Tetsu-to-Hagané
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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 63 (1977), No. 1

  • 1977年の新年に当つて

    pp. 1-2

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  • Production and Technology of Iron and Steel in Japan during 1976

    pp. 3-27

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  • Configulation of the Raceway in the Experimental Furnace

    pp. 28-36

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    The tuyere combustion zone has been studied on an experimental furnace by measuring dimensions and temperature in the raceway.
    The effects of variables such as the blast velocity, tuyere diameter, and coke size are studied. Expressions are derived for estimating the length, width, and height of the raceway in terms of the velocity and density of the blast air, tuyere diameter, and coke properties such as the size, density, and shape factor.
    Discussion is carried out according to the idea that the compressive force of blast to the coke bed is balanced with tendency of collapse of the raceway wall, and that coke in the raceway is fluidized by raceway gas.
    Measurements of operating blast furnaces by rod test are shown to be generally in good agreement with those on the experimental furnace.
  • The Model Experiment on the Reaction between the Liquid and the Swarms of Gas Bubbles by NaOH-CO2 System

    pp. 37-44

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    The gas bubble swarms has been applied as and effective means to the gas-melt reaction in many steel making processes such as the oxygen blow in electric furnace, or bottom blown oxygen converter operations. There have been, however, few fundamental studies available for understanding of the process because of the difficulty of estimation of gas bubble characteristic which is thought to be a basic factor for the reaction efficiency. Standing on this viewpoint, this study has been undertaken to clarify the influences of operation or vessel design at on this viewpoint, this study has been undertaken to clarify the influences of operation or vessel design conditions on the efficiency of gas-liquid reaction, mainly aiming at the bottom blown converter process, by applying the experimental technique of chemical engineering.
    The model test of NaOH solution-CO2 gas bubbles was conduted in the range of (Re) n=103-104 and the effects of the gas blow rate, nozzle conditions, depth of liquid, directions of blowing etc. on the volumetric mass transfer coefficient AKL were investigated by the continuous measurement of PH in solution. The results are summarized as follows:
    (1) The diameter of nozzle, d0 had little effect of AKL, and AKL was proportional to the gas blow rate Vm as expressed as AKL=β. Vm 0.65 where β is a constant of proportionality.
    (2) When the number of nozzle was increased, AKL per one nozzle was decreased. This phenomenon may be explained by the cell model that the bulk is divided into the cells ruled by the number of nozzle.
    (3) The effects of the liquid depth and end effect on AKL were qualitatively illustrated for each bottom, side, top blowings.
    Finally, the application of experimental technique of chemical engineering to the metallurgical research and the application of the present model teet to practical problems were discussed.
  • Direct Observation of “A” Segregation by Dump Test

    pp. 45-52

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    A direct observation of “A” segregation in 4 ton sand cast ingots, which had been dumped at 40 and 120min after pouring respectively, was made to discuss the formation mechanism of “A” segregation with the result of temperature measurement into consideration.
    The results obtained are as follows:
    1) The “A” segregation was found to be formed at the solidification front where the fraction solid was between 0.3 and 0.35, or in the region of lower fraction solid.
    2) The interdendritic enriched liquid metal could flow into the strings, even when the fraction solid of the neighborhood was 0.7.
    3) The transition of “A” segregation zone to “V” segregation zone in an ingot is caused by a suction effect.
    4) The growing direction of primary dendrites in the strings was reverse to the solidification wave in an ingot; i, e. solidification in the strings proceeds outwards from the inside of an ingot.
    x

    Readers Who Read This Article Also Read

    1. Formation Condition of “A” Segregation Tetsu-to-Hagané Vol.63(1977), No.1
  • Formation Condition of “A” Segregation

    pp. 53-62

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    A simulation test of “A” segregation was made successfully by means of horizontal unidirectional solidification of 14kg ingot. “A” segregations reproduced by this method under several cooling conditions were investigated from the viewpoints of cooling and solidification rates.
    The results obtaind are as follows
    1) “A” segregation is formed at the solidification front where the fraction solid is about 0.35 and it's inclination is determined by the vecter sum of the proceeding velocity of the solidification front and the upward velocity of solute enriched liquid metal.
    2) The critical condition for formation of “A” segregation of 0.7%C steel can be expressed by the following formula. where, R is solidification rate (mm/min) and ε is the cooling rate (°C/min)
    3) The size of “A” segregation spots are determined by the staying time in solid-liquid zone.
    x

    Readers Who Read This Article Also Read

    1. Studies on the Reductions of Solute Segregation in the Steel Ingots from the Viewpoint of Solidification Rates Tetsu-to-Hagané Vol.57(1971), No.2
    2. ON THE Λ A SEGREGATED ZONE OF LARGE CARBON STEEL INGOTS (III) Tetsu-to-Hagané Vol.42(1956), No.4
    3. 日本鐵鋼協會第55回講演大會講演大要3 Tetsu-to-Hagané Vol.44(1958), No.3
  • Simulation of the NRIM Continuous Steelmaking Process

    pp. 63-72

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    A mathematical model of the NRIM continuous steelmaking process has been developed on the basis of the assumption that the rate limiting step in the steelmaking reaction is mass transfer which is the function of flow rates of jetted oxygen and generated CO gas. Resistance constants in mass transfer equations and other system parameters used in the model are determined by the complex optimization method to get a good agreement with the actual data in steady state. Results applied for the start-up simulations for the NRIM process operations show that the model can represent the actual process with accuracy. This means that the parameter constants in steady state are available for the unsteady state simulation, so that the model can be used for an optimal designing of the continuous steelmaking process and for the development of the process control strategy. Moreover, the assumption that the gas flow rates have an important role for bath mixing can provide a valuable aid to understand the steelmaking reaction kinetics.
  • Effect of Vanadium and Niobium on Austenite Grain Growth Kinetics in Low Carbon High Strength Steel

    pp. 73-79

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    The coasening of austenite grains has been studied kinetically in low-carbon high-manganese steels containing Al, V, and Nb, respectively.
    The austenite grain growth rate is remarkably decreased by a small addition of Nb. In contrast, the effect of V is very small.
    The activation energy for the austenite grain growth in the steels containing Al, V, and Nb in solution has been determined to be 65.4, 65.0, and 3.7kcal/mol, respectively; the energy is remarkably increased by a small addition of Nb. This can be attributed to the fact that the activation energy for the diffusion of Nb in austenite and the binding energy between Nb and austenite grain boundary are both great.
    The rate constant of the grain growth below 1250°C in the steels containing more than 0.10wt% Nb is smaller than that predicted by “Impurity drag model”. This is considered to be due to the presense of Nb (C, N) which is not dissolved. Such undissolved particles have a great effect of the austenite grain growth.
  • Discontinuous Grain Growth Phenomena and Grain RefiningTreatments in High Speed Tool Steel

    pp. 80-89

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    A discontinuous austenite grain coarsing phenomenon of double hardened high speed tool steel and the procedure to control the grain gtowth on the second hardening have been studied under various heat treatment conditions. It is found that the discontinuous austenite grain growth is caused by disolusion of metastable carbides which have precipitated as a fine dispersion during the early stage of second hardening and that the grain coarsing on the double hardening can be controlled by intermediate heat treatment, i. e., rapid colling from α zone just under Ac1 or γ zone just above Ac3.
    A heat treatment that the high speed tool steel of 6-5-4-2 type is quenched from γ zone just above Ac3 followed by heating at α zone just under Ac1, is effective for preventing the discontinuous austenite grain growth and for refining austenite grain on subsequent austenitization.
  • C-O Relations of the Extremely Low Carbon Austenitic Stainless Steels and Nickel Base High Alloys in Vacuum Induction Melting

    pp. 90-97

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    The C-O carbon vs. oxygen relations of extremely low carbon austenitic stainless steel and Ni-base alloy, in comparison with iron, were studied for the vacuum refined melts together with some thermodynamic considerations.
    Sampling was made during the quiescent period of melts in a 200kg vacuum induction furnace with the MgO lining, and then the chemical compositions were determined.
    During quiescent period after violent boiling the C-O relations in the stainless steels with C%≈0.01 were shown to be in equilibrium and the following relations were obtained.
    Melt Temp. (°C)
    Fe 1600
    Austenitic
    Stainless
    steel
    Ni base 1550
    high alloy
    Calculated values of PCO for the iron melts were about 10times higher than those for stainless steels. It is considered that the effect of refractory on the oxygen potential of molten steel depends on accompanying elements.
    For the Ni base high alloys it was found that the C-O relation was similat to those for steel and the efficiency of deoxidizer added at tapping was greater than those for steels.
  • Effects of Residual Carbides on the Notch Slow Bending Fracture in High Carbon and Low Chromium Steels

    pp. 98-107

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    A study has been made of effects of residual carbides on the notch slow bending fracture in high carbon and low chromium steels.
    Results obtained are as follows:
    Absorbed energy obtained of the 2mmV notch test specimens decreases with an increase in mean particle size of residual carbides in specimens containing 13 per cent of residual carbides in volume, but increases with an increase in mean particle size of residual carbides in specimens containing 8 per cent of residual carbides in volume, regardless of the test temperature. It is assumed that the former depends primarily on the resistance of fracture of residual carbides or the resistance of separation of them from matrix owing to fracturing at the interface of them, while the latter depends primarily on stress concentration at the interface of residual carbides under 2mmV notch.
    On the other hand, absorbed energy obtained of the 2mmV notch test specimens with pre-crack increases with an incresae in mean particle size of residual carbides, regardless of amounts of residual carbides and the test temperature, this being distinct from the results obtained of 2mmV notch test specimens. It is assumed that these results depend primarily on stress concentration at the interface of residual carbides.
  • Solid Solubility of Selenium in Fe-3.25% Silicon Alloy

    pp. 108-117

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    The solubility of selenium in Fe-3.25% silicon alloy was determined by equilibrating the alloy with a gaseous mixture of H2 and H2Se. The composition of the gas mixture, was controlled by adjusting thetemperature of the following reaction:
    FeSe (s or l) +H2 (g) _??_Fe (s) +H2Se (g)
    The results obtained are as follows:
    1) The solidus and the liquidus temperature of FeSe were found to be 1270° and 1318°K, respectively. Equilibrium constant, K=PH2Se/PH2, was determined to be
    logK=-3760/T+0.15 (T<1270°K)
    logK=-2200/T+0.53 (1318°K<T)
    2) In the absence of manganese, the solubility of selenium was found to be 0.016% (in wt%) at 1200°C, 0.022% at 1250°C and 0.061% at 1300°C. In the presence of 0.05% manganese the solubility ofselenium was found to be 0.014% at 1200°C, 0.017% at 1250°C and 0.041% at 1300°C. In the presenceof 0.10% manganese the selenium solubility was 0.011% at 1200°C, 0.015% at 1250°C and 0.030% at1300°C.
    3) The solubility product of manganese and selenium was found to be strongly dependent on manganesecontent in the range of manganese levels measured.
  • Alloy Design of Solid Solution Strengthened Ni-Cr-W Superalloy

    pp. 118-124

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    For the purpose of developing cobalt-free tube materlals for the heat-exchanger of nuclear steel-making process, an alloy design has been conducted with respect to the Ni-Cr-W system.
    Theoretically promising composition ranges in the Ni-Cr-W system are determined by the conditions that average electron vacancy number Nv is smaller than Barrows' critical electron vacancy number Nc and that lattice parameter a is greater than 3.580 Å. some compositions in the above mentioned range have been examined experimentally and 23% Cr-18%W has been determined as the best composition from the creep rupture strength point of view.
    Effects of carbon and magnesium on the creep rupture strength of 23%Cr-18%W-Ti-Zr-Bal. Ni alloy have been studied. The long-term creep rupture strength decreases with the increase of carbon content in the range from 0.03% to 0.14%. Up to 90 ppm magnesium does not significantly affect the creep rupture strength of the alloy at 1000°C, but about 160 ppm magnesium significantly reduces the creep rupture strength at that temperature.
    In conclusion, 23%Cr-18%W- (0.3%Ti) - (0.05%Zr) -0.03%C-Bal. Ni alloy has a high possibility of satisfying the creep rupture strength target, that is more than 1kg/mmmm2 at 1000°C and 105 hours.
  • Alloy Design of Ni-Cr-Mo Solid Solution Strengthened Superalloy

    pp. 125-129

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    In order to examine the possibility of developing an intermediate heat-exchanger material for the nuclear steel making which is cheaper than 23% Cr-18% W-Ni alloy developed in the previous study, an alloy design has been conducted with respect to austenitic Ni-Cr-Mo three component system.
    Theoretically promising composition range is determined by the following conditions; (1) average electron vacancy number NV is smaller than Barrows' critical electron vacancy number, (2) lattice parameter is greater than 3.580 Å, (3) NV is greater than 1.90.
    As a result of experimetal examination, it has been shown that 26% Cr-9.5% Mo is the best in the theoreti-cally promising composition range from 1000°C creep rupture strength point of view, and that an addition of about 0.07% carbon increases creep rupture strength at 1000°C. The target creep rupture strength, that is, higher than 1kg/mmmm2 at 1000°C-105 hours, however, is not satisfied.
    26% Cr-9.5% Mo-Ti-Zr-C-Bal. Ni alloy which has been developed in the present study has almost the same creep rupture strength at 1000°C as that of Inconel 617, and seems to be applicable to various high temperature parts in nuclear power plants, because it contains no cobalt.
  • Grooving Corrosion Resistance of ERW Low Alloy Steel Pipes in Sea Water

    pp. 130-138

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    The grooving corrosion resistance of the ERW Cu-Sb, Cu-Ti, and Cu-Ti-Cr low alloy steel pipes were investigated. Corrosion tests carried out in artificial seawater showed that these pipes had grooving corrosion resistances four to seven times higher than that of a plain carbon steel pipe. Difference in the degree of polarization between the weld and the base metal, as determined by polarization curves in 3% NaCl solution, was large in the carbon steel pipe, the weld being less polarized and small in low alloy steel pipes. A microscopic observation of the non-metallic inclusions revealed that there was a smaller quantity of MnS inclusions, inititation sites of the grooving corrosion, in the welds of these low alloy steel pipes than in the welds of carbon steel pipe. It was considered that the good grooving corrosion resistances of the low alloy steel pipes were due to the decrease of MnS inclusions in the welds, the elimination of S2- ion by the addition of copper, and the increase of the corrosion resistance of the base metal by the addition of chromium.
  • The Improvement of Stress-Relaxation Properties of PC Wire by “Warm-Straightening”

    pp. 139-146

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    Various properties of highcarbon PC wire treated by cold-straightening and bluing (“CS+B”) and those by warm-straightening (“WS”) were compared and the following results obtained.
    It was found that the greater the bending deviation during straightening, the straighter was the processed wire and the more stable was the torsion value. There was an increase in the diameter of the wire in the “CS” process and in the “WS” process at intermediate temperatures, but it was found that at higher temperatures the diameter reached a maximum and then gradually decreased, becoming less than the original diameter above 400°C.
    The maximum tensile stength and sectional-hardness were obtained for “CS+B” wire when treated at 200°C and 250°C respectively, while for “WS” wire the maximum values were obtained at 300°C. The “WS” wire had a lower stress-relaxation value than “CS+B” wire, this being paricularity evident at high autoclave temperatrue. One reason may be that the “WS” wire has a higher elastic limit than “CS+B” wire.
    Minimum relaxation values for both “CS+B” wire and “WS” wire were obtained at a temperature approximately 50°C above that at which σ0.2 and σ0.02 showed a maximum and this corresponded with the results of creep tests performed at intermediate temperatures.
    It is considered that in the “WS” process the dislocations increase and there are repeated lockings of these dislocations by solute atoms and that the composite effect of aging and process hardening results in a fixed structure of dislocations.
  • On a Computer System for X-Ray Diffraction

    pp. 147-153

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    This paper describes an automated system for X-ray diffractometry. This system has been developed with the main intentions of extending operation times, preparing labor-saving devices, and acquiring experimental data with better precision.
    An IBM-1800 computer executes both the offline data processing and online device control for five kinds of X-ray spectrometers in the system.
    Its implementation allows a substantial reduction in manpower with a considerable technical improvement over the previous methods, as descrived in the following.
    (1) Only two persons are required to operate this system instead of five. (2) This system is continuously operated about one hundred hours in a week. Operation times are more than trebled as before. (3) Digital-to-analogue, and analogue-to-digital converters are not required since digital outputs from scalers are transmitted to the computer. Some appropriate software are applied for data processing, then signal to noise ratio of diffracted intensity is remarkably increased.
    Using the newly developed x-ray diffractometers for determining pole figure and the computer control, pole density functions with better precision can be derived, for diffracted intensities are acquired by the inquiry and answer system.
  • Changing Corporate Environment and Countermeasures of the Steel Industry

    pp. 154-173

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  • An Analytical Solution for “Multiple Reaction-Interfaces Model” of Porous Hematite Reduction

    pp. 174-175

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  • 報告

    pp. 176-182

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    [in Japanese]
  • 抄録

    pp. 183-188

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  1. blast furnace
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