecules. The value of (-dS/dρ) for the precipitation of iron-nitrides was estimated to be -1.8V·Ω-1cm-1deg-1. The 400-480°C stage in the isochronal annealing of the cold rolled specimen could be identified as due to pre-precipitation clustering of AlN, since the (-dS/dρ) value was approximately the same as that of the precipitation of hexagonal AlN (-0.47V·Ω-1cm-1deg-1).
  • Effect of Substitutional Solid Solution Elements (W, Mo, Al, Mn and Cu) on the High Temperature Strength of 17Cr-14Ni Austenitic Steel

    pp. 980-989

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    The effect of single addition of such solid solution elements as W, Mo, Al, Mn and Cu on the creep and creep rupture properties of carbon free 17Cr-14Ni steel were studied at 700°C.
    The steady state creep rate, ∈s, was analyzed in terms of three factors, stacking fault energy, γ, elastic modulus, E, and diffusion constant, D, using a Sherby-Barrett equation: ∈s=Aγm (σ/E) nD, where A and σ are a constant and the applied stress, respectively, and m and n are fixed to 1 and 7, respectively, for application to the austenitic steels.
    Since it was found that the effect of solute elements on the steady state creep rate of 17Cr-14Ni steels can not be analyzed only by the above three factors, the size effect of solute atoms was proposed as a fourth and important factor.
    As a certification of this assumption, the linear relation between the lattice distortion induced by solute elements and logarithmic steady state creep rate was found experimentally.
    It was concluded from these results that the size effect of solute atoms is the most important strengthening factor controlling the steady state creep rate of austenitic heat resisting steels.
  • The Effect of Si on the Mo-Type High Speed Tool Steel

    pp. 990-999

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    Rod-shaped primary carbides, M2C, which were aligned with rolling direction are frequently observed in high-carbon, high-molybdenum high-speed tool steel. It was known that the phase disappeared by silicon addition to the steel. Therefore, the effect of silicon on the carbide transformation and the heat treatment characteristics in AISI M7 was studied under various nitrogen content.
    The results obtained are as follows:
    (1) The carbide precipitated at the eutectic reaction was M2C and not M6C, and had a plate-like morphology.
    (2) Silicon in the matrix accelerated the transformation of M2C to M6C by entering into M2C during heating the ingot above 640-700°C. Considerable primary carbides were retained as M2C even after hot working, when the silicon content in the steel was little.
    (3) It was considered that the retained M2C, having the plate-like morphology, became reorientated parallel to the hot working direction, without spheroidization, and therefore was microscopically observed as rod-shaped carbide.
  • Microstructures and Mechanical Properties of Sintered, Hot-Forged High-Carbon High-Molybdenum and High-Carbon High-Chromium Tool Steels

    pp. 1000-1007

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    Steel powders containing (2.28, 2.65) %C-(13.23, 17.32) %Mo-3.9%Cr-7%W-3.5%V-9.4%Co and (3.12, 3.61) %C-(12.69, 12.31) %Cr-1.0%Mo have been produced by water-atomization. Fully densified steel bars have also been made by sintering in a vacuum, hot-extrusion and hot-forging. Microstructures and mechanical properties of the dense steels have been investigated as a function of heat treatment.
    In the high-carbon and high-molybdenum steels, fine nodules of M6C (Mo, W-rich) type carbide and fine rods of M2C (Mo-rich) type carbids are uniformly distributed. It is also observed that fine nodules of M7 C3 (Cr-rich) type carbides are uniformly distributed in the high-carbon and high-chromium steels. High hardness is easily obtainable by heat treatment. Grinding is also easy because of the uniform distribution of the fine carbides. However, transverse rupture strength and notch toughness are relatively low. Wear resistance of the steels is improved by increasing the diameters of the unsoluble carbides. Strength and toughness may be improved by sufficient reducing of the oxygen contents of the dense steels.
  • Boiling Phenomena and Effects of Water Temperature on Heat Transfer in the Process of Immersion Cooling of a Heated Steel Plate

    pp. 1008-1015

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    In order to apply an immersion cooling to the manufacturing process of iron and steel, it is necessary to clarify the characteristics of the immersion method. As the first step, the boiling phenomena and cooling abilities were investigated for a steel plate of about 930°C immersed into the still water of 20-90°C. The results obtained are as follows:
    (1) When a plate is immersed, nucleate boiling begins from the edge of a plate and subsequently travels to the center.
    (2) When a plate is horizontally immersed, the lower surface of the plate is covered with stable vapor film. Consequently, the released heat from the lower surface is smaller than the upper.
    (3) When a 28×220×220mm3 plate is vertically immersed, the heat transfer coefficient α between the plate and water is a function of surface temperature θs and water temperature θw. These are related by the following equation. Here, A, B, and K are constants which depend onθs.
    α= [10 (A+B·θs)] · [1-K· (θw-26)]
    [α]: kcal/mm2·h·deg, [θs, θw]: °C
    (4) α reaches a maximum in the θs range from 200 to 300°C and its value is 7-10×103kcal/mm2·h·deg in the θw range from 20 to 30°C.
  • Effect of Metallurgical Factors of Low Carbon Steel Sheets on Stress Corrosion Cracking in Methanol Solution

    pp. 1016-1025

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    Studies were carried out on the effects of chemical composition, manufacturing condition and heat-treatment of low carbon rimmed hot rolled steel sheets on susceptibility to stress corrosion cracking in 60°C reagent methanol containing 0.01 wt% formic acid and 0.1 wt% water by using a constant strain rate test. Similar studies were done for various cold rolled steel sheets and pure iron sheets.
    Carbon content (0.001-0.12wt%) did not affect the susceptibility. Chromium additions (0.04 wt% and over) increased the resistance to cracking, whereas temper rolling and lower coiling temperature of hot rolled sheets decreased the resistance. Also the higher cooling rate of steel sheet cooled from austenite region and low temperature heat treatments (100-300°C×5h) decreased the resistance.
    The effect of strain rate on the SCC susceptibility of a bent or straight form specimen in the methanol solution was investigated. It was found that the both specinlens showed SCC at the strain rate ∈=10-4-10-5 sec-1 and the cracking depth observed in the bent specimen (max 0.28mm) was greater than that in the straight specimen (max 0.05mm).
    The same SCC as that in the methanol solution was observed in reagent ethanol (C2H5OH), methyl cellosolve (H3COC2H4OH), and ethylene glycol (C2H4 (OH) 2) containing formic or acetic acid and water.
  • Determination of Trace Amount of Phosphorus in Iron and Steel by Indirect Atomic Absorption Spectrometric Method Combined with Extraction of Phosphomolybdic Acid

    pp. 1026-1034

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    In order to improve the mechanical properties of steel, the low P-containing iron and steel are produced. Therefore, the determination of P in ppm order is required to know exactly 0.00n%, but the application of the conventional method, e. g., JIS G 1214-1969 is very difficult for the reason of its poor sensitivity. Consequently, an atomic-absorption spectrophotometry was studied to determine P in iron and steel by an indirect amplification procedure.
    The present method comprised the process that phosphomolybdic acid, H3PO4 (MoO3) 12, was formed in nitric acid solution and selectively extracted away from other heteropoly acids and molybdate reagent into isobutyl acetate, and then the twelve molybdate ions associated with one phospnate ion were determined by direct atomic absorption spectrophotometry in the isobutyl acetate phase.
    The interference with Nb, Ta, Ti, V, W and Zr could be avoided by the addition of hydrofluoric acid and adjustment of the nitric acid concentration above 6N.
    The coefficients of variation as the reproducibilities of this method were 13.3%, 3.2%, and 1.7% for 0.05μg P/ml, 0.5μg P/ml and 1.0μg P/ml, respectively. Therefore, it was recognized that the diffreence of 0.001% in phosphorus content less than 0.01% could be judged certainly and phosphorus of ppm order in iron and steel could be exactly determined.
  • Extension of Ergun Equation to Two Dimensional Flow in Packed Beds

    pp. 1035-1036

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    Two kinds of the extension of Ergun equation hitherto used to two dimensional flow system; grad P=-(f1+f2|u|) u (type I) and ∂P/∂x=-(f1+f2|ux|) ux, ∂P/∂y=-(f1+f2|uy|) uy (type II), were critically examined on their transformability of the coordinate system, their consistency in the direction along a streamline with one dimensional Ergun equation and orthogonality between isobars and streamlines.
    Conclusively, the expanded type I of Ergun equation must be applied to two demensional flow system of the packed beds.
    x

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  • M5B3-Type Boride in Nickel-Base Superalloy

    pp. 1037-1039

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    No boride other than of M3B2-type has been reported to be present in nickel-base superalloys, and most of the M's in M3B2 are considered, for PHACOMP, to be molybdenum or tungsten.
    However, tungsten-rich M3B2 is not probable to form in some recent nickel-base alloys containing tungsten instead of molybdenum, since the W-B system does not have a boride of this type.
    In this experiment, high-boron cobalt-free Mar-M200 type alloys, containing tungsten but free from molybdenum, were examined to determine the type of boride. X-ray and chemical analyses of the residue indicated that the boride in the alloys was M5B3 which was considered to be formed by substituting a portion of chromium atoms in Cr5B3 by tungsten atoms, i. e. (Cr, W) 5B3. W5B3, however, is not present in the W-B system.
  • Materials Trends in Geothermal Power Plants

    pp. 1040-1052

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  • 技術貿易の背景を考える

    pp. 1053-1055

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  • Some Impressions in West Germany

    pp. 1056-1060

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  • 抄録

    pp. 1061-1066

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