Tetsu-to-Hagane

Development of Wire Coil Annealing Furnace for Speciality Steel

Isamu EGUCHI

1985 Volume 71 Issue 8 Pages 925-933
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_925

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Continuous Casting of Steel-Today, Tomorrow-

Koki GUNJI

1985 Volume 71 Issue 8 Pages 934-938
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_934

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Fundamental Properties of Coal for Its Utilization

Mitsuhiro SAKAWA, Yuzo SANADA

1985 Volume 71 Issue 8 Pages 939-944
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_939

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Hardness Measurement on Mill Rolls

Saburo SEKIYA, Toshio MOCHIZUKI

1985 Volume 71 Issue 8 Pages 945-950
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_945

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Lowering Si Content in Pig Iron by Powder Injection into Blast Furnace

Tomio HARU, Mitsuo SAINO, Kazuo OKUMURA, Yasuhiko SAKAGUCHI, Toshihiro ...

1985 Volume 71 Issue 8 Pages 951-957
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_951

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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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Chemical Potential of Components in Slag and Steel in Various Steelmaking Converters

Kazuhiro S. GOTO, Shu YAMAGUCHI, Kazuhiro NAGATA

1985 Volume 71 Issue 8 Pages 958-964
Published: June 01, 1985
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_958

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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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Direct Quenching Process in Seamless Tube Manufacturing

Yutaka MIHARA, Yasushi UENO, Hiroshi KAMIO, Masayuki HATANAKA

1985 Volume 71 Issue 8 Pages 965-971
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_965

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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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Monitoring of the Hydrogen Permeation Behavior in Pipeline

Harushige TSUBAKINO, Tetsuya MIZUNO, Koji YAMAKAWA

1985 Volume 71 Issue 8 Pages 972-977
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_972

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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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Effects of Stacking Fault Precipitation of NbC on Hot Deformation of Austenitic Stainless Steel

Kazuhito KAMEI, Yasuhiro MAEHARA, Yasuya OHMORI

1985 Volume 71 Issue 8 Pages 978-985
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_978

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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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Effects of Alloying Elements on Mechanical and Metallurgical Properties of Cr-Mo-V-Ti-B Pressure Vessel Steels

Tohru ISHIGURO, Keizo OHNISHI, Juro WATANABE

1985 Volume 71 Issue 8 Pages 986-993
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_986

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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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Influence of Martensite Morphology on Initial Yielding and Strain Hardening in a 0.11C-1.36Mn Dual-phase Steel

Kohichi SUGIMOTO, Tsuneaki SAKAKI, Toshiro FUKUSATO, Ohmi MIYAGAWA

1985 Volume 71 Issue 8 Pages 994-1001
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_994

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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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Stress Exponent of Steady State Creep Rate and Activation Energy for Creep of Solid Solution Strengthened 25Cr-35Ni Steels

Yoshihiro KONDO, Takashi MATSUO, Ryohei TANAKA

1985 Volume 71 Issue 8 Pages 1002-1008
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1002

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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, Q_c, due to the addition of solute elements were discussed by using the following steady state creep rate equation, namely,
ε_s ∝ (σ_a-σ_f) ^n₀ exp(-Q^*_c/RT),
where σ_f 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 Q_c 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 Q_c 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 Q_c was explicable by the temperature dependence of the friction stress.

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Precipitation of π-Phase in Ni-20Cr-20W Alloy during Creep Rupture Test in Air

Takashi MATSUO, Keiichi OHMURA, Ryohei TANAKA

1985 Volume 71 Issue 8 Pages 1009-1016
Published: June 01, 1985
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1009

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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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Estimation of Hydrogen Attack Limit of 21/4Cr-1Mo and 3Cr-1Mo Steels

Tadamichi SAKAI

1985 Volume 71 Issue 8 Pages 1017-1024
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1017

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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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Low Cycle Fatigue of Carbon Steel in High Temperature Pure Water Environment

Makoto HIGUCHI, Hiroshi SAKAMOTO

1985 Volume 71 Issue 8 Pages 1025-1031
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1025

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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 K_en was proposed to correct the design fatigue strength of carbon steel in high temperature water.

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Corrosion and Plugging Behavior of Carbon Steel Pipes with Special Reference to Microbial Corrosion

Toshinori OZAKI, Hiroshi ASANO

1985 Volume 71 Issue 8 Pages 1032-1039
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1032

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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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Multiple Regression Analysis between Fatigue Crack Growth Rates in Sea Water and Chemical Compositions of 1000-1200 MPa Grade Steels

Norio MARUYAMA, Masae SUMITA, Iku UCHIYAMA

1985 Volume 71 Issue 8 Pages 1040-1047
Published: June 01, 1985
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1040

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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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[title in Japanese]

[in Japanese]

1985 Volume 71 Issue 8 Pages 1048-1050
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1048

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

1985 Volume 71 Issue 8 Pages 1056-1058
Published: June 01, 1985
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.71.8_1056

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