ISIJ International
New Arrival Alert : OFF

You can use this feature after you logged into the site.
Please click the button below.

Log in / Sign up
ONLINE ISSN: 1347-5460
PRINT ISSN: 0915-1559

ISIJ International Vol. 29 (1989), No. 6

  • Exergy Evaluation on the Pellets Production and Direct Reduction Processes for the Fired and Nonfired Pellets

    pp. 447-454

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.447

    In order to make a clear evaluation of overall energy requirement for the production systems of directly reduced iron through pellets from iron ore powders, exergy analysis was applied to the two systems. The first one consists of pelletizing, firing and reduction processes, Fired pellets method, and the second one includes pellets curing process instead of firing process, Nonfired pellets method.
    Being compared with enthalpy balance, exergy analysis has two advantages in that the exergy expresses the quality of energy and evaluates different kinds of energy like chemical, thermal, pressure and mixing energy by a unified measure.
    As a result of exergy analysis, fired pellets lose less exergy than nonfired pellets in the shaft furnace. As the overall systems, however, exergy requirement in the nonfired pellets method is about 50% of that in the fired pellets method. This marked difference is caused by the large exergy loss in the firing process. Furthermore, exergy loss in the production of nonfired pellets will be decreased by decreasing the amount of cement added as binder.
  • Drop Generation due to an Impinging Jet and the Effect of Bottom Blowing in the Steelmaking Vessel

    pp. 455-461

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.455

    Experimental results of drop generation in a laboratory model water bath with top blowing and combined blowing are given. It was found that with top blowing alone two different mechanisms of drop generation exist, each having its own characteristic drop generation rate. The two mechanisms, identified by high speed film analysis, are shown to be a function of the blowing rate. Bottom blowing is shown to significantly increase drop generation rate and that the increase is caused by the interaction of the top blowing and the bottom blowing in the impingement zone, and not by the bottom blowing as such. Drop size distribution generated by a gas jet impinging on a liquid surface is normal. Mean drop size is increased by the introduction of bottom blowing.
    x

    Readers Who Read This Article Also Read

    1. Analysis of Droplet Generation in Oxygen Steelmaking ISIJ International Vol.49(2009), No.1
    2. Fluid Flow Analysis of Jets from Nozzles in Top Blown Process ISIJ International Vol.43(2003), No.2
    3. A Model Study of Droplet Generation in the BOF Steelmaking ISIJ International Vol.30(1990), No.4
  • Three-dimensional Velocity Fields for Newtonian and Non-Newtonian Melts Produced by a Rotating Magnetic Field

    pp. 462-468

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.462

    A model is developed to calculate fluid flow in Newtonian and non-Newtonian systems subjected to rotational electromagnetic stirring. In the former case, transport equations for K, the turbulence energy, and ε, its rate of dissipation, were used to deduce the effective viscosity, while in the latter case, constitutiv relations were used to relate the shear stress to the rate of strain. The body forces due to the rotating magnetic field are deduced from the established analytical results obtined from the solution of Maxwell's equations.
  • A Mechanism for the Local Corrosion of Immersion Nozzles

    pp. 469-476

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.469

    A mechanism for the local corrosion of immersion nozzles at the slag–metal interface was quantitatively substantiated by combining results from kinematic analysis of immersion tests with direct observations using a high temperature X-ray radiographic technique.
    For steels containing low carbon levels (e.g., steel for continuous casting), the dissolution of oxides from the nozzle into the slag film is the rate controlling step of the local corrosion process. For steels contaning higher carbon levels (e.g., in the vicinity of carbon saturation), dissolution of graphite from the nozzle into the metal is rate controlling.
    It was found that if the nozzle:
    (i) has a high resistance to corrosion by liquid slags; and
    (ii) is easily wetted by the slag.
    Then it will exhibit a good resistance to local corrosion at the slag–metal interface.
  • The Densities and the Surface Tensions of Fluoride Melts

    pp. 477-485

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.477

    The densities and the surface tensions of molten pure fluorides were measured by the Archimedean method and the maximum bubble pressure method, respectively. It was shown that the physico-chemical properties of pure alkaline metal and alkali-earth metal fluorides mainly depend on the Coulomb forces experienced by foreign ions, I (=ZaZc/(ra+rc)2). However, magnesium fluoride shows slightly different behavior from other fluorides, that may result from the reduction of the cation-anion attractive force, I by shielding effect of larger fluorine ions to smaller magnesium cation. Surface tensions of pure fluoride melts were changed as a function of KZaKZc/(VM)2/3, where VM and K are the molar volume of a melt and a packing parameter of anions on the cleavage plane (for NaCl structure, K=1, for Rutile structure K=√(1+√2)/2 and for CaF2 structure K=4/√3). It suggests that the surface structure of a melts refers to that of the corresonding solid cleavage plane.
  • Effect of CaO Added with SiO2 and/or Al2O3 on Reduction Rate of Dense Wustite by Hydrogen

    pp. 486-494

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.486

    The dense wustite plates containing CaO together with SiO2 and/or Al2O3 have been reduced isothermally in a stream of hydrogen at temperatures between 670 and 930°C.
    Reduction rate of the specimens added CaO together with SiO2 or Al2O3, increases monotonously along with the increase of CaO addition at temperatures below 730°C. However, reduction rate at temperatures above 800°C of these specimens, and reduction rate of the specimens added CaO together with SiO2 and Al2O3 shows lowering once with the increases of CaO addition, and then increases after lowering. In every case, when addition of CaO increases to a certain extent, reduction rate reaches close to the maximum rate obtained at the reduction of the specimen added CaO alone.
    A part of these added oxides are dissolved in FeO phase to make solid solution, and the rest form composite oxide phase and coexist with FeO phase. It is made clear that the reduction of FeO phase is affected mainly by oxides dissolved. Oxides dissolved in FeO phase are thought to cause changes in structure of reduced iron, and result signicant effects on reduction rate of FeO phase.
  • Solidification and Roll-bonding of Shells in Twin-roll Casting Process

    pp. 495-502

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.495

    Basic phenomena of the twin-roll casting have been investigated by paraffin model casting, thermal analysis and steel casting experiments. The influence of the roll gap on roll-bonding behavior of the solidified shells and temperature distribution of the molten pool have been mainly investigated by paraffin model casting. On the other hand, the change of the molten pool temperature during casting has been calculated by the numerical analysis method. Based on the results of these simulations, twin-roll casting of the steel has been carried out.
    Through these experiments and numerical simulation, it has been recognized that roll gap relates closely to segregation, crack occurence and breakout of the cast strip, and the decrease of the molten pool temperature. An appropriate roll gap should be a gap which does not cause breakout, but minimizes the squeezing out the mushy-state layer. It is also found that the tendency of segregation and crack occurence in the steel strip are well explained by paraffin model casting.
    x

    Readers Who Read This Article Also Read

    1. Effect of Heat Treatment on the Bond Interface Structure of A3003/SUS304L Clad Material QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY Vol.22(2004), No.2
    2. Bonding Quality of Copper-Nickel Fine Clad Metal Prepared by Surface Activated Bonding MATERIALS TRANSACTIONS Vol.51(2010), No.4
    3. Infrared Brazing Titanium Alloys Using Clad Ti–15Cu–15Ni Fillers with Different Clad Layers ISIJ International Vol.49(2009), No.4
  • Hot-rolled Steel Sheet with Excellent Flash Weldability for Automotive Wheel Rim Use

    pp. 503-510

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.503

    As for the steels for wheel rim, CC killed steel will be more prevalent instead of rimmed steel in accordance with the increase of CC ratio in steel production. In addition, from the point of weight reduction of cars, high strength steels are tried to put into practice. As far as wheel rim is concerned, flash weldability is very important as well as formability of steels.
    In this report, flash weldability of CC killed steel, HSLA (High Strength Low Alloy) and DP (Dual Phase) steels are investigated. In flash welding of CC killed steel, control of Al content, in addition to Si and Mn contents, is found to be required in order to avoid the detect formation due to Si-Mn-Al oxide. On the other hand, coiling temperature is important in high strength steels, especially DP steels, in order to prevent softening of weld heat affected zone.
  • Effect of Aluminum Oxide on Carbon Deposition of Fe–Al Alloys in Carburizing Gas

    pp. 511-516

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.511

    The behavior of carbon deposition on as polished or oxidized Fe–Al alloys containing 05.7 mass% Al in 10% CH2–H2 mixture at 1 203 K was studied by metallogrphy and thermogravimetry to elucidate the effect of alumina on carbon deposition on the alloys in carburizing gas. Aluminium works to accelerate the deposition of filamentous carbon by promoting Fe3C decomposition. However, carbon deposition on as polished alloys containing 2.0 mass% Al or more is markedly retarded because of the formation of Al2O3 on the surface despite of the carburizing atmosphere. Under this condition, Al2O3 may have formed by the reaction of aluminum in the alloy with small amounts of oxidizing gases such as O2 and H2O present in the atmosphere. On oxidation in air, Fe2O3, Fe3O4, and FeO form on iron and small additions of aluminum (≤2.7 mass% Al) retard the formation of Fe3O4 and FeO and a further addition of aluminum up to 5.7 mass% causes the formation of Al2O3 besides FE2O3. The exposure of the alloys containing 2.0 mass% Al or less to 1–%CH4–H2 mixture after the oxidation in air causes a rapid mass gain. It may be due not only to the promoting action of aluminum for filamentous carbon deposition but also to the formation of active iron by reducing iron oxides and to the increase in the reaction area by spalling the scale. Carbon deposition on the alloys containing 2.7 mass% Al or more, however, is greatly depressed because Al2O3 forms or remains even during carburization.
  • Morphology and Microstructure of Electrodeposited Zinc-Iron Binary Alloys

    pp. 517-523

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.517

    Zinc-iron electrodeposited steel sheets have been adopted for automobile bodies for their improvements in the corrosion resistance and organic-coating capability. In principle, these properties depend on the crystal structure, morphology and microstructure of deposits. The deposits of various iron content were prepared galvanostatically from sulfate bath and examined by scanning and transmission electron microscopy. The single η-phase of 99.5 at% zinc exhibits a morphology of randomly oriented hexagonal plates which are thin in the direction of c-axis. With the increase of iron contentin the deposits, the Γ-phase forms in addition to the η-phase. The η-phase plates stack in the direction of c-axis and form the hexagonal columnar crystals having triangular pyramidal shape. The Γ-particles disperse within the grains and along grain boundaries of these η-phase plates. The Burgers relationship holds between the η- and Γ-particles. The hexagonal columnar crystals of 91.2 at% zinc form steps on {10·0}η surfaces. With an increase of iron content to 85.1 at% zinc, however, the steps on {10·0}η surfaces are flattened. With further increase of iron content to 73.0 at% zinc a large amount of Γ-particles are produced, and these Γ-particles can no more be absorbed within the η-phase. These excess Γ-particles form granular crystals, and precipitate among the hexagonal columnar crystals.
  • A Consideration about the Concept of Effective Thermal Conductivity in Continuous Casting

    pp. 524-528

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

    DOI:10.2355/isijinternational.29.524

Article Access Ranking

21 Jan. (Last 30 Days)

  1. Heat Transfer Characteristic of Slit Nozzle Impingement on High-temperature Plate Surface ISIJ International Advance Publication
  2. Hydrogen Embrittlement Susceptibility Evaluation of Tempered Martensitic Steels Showing Different Fracture Surface Morphologies Tetsu-to-Hagané Vol.105(2019), No.1
  3. Effects of Impurities and Processing Conditions in Al–1%Mn Alloys on the Formation of Thermally Stabilized Substructures MATERIALS TRANSACTIONS Vol.59(2018), No.11
  4. Fusion Zone Microstructural Evolution of Al-10% Si Coated Hot Stamping Steel during Laser Welding ISIJ International Vol.59(2019), No.1
  5. A Review of the Chemistry, Structure and Formation Conditions of Silico-Ferrite of Calcium and Aluminum (‘SFCA’) Phases ISIJ International Vol.58(2018), No.12
  6. Effects of Sulfur and Titanium Interaction in Molten Pig Iron on Erosion of Carbon Brick ISIJ International Vol.59(2019), No.1
  7. Recent Progress on Advanced Blast Furnace Mathematical Models Based on Discrete Method ISIJ International Vol.54(2014), No.7
  8. Preface to the Special Topics Entitled “To Solve Problems of Hot Rolling Rolls” Tetsu-to-Hagané Vol.104(2018), No.12
  9. Effect of Annealing Time on Oxides Phases and Morphology along Oxidized Depth of Fe-3%Si Steel during Decarburization ISIJ International Vol.59(2019), No.1
  10. Preparation of High-Carbon Metallic Briquette for Blast Furnace Application ISIJ International Vol.59(2019), No.1

Search Phrase Ranking

21 Jan. (Last 30 Days)

  1. blast furnace
  2. blast furnace productivity
  3. blast furnace permeability
  4. 鉄と鋼
  5. laser welder
  6. titanium
  7. activity feo
  8. argon steel
  9. eaf operation
  10. electric arc furnace