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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 90 (2004), No. 3

  • A Review of Japanese Packaging Market and Its Technologies

    pp. 113-127

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    The Japanese packaging market is reviewed and analyzed in terms of the materials, the products and the technologies. The shipment of packaging materials by value has been decreasing since 1991 and was counted about 6000 billion yen in 2001, whereas the amount has been almost constant with slight increases of plastics and paper. This means that the material and cost reductions are extremely demanded. The largest market for hermetically sealed packages is drinks. The share of PET bottles in the total non-alcoholic drinks was 51% followed by steel cans (25%), cartons (10%), aluminium cans (9%) and glass bottles (4%). In the alcoholic drinks sector aluminium cans are dominant. In the food and the general-use sectors flexible pouches have been increasing by replacing glass jars, cans and plastic bottles from the standpoints of convenience and waste reduction. It seems that there are two main trends in the development of packaging. One is differentiation and the other is rationalization. Differentiation by decoration, shaping, adding functions has commonly applied to the packages for soft drinks and other commodities. As for cost effective or mass consumption products such as "beer", low alcoholic drinks etc., rationalized packages are preferred. PET-coated 2pc cans, Hi-barrier PET bottles and improved filling systems etc. are introduced. Recycling of packages is also reviewed. As the role of packaging becomes increasingly important under increasing world population and the world warming, developing packages and packaging systems with less environmental and economical impact is essentially important.
  • Emulsion Type Rolling Oil with High Performance for Friction Pickup in High Speed Cold Rolling

    pp. 128-133

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    The prevention of friction pickup, which occurs under the condition in high rolling reduction and/or high speed, is required to improve productivity in cold steel rolling. In order to prevent the friction pickup at high speed cold rolling, new rolling oils of emulsion type are developed in this paper. The emulsions consist of a synthetic ester with a viscosity of 100cSt, emulsifier and additive. In the experiments, the emulsion concentration is changed, and two emulsifiers and several additives are used. The effects of emulsion concentration, emulsifier, extreme-pressure agent and new additive on friction pickup are investigated. For the evaluation of friction pickup, the sliding-rolling simulation testing machine is used. The experimental results obtained are as follows.
    (1) When the emulsion concentration and the emulsion particle size increased, the limit reduction of friction pickup increased.
    (2) When the extreme-pressure agent of P system or inactive S system was added, the limit reduction of friction pickup did not increase.
    (3) When new additives of Ca sulfonate and extreme-pressure agent of active S system were used, the limit reduction of friction pickup increased largely.
  • Mechanism for Suppression of Surface Hot-shortness in Cu Containing Ferritic Stainless Steel

    pp. 134-140

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    This paper investigates why Cu containing ferritic stainless steel does not exhibit surface hot-shortness even when it contains much more than enough Cu to show the hot-shortness in mild steel. A 2.4% Cu containing 16% Cr stainless steel and a 0.3% Cu containing mild steel were employed and they were heated up to 1250°C in atmospheres of 20%H2O-1%O2-bal.N2 and 10%H2O-1%O2-bal.N2 for the stainless and the mild steels, respectively, in order to produce the same amount of scale. Their surface hot-shortness was assessed by measuring the number of cracks occurring in hot-deformed specimens and the microstructure around the scale/steel interface was closely observed by optical microscopy and SEM.
    No cracks were observed in the 2.4%Cu-16%Cr stainless steel while severe cracks were found in the 0.3% Cu mild steel although the amount of scale for the former was nearly the same or a little larger than that for the latter. For the 2.4%Cu-16%Cr stainless steel, Cu enriched liquid alloys were observed in the inner scale zone and no concentration of Cu was found at the scale/steel interface. In addition, a complicated structural zone called metal/oxide mixed zone covered the steel surface. The suppression of surface hot-shortness in Cu containing ferritic stainless steel was explained in terms of the structural characteristics of the scale/steel interface and the different diffusion rate of Cu atoms between α-phase matrix and γ-phase matrix at 1250°C.
  • Effects of Ti-based Oxide Inclusions on Formation of Intragranular Ferrite in Steels

    pp. 141-145

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    Dispersion of fine proeutectoid ferrite and/or enhancement of formation of intragranular bainite have been performed to improve mechanical properties at/around welded region in steels. In the present study, effects of Ti-based oxide inclusions on the nucleation and growth processes of proeutectoid ferrite and bainite are examined in terms of the number density and size of the inclusions in steels with different γ-grain sizes. Ti-oxide acts as effective nucleation site of granular proeutectoid ferrite and bainite. Especially, it could be suggested that fine inclusions induce nucleation of high density of intragranular bainite. On the other hand, growth of (Ti, Mn)-oxide on grain boundary enhances both the depletion of Mn at/around grain boundary and formations of elongated proeutectoid ferrite along grain boundary, Widmanstätten ferrite and aggregate of nearly single-variant of bainite at grain boundaries. The Mn depletion could form the three kinds of ferrites mentioned above, remarkably, at grain boundaries, resulting in the suppression of formation of intragranular bainite.
  • Roping Property of SUS430 Cold-rolled Sheet

    pp. 146-153

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    This study investigates the origin of the roping of SUS430 ferritic stainless cold-rolled sheet, paying attention to the heterogeneous factors in the hot-rolled sheet thickness, and the effects of the colony structure and the α' phase in hot-rolled sheet on the behavior of the roping during cold rolling. The origin of the roping was the mid-thickness with strong α-fiber texture. As ascertained by temper color method, the hot-rolled sheet with severe roping after cold rolling had large {001} and {111} colonies with different deformation properties, while that with slight roping had a small {001} colony. The behaviors of the roping and the texture during cold rolling depended on the hot rolling condition and cold rolling reduction. The improvement of the roping of SUS430 cold-rolled sheets is brought by the control of {001} colonies in hot-rolled sheet and the formation of the deformation zone around α' phase in high cold rolling reduction.
  • Tensile Properties and Surface Reaction Layer of Biomaterial, Ti-29Nb-13Ta-4.6Zr, Cast by Dental Precision Casting Process Using Various Investment Materials

    pp. 154-161

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    Ti-29Nb-13Ta-4.6Zr for biomedical applications and conventional α+β type titanium Ti-6Al-4V ELI for biomedical and dental applications are subjected to dental precision casting using commercial alumina based and magnesia based investment materials, and modified magnesia based investment material. Mechanical properties and surface reaction layers of cast Ti-29Nb-13Ta-4.6Zr were investigated in order to find the suitable investment material for dental precision casting of Ti-29Nb-13Ta-4.6Zr in comparison with Ti-6Al-4V ELI. The following results were obtained.
    Elongation of Ti-29Nb-13Ta-4.6Zr cast into commercial alumina based investment material is lower than those cast into commercial magnesia and modified magnesia based investment materials although no big difference in strength is obtained regardless of the investment materials. The formation of surface reaction layer composed of oxide and α-case is restrained by magnesia and modified magnesia based investment materials as compared with alumina based one. The modified magnesia based investment material is better for casting of Ti-29Nb-13Ta-4.6Zr as compared with magnesia and alumina based investment materials.
  • Fine-grained Ferritic Steels without Upper/Lower Yielding

    pp. 162-169

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    Fine-grained ferritic steels without upper and lower yielding were created under caliber rolling in the range of C=0.050.44 mass% and N=0.001 mass%. The grain size of steels created was about 1 μm. Upper and lower yielding disappeared by adding the amount of Ti given by Ti>4C +3.43N, because C and N are fixed as TiC and TiN. Here, Ti, C and N are mass%. On the other hand, upper and lower yielding existed, when Ti<4C +3.43N. The difference in strength between fine-grained steels with and without yielding i.e. the solid solution strength due to C was estimated to be 100 MPa with the yield stress and 70 MPa with the tensile strength. TiC particles smaller than 10 nm precipitated, adjusting the thermo-mechanical process of creating fine-grained steels. The precipitate dispersion strength due to TiC was estimate to be 300 MPa at C_??_0.05 mass% and Ti_??_0.2 mass%, This strength is equivalent to 1500 MPa per 1 mass% Ti. As the results, the maximum tensile strength reached about 900 MPa at C=0.075 mass% and Ti_??_0.3 mass% in 2-μm fine-grained steels. Fine-grained steels with and without yielding also showed high toughness and high fatigue strength.
  • Fatigue Properties and Fracture Surface Analysis of Plazma-nitrided Cold Work Tool Steel

    pp. 170-176

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    Rotating fatigue properties of plazma-nitrided cold work tool steel have been investigated using modified SKD11 (Mod.SKD11), which contains 0.8C-8Cr-2Mo-0.5V. Specimens were tempered at 470, 520 and 540°C after quenching from 1030°C. Plazma-nitiriding was conducted at 450°C for 3 h after tempering. These tempering temperatures were decided by the following reasons: the hardness is same for the materials tempered at 470 and 540°C, the material tempered at 520°C has the highest hardness, and the material tempered at 470°C contains 15 vol% retained austenite which has a possibility of toughening the nitrided hard layer. Fatigue lives of nitrided specimens was five times longer than non-nitrided specimens, especially at higher stress amplitude. It was considered that crack initiation sites for nitrided specimens were shifted to interior of specimens because of generation of hardened layer and compressive stress near specimen surface by nitriding, while fatigued cracks generated at or near surface for non-nitrided specimens. At crack initiation sites, carbides or inclusions were observed in all specimens. Fatigue strength of nitrided specimens tempered at 470°C was higher than other nitrided specimens. It was considered that stabilized γR was contributed to suppress cracking of the carbides, which act as fatigue crack initiation sites.
  • Hydrogen Embrittlement of Ultra High Strength Low Alloy TRIP-aided Steels

    pp. 177-182

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    The amount of charged hydrogen and its effect on ductility in three kinds of ultra high strength low alloy TRIP-aided steels with different matrix structure were investigated. These TRIP-aided steels, especially the TRIP-aided steels with bainitic ferrite matrix, were charged hydrogen more than the conventional tempered martensitic steel. This was principally associated with retained austenite trapped so much hydrogen in solute. Hydrogen embrittlement was considerably suppressed in the TRIP-aided steels, especially in the TRIP-aided steel with annealed martensite matrix. It was considered that the scanty hydrogen embrittlement of the steel was caused by trapping of much hydrogen into retained austenite, uniform fine structure, TRIP effect of retained austenite and appearance of quasi-dimple fracture.

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