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Yoshihiko OSAKI, Michio HASHIMOTO, Mitsumasa TSUKADA
1986 Volume 72 Issue 2 Pages
173-181
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Yasushi NAKAMURA, Ryoichi SUZUKI
1986 Volume 72 Issue 2 Pages
182-188
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Kouji TAKATANI, Yuji IWANAGA
1986 Volume 72 Issue 2 Pages
189-194
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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The thermal degradation behavior of coke in the blast furnace is investigated by experiments with rapid heating and model analysis considering the intraparticle temperature and stress distributions.
It is presumed that the thermal stress is closely related to the expansion and contraction of coke during heating and there exist two types of crack in coke in the blast furnace. One is breakage with exfoliating spherical husk and the other is split from surface to inside.
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Hideo SHIMIZU, Ken-ichi SATO, Masateru KOJIMA, Yoichi AMINAGA, Fumio N ...
1986 Volume 72 Issue 2 Pages
195-202
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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In order to establish the evaluation method of coke quality in the blast furnace, it is important to investigate the coke degradation behavior in the furnace.
From this point, the sampling of coke was done during the shut-down at three levels-lower shaft, bosh and tuyere. The degradation behavior of coke and the mutual correlation between the coke properties and operational conditions were investigated. From the operational results of the blast furnace, the degradation behavior of coke at the lower part of the blast furnace and the relation between the blast conditions and degradation degree of coke were discussed.
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Tsukasa TAKADA, Hideaki SOMA, Toshiyuki IRITA, Eiji KAMISAKA, Haruo KI ...
1986 Volume 72 Issue 2 Pages
203-209
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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In situ Reaction Vertical Probe which is able to estimate the both effects of mechanical force and reducibility in the blast furnace has developed.
Several types of sinter with different RDI were charged into an operating blast furnace. After the recovery of the sinter, degradation was observed.
It was ascertained from the investigation that as the RDI value of the sinter increased, its in-furnace degradation ratio became higher, and that the RDI value was almost equal to the degradation ratio when the sinter was kept in a low temperature reserve zone (about 60 minutes in this test).
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Yoshiyasu MORITA, Katsuyuki TOKIMASA
1986 Volume 72 Issue 2 Pages
210-217
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Thermal fatigue life evaluation is conducted for the steel shell of a blast furnace where hot spots have occurred repeatedly. Thermal elasto-plastic FEM analysis is used and, as a method of thermal fatigue life evaluation, the strain-range partitioning creep-fatigue analysis is adopted. It is proved to be possible to predict the remaining life of the steel shell successfully based on the following results:
(1) It is the center of a hot spot on the inner surface of the steel shell that undergoes the largest cyclic deformation during a cycle of a hot spot.
(2) Thermal fatigue damages, which are accumulated by repetition of hot spots, consist of those resulted from both the plastic strain range and the ratchetting strain.
(3) A higher hot-spot temperature, a thicker steel shell and a larger hot-spot diameter reduce thermal fatigue life of the steel shell.
(4) Total value of thermal fatigue damages at the notched part of the steel shell can be detected by measuring the increase in shell thickness of its smooth part independent of a hot-spot temperature.
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Toshiharu FUJISAWA, Masamichi SUZUKI, Yoshimoto WANIBE, Hiroshi SAKAO
1986 Volume 72 Issue 2 Pages
218-224
Published: February 01, 1986
Released on J-STAGE: February 16, 2010
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Experimental study and thermodynamic consideration studies have been conducted on the equilibrium relationships in Fe-Al-Si-O system. The quantitative relations between the compositions of molten iron alloys and the oxide phases were determined experimentally. The equilibrium constants for the deoxidation by silicon and aluminum and for the formation of mullite (3Al
2O
3· 2SiO
2) from its constituent oxides were determined.
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Tsao TING, Hiroshi G. KATAYAMA, Akihiko TANAKA
1986 Volume 72 Issue 2 Pages
225-232
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Experiments were made to obtain phosphorus distribution ratio between molten iron and CaO-MgO-Fe
tO-SiO
2 slag in a magnesia crucible at the temperatures of 1550°C and 1600°C. The results showed that the phosphorus transfer between iron and slag was so fast that the phosphorus equilibrium was maintained with the dissolution of magnesia from the crucible into the slag. The equations for phosphorus partitions obtained in this study are as follows.
log[(%P
2O
5)/[%P]
2·(%Fe
tO)
5]=0.143[%CaO)+0.55(%MgO)]+13980/
T+16.08
log[(%P)/[%P]·(%T.Fe)
5/2]=0.065[%CaO)+0.55(%MgO)]+12230/
T-10.08
These equations could be applied to CaO-MgO-Fe
tO-SiO
2 slags which were not saturated with magnesia as well as those saturated. The variation of the activity coefficients of Fe
tO and P
2O
5 with the theoretical optical basicity of slags was also discussed.
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Terutaka TSUMURA, Yasutaka OKADA, Hiroo OHTANI
1986 Volume 72 Issue 2 Pages
233-240
Published: February 01, 1986
Released on J-STAGE: February 16, 2010
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Boron treatment for Cr-Mo steels has been performed to obtain the higher strength with heavy thickness. But in these steels, even under the quenched microstructure, microalloying elements affect the toughness on tempering treatment at high temperature. So, the effect of Ti, B and N on the toughness and microstructures has been investigated in B-treated Cr-Mo steels tempered at high temperature. The results are as follows:
(1) In the case of Ti/N ≥ 3.42, the excess dissolved B ([B]) causes the precipitation of coarse M
23(C, B)
6 type boro-carbides and the formation of denuded zone along grain boundaries on tempering treatment at the temperatures higher than 600°C, and therefore the toughness decreases. But proper [B] causes no coarse boro-carbides precipitates along grain boundaries.
(2) In the case of Ti/N<3.42, the precipitation of BN occurs after hot rolling. However such non-equilibrium BN precipitates partially transform to AIN at the austenitizing treatment and [B] occurs. If [B] content is excess, then M
23(C, B)
6 precipitates and coagulates on grain boundaries during tempering treatment at high temperature, and consequently the toughness decreases. If [B] content is proper, then microstructures are fine and BN precipitates take no effect on the toughness.
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Masato MURAKAMI, Koji SHIBATA, Toshio FUJITA
1986 Volume 72 Issue 2 Pages
241-248
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Fe-Mn alloys have similar microstructure to Fe-Ni alloys in iron rich region, therefore they have promising potential as structural materials at cryogenic temperatures. Fe-Mn alloys, however, lose their toughness by catastrophic intergranular failure when tested at low temperatures. This is attributed to the segregation of impurities to grain boundaries. The segregation can take place at higher temperatures than 600°C, in both austenite(γ) and two phase(χ+γ) region.
An addition of molybdenum has been found to be effective in reducing the segregation of phosphorus in the two phase region and enhances toughness. However, no perceivable difference was observed in the segregation in the γ field.
Double temper has been also identified as a beneficial treatment for improving toughness, which promoted the reversion of austenite along grain boundaries and reduced the susceptibility to intergranular failure.
As a result it was shown that fairly good toughness could be achieved in Fe-6Mn-0.2Mo-0.05C alloy with QLT(800°C/1h/W.Q./700°C/1h/W.Q./600°C/1h.W.Q.) treatment.
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Kazuo HOSHINO, Takeshi UTSUNOMIYA
1986 Volume 72 Issue 2 Pages
249-256
Published: February 01, 1986
Released on J-STAGE: February 15, 2010
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The effects of Si and Ti on the precipitation behavior of 14Cr-7Ni martensitic stainless steels during aging treatment have been investigated. Precipitates are examined by transmission electron microscopy, X-ray diffraction analysis and so on.
In the steels containing Ti only, the shape of precipitates in the matrix changes from fine particles to rodshaped as the aging stage proceeded from peak hardness to over-aging. The precipitates are iderntified as Ni
3Ti, η phase. At an early stage of aging, predominant precipitations take place at grain boundaries.
On the other hand, in the steels containing Si and Ti in combination, fine spherical precipitates are formed uniformly in the matrix. They are identified as Ni
16Ti
6Si
7(G-phase) and coherent to the matrix. It is suggested that the coherent strain induced by the precipitates hardens the steel remarkably.
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Harushige TSUBAKINO, Atsushi ANDO, Takashi MASUDA, Koji YAMAKAWA
1986 Volume 72 Issue 2 Pages
257-263
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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An electrochemical permeation method using molten sodium hydroxide is presented to detect hydrogen in a steel at elevated temperatures (673-773 K) in the range of practical interest for hydrogen attack.
The results are as follows:
(1) The most suitable potential range to detect hydrogen is from -0.8 to -0.6 V vs Air/O
2- (ZrO
2).
(2) The experimental permeation curves for specimens with thickness above 4 mm agree fairly well with the theoretical ones.
(3) Diffusivities of hydrogen in the steel 6.5 mm thick in this study are in good agreement with the values obtained from a usual gaseous method.
(4) The detection limit of hydrogen content in the steel in this study is less than 0.1 ppm.
(5) Therefore, this electrochemical method will be useful to predict the hydrogen attack of steels.
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Yoshiko FUNAHASHI, Yoshikazu KAMINO, Sen-ich HARIMAYA
1986 Volume 72 Issue 2 Pages
264-270
Published: February 01, 1986
Released on J-STAGE: May 07, 2010
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Based on the studies of electrochemical stability of Mo carbides, a new method for state analysis of M
2C in Cr-Mo steel was established. By use of this method, the precipitation behavior of carbides during creep rupture test was examined.
Results obtained are as follows:
1) M
2C in Cr-Mo steel was electrochemically less stable than carbides of M
3C, M
7C
3 and M
23C
6, but almost as stable as M
6C. The electrochemical stability of carbides in Cr-Mo steel is in the following order M
2C≅M
6C<M
3C<M
7C
3≅M
23C
6.
2) M
2C can be selectively decomposed by the secondary electrolysis of primary electrolytic residues, prepared in the porous-graphite electrode, at the anode potential of +0.65 V vs. SCE in 4% methyl salicylate-1% salicylic acid-2% LiCl-methanol. M
6C is also decomposed at the same condition.
3) The amount of M
2C can be determined by the dissolved amount of Mo after the secondary electrolysis. When M
6C is present in primary electrolytic residues, the amount of M
2C is calculated by subtracting the amount of Mo as M
6C, amount of which is calculated from the dissolved amount of Fe (Fe as M
6C) after the secondary electrolysis, from the dissolved amount of Mo by the same treatment.
4) The amount of M
2C precipitated during the creep rupture test is found to roughly correspond to the change in the master rupture strength of the specimens. The creep rupture strength is increased with increasing the precipitation amount of M
2C in these specimens.
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Hiroshi OIKAWA
1986 Volume 72 Issue 2 Pages
271-275
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Yoshikazu RO, Hidehiro ONODERA, Katsumi OHNO, Toshihiro YAMAGATA, Isao ...
1986 Volume 72 Issue 2 Pages
276-283
Published: February 01, 1986
Released on J-STAGE: February 16, 2010
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The effect of volume fractions of α and β phases on the superplasticity was investigated for the five Ti--Al-V alloys, of which chemical compositions being on the tie line including the Ti-6Al-4V at 900°C. The testing temperature was 900°C and the initial strain rate range was from 6.67 × 10
-5 to 2.50 × 10
-2/s.
In spite of wide distribution of the volume fraction of the α phase in the alloys, all showed a good superplasticity under certain strain rate conditions. The superplastic elongation became the maximum at about equal volume fractions of α and phases, and decreased with deviation from that fraction. The initial average grain size of the alloys was dependent on the volume fraction ratio of the phases and found to become the minimum at equal volume fractions.
At a strain rate of 6.67 × 10
-4/s, the average grain size of alloys after fracture was independent of the initial average grain size and the volume fraction ratio of the phases of the alloys. The average grain size after fracture was 8 μm. At the same strain rate, the strain induced grain growth rate of alloys increased with decreasing initial average grain size.
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Hidehiro ONODERA, Katsumi OHNO, Toshihiro YAMAGATA, Michio YAMAZAKI
1986 Volume 72 Issue 2 Pages
284-291
Published: February 01, 1986
Released on J-STAGE: February 16, 2010
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Effects of β-stabilizer content in β phase at solution treatment temperature on microstructures after quenching from solution temperature. aging characteristics, and tensile properties were investigated by using 9 α-β titanium alloys(Ti-Al-V-Sn-Zr-Mo-Cr-Fe system). The main results obtained are as follows:
(1) Partitioning of each element to α and β phases at solution treatment temperature could be well estimated from each Ti-
j (
j=Al, V, etc.) binary phase diagram.
(2) Phase stability of β phase was considered to relate well with electron-atom ratio(
e/
aβ). Phase transformations in the alloys during quenching could be classified by
e/
aβ. From changes of electrical resistivity during heating, it was considered that athermal and isothermal ω phase were formed in the alloys GT-33, 45, and 46(
e/
aβ=4.06-4.16).
(3) Effects of microstructural and compositional factors Volume fraction(
Vα), grain diameter(
dα), and degree of solid-solution strengthening(
dDEα) for primary α phase,
e/
aβ for prior β phase, and aging temperature(
Tag) on tensile properties at 300°C were examined by using multiple regression analysis. Following regerssion equations were obtained.
σ
u(kgf/mm
2)=207.72-318.29
Vα+119.43
Vα·
dDEα+178(1-
Vα)·(
e/
aβ-4)-19(1-
Vα)·
Tag/100
El.(%)=-19.86-39.28
Vα+13.08
dDEα+2.95
Tag/100
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Fumiaki IKI, Shigeo TSUJIKAWA
1986 Volume 72 Issue 2 Pages
292-299
Published: February 01, 1986
Released on J-STAGE: May 07, 2010
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A concept of repassivation potential,
ER, for crevice corrosion had been developed for stainless steels. Applicability of the
ER concept to C. P. Ti was confirmed through the corrosion test in 25% NaCl solution at 100°C.
ER for growing crevice with penetration depth deeper than a critical depth,
h* (≅12 μm), was found to be a well reproducible electrochemical parameter which coincides with the critical potential,
VCREV, below which the growing crevice does not initiate.
The repassivation method was also applied to determine critical conditions in terms of NaCl concentration and temperature for crevice corrosion of specimens kept at -0.2V, SCE which was more noble than
ER and was included in the spontaneous potential range of passivated Ti in deaerated NaCl solutions measured previously. Crevice corrosion which had been initiated in 25% NaCl solution at 100°C continued to grow in successively diluted NaCl solutions not lower than 0.75% in NaCl concentration and to grow at successively lowered temperatures not lower than 50, 70, and 90°C in 25, 3, and 1% NaC1 solutions, respectively. Critical conditions in terms of temperature and NaCl concentration determined as above were confirmed to agree with the reported results obtained by immersion tests for crevice corrosion resistance of C. P. Ti.
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Hiroshi SATOH, Fumio KAMIKUBO, Kazutoshi SHIMOGORI
1986 Volume 72 Issue 2 Pages
300-307
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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It has already been made clear that corrosion resistance of titanium is improved by change of passive film composition from TiO and Ti
2O
3 to TiO
2. Therefore, in this paper, the effect of TiO
2 coating on corrosion resistance of titanium was investigated Anodized, thermally oxidized and PdO/TiO
2 coated titanium specimens were used. Anodized titanium showed the same corrosion resistance as polished titanium did. This is due to the fact that anodized film was consisted of hydrated TiO
2 which dissolved in an HCl solution for short time. Corrosion resistance of titanium was significantly improved by thermally oxidation because of formation of TiO
2 which was stable even in a highly acidic solution. PdO/TiO
2 coated titanium showed an excellent corrosion resistance in HCl solutions. Moreover, crevive corrosion was suppressed by the coating. Many cracks were observed in PdO/TiO
2 films and titanium substrate was exposed at the crack. However, titanium substrate is polarized anodically to passive potential region by PdO/TiO
2 film because the coating film has high corrosion potential. This is a reason why PdO/TiO
2 coated titanuim shows an excellent corrosion resistance.
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Takashi WATANABE, Hiromitsu NAITO, Kenichi SUZUKI, Yasushi NAKAMURA
1986 Volume 72 Issue 2 Pages
308-313
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Hydrogen absorption behavior of commercially pure titanium in the solution system NaCl-HCl has been studied in relation to corrosion by means of Glow Discharge Spectroscopy (GDS).
Results obtained are as follows.
(1) The hydrogen absorption layer on titanium formed by corrosion can be analyzed by means of GDS.
(2) When the passive film on titanium begins to break down in NaCl-HCl, hydrogen absorption can occur.
(3) The rate of hydrogen absorption is parabolic, indicating that hydrogen diffusion through the hydrogen absorption layer is rate controlling. The diffusion coefficient of hydrogen in titanium is 2.75-3.68 × 10
-12 cm
2/s.
(4) X-ray diffraction patterns of the surface of hydrogen absorption layer show the presence of TiH
2.
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Shin-ichi NAGASHIMA
1986 Volume 72 Issue 2 Pages
314-320
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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Takehide SENUMA, Hiroshi YADA, Hirobumi YOSHIMURA, Hisaaki HARADA, Tak ...
1986 Volume 72 Issue 2 Pages
321-328
Published: February 01, 1986
Released on J-STAGE: February 16, 2010
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In this paper, the deformation resistance and recrystallization behavior in high temperature working (600-850°C) with high strain rates (2-150
l/
s) which covers the most hot rolling conditions have been investigated.
In the usual hot rolling condition the dynamic recrystallization does not occur and the resistance to hot deformation is determined by the balance between strain hardening and dynamic recovery. The flow stress sharply increases with increase in the impurity content at higher purity condition while the hardening rate due to the increase in the impurity content becomes smaller if the range exceeds a certain value. The recrystallization and grain growth behavior of commercially pure titanium is similar to that of plain carbon steels in austenite phase. In commercially pure titanium deformation bands, which act as nucleation site for recrystallization, are more easily formed than in plain carbon steels.
The activation energy for hot deformation and recrystallization lies in a range between 220-260 kJ/ mol which is nearly the same for low strain rate deformation.
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[in Japanese], [in Japanese], [in Japanese]
1986 Volume 72 Issue 2 Pages
329-341
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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[in Japanese]
1986 Volume 72 Issue 2 Pages
332
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
1986 Volume 72 Issue 2 Pages
344-345
Published: February 01, 1986
Released on J-STAGE: June 30, 2009
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