Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 94 , Issue 9
Showing 1-8 articles out of 8 articles from the selected issue
Casting and Solidification
Regular Article
  • Masayoshi Sasaki, Kiyotaka Matsuura, Kenichi Ohsasa, Munekazu Ohno
    Type: Regular Article
    Subject area: Casting and Solidification
    2008 Volume 94 Issue 9 Pages 331-335
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    We performed casting experiment of S45C steel, focusing on the effect of addition of Ti and B on as-cast austenite grain structure. Without the addition of these elements, the austenite structure consists of columnar grains over the whole sample in the present casting conditions. The addition of Ti and B leads to the formation of equiaxed austenite grains and, importantly, fully equiaxed austenite structure was observed in the sample with 0.2 mol% Ti and 0.4 mol % B. The microstructural observations indicated that this behavior of austenite structure stems from the columnar-to-equiaxed transition of ferrite dendrite structure. The addition of these elements, furthermore, leads to refinement of the columnar austenite grains.
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Instrumentation, Control and System Engineering
Technical Report
  • Naomi Yabuta, Takaya Hada, Naoki Kimura, Yoshifumi Tsuge
    Type: Technical Report
    Subject area: Instrumentation Control and System Engineering
    2008 Volume 94 Issue 9 Pages 376-381
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    Recently many companies try to promote SCM (supply chain management). The objective of SCM is to maximize the operation efficiency covering the entire process of supply chain and minimize the loss opportunity of sales.
    Because of production lead time of re-roll maker is generally longer than crude steel maker, it is more effective to introduce SCM to re-roll maker.
    Toyo Kohan, which is one of the re-roll makers, has been promoted SCM since 2002. Until now, we have established the consistent production control system, hot band procurement system and business support system for SCM. These systems have performed very well so far. As for the next step of promoting SCM, we have developed WEB sales information system to make closer relation with our customers. Using this system, we can accept orders, provide shipping and stock information and exchange delivery information with our customer. This new system has been introduced 2005. This paper is described outline of this system.
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Chemical and Physical Analysis
Regular Article
  • Hideyuki Matsuta
    Type: Regular Article
    Subject area: Chemical and Physical Analysis
    2008 Volume 94 Issue 9 Pages 336-344
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    Emission characteristics of the laser ablation–hollow cathode helium glow discharge source were examined. It was found that one of the major excitation mechanisms of atomic emission lines having excitation energies of around 3 eV is collisions of electrons with analyte atoms, and that the collisions between sample atoms and metastable helium atoms in the glow discharge plasma play an important role in the excitation of emission lines having excitation energies larger than 4 eV. Emission peaks of atomic helium and carbon contaminants were sufficiently suppressed by the present method, i.e. simply subtracting the emission spectrum with glow discharge alone from the spectrum with both glow discharge and laser ablation. Since it is possible to distinguish between atomic emission spectrum of carbon contained in a steel sample and the spectrum of carbon contaminants in the plasma gas, the response time for the analysis of carbon will be shortened using the present method.
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  • Shunya Inoshita, Shogo Suzuki, Yukiko Okada, Masahiko Kato, Shoji Hira ...
    Type: Regular Article
    Subject area: Chemical and Physical Analysis
    2008 Volume 94 Issue 9 Pages 345-350
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    “Tatara” is a traditional iron and steel making process in Japan. It is a kind of directly refining steel making method using a sand iron. By the authors' study, it turned out that we could estimate the source region of raw material of “Tatara” by As and Sb concentration ratio in “Tatara” sample. However, the concentration of these elements in “Tatara” sample is very low (ppm or sub-ppm order), therefore, quantitative analysis is very difficult. In this study, As and Sb in “Tatara” sample (iron lump, sand iron and slag) were determined by Neutron Activation Analysis combined with Multiple Gamma-ray detection (NAAMG). NAAMG is high sensitive and non-destructive analysis method which combined Neutron Activation Analysis (NAA) and multiple gamma-ray detectors. Each “Tatara” sample (iron lump, sand iron and slag) was irradiated for 1–2 h (for As measurement), and 8–17 h (for Sb measurement) in JRR-3M HR irradiation field (thermal neutron flux was about 9.0×1017 n m−2 s−1). After the end of irradiation, cooling time was 4–5 d (As), and 19–36 d (Sb). Coincidence gamma-rays were measured by gamma-ray detector array, GEMINI-II for 1–8 h (As), and 2–41 h (Sb). Iron and steel certified reference materials were used as comparative standards. As a result of measurement, the concentration of As and Sb in all “Tatara” samples were determined by NAAMG and these were sub-ppm order. Lower Limit of Determination (LLD) of As was 0.1 ppm order and Sb was 0.01 ppm order.
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Forming Processing and Thermomechanical Treatment
Regular Article
  • Akihiko Nagasaka, Yuichi Kubota, Koh-ichi Sugimoto, Atsushi Mio, Tomoh ...
    Type: Regular Article
    Subject area: Forming Processing and Thermomechanical Treatment
    2008 Volume 94 Issue 9 Pages 351-356
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    Effect of YAG laser cutting on stretch-flangeability of 0.2C–1.5Si–1.5Mn (mass%) ultra high-strength TRIP-aided sheet steel with bainitic ferrite matrix (TBF steel) having different martensite start temperatures, which were austempered at 375 or 450°C, was investigated for automotive applications. Hole notches of 5 mm diameter were produced by YAG laser cutting or mechanical punching for hole-expanding test. The stretch-flangeability was evaluated using hole-expanding ratio (λ).
    In TBF steel, laser cutting resulted in much higher stretch-flangeability than mechanical punching. The hole-expanding ratio (λ) of TBF steel austempered at 375°C in the case of laser cutting at average powers between 50 and 100 W was higher than that at 450°C, and also higher than mechanical punching. Furthermore, the strength–stretch-flangeability balance (TS×λ) of TBF steel austempered at 375°C showed the highest stretch-flangeability by laser cutting at 100 W. We found that compared with mechanical punching, YAG laser cutting contributed to the improvement of the TS×λ of 1100 MPa class TBF steel with fine bainitic ferrite matrix.
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Welding and Joining
Regular Article
  • Tadafumi Hashimoto, Hidenori Terasaki, Yu-ichi Komizo
    Type: Regular Article
    Subject area: Welding and Joining
    2008 Volume 94 Issue 9 Pages 357-362
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    The solidification cracking susceptibility with the dependence of the selection of the primary phase was clarified with the Trans-Varestraint test, since the solidification mode of alloy tool steel (SKD61) was transited from FA mode (L → L+δ → L+δ+γ → L+γ→γ) to A mode (L → L+γ → γ) at high solidification velocity. It was obtained that the Brittle Temperature Range was enhanced to 587K for A mode while it was 105K for FA mode in the augmented strain of 2%.
    In order to clarify the change of dendrite morphology during the solidification process, the liquid tin quenching was curried out. Though the interdendritic microsegregation can be reduced due to the dendrite arm development, the solidification cracking susceptibility was sensitized in A mode solidification. Therefore, the selection of the primary phase is extremely important.
    The effect of primary phase selection on the interdendritic microsegregation was theoretically proven using the solidification velocity dependence of microsegregation model taking into the diffusion of the solute in the solid phase. It was found that the solidification cracking susceptibility obtained by the Trans-Varestraint test can be simply evaluated as the influence of the mode transition below the solidification velocity of 10 mm s−1 and the reduction of Si, P and S content can be effective on decreasing the risk of solidification crack.
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Transformations and Microstructures
Regular Article
  • Nobuaki Oku, Kentaro Asakura, Junya Inoue, Toshihiko Koseki
    Type: Regular Article
    Subject area: Transformations and Microstructures
    2008 Volume 94 Issue 9 Pages 363-368
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    In-situ observation of austenite-to-ferrite transformation in low carbon steel was conducted with a laser scanning confocal microscope. Development and kinetics of ferrite plates during continuous cooling process were studied. It was in-situ observed that the ferrite plates nucleated at either austenite grain boundary or allotriomorphic ferrite, and grew with keeping the Kurdjumov–Sachs orientation relationship with prior austenite. Surface relief was induced by the formation of ferrite plate. When the ferrite plate nucleated at pre-existing grain boundary ferrite, gradual change in growth direction by the sympathetic nucleation was confirmed both by the observation and EBSP analysis. Temperature dependency of the observed growth rates of the plates was in a good agreement with the Zener–Hillert model, which indicates the growth is controlled by the diffusion of carbon.
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Social and Environmental Engineering
Regular Article
  • Xinghe Zhang, Jusen Asuka, Nozomu Kawabata, Izumi Omura, Gyozo Kawahar ...
    Type: Regular Article
    Subject area: Social and Environmental Engineering
    2008 Volume 94 Issue 9 Pages 369-375
    Published: September 01, 2008
    Released: August 15, 2009
    JOURNALS FREE ACCESS
    This paper provides the design of a Clean Development Mechanism project at the coke industry in Shanxi province, China. The target of this project is to reduce emission of carbon dioxide by installing coke dry quenching equipment into mechanical coke ovens of Shanxi Antai Group Co., Ltd. This paper demonstrates how the anthropogenic emission of carbon dioxide is reduced by this project activity below those that would have occurred in the absence of CDM project. Moreover, this paper shows that this project achieves not only emission reduction of carbon dioxide but energy saving, water saving and emission reduction of other pollutants such as sulfur dioxide.
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