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

Tetsu-to-Hagané Vol. 95 (2009), No. 10

  • Probing the Inner Structure of Blast Furnace by Cosmic-ray Muon Radiography

    pp. 665-671

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    DOI:10.2355/tetsutohagane.95.665

    The visualization of the inner state of a blast furnace was investigated by exploiting the feature of cosmic-ray muon that attenuates according to the density and the thickness of the object through which it penetrates. The distribution of the cosmic-ray muon accumulated in an object in a blast furnace during a certain period has been determined by a probing system provided with two sets of a pair of panels with plastic scintillation counters segmented in parallel along each direction of both sides. First, measurement was performed in the furnace hearth structure that had been taken out after the shutdown of Oita No. 2 Blast Furnace repaired in 2004. Next, another measurement was performed in the same manner in the renewed furnace hearth of Oita No. 2 Blast Furnace which had just started working after its repairs. The density of the material at the iron-rich portion inside the hearth was estimated from the accumulation ratio obtained from the relation between the intensity of the muon channel passing through the iron-rich part in the hearth and that passing through its opposite channel symmetric to the coordinate origin. Then, the level of the furnace bottom brick, meaning its eroded thickness, was estimated from those accumulation ratios in relation to each channel crossing both the iron-rich part and the furnace bottom brick. The possibility of the density distribution of the material inside a blast furnace and the remaining thickness of bricks being estimated by this measurement method was identified.
  • New Proposal to Take into Account Precipitation of Copper Sulfide by Residual Level of Copper in Quantitative Chemical Analysis of Each Kind of Sulfide (Tai-Betsu Analysis)

    pp. 672-681

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    DOI:10.2355/tetsutohagane.95.672

    From viewpoints of chemical analysis and TEM microanalysis, evidence is reported concerning the necessity to take into account copper sulfide precipitation in steel even by the amount of Cu as small as 0.01%, which has been regarded as one of unavoidable impurities and as solid solution in blast furnace-LD converter-based steel. It is also shown that copper in intentional-Cu-added Ti-added steel (0.05% and 0.12%) acts as sulfide-former, which has been considered as solute in steel and as acting an element for free-standing ε-Cu precipitation through long-hour-aging treatment.
  • Metallurgical Analysis of Iron Slag and Iron Lump Excavated from Precinct of the Nishi-Honganji Temple

    pp. 682-689

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    DOI:10.2355/tetsutohagane.95.682

    Goeido was restored from 1998 to 2009 at the Nishi-Honganji in Kyoto. Lots of iron slag, iron lump and tuyere were excavated from the precinct of Nishi-Honganji, when a construction of disaster prevention was done in autumn of 2006. These iron slag was investigated by metallurgical analysis of some scientific methods. Metallurgical structures in the iron slag were observed by an optical microscope and an electron probe micro analyzer (EPMA). Chemical compounds in the iron slag were identified by a X-ray diffraction method. From these analytical results, Fayalite (Fe2SiO4) and Wustite (FeO) being principal chemical compounds in the iron slag were observed in all samples. Especially, Wustite is characteristic chemical compound produced from a smithing process. Therefore, it was founded that these iron slag was disposed after the smithing. Moreover, multielements in the iron slag and iron lump were determined by a neutron activation analysis (INAA). Especially, the ratio of arsenic concentration to antimony concentration in the iron is able to use as an indicator for estimation the place of production of the raw materials used to make the iron. The ratio in the iron lump and the ratio in previously analyzed iron nails for roofing tiles or for Urakou were almost the same. Therefore, the place of production of the raw material as iron sand from Oku-izumo area in Shimane.
    As these results, it was founded that a large amount of iron crude materials were carried from Oku-izumo to the precinct of Nishi-Honganji, and these were processed for iron nails by the smithing.
  • On-line Analysis of Mn Concentration in Molten Steel by Atomic Absorption Spectrometry

    pp. 690-694

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    DOI:10.2355/tetsutohagane.95.690

    Manganese is one of the important elements for characterization of steel and its concentration is controlled in a steelmaking process. Recently, manganese ore can be used in a basic oxygen furnace blowing because the amount of slag is drastically reduced. Accordingly, if changes of the manganese concentration can be monitored more rapidly and accurately during the basic oxygen furnace operation, manganese ore can be utilized to control the final component of molten steel instead of expensive manganese alloy.
    In this work, we focus on the vapor generated naturally from the molten steel and investigated an on-line system for monitoring the manganese concentration applying the principle of an atomic absorption spectrometry. In using a lab-melting furnace, we confirmed good correlation between the absorption ratio (Mn/Fe) and the manganese concentration within 0.2% in the molten steel.
  • Estimation of Scratched Contact Fatigue Life with Artificial Dent of SUJ2 Steel Carbonitrided to Controlled Surface Nitrogen Content

    pp. 695-703

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    DOI:10.2355/tetsutohagane.95.695

    It was obvious that NH3 partial pressure, H2 partial pressure, carbon activity, and atmospheric imbalance of NH3 partial pressure in a furnace is essential for carbonitriding process, thus, quantum shift of nitrogen concentration in the steel will be achieved in the factory. The scratched contact life is very important performance for rolling bearings, however, there is no research about relationship between nitrogen concentration and the scratched contact life. Keeping this situation in mind, the scratched contact life of SUJ2 (SAE52100 equivalent) of which nitrogen concentration accurately controlled is investigated in this research. To avoid uncertain accidents occurred by additive contamination to lubrication oil, ball bearing's inner rings added the artificial dent by Rockwell indenter (196 N) were used for the scratched contact life test. Weibull slope of the test results by this operation condition became shaper than that of test result by general test method (i.e., bearing's rolling contact fatigue life test under contaminated lubrication condition). Therefore, it is thought that the test method in this research is suitable to get quantitative data. Significance test of the results appeared that when the surface nitrogen concentration is over 0.05 mass%, the scratched contact life is superior to that of normal SUJ2 with a reliability of 99%. Besides, experimental results revealed that, when the surface nitrogen concentration is 0.4 mass%, the life can be longer than that of 0.1 mass% nitrogen concentration. The sample whose surface nitrogen concentration is 0.4 mass% demonstrated L50 life that was 4 times as long as normal SUJ2.
  • Analysis of Global Demand for Iron Source by Estimation of Scrap and Relationship between Primary and Secondary Iron Source and Crude Steel Production

    pp. 704-709

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    DOI:10.2355/tetsutohagane.95.704

    Steel is produced from either primary iron (iron ore), secondary iron (scrap) or a mixture of both. The Utility of Stock hypothesis, which assumes that the in-use stock of constructional material is a function of GDP, was formulated and the clear correlation between the world steel stock and the GDP led to the estimation that the world demand for primary iron (iron ore) depends not on the volume of GDP but on the variation of GDP, as already reported. In this study, the world consumption of scrap (secondary iron) is computed, and the relationship between the crude steel production and the flow of primary and secondary iron is analyzed. It becomes clear that the flow of primary iron has the controlling effect on the world production of crude steel.
  • Analysis of Global Demand for Iron Source by Estimation of In-use Steel Stock

    pp. 710-719

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    DOI:10.2355/tetsutohagane.95.710

    The Utility of Stock hypothesis, which assumes that the in-use stock of constructional material is a function of GDP, was formulated and the clear correlation between the world steel stock and the GDP led to the estimation that the world demand for iron ore (primary iron) depends not on the volume of GDP but on the variation of GDP, as already reported. In this study, the world steel stock in use is computed. Sensitivity analyses are conducted to show the effect of lower reliable data such as the usage period (lifetime) of iron-containing final products. Clear correlation is found between the in-use steel stock and the steel stock. Hence, the Utility of Stock hypothesis is verified.
  • Substance Flow and Stock of Chromium Associated with Cyclic Use of Steel in Japan

    pp. 720-729

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    DOI:10.2355/tetsutohagane.95.720

    Previous studies pointed out that some ferritic stainless steel scrap is mixed in carbon steel scrap and chromium is accumulated in carbon steel product. This paper analyzed Japanese substance flows of chromium involved in stainless steel, other alloy steel and carbon steel by using a dynamic modeling. Those substance flows covered 97% of chromium consumption in Japan. To classify different kind of alloys, stainless steel is subdivided into 13Cr, 18Cr, Cr–Ni, and Cr–Ni–Mo. Heat-resistant steel, structural alloy steel, bearing steel, and spring steel are also taken into account as steel alloys including chromium. Carbon steel is classified into BOF (basic oxygen furnace) carbon steel and EAF (electric arc furnace) carbon steel due to difference of raw materials. It was found that in-use stock of chromium as stainless steel and other alloy steel were 3.4 Tg and 0.7 Tg in 2005, respectively. Other chromium stock as an alloying element in carbon steel was estimated as 0.7 Tg in 2005, which is dissipated into the carbon steel cycle. From the results of the dynamic model, rates of ferritic stainless steel and other alloy steel recovered as carbon steel were approximately 40% and 80% in 2005, respectively. Chromium accumulation in EAF carbon steel was dynamically analyzed from 1990 to 2030. Based on an assumption that future steel demand is same to the current demand, it was predicted that the average chromium content in EAF carbon steel would gradually increase and reach to 0.24% in the year 2030.

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  1. blast furnace
  2. blast furnace permeability
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  5. tuyere abrasion
  6. tuyere erosion
  7. tuyere failure
  8. lme
  9. wear on tuyere
  10. 鉄と鋼