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Katsuyoshi TANAKA
1985 Volume 71 Issue 2 Pages
147-156
Published: February 01, 1985
Released on J-STAGE: June 19, 2009
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Yoshio KAMIYA
1985 Volume 71 Issue 2 Pages
157-163
Published: February 01, 1985
Released on J-STAGE: June 19, 2009
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Jun-ichiro TANAKA
1985 Volume 71 Issue 2 Pages
164-166
Published: February 01, 1985
Released on J-STAGE: June 19, 2009
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Hideomi KOINUMA
1985 Volume 71 Issue 2 Pages
167-174
Published: February 01, 1985
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Yoshimasa KAJIWARA, Takao JIMBO, Tadatsugu JOKO, Yo-ichi AMINAGA, Taka ...
1985 Volume 71 Issue 2 Pages
175-182
Published: February 01, 1985
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The burden distribution in bell-less charging was investigated by the use of a full scale experimental apparatus and simulation models were developed on the basis of experimental results.
The discharge behavior of burden from the bunker was found to be primarily funnel flow and was quantitatively evaluated by the simulation model considering the velocity distribution of particles in the flow region above discharge hole. Sinter showed a stronger tendency to be funnel flow than coke.
The burden trajectory in and outside the chute was successively estimated by solving the equation of motion on a single particle.
The mixed layer formation was observed in bell-less charging as well as bell-armor charging. The extent of the mixed layer in bell-less charging was found to be expressed by the same experimental formula for bell-armor charging through the proper evaluation of "formation energy of mixed layer".
The validity of the simulation model was confirmed by the comparison with experimental results in various charging schedules. The simulation model was successfully applied to the flat profile charging.
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Kazuhiro NAGATA, Nobuo TSUCHIYA, Kuniyoshi URATA, Masao MATSUOKA, Kazu ...
1985 Volume 71 Issue 2 Pages
183-188
Published: February 01, 1985
Released on J-STAGE: June 19, 2009
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Oxygen sensors have been newly designed and tested for continuous measurements of oxygen potentials in pig iron and slag at blast furnaces in operation. The key points of constructions of the sensors are that 1) one-end closed tube of ZrO
2. 9mol % MgO is used as a solid electrolyte, 2) graphite tube is used as a mount of the electrolyte and also 3) as an electrode in contact with pig iron, and 4) air-Pt electrode is used as a reference electrode. The sensors were tested in the runner at the skimmer of the blast furnaces. Oxygen potentials have been reliably measured for 157 min during 3 taps for pig iron and 78 min for slag in maximum.
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Tsutomu NISHIDA, Kozo TANAKA, Teruhisa UEHARA, Takeshi YABATA, Sei TAK ...
1985 Volume 71 Issue 2 Pages
189-196
Published: February 01, 1985
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No. 2 blast furnace in Kobe Works was blown in on February 4, 1981 and because of the economic conditions it was blown out on April 22, 1983. Since its working period was very short (about 2.2 years), it was banked with the expectation of blowing in after several years.
The methods employed were :
(1) to lower the stock line down to just above the level of the SiC brick lining (lower shaft) with the burden being replaced by coke,
(2) to cool the furnace by N
2 gas,
(3) to preserve the furnace brick under N
2 atmosphere.
Two samples of SiC brick at lower shaft part were collected just after and at 8 months after blowing out, and then they were investigated. It was found that there was no impairment in the SiC brick during this 8-month period.
Hot stoves were cooled by the natural cooling method with keeping airtight and their cooling periods were about 3 months. After cooling them, the observations inside them were done and it was confirmed that the damage of the brick was very little, so the reoperation of them would be of no trouble.
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Minoru SASABE, Kouichi SAKAI
1985 Volume 71 Issue 2 Pages
197-203
Published: February 01, 1985
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In order to obtain a guide for determination of oxygen potential in molten slag, the discussion is made on the reason why EMF is induced from oxygen concentration cell of which electrode immersed in molten slag does not contact at the surface of the solid electrolyte. The following conclusions are obtained :
1) The EMF is determined only by oxygen chemical potential in the slag when solid electrolyte doesn't dissolve into the molten slag. On the other hand, The EMF is determined by oxygen chemical potential and diffusion potential induced by the dissolved materials when solid electrolyte is dissolved into the molten slag.
2) In the case of the oxygen concentration cell of which electrode immersed in the molten slag doesn't contact at solid electrolyte surface, the minimum distance between the solid electrolyte surface and the electrode under the present experimental condition was 2 mm in order to prevent influence of diffusion potential.
3) Oxygen probe for molten steel with molybdenum electrode should not be used in molten slag, except the slag being rapidly flowing.
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Tetsuya NAGASAKA, Yasutaka IGUCHI, Shiro BAN-YA
1985 Volume 71 Issue 2 Pages
204-211
Published: February 01, 1985
Released on J-STAGE: June 19, 2009
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The reduction rate of liquid wustite contained in an iron crucible under Ar-CO, CO-CO
2 or Ar-CO-CO
2 gas mixtures has been measured by using thermobalance at 1 400 and 1 450°C. The experimental region of partial pressure of CO was
PCO=0.02 -0.18 atm (Ar-CO) and
PCO=0.07-0.84 atm (Ar-CO-CO
2 and CO-CO
2).
The apparent reduction rate became constant in the region of gas flow rate above 2.5
l/min. Under this experimental condition, the rate of reduction was controlled by the chemical reaction at the interface, and was expressed by the following equation :
r=
kc(
Ke-α)
PCO (g-oxygen/cm
2·s),
where
Ke and α are the equilibrium constant of the reaction among gas, liquid wustite and solid iron, and
PCO2/
PCO in the gas phase, respectively. The apparent rate constant of the chemical reaction,
kc, was expressed by the following equation :
kc=1.18 exp(-24 300/
RT) (g-oxygen/cm
2·s·atm).
The reduction rate of liquid wustite with CO was 6 times larger than that of solid wustite.
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Ryo INOUE, Hideaki SUITO
1985 Volume 71 Issue 2 Pages
212-219
Published: February 01, 1985
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The phosphorus distribution ratios between carbon-saturated iron melts and Na
2O-SiO
2, Na
2O-SiO
2-MO (M=Mg, Ca, Ba), CaF
2-CaO or CaF
2-CaO-Al
2O
3 slags have been obtained as a function of slag compositions and temperatures. The phosphorus distribution ratios in the Na
2O-SiO
2-MO (M=Ca, Ba, Mg) system were found to decrease when Na
2O was replaced by MgO, CaO and BaO at a constant SiO
2 content. The temperature dependence of phosphorus distribution ratios in the CaF
2-CaO and CaF
2-CaO-Al
2O
3 systems has been observed in the temperature range of 1 430°C to 1 550°C, while in the Na
2O-SiO
2 system it has not been observed at 1 250°C and 1 350°C. The phosphorus distribution ratios in the MF
2-MO (M=Mg, Ca, Ba, Na) system were found to decrease in the order of Na>Ba>Ca>Mg.
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Kazuo KITAMURA, Tomoo TAKENOUCHI, Yoshiyuki IWANAMI
1985 Volume 71 Issue 2 Pages
220-227
Published: February 01, 1985
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In order to reduce the susceptibility to embrittlement of steels such as a rotorshaft for power plant, which are to be used at high temperatures, experiments were carried out on the optimum conditions for the removal of tramp elements like Sn, Sb and As by the addition of CaC
2. Industrial scale tests were also carried out, based upon the experimental results obtained. The results obtained can be summarized as follows.
(1) These impurities can be removed by reduction, and the reduction was accelerated by the rapid decomposition of CaC
2 at low initial carbon content and high temperatures.
(2) The amount of impurities removed was found to be proportional to the increase in carbon content during reaction and the initial impurity content. The proportional constant increased in the order of Sn, P, Sb and As.
(3) It was found from the industrial scale tests that the impurities could be favorably removed by using Ar stirring from the bottom of the ladle and by using CaC
2 injection increasing the reaction surface area.
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Naomi MATSUMURA, Masaharu TOKIZANE
1985 Volume 71 Issue 2 Pages
228-235
Published: February 01, 1985
Released on J-STAGE: January 19, 2010
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Austenite grain refinement of low carbon steels prepared with and without addition of minor amount of niobium was attained by a thermomechanical processing in order to obtain the materials with (α+γ) microduplex structure in the intercritical temperature field. Such materials showed superplastic behavior during high temperature tensile deformation. The largest elongation to failure value of 738% and high value of strain rate sensitivity exponent,
m, (>0.6) were obtained by tensile deformation at 790°C and at strain rate of 5×10
-3 min
-1in the Nb-bearing steel. Moreover, elongation to failure value of about 300% was obtained by tensile deformation at around 800°C and at strain rate of 5×10
-1 min
-1 which may be applicable for practical forming process. The largest elongation to failure value and the highest
m-value were, as a whole, obtained at around the temperature where the specimens are composed of nearly equal volume fraction of α and γ phase.
A minor addition of niobium presumably promoted superplasticity of low carbon steel through a suppressive effects of finely dispersed precipitates of niobium-carbide (or-carbonitride) on grain growth during high temperature deformation.
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Toshio OGATA, Keisuke ISHIKAWA, Kotobu NAGAI, Keijiro HIRAGA, Yuji NAK ...
1985 Volume 71 Issue 2 Pages
236-241
Published: February 01, 1985
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A Fatigue Testing Machine at Liquid Helium Temperature with new re-condensing type cooling system was installed in National Research Institute for Metals, Tsukuba Laboratories. The machine has been designed for long-term fatigue testing at liquid helium temperature. The machine has a recondenser in the closed test machine cryostat. Helium mist is transferred to the recondenser from the refrigerator and evaporated helium gas is recondensed in the cryostat. The liquid helium level in the cryostat is kept constant without additional supply of liquid helium during the testing. This recondensing type cooling system has achieved long-term continuous operation for more than 460 h.
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Noboru ISHIKAWA, Toshiaki FUJIMORI
1985 Volume 71 Issue 2 Pages
242-249
Published: February 01, 1985
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It is feared that non-metallic inclusion will impair ductility and toughness in through thickness direction of rolled steels. In beam-column joints of steel frame of building, the stress occurs in through thickness direction of steel plate. Therefore, the size estimation of inclusion in rolled steels used in actual structure is necessary to maintain the performance of joints.
This paper describes ultrasonic inspection methods for estimating the size of non-metallic inclusion.
The two kinds of ultrasonic inspection methods were examined and the abilities for measurement were discussed.
The following results were obtained.
(1) The "C-scope method" with an immersion focusing type probe is effective for inspecting the shape and size of flat form defects such as leaf type inclusion around focusing point. But, this method is difficult to apply in actual structure.
(2) The "Acrylic resin delayed method" with AVG diagram is applicable to inspection of rolled steel in actual structure. This method, however, tends to underestimate the area of defects comprised of non-metallic inclusion. This paper proposes equations for estimating the size of inclusion based on the sound field of the probe and the reflection loss on the interface between inclusion and steel matrix.
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Kazuo FURUYA, Takashi YAMAMOTO, Toshio KAINUMA, Iku UCHIYAMA
1985 Volume 71 Issue 2 Pages
250-257
Published: February 01, 1985
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The effects of thermal aging on the low cycle fatigue behavior of Ni-15Cr-25W alloy (KSN) were investigated at 1 273 K in the simulated helium gas (He-2) for High Temperature Gas-cooled Reactor (HTGR). Fully reversed strain control tests were made at a strain rate of 1 × 10
-3s
-1 with holdtimes of 0, 6 and 60 min. The thermal aging at 1 273 K for 1 000 h caused the precipitation of α
2 phase (bcc-W) in the matrix and on grain boundaries of KSN.
Although a degradation of fatigue lives was observed with increasing the period of holdtime for both solution annealed and aged KSN (KSN-SA and -AGE), fatigue life was significantly larger for KSN-AGE than that for KSN-SA. The morphology of intergranular fracture of two materials indicated that the existence of α
2 particles at the grain boundaries increased both cycles to initiation and those to propagation of fatigue crack. The role of α
2 precipitates was to reduce the weakening of grain boundaries and the oxidation rate by changing the corrosion products at a crack tip from Cr-oxides for KSN-SA to Ti/Al-oxides for KSN-AGE.
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Keishi NAKANO, Masao KANAO, Takao AOKI
1985 Volume 71 Issue 2 Pages
258-265
Published: February 01, 1985
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Slow strain rate tensile tests were carried out on specimens of a high tensile structural steel( JIS SM50B) in 3.5 %NaCl solution as a function of strain rate under freely corroding and cathodically polarized conditions. The main rasults obtained are as follows;
(1) A tendency of decrease in ductility was notable at potentials less than -850mV(SCE) with strain rates less than 7×10
-5 s
-1. This decrease in ductility was attributed to cathodically charged hydrogen induced cracking.
(2) The hydrogen induced cracking resulted in formation of transgranular cracks and their crystallographic planes were found not to be cleavage but mainly parallel to {110} slip planes.
(3) The hydrogen induced cracking was not observed under constant load condition in the range of cathodic potential studied, so it was suggested that the continuous plastic deformation played an important role for the hydrogen induced cracking to occur.
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Minoru KAMADA, Kenichiro SUEMUNE, Masami OOSAWA, Masaaki SHIBATA
1985 Volume 71 Issue 2 Pages
266-273
Published: February 01, 1985
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In order to develope the production method of enameling steel sheet by continuous casting, it is necessary to prevent fishscaling of killed steel. The effect of B and N in steel on fishscaling and hydrogen permeation of Al killed steel sheet has been studied using the specimens prepared from vacuum melting.
Fishscaling was reduced appreciably by adding B into steel, and remarkably by adding B and N. As B. and N contents increased, hydrogen permeation and fishscale susceptibility reduced. As a close correlation existed between the fishscale susceptibility and insoluble B (B as BN) in steel, it was considered that the reducing effect by B and N addition was due to boron nitride depositing in steel. In order to prevent fishscale perfectly, it was necessary to contain insoluble B more than 0.002% for cold rolled steel sheet and 0.008% for hot rolled steel sheet, respectively.
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Mitsutane FUJITA, Yoshikuni KAWABE, Hirosada IRIE, Susumu TSUKAMOTO
1985 Volume 71 Issue 2 Pages
274-280
Published: February 01, 1985
Released on J-STAGE: January 18, 2010
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The influence of specimen size on the tensile strength of electron beam welded joint has been studied for four maraging steels. The strength was measured using specimens different in the plate width (
W) and thickness (
t) and the width (
H) of the weld metal. The influences have been discussed on the basis of the plastic constraint of the base metal having higher strength than the weld metal.
The strength of welded joint rises gradually and reaches a constant value as
W increases when
t and
H are both constant. This constant value of strength corresponds to the strength of infinitely wide welded joint. The minimum width (
W∞) at which the constant value is achieved is determined. When
W and
t are constant, the strength of welded joint of the width
W∞ increased with the decrease in
H. When
W and
H are constant, it increases with the increase in
t. The strength of welded joint increases with the decrease in the relative thickness (
H/
t) as the degree of the constraint from the base metal of the deformation of the weld metal increases. The width
W∞ is roughly given by
W=5
t in case (
H/
t) ≤1 and
W=5
H in case (
H/
t)>1. Similar results have been reported for high tension steels.
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Shoji HAYASHI, Yoshiaki IGUCHI, Jiro HIRAO
1985 Volume 71 Issue 2 Pages
281-283
Published: February 01, 1985
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[in Japanese], [in Japanese]
1985 Volume 71 Issue 2 Pages
286-286,290
Published: February 01, 1985
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
1985 Volume 71 Issue 2 Pages
298-300
Published: February 01, 1985
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