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

Tetsu-to-Hagané Vol. 73 (1987), No. 11

  • Quality Specification of Pig Iron for Use in Gun-Casting by U. HUGUENIN and Pig Iron Made from Sand Iron Are by "Tatara" Process

    pp. 1443-1452

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  • Spinodal Decomposition in Ceramic Materials

    pp. 1453-1460

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  • Trends of Die Steel

    pp. 1461-1470

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    Readers Who Read This Article Also Read

    1. 性質 Tetsu-to-Hagané Vol.52(1966), No.4
    2. STUDY ON CARBIDES IN COMMERCIAL SPECIAL STEELS BY ELECTROLYTIC ISOLATION (V) Tetsu-to-Hagané Vol.44(1958), No.5
    3. 性質 Tetsu-to-Hagané Vol.47(1961), No.3
  • Today and Future for Industrial Applications of Diamond

    pp. 1471-1478

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  • Artificially Structured Metallic Multilayers

    pp. 1479-1484

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  • The Trend of Applied Magnetic Engineering and the Expectation to Development of Magnetic Materials

    pp. 1485-1495

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  • Heat Transfer between Liquid and a Sphere in Bubbling Flow

    pp. 1496-1503

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    The characteristics of bubbling flow of air and water approaching an ice sphere were made clear by means of the photographic recording method and the electroresistivity probe technique. The melting process of the ice sphere was recorded by a video camera and the local Nusselt number Nuθ, was determined from a change in local radius with the aid of a digitizer supported by a large scale computer. Here, the initial radius of sphere was used as a representative length. The measured values of Nuθ, increased appreciably all over the surface of the sphere compared to the values in single phase flow of water. As a result, the mean Nusselt number Nu averaged over the surface also increased. The increasing rate of Nu decreased gradually with the passing frequency of bubbles nb and finally the effect of bubbles on Nu diminished. The effect of the Reynolds number based on the cross-sectional mean velocity of water and the initial diameter of sphere decreased with an increase in nb.
  • Fundamental Investigation on Production Conditions of New Iron Ore Agglomerates for Blast Furnace Burdens and Evaluation of Their Properties

    pp. 1504-1511

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    Although conventional agglomerates, such as pellets and sinter, have superior properties as blast furnace burdens, they also have inferior properties. The purpose of the present investigation is to develop a new iron ore agglomeration process that differs from the conventional ones and to improve properties of the agglomerates. The main results obtained are as follows:
    (1) Differing from conventional mini-pellets adding sinter, the agglomerates, composed of diffusional bonding structure, were constituted of aggregates of irregular shaped pellets controlled 5 to 10 mm in size.
    (2) Fine ores such as pellet feeds could be used in large quantities as raw materials for this process as compared with conventional sinter process, because they were granulated completely.
    (3) According to an estimation method by mathematical model for fine coke addition to the raw materials, it was clarified that the method for preferential addition of the coke on surface of green ball was suitable because of the effective coke combustion. It was verified by pot grate furnace tests.
    (4) The properties of the new agglomerates produced experimentally were found to be superior to those of sinter. The good properties were considered to depend mainly on the micro-and macro-structures and process characteristics.
  • The Reduction Behavior of Chromium Ore Pellet Containing Carbonaceous Material in Flowing N2-CH4 and N2-H2 Atmospheres

    pp. 1512-1518

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    Chromium ore pellet containing carbonaceous material was reduced at various temperatures between 1 000 and 1 200°C in flowing N2-CH4 and N2-H2 atmospheres. Below 1 050°C the reduction rate in N2-CH4 atmosphere was much higher than that in N2-H2 atmosphere. From the consideration about the results of the present and previous works, it was reasoned that such a promoting effect of CH4 was attributed to the enhanced conversion of CO2 and H2O to CO and H2 with CH4 and fine carbon deposited from it. To the contrary, above 1 100°C the reduction was retarded in N2-CH4 atmosphere. This seemed to be attributed to the fact that in higher temperature range the deposited carbon hindered the mass transfer of gas species through the inside of pellet because it clogged to a large extent the pores, particularly in the peripheral zone of pellet.
  • Influence of Hydrogen on Reduction of Iron Ore Sinter with Ar-CO-H2 Mixture under Heating-up Condition

    pp. 1519-1526

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    Iron are sinter was reduced in a graphite crucible with Ar70%-(CO + H2)30% gas mixtures and the effect of addition of H2 gas to Ar-CO gas mixtures on reduction was investigated during heating at constant rates. The process was followed by gas analysis. Apparent reduction rates with CO, H2 gases and C, and overall rate as the sum of those rates were separately calculated from the mass balances of oxygen and carbon.
    The reduction rate increased with addition of H2 gas, especially at the temperatures below 1 100°C, and the smelting reduction above 1 280°C decreased. The overall rates of reduction with Ar-CO-H2 gas mixture were computed assuming the additivity for the reductions with CO and H2 gases. Then, it was found that there were negative deviation from additivity about 450-600°C and positive one in the range of 600-800°C. The extraneous effects were attributed to the direct reaction of iron oxide with CO gas and C promoted by H2 gas addition. It was also concluded that water-gas shift reaction played at least no important role in accelerating the reduction.
  • Simulation Model of Burden Distribution in Blast Furnace Equipped with Bells and Movable Armors

    pp. 1527-1534

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    A reliable simulation model of burden distribution in blast furnace was developed. This model has the following features:
    (1) A wide range of burden mixtures of sinter and pellets may be given.
    (2) A variety of charging conditions such as coke base, ore/coke, several combinations of coke and ore batches, movable armor settings, and a stock line may be given.
    (3) Burden profiles will be reproduced with an exellent similarity by use of classification of burden profiles into five patterns.
    (4) The influence of burden bed profiles prior to charging on burden distribution is taken into account.
    (5) The reduction of surface angle with the increase of gas flow rate, and/or with the descent of burden in stack is taken into account.
  • The Mechanism and the Countermeasure of the Local Corrosion of Blast Furnace Trough Material at the Slag-Metal Interface

    pp. 1535-1542

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    Slag film formed between trough material and metal is always in liquid state in the local corrosion zone, while percentage of solid phase of the film in the metal zone increases with increasing dipping time. Changes in the composition of the slag film are detected along the surface of the trough material in directions vertical to and also perpendiculer to the surface in the corrosion zone. By combining the above results with those obtained in the previous studies1)2) on the local corrosion of this system, the following mechanism of the local corrosion is proposed: The local corrosion is caused by the active motion of the slag film induced by the Marangoni effect and also by CO bubbles evolved along slag film-metal interface.
    Local corrosion zone in the blast-furnace trough is extended in vertical direction mainly due to the formation and removal of the film caused by the up and down motion of the slag-metal interface level caused by the variation of the flow rate of pig iron in the trough.
    Some countermeasures against the local corrosion are proposed from the standpoint of suppressing the film motion.
  • Interaction between Gas Jets from Two Orifices in Liquid

    pp. 1543-1550

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    A study has been made of the interaction between gas jets from two orifices in liquid by using a high speed cinecamera. Nitrogen was injected into a mercury bath through two orifices of 0.1 cm in diameter (do) located at the transparent vessel bottom. The distance between the two orifices (L) was varied from 0.2 to 2.0 cm. Additionally, experiments were done of helium injection into the water bath through two orifices (do= 0.2 cm, L=-0.64.0 cm).
    The bubbling behavior at two orifices has been classified into three patterns. "Coalescing" : two adjacent bubbles growing at the orifice exits coalesce into one. "Contacting" : the adjacent bubbles contact without coalescing. "No contacting" : the adjacent bubbles do not contact. "Coalescing" occurred more frequently with decreasing L, while "no contacting" time fraction increased with increasing L. The time fraction for "contacting" increased to a maximum and then decreased, as L increased. The jetting behavior at two orifices was found to be strongly influenced by L. In certain ranges of L, jetting at two orifices occurred more frequently than in the case of a single orifice. A theoretical model is given to explain the interaction between gas jets from two orifices in liquid.
  • Effects of Alloying Elements on Interdendritic Microsegregation of Carbon Steel

    pp. 1551-1558

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    Effects of alloying elements on interdendritic microsegregation of carbon steels during solidification were analyzed by unidirectional solidification experiments and mathematical analysis. In the mathematical analysis, the diffusion of solutes in solid and redistribution of solutes at solid/liquid and at δ/γ interfaces were taken into consideration. Based on the observed and calculated results, it was found that microsegregation decreased by addition of ferrite former elements, and on the other hand, it increased by addition of austenite former elements. It was clarified that the addition of ferrite former elements caused the increases of the extent of diffusion in solid and that of redistribution between δ and γ phases, which reduced microsegregation.
    x

    Readers Who Read This Article Also Read

    1. Interfacial Tensions between Mutual Interfaces of Liquid Iron, SiO2-Al2O3-MnO-MnS Slags and MnS Based Sulfide Tetsu-to-Hagané Vol.81(1995), No.9
  • Kinetics of Nitrogen Desorption from Liquid Iron with Low Nitrogen Content under Reduced Pressures

    pp. 1559-1566

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    The kinetics of nitrogen desorption from liquid iron with less than 50 ppm nitrogen content under reduced pressure has been studied between 1520°C and 1 700°C.
    The nitrogen desorption rate was described by 2nd order reaction with respect to [%N] under these conditions. The apparent activation energy for desorption rate was 35.4 kcal/mol.
    The overall nitrogen desorption rate constant, kov, decreases with the increase in total pressure, [O] and [S] contents. The degree of harmful influence of oxygen in iron melt on kovwas about 2.5 times that of sulfur. But, kov in low oxygen and/or low sulfur concentration range was greater than those of previously published studies. The rate determining step of desorption in this concentration range tends to be mass transfer in diffusion layer at gas and/or metal.
    Assuming the mixed control model, the chemical reaction rate constant, kr, is estimated as follows,
    kr= 15.0{1/(1 +161[%O]+ 63.4[%S])} 2 [cm/s·%]
    The adsorption coefficients of oxygen, χO, and sulfur, χS, at 1600°C are given as follows,
    χO=161, χS= 63.4
  • Sequential Dephosphorization and Desulphurization of Hot Metal by Newly Developed Pretreatment Furnace

    pp. 1567-1574

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    A new technology for hot metal pretreatment with the modified BOF has been developed at Kobe Works. This technology has been successfully applied to mass production of high-grade steel since November 1983. The furnace for hot metal pretreatment has an 80 t capacity and is equipped with two lances for flux injection and oxygen top blowing. Hot metal is desiliconized and dephosphorized with oxygen and lime-iron oxide based flux in the first stage of refining, and desulphurization with soda ash injection is followed without deslagging.
    This paper describes the pretreatment technology and results of the operation. Features of this process are as follows:
    (1) Excellent reaction efficiency and reaction rate because of the suitable furnace shape for refining.
    (2) Sequential and rapid dephosphorization and desulphurization treatment within about fifteen minutes.
    (3) Low treatment cost by using cheap submaterials, such as lumpy burnt lime, BOF slag.
    (4) Increase of the manganese content in the hot metal and dephosphorization reaction efficiency by the addition of manganese ore.
    (5) Treatment of hot metal with high silicon content(Si ≈ 0.40%) in reasonably short time and with low cost.
  • Development of the Endpoint Control System for VOD Refining Process

    pp. 1575-1581

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    For the endpoint control of VOD refining, a new simplified mathematical model suitable for online application has been developed on the following procedures.
    (1) The equation of oxygen consumption in the period of vacuum oxygen decarburization is formulated, which comprises the range from low carbon to high carbon.
    (2) The carbon content in the melt in the period of vacuum decarburization and temperature rise are formulated.
    (3) By means of above-mentioned equations, the control system for carbon content and temperature at the endpoint of decarburization has been developed.
    At VOD shop in Amagasaki, the system is being used for the endpoint control, and is contributing to the decrease of the amount of reduction agent, flux and blown oxygen by prevention of excessive decarburization.
  • The γ→α Transformation and Carbide Precipitation of 2Cr and 9Cr Steels

    pp. 1582-1589

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    The γ→α transformation and the carbide precipitation in 2Cr and 9Cr steels were investigated by using optical and electron microscopy. In the 2Cr steel, the proeutectoid ferrite was observed at early stages of transformation, while the lamellar structure with α and cementite was observed at later stages around the nose temperature. In the 9Cr steel, the eutectoid structure composed of α and M23C6 were observed from early stages of transformation. Above the nose temperature, α and M23C6 appeared as a lamellar structure. Below the nose temperature, carbides were aligned in ferrite. Factors affecting the rate of the γ→α transformation and the morphology of carbide precipitation are discussed in this paper.
  • Effect of Carbon Content on the Diffusion Bonding of Iron and Steel to Titanium

    pp. 1590-1597

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    A commericially pure titanium has been diffusion-bonded to iron and steels of various carbon contents ; low carbon steel with 0.01%C(ULC), mild steel with 0.19%C(S20C) and spheroidal graphite cast iron with 3.75%C(FCD). The tensile strength of joints bonded below 900°C was hardly influenced by the carbon content, and increased with the rise in bonding temperature. Above 900°C, however, the strength of the Ti-to-ULC joint showed a constant value, that of the Ti-to-S20C joint decreased, and that of the Ti-to-FCD increased with the rise in bonding temperature. The interlayer forming along the bond interface consisted only of TiC in the Ti-to-FCD joint and of TiFe and TiFe2 in the Ti-to-ULC. Since Ti and Fe diffused over much longer distances in the Ti-to-ULC than in the Ti-to-FCD, the TiC layer may be considered to interfere with the interdiffusion of Ti and Fe, and consequently to suppress the formation of TiFe and TiFe2 which decrease the joint strength more seriously than TiC. The interlayer in the Ti-to-S20C consisted of TiC as well as TiFe and TiFe2. The coexisting carbide and intermetallic compounds in the interlayer, seems to reduce the joint strength to a more extent than those formed individually.
  • Texture Formation of Ti-added Extra Low Carbon Sheet Steels Hot-rolled below Ar3 Transformation Temperature

    pp. 1598-1605

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    In this paper, the texture formation of Ti-added extra low carbon sheet steels hot rolled below Ar3 transformation temperature has been investigated. A remarkable feature of the texture of the sheet hot-rolled below Ar3 is an inhomogeneous formation through the thickness. In the case of Ti-added extra low carbon sheet steels, the recrystallization texture of the surface layer is characterized by a high intensity of Goss orientation while ND // {111} is the main orientation of the recrystallization texture in the midplane. A calculation deriving r-values from data of a three dimensional analysis of the texture shows that the surface layer deteriorates the deep drawability of the sheet.
    With the aid of a computer program calculating the strain distribution in the roll bite and a crystal rotation model developed by DILLARMORE and KATOH, the cause of the inhomogeneous texture formation has been studied. The calculation result shows that the surface texture is strongly influenced by the friction between roll and sheet. With decreasing friction, the surface texture gradually becomes similar to that of the midplane.
    In the consideration of the calculated result, hot rolling experiments were carried out at a newly developed laboratory multipass hot rolling mill equipped with a lubrication facility. Ti-added low carbon steel sheet hot-rolled below Ar3 in a lubricated condition shows a nearly homogeneous texture through the thickness with a main orientation of ND // {111} and consequently a high r-value.
  • 原子を視る-極微の世界の落とし穴

    pp. 1606-1607

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  • 日本語同志の通訳も必要ではないか?/チタン関連研究の講演動向

    pp. 1611-1612

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