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

Tetsu-to-Hagané Vol. 49 (1963), No. 7

  • 研究における評価

    pp. 969-970

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  • Manganese Ores used for Production of High Carbon Ferromanganese

    pp. 971-975

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    To study on the reducibility of some manganese ores which are used for ferromanganese production, we investigated their properties in the first place. We obtained the following results of X-ray diffraction, differential thermal analysis and thermal balance analysis.
    (1) Foreign ores are mostly MnO2 ores, and their attendant minerals are MnO·OH, 3Mn2O3·MnSiO3, hydrated Mn oxide, SiO2, etc. MnO2 ores have α-, β-, γ- and/or δ-phases and most of them are these mixtures.
    (2) In every MnO2 ore, γ- and δ-phases are incompletely crystalline, and they are reduced to Mn2O3 or Mn3O4 easily at comparative low temperature. Ghana ore, which is γ-MnO2, belongs to the above group, and is expected to have high reducibility.
    (3) Domestic ores are mostly manganese carbonate ores or silicate ores, and mineral compositions of burnt ores represent variations in the burning temperature and atmosphere.
    (4) Quantitative studies on such mineral compositions will be continued futhermore.
    x

    Readers Who Read This Article Also Read

    1. Equilibria between Mn Alloy Melts Satulated with C and Various Kinds of Molten Slags and Calculation of the Activities Tetsu-to-Hagané Vol.66(1980), No.10
    2. Oxidation-Reduction Equilibria of Manganese in MntO-CaO-SiO2-Al2O3 Melts Tetsu-to-Hagané Vol.73(1987), No.16
    3. 雑録 Tetsu-to-Hagané Vol.41(1955), No.4
  • On Effects of Acceleration of Carbon Deposition on Hanging

    pp. 976-982

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    In the report “Studies of hanging of a blast furnace-I”, we reported the results of investigation into the cause of the phenomenon that the permeability of iron ore bed is reduced. In this report, in order to exploit this phenomenon in the tendency of hanging in a blast furnace, we investigated the effects of some factors on the time till the permeability of iron ore bed is reduced.
    The results obtained were as follows:
    (1) About such factors which affect chemically on CO-resolution reaction, as FeO content in ore, CO and CO2 in reducing gas, a close relationship between acceleration of carbon deposition and the time till the permeability of iron ore bed is reduced was established.
    (2) The catalytic action of H2 in reducing gas was weak, and there was no effect of H2 in reducing gas under 10% H2.
    (3) Ore size and ore/coke ratio affect physically the Tendency of hanging in a blast furnace.
  • On the Gas Decarburization of White Pig Iron Used for White Heart Malleable Cast Iron

    pp. 982-988

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    The decarburization of white pig iron such as used for making the white heart malleable cast iron was studied mainly in the exothermic atmospheres of CO-CO2-H2-H2O system converted from propane. The process of decarburization of white pig iron under various heating conditions was considered by comparing the decarburization behavior of the exothermic gas containing hydrogen about 10% converted at air ratio 14 with that of the wet hydrogen containing water vapour 4% and that of the mill scale forming atmospheres of the simple CO-CO2 system around it. The results obtained were as follows.
    In the flow of an exothermic gas, the decarburized amount of white pig iron was increased through a rising of propane-air ratio for producing the gas up to 10, but it was nearly independent of the variation of the air ratio in the range of 10 to 17 due to the concentration difference for carbon diffusion in the austenite phase reaching its maximum (when heated at 950°C for 4hours in the gas cooled at 18°C after converted at 1000°C).
    The decarburized weight in each atmosphere was decreased slightly in the order of the flow of wet hydrogen, the flow of the exothermic gas and the mill scale owing to the rising of the concentration difference for carbon diffusion in austenite due to the rising of surface carbon content with carbon potential of the atmospheres. It was observed that the surface structure of the decarburized layer which formed in each atmosphere in the experimental range 750 to 1100°C was uniform single ferrite only, so that the surface carbon content was kept to within the limit of the solid soiubility of carbon in α iron phase.
    Free cementite in the white pig tends to be stabilized and its graphitization becomes difficult with an increasing of the hydrogen amount in the decarburizing atmospheres. The rate of dissolution of graphite into unsaturated austenite as caused by decarburizing reaction was relatively small compared with that of cementite, hence the rate of decarburization was lowered with the progress of graphitization.
  • Partition of Alloying Elements between Phases and the Relation between the Amount of δ Ferrite and Magnetic Property for Cr-Ni Stainless Steels

    pp. 989-995

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    Properties of δferrite in Cr-Ni stainless steels and its microstructural change during aging are influenced by the composition of δ ferrite.
    Therefore it is very important to examine the composition of δ ferrite in studying the effect of δ ferrite on the properties of Cr-Ni Stainless steels.
    This report is concerned with an analysis of phases in Cr-Ni stainless steels using the electron probe X-ray microanalyzer. Comparison of measured values with chemically analytical values, and correction of measured values were made. Partition of alloying elements between phases and the effect of an additional element on the composition of σ phase were investigated.
    The studies were also extended to an investigation of the relation between the amount of δ ferrite and the intensity of magnetization.
    The following results were obtained:
    i) The concentration of an austenite-former was higher in austenite than in δ ferrite.
    The ratio of the concentration of an austenite-former in austenite to that in δ ferrite was the greater, the higher the potency of the austenite-former. The concentration of a ferriteformer was higher in δ ferrite than in austenite but there was no relation between the partition ratio (Cδ/Cγ) and the potency of a ferrite-former.
    ii) Addition of Ti, Mo and Mn to the steels greatly promoted the formation of σ phase from δ ferrite. Mo and Ti decreased considerably the concentration of Cr in σ phase but it seemed that Mn decreased it slightly.
    iii) A linear relation between the amount of δ ferrite and the intensity of magnetization was observed. The amount of martensite could be estimated from the change in the intensity of magnetization after subzero treatment of specimens with a structure consisting of austenite, martensite and δ ferrite. The amount of martensite was decreased but that of austenite was increased with an increasing temperature of solution treatment.
  • The Effects of Grain Size and Deformation Rate on the Tensile Properties of Mild Steel at Low Temperature

    pp. 996-1003

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    A mild steel with 0·15%C, having three kinds of grain diameter, was tested at temperatures from room temperature to liquid nitrogen one under impact and quasi-static tensile loadings.
    Experimental results are summarized as follows: -
    (1) The increase of lower yield stress with the lowering of temperature was much greater than that of tensile strength in both static and impact tensile test. Below the temperature at which brittle fracture was observed, the yield stress (brittle fracture strength) was almost constant.
    (2) The transition from ductile to brittle fracture was observed on the unnotched test piece in both static and impact tension test. The transition temperature registered in the latter test was higher by 60°C than that in the former. The transition temperature was also affected by the grain size, i. e., the specimen N1 (grain diameter: 0·091mm), no matter what the deformation rate was changed, had the temperature higher by 40°C than one with N3 (grain diameter: 0·017mm). This 40°C was quite equal to the difference between the transition temperatures of the respective specimens (N1 and N3) in Charpy V-notch test.
    (3) Although the lower yield strength and tensile strength were functions of deformation rate as σ=Alog∈+B (σ: yield strength or tensile strength, ∈: strain rate, A and B: constants) at a given temperature, the deformation rate dependence was larger for the lower yield strength. This dependence increased with the decrease of the temperature, at which ductile fracture occurred. However, it became very small when the specimen fractured in brittle manner.
    (4) The lower yield stress (or brittle fracture strength) σu obeyed quite well the relation σui+kd-1/2i, k: constants, d: grain diameter). The value of k for the impact tensile test was larger_than that for the static one.
    (5) In the range of temperatures at which ductile fracture occurred, k was found to be not a function of temperature but of deformation rate, and frictian stress σi was a function of both temperature and deformation rate. σi=α exp (-βT) (α, β: constants, T: temperature) was found at a given deformation rate. Meanwhile, when the brittle fracture occurred, the constant k became larger but independent of the temperature and of the deformation rate, and σi had not any dependence on the temperature but a slight one on the deformation rate.
  • On the Hydrogen Embrittlement of a Quenched Plain Carbon Steel

    pp. 1003-1008

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    To investigate the hydrogen embrittlement of a quenched plain carbon steel, the specimens of 0·3% carbon steel were annealed at 700°C, and quenched in a martemper oil and in water.
    Then, tensile tests of the specimens were carried out right after the specimens were made to absorb hydrogen through electrolysis. The volume of hydrogen which the quenched and annealed specimens absorbed was measured and the internal friction of the specimens before and after absorbing hydrogen was measured by a transversal vibrating method.
    The experimental results were as follows: -
    (1) The degrees of the hydrogen embrittlement of the specimens quenched in water, quenched in a martemper oil and annealed at 700°C after hot rolling, were 7·2 38·5 and 42·8% respectively, where the degree of hydrogen embrittlement was shown by { (∈0-∈) /∈0} ×100, and ∈0 was the reduction of area before hydrogen absorption, ∈ was the minimum value of reduction of area owing to the increasing of the volume of absorbed hydrogen in the steel.
    (2) The hydrogen evolution at the room temperature was almost finished in two hours and both elongation and reduction of area recovered.
    (3) Both internal frictions at the room temperature of the sample after and before hydrogen absorption were the same.
  • The Composition of Quenching Oil and the Quenching Effects of Fatty Oil and Fatty Acid Ester

    pp. 1008-1015

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    The quenching effects of several kinds of commercial mineral oil were examined using test piece A (0·7%C steel, 11·5_??_×20mm). Further, the quenching effects of various fatty oils, fatty acid ethyl esters and fatty acids were tested. The following conclusions were obtained:
    (1) The quenching effect of oil must be studied from the point of view of its boiling point, the intensity of polarity and contents of some hydrocarbons having higher boiling points.
    (2) The phenomena observed during quenching are closely related to the composition of mineral oils. Generally, the duration of gas film adhering to the specimen during quenching is shorter for the oil in which the thermal cracking of hydrocarbons takes place remarkably.
    (3) Quenching effects of rape seed oil and soya bean oil are almost the same, so all fatty oils having higher molecular weight will give the same quenching effect.
    (4) Castor oil gives more marked quenching effect, because of its thermal instability.
    (5) The esters and the fatty acids have almost the same quenching effects, which are lower than those of fatty oils.
    x

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    2. Continuous Annealing of Cold-Rolled Sheets Tetsu-to-Hagané Vol.49(1963), No.1
    3. 日本鉄鋼協会第60回講演大会講演大要 Tetsu-to-Hagané Vol.46(1960), No.10
  • On Iron-Steel Technology Joint Research in Postwar Japan

    pp. 1016-1021

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  • Continuous Casting of Wide-Slabs

    pp. 1022-1027

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  • 抄録

    pp. 1028-1033

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  • 特許記事

    pp. 1037-1040

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  • 鉄鋼ニューズ

    pp. 1041-1042

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