Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 81 , Issue 11
Showing 1-17 articles out of 17 articles from the selected issue
  • Kouji TAKATANI
    1995 Volume 81 Issue 11 Pages 1031-1036
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (1620K)
  • Takashi INAMI, Kanae SUZUKI
    1995 Volume 81 Issue 11 Pages 1037-1042
    Published: November 01, 1995
    Released: November 17, 2010
    JOURNALS FREE ACCESS
    Dense wustite plates have been reduced at 1273K with CO-CO2 gas mixture which has a chemical potential to form metallic iron. In early stage of the reduction, no formation of metallic iron was observed and only the composition of the wustite changed. The composition change was followed by the changes of the lattice parameter and the mass of the sample. A mixed chemical reaction/solid state diffusion limited model was applied to the reduction rate. The reduction rate r was expressed by the following equation, r=k'·(1-α/Ks)·Pco(kg-oxygen/m2·s)
    where Ks and α are the Pco2/Pco ratio in the gas mixture in equilibrium with the surface wustite and that in the reducing gas mixture, respectively. The apparent chemical reaction rate constant k' changed with Ks and was expressed as follows, k'=1.18×10-10·Ks0.34(kg-oxygen/m2·s·Pa).
    On the other hand, the inter-diffusion coefficient D was independent of the iron ion vacancy concentration y and was estimated as D=5.4×10-10(m2/s) at 1273K. The iron ion concentration profile, estimated from the lattice parameter, and the mass change of the reduced wustite were explained reasonably by the model.
    Download PDF (1367K)
  • Xinghe ZHANG, Reijiro TAKAHASHI, Jun-ichiro YAGI
    1995 Volume 81 Issue 11 Pages 1043-1048
    Published: November 01, 1995
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    Reaction rates for the reduction of iron oxide, the gasification of coke and the thermal decomposition of the binder in oxidized iron-scrap briquettes containing pulverized coke were measured under the conditions of elevating and fixed temperatures in the nitrogen atmosphere. The reaction rates were obtained by examining the various factors affecting the reaction mechanisms. The weight change of the briquette calculated by the rate equations agreed well with experimental values. The rate equations can therefore be applied to the mathematical simulation model of a cupola process to which oxidized iron-scrap is charged as a burden material.
    Download PDF (1301K)
  • Xianming HUANG, Wayah Giri ISCHAK, Hiroyuki FUKUYAMA, Toshiharu FUJISA ...
    1995 Volume 81 Issue 11 Pages 1049-1054
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Solubility of boron in molten Fe-B-N alloy equilibrated with solid BN at 1723K under various partial pressure of nitrogen, and the solubility of carbon in molten Fe-C-B alloy in the temperature range from 1573K to 1723K were measured to determine the thermodynamic parameters of boron in liquid iron.
    By using the interstitial model, the activity coefficient of boron at infinite dilution (ΨB0) and the interaction parameters (θij) in liquid iron were determined as follows:
    lnΨB0=-5.15, θNB=3.97, θBB=-0.12(1723K)
    θCB=18900/T-6.34(1573K1723K)
    Download PDF (1264K)
  • Toshiyuki KAJITANI, Hisao ESAKA, Masamitsu WAKOH, Hideyuki MISUMI, Shi ...
    1995 Volume 81 Issue 11 Pages 1055-1060
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    In order to investigate initial solidification of ultra low carbon steel, dip tests of chill block have been carried out. Large irregularity of shell thickness is obtained in ultra low carbon steel. Deformation of solidified shell increases the irregularity by forming air gap between shell and chill. However, irregular growth is also observed before the shell defomiation.
    Detail analyses of solidified microstructure reveal the characteristic of the irregular growth in ultra low carbon steel. Fine cellular structure exists near the surface of shell and induces the irregular growth. Number of nuclei in ultra low carbon steel is smaller than that in middle carbon steel.
    Furthermore, cooling curve on the onset of solidification is measured using very fine thermocouples. There exists large undercooling for nucleation in the case of ultra low carbon steel.
    Based on these microscopic analyses, the irregular growth originates from low nucleation rate in ultra low carbon steel. Fine cellular structure which is due to large undercooling for nucleation, grows from nuclei with high velocity, and results in the irregularity of shell thickness. Then the irregularity is amplified by the deflection of thin shell part.
    Download PDF (5263K)
  • Hideaki MIZUKAMI, Kentaro MORI, Naotake YOSHIHARA, Hideo NAKAMURA
    1995 Volume 81 Issue 11 Pages 1061-1066
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    In powder making process such as EBRD(Electron Beam Rotating Process), it is important to solve a problem that some of the molten metal droplets partially solidify and remain on the rotating disk before disintegration.
    The solidification phenomena of Ti-6Al-4V alloy droplets on the rotating disk, and the effect of various factors on the solidified amount were experimentally studied.
    The results obtained were as follows.
    (1) Molten metal droplets partially solidified on the rotating disk, and the solidified shell on the disk is necessary for better atomization.
    (2) In the case of a water-cooled copper disk, the heat flux qd to the disk is 28.6 cal/cm2sec and the solidified amount, η(%) is expressed as
    η(%)=-(CpΔTW-qdA+qe)/ΔHW), (Cp ; specific heat, ΔT ; super heat, W ; rate of melt supply, A ; disk surface area, qe ; heat input from external heat source, ΔH ; latent heat)
    Heat input on the disk reduces the solidified amount. For example, 5kW is necessary for preventing the solidification at the melt supply of 3kg/min and the disk diameter of 80mm.
    (3) In the case of disk made of heat insulating material such as graphite or Ti-6Al-4V alloy, it is difficult to maintain the continuous atomization because of the lack of deformation strength of rotating disk or disk holder.
    Download PDF (3272K)
  • Shigeyuki MORI, Yoshiro MATSUMOTO, Masaru ABE
    1995 Volume 81 Issue 11 Pages 1067-1072
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Al-Mn electroplated galvannealed steel sheet has been developed due to its corrosion-resistibility. In the analyses of metal coatings, the x-ray fluorescence analysis (XRFA) has been applied because of its advantage on speed and nondestructive nature. The XRFA needs, in general, the analytical curves that describe the relationships between the fluorescent x-ray intensity and the coating weight or the composition. To establish the analytical curve, many standard specimens are required, that need lots of money and time to prepare.
    Although the standard-less analysis technique of XRFA known as the fundamental parameter (FP) method has solved this problem, it sometimes brings errors to the analytical values. It is because the FP method assumes that the specimen is completely free of inhomogeneity, i.e. the coating weight and the composition is constant at least over the irradiated area.
    Therefore, we developed the analysis method for the specimens that have inhomogeneity to some extent ; the measured intensity was corrected according to the inhomogeneity ; using this corrected intensity, the specimens were analyzed by FP method. As a result, the Al-Mn coating weight and the Mn concentration were determined as accurate as 0.24 g/m2 and 0.96 mass%, respectively.
    Download PDF (5467K)
  • Kenichi MASUHARA, Koji MORI, Kenji KOSHIISHI
    1995 Volume 81 Issue 11 Pages 1073-1078
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    It was found that surface resistivity of poly (vinyl chloride) (PVC) coated steel sheets is largely reduced by an alkali treatment after electron beam induced graft-polymerization onto PVC, and that anti static proprety is provided to the PVC film. The following results were gained about the mechanism of conductivity for the PVC film.
    1) By the treatment of methacrylic acid grafted layer with KOH aqueous solution, the graft layer becomes hydrophlic. This is supported by the analytical results of IR and EPMA that the graft layer is substituted with pottasium.
    2) Regardless of the KOH treatment conditions, an saturated surface resistivity exits. As the thickness of graft layer increases, saturated surface resistivity decreases. As the atomic weight of alkali metal increases (the radius of the hydrated ion decreases), surface resistivity and saturated surface resistivity decrease.
    3) Surface resistivity increases as relative humidity decreases. It is assumed that the conductivity is given by the increase in mobility of the hydrated alkali ion when free water in the graft layer increases.
    Download PDF (1089K)
  • Toshiyasu NISHIMURA, Ken-itsu TANAKA, Yoshiaki SHIMIZU
    1995 Volume 81 Issue 11 Pages 1079-1084
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Relation between corrosion resistance of steel and NaCl concentration has been studied by wet and dry corrosion test. Corrosion products of steel were directly analyzed in wet and dry corrosion test using In-situ X-ray diffraction equipment. Corrosion rate of steel increased with increasing NaCl concentration. The reduction reaction of rust accelerated corrosion of steel. Ratio of β-FeOOH in rust tends to increase with increasing NaCl concentration. β-FeOOH is reduced to amorphous intermediate oxide in wet cycle, and reproduced in dry one. Amorphous intermediate oxide is reduced to Fe3O4 in constant current reduction, but hardly reduced to that in actual wet and dry corrosion cycle.
    Download PDF (1300K)
  • Kenichi MASUHARA, Koji MORI, Kenji KOSHIISHI, Takashi SASAKI
    1995 Volume 81 Issue 11 Pages 1085-1090
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Adhesion of poly (ethylene terephalate) film by Electron Beam Curing (EBC) method which can be thought as an energy-saving process was studied for the purpose of bestowing economically design and distinctness of image on thermosetting high molecular weight polyester precoated steel sheets.
    Adhesion of EB curable resins onto metal is generally poor. In this report, addition of EB curable phenolic resole oligomer with bifunctional acrylates to the top coat used for precoated steel was studied in order to increase the adhesion of an EB curable adhesive, and it was found that the phenolic oligomer is tremendously effective for the improvement of adhesion.
    The reasons why the phenolic oligomer provides excellent adhesion were 1) elongation at break of the top coat to which the phenolic oligomer is added is little decreased by EB irradiation, and the formability does not reduce. 2) As the phenolic oligomer is unevenly distributed to the surface layer of the top coat, it is suggested that the contact frequency of the phenolic oligomer to the EB curable adhesive is so high that graft polymerization between them is liable to occur.
    Download PDF (3159K)
  • Masato KURITA, Kazuo TOYAMA, Shigeki NOMURA, Kazutoshi KUNISHIGE
    1995 Volume 81 Issue 11 Pages 1091-1096
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    This study is made to clarify the effect of strengthening mechanism of dual phase (ferrite plus martensite phase; DP) steels on the fatigue properties in comparison with ferrite pearlite steels. Several DP steels were obtained to change the kind of strengthening mechanism by adding various alloying elements to the low C-Mn-Cr-Mo DP steel. The strain-controlled and load-controlled fatigue tests were performed. Main results were as follows:
    (1) Solid solution strengthening elements, such as silicon and phosphorus, and precipitation strengthening elements, such as niobium and titanium, exhibited a significant increase in fatigue limit. Increasing the carbon content, however, contributed to the fatigue limit to a very small extent.
    (2) Considering the fact that the fatigue cracks initiated at the ferrite matrix, not in the second hard phase martensite, the experimental results are explained by strengthening of ferrite matrix being more effective to obtain a high fatigue limit than that of hard phase as well as in ferrite pearlite steels.
    Download PDF (5352K)
  • Shigeyoshi NISHIYAMA, Yoshitaka HONDA, Daizo SATO, Hirokazu TANABE
    1995 Volume 81 Issue 11 Pages 1097-1102
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Fe-36Ni alloy (invar alloy) is used for shadow masks in color cathode ray tubes. For improving the formability, it is necessary to obtain a low yield strength and high r-value after annealing. Recrystallization temperature, r-value and development of crystal orientation of invar alloy were investigated by changing cold rolling reduction and annealing condition such as annealing temperature and soaking time. The results obtained are as follows:
    (1) The cube orientation that is the typical recrystallization texture of face centered cubic metals was observed in the invar alloy recrystallized after heavy cold rolling reducion.
    (2) The (111) orientation was observed after recrystallization following light cold rolling reduction. It was found that the sheets with the highly intensitied (111) orientation showed the high r-value.
    Download PDF (1336K)
  • Tsuyoshi YAGI, Michihiko NAGUMO
    1995 Volume 81 Issue 11 Pages 1103-1108
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The fracture process at ductile-brittle fracture transition region of low carbon steels has been compared for J-integral tests and instrumented V-notch Charpy tests. Three steels of ferrite-pearlite structure, A and B, and of mixed structure with bainite, C, were employed. Only differences of the compositions are respective Ni to Mn ratios, and characteristic differences in the ductile-brittle transition behaviors such as the transition temperature, R-curve and brittle fracture initiation stage have been observed. From the analysis of the instrumented test, a Charpy energy is decomposed into the energies dissipated in involved fracture processes. On contrary to steel A and B, decreases of the energy transition temperature and of temperature dependence of stretched zone width at Charpy test compared with at the fracture toughness test are observed with steel C. These differences are originated in Region II where blunting of the notch tip proceeds associated with the extension of the stretched zone. Referring to the stress analyses, the estimated local stress at the brittle fracture initiation site of Charpy tests is about a half of that of J-integral tests. The inconsistency of the transition temperature takes place for steel C which shows pop-in at the J-integral test. It is discussed that the inconsistency of the transition temperature is caused by the suppression of pop-in at Charpy test because of its low local stress.
    Download PDF (4921K)
  • Shunkichi MIYOSHI
    1995 Volume 81 Issue 11 Pages N534-N540
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (10369K)
  • Akiyuki KAGAMI
    1995 Volume 81 Issue 11 Pages N541-N546
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (1507K)
  • Tadashi MAKI
    1995 Volume 81 Issue 11 Pages N547-N555
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (5353K)
  • Shinichi YUU, Toshihiko UMEKAGE
    1995 Volume 81 Issue 11 Pages N556-N563
    Published: November 01, 1995
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Download PDF (6481K)
feedback
Top