Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 71 , Issue 8
Showing 1-19 articles out of 19 articles from the selected issue
  • Isamu EGUCHI
    1985 Volume 71 Issue 8 Pages 925-933
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Koki GUNJI
    1985 Volume 71 Issue 8 Pages 934-938
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Mitsuhiro SAKAWA, Yuzo SANADA
    1985 Volume 71 Issue 8 Pages 939-944
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
  • Saburo SEKIYA, Toshio MOCHIZUKI
    1985 Volume 71 Issue 8 Pages 945-950
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • Tomio HARU, Mitsuo SAINO, Kazuo OKUMURA, Yasuhiko SAKAGUCHI, Toshihiro ...
    1985 Volume 71 Issue 8 Pages 951-957
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    In order to lower the Si content in pig iron, the injection of powder restraining the reduction of SiO2 was examined at Chiba No. 2 Blast Furnace with 1380m3 inner volume and 20 tuyeres.
    The powder used is CaCO3 or iron oxide and it was injected through 5 tuyeres of 20 ones.
    In case of the injection of CaCO3 powder in 8kg/t-p,
    1) Si content in pig iron decreased from 0.84% to 0.68% at 1500°C.
    2) S content in pig iron decreased from 0.034% to 0.027% at 1500°C.
    3) Si content in fine particles sampled in raceway is less than that without injection of CaCO3 powder.
    In case of the injection of iron oxide powder in 32kg/t-p,
    1) Si content in pig iron decreased from 0.72% to 0.57% at 1470°C.
    2) S content in pig iron increased from 0.04% to 0.05% at 1470°C.
    3) Si content in fine particles sampled in raceway is less than that without injection of iron oxide powder.
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  • Kazuhiro S. GOTO, Shu YAMAGUCHI, Kazuhiro NAGATA
    1985 Volume 71 Issue 8 Pages 958-964
    Published: June 01, 1985
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    Chemical compositions of slags and steels at the blow-end of LD converter and various top and bottom blown converters have been collected. The number of the samples was 27 in the conventional LD, 75 in LD-OB, 30 in LD-AB, 23 in STB, and 4 in Q-BOP vessels.
    The chemical potentials of P, Fe, Mn and O have been calculated in the slags as well as in the steels from the oxygen pressures in slag measured by oxygen sensors.
    The magnitude of non-equilibrium between slags and steels tends to decrease with a decrease of carbon content in steels and with an increase of the amount of gas injected from the bottom.
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  • Yutaka MIHARA, Yasushi UENO, Hiroshi KAMIO, Masayuki HATANAKA
    1985 Volume 71 Issue 8 Pages 965-971
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Direct quenching in a seamless tube production mill contributes to a considerable amount of energy saving because a high proportion of the seamless tubes is heat treated. Moreover, it contributes to an improvement of mechanical properties of tubes due to a high hardenability of direct quenching. For its application to a production mill, the most important point is to secure enough temperature of tubes at the quenching zone and to develop a suitable cooling method for on-line quenching. This report refers to temperature evaluation of tubes throughout the rolling process by a theoretical model and also refers to the development of new quenching facilities installed in a new mill. In order to secure high temperature at the end of the rolling train, special rolling processes, such as bar retract operation system in 3-roll transval mill and tandem arrangement of retained mandrel mill with sizing mill, are adopted for the new mill. Those special processes enable the direct quenching even without any reheating furnace. In the processes the uniform and non-deformation cooling system of a long tube up to 29m is accomplished by the rotation of the tube with rapid longitudinal jet flow inside and the curtain wall laminar flow along the outer surface of the tube.
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  • Harushige TSUBAKINO, Tetsuya MIZUNO, Koji YAMAKAWA
    1985 Volume 71 Issue 8 Pages 972-977
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    A monitoring apparatus and some techniques to measure hydrogen content in line pipe steel over a long term have been developed and established, by using electrochemical permeation method (nickel-plating method).
    This monitoring system consists of cells for nickel-plating and monitoring, which are made from acrylic resin, pumping equipment for supply of electrolyte and electronic equipment (YOSHIZAWA type). The cells can be easily set at any position on the external surface of the line pipe. After nickel-plating, the monitoring cell is set and filled with 1N NaOH solution and then the electronic equipment is operated potentiostatically at 150 mV vs Hg/HgO. Anodic current decreases gradually to the value less than 0.04 μA/cm2 within one day. After such preparation, the hydrogen content can be monitored. The detection limit of the hydrogen content by this monitoring system is 0.01 ppm.
    The field test for monitoring hydrogen content in line pipe is performed with high reliability over three months.
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  • Kazuhito KAMEI, Yasuhiro MAEHARA, Yasuya OHMORI
    1985 Volume 71 Issue 8 Pages 978-985
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The hot deformation of Nb-bearing austenitic stainless steel has been studied by means of tensile test with particular attention to both stacking fault precipitation and dynamic precipitation of NbC. Tensile test was carried out at temperatures ranging from 823 to 1173 K at an initial strain rate of 2.1 × 10-4 s-1.
    The results obtained are as follows:
    (1) Although the yield strength of the solution-treated specimen was quite low, remarkable work hardening during the deformation occurred at temperatures ranging from 1023 to 1123 K. In this temperature region large ductility trough accompanied by intergranular ductile fracture was also observed. This can be explained in terms of the dynamic precipitation of NbC within the grains as well as on the grain boundaries.
    (2) In the aged specimen, on the other hand, the yield strength was much larger than that of solutiontreated one and work hardening during the deformation was less significant. Such a high yield strength can be explained in terms of the "small grains" formed by the hard stacking faults where the fine NbC particles precipitated. The ductility trough in this case was rather shallow because of suppression of dynamic NbC precipitation.
    (3) At the temperatures above 1123 K the ductility of the solution-treated specimen increased with increasing deformation temperature, but that of the aged specimen was largely reduced. This ductility loss could be ascribed to the crack formation observed along coherent twin boundaries.
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  • Tohru ISHIGURO, Keizo OHNISHI, Juro WATANABE
    1985 Volume 71 Issue 8 Pages 986-993
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Recently, larger and thicker reactor vessels have been required in hydrogenation processes in order to search the scale merit and to upgrade the service temperature and pressure. The objective of the present work is to develop a heavy-section Cr-Mo pressure vessel steel with enhanced design stress intensity and higher resistance to hydrogen attack, by conducting a set of experiments with regard to the effect of micro alloying elements.
    Effects of Cr, Mo, V, Ti, B and Si were investigated on various properties such as hardenability, tensile strength, impact toughness, creep rupture strength, hydrogen attack susceptibility and weldability. As a results of this alloy modification program, the best composition was found out to be low Si-3%Cr-1% Mo-1/4% V-Ti-B.
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  • Kohichi SUGIMOTO, Tsuneaki SAKAKI, Toshiro FUKUSATO, Ohmi MIYAGAWA
    1985 Volume 71 Issue 8 Pages 994-1001
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The influence of the martensite morphology (the network structure, the isolated island and the finegrained island) on the mechanical properties, particularly initial yielding and strain hardening, of a dualphase steel was examined and discussed on the basis of the micromechanics.
    (1) The network structure of martensite increased 0.2% proof stress, ultimate tensile strength and strainhardening rate compared with the isolated martensite island. One of the reasons for this is that the internal stress arising from the difference between the strengths of the ferrite and the martensite was not so much relaxed in the former structure as in the latter one.
    (2) A dual-phase steel with fine-grained isolated martensite islands exhibited rather higher 0.2% proof stress and ultimate tensile strength due to mainly fine-grained strengthening, and also the highest uniform and total elongation and reduction of area since the void formation around the martensite islands was suppressed.
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  • Yoshihiro KONDO, Takashi MATSUO, Ryohei TANAKA
    1985 Volume 71 Issue 8 Pages 1002-1008
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Based on the analysis of many creep data obtained previously from strain dip test to estimate the effective stress of the solid solution strengthened 25Cr-35Ni steels, the increases of the stress exponent of the steady state creep rate, n, and the activation energy for creep, Qc, due to the addition of solute elements were discussed by using the following steady state creep rate equation, namely,
    εs ∝ (σaf) n0 exp(-Q*c/RT),
    where σf is the friction stress, n0 the effective stress exponent of the steady state creep rate and Q*c the activation energy for creep at constant effective stress.
    It was suggested that the values of n and Qc could be calculated by considering the applied stress and temperature dependence of the friction stress, respectively.
    It was found that the calculated values of n and Qc were in good agreement with those obtained from the creep test.
    Then, it was concluded that the change in n with addition of solute elements was mainly attributed to the differences of the effect of various elements on the applied stress dependence of the friction stress and the ratio of the friction stress to the applied stress, while most part of the increase of Qc was explicable by the temperature dependence of the friction stress.
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  • Takashi MATSUO, Keiichi OHMURA, Ryohei TANAKA
    1985 Volume 71 Issue 8 Pages 1009-1016
    Published: June 01, 1985
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    In metallographic study of Ni-20Cr-20W alloy specimens creep ruptured at temperatures of 900 and 1000°C in air, it has been observed that a β-Mn type nitride, π-phase, is formed in contact with α2-W phase precipitated on grain boundary in the vicinity of intergranular cracks. The appearance of the π-phase in the nitrogen free Ni-Cr-W alloy is mainly attributed to the nitrogen in air through the intergranular cracks. And no decreases in creep resistance and rupture elongation were observed due to the precipitation of π-phase.
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  • Tadamichi SAKAI
    1985 Volume 71 Issue 8 Pages 1017-1024
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Void growth caused by hydrogen attack was measured as to the specimens of 21/4Cr-1Mo and 3Cr-1Mo steels with various amounts of impurity elements exposed to hydrogen of 300kgf/cm2 at temperatures from 600 to 550°C. It was confirmed that impurity elements such as P and Sn have strong effects especially on void nucleation. Microanalysis suggested that the nucleation sites were both carbides and MnS in a Sn-bearing steel, while the nucleation at carbides was suppressed in a P-bearing steel. The data on the void growth were extrapolated to lower temperatures at various hydrogen pressures by using the equation led by CHUANG et al. for non-equilibrium void growth. Constants in the equation were determined so that the calculated results fitted the observed data. The extrapolation gave hydrogen attack limit as defined by the conditions in which total void section per unit area of grain boundary attained 5 per cent at 105 h. The limit conditions for 21/4Cr-1Mo and 3Cr-1Mo steels were affected and reversed by impurity elements.
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  • Makoto HIGUCHI, Hiroshi SAKAMOTO
    1985 Volume 71 Issue 8 Pages 1025-1031
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    An environmental fatigue test machine was developed and axial strain controlled fatigue tests could be conducted in the pressurized high temperature pure water using it. The fatigue life of carbon steel in the environment was investigated.
    Results obtained are summarized as follows;
    (1) In 250°C pure water containing 8 ppm dissolved oxygen, the fatigue life of carbon steel degraded markedly with decrease in strain rate in the comparatively large strain amplitude (above 0.25%). However, in the small strain amplitude, there was no degradation in fatigue life.
    (2) The environmental fatigue degradation was significant in the temperature range of 250°C to 290°C and in the dissolved oxygen contents above 0.2 ppm.
    (3) It was supposed that the conspicuous environmental fatigue degradation was caused by the combination effects of SCC and dynamic strain aging.
    (4) The prediction method of fatigue life of carbon steel in high temperature water was proposed with considering strain rate.
    (5) The environmental correction factor Ken was proposed to correct the design fatigue strength of carbon steel in high temperature water.
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  • Toshinori OZAKI, Hiroshi ASANO
    1985 Volume 71 Issue 8 Pages 1032-1039
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Various feed water pipes which were used for supplying cooling water to turbines in hydroelectric power stations for three to twenty years showed severe plugging problems because of tuberculation. Beneath tubercles, locally corroded large pits were observed.
    Results of water and corrosion product analysis suggest that bacteria might be associated with the tuberculation. Qualitical analysis of the tuberculation suggests the preventive ways of plugging or corrosion penetration.
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  • Norio MARUYAMA, Masae SUMITA, Iku UCHIYAMA
    1985 Volume 71 Issue 8 Pages 1040-1047
    Published: June 01, 1985
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    The relationship between the degree of the effect of synthetic sea water in the freely corrosive condition on fatigue crack growth rate (FCGR) and alloying elements has been examined by the multiple regression analysis using 32 kinds of 980-1176 MPa grade steels which were quenched from 850°C and were tempered at 615°C. The maximum value of the ratio of FCGR in sea water at 0.167 Hz to that in air was used as the degree of the effect of sea water on FCGR. The stress ratio of 0.10 was used. The following results are obtained.
    1) FCGR of the steel containing more than 1% Cr or containing more than 0.8% Mo is relatively high in sea water because cracks propagate through grain boundaries. However, the addition of less than 1% Cr or of less than 0.8% Mo has no influence on FCGR in sea water.
    2) The addition of Si has detrimental influence and the addition of Cu, Mn or Al has beneficial influence on FCGR in sea water.
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  • [in Japanese]
    1985 Volume 71 Issue 8 Pages 1048-1050
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1985 Volume 71 Issue 8 Pages 1056-1058
    Published: June 01, 1985
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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