Tetsu-to-Hagane

Delayed Cracking Caused by Hydrogen in Steel Welding

Haruyoshi SUZUKI, Nobutaka YURIOKA

1981 Volume 67 Issue 10 Pages 1657-1669
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1657

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Recent Trends in Special Steels for Automobiles

Tetsuo KATO, Shozo ABEYAMA, Norioki UYEHARA

1981 Volume 67 Issue 10 Pages 1670-1676
Published: August 01, 1981
Released on J-STAGE: January 19, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1670

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Resources and Exploitation of Iron Ores

Nobunao NISHIDA

1981 Volume 67 Issue 10 Pages 1677-1685
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1677

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Tendency of Vacuum Heat Treatment

Kyuhiko YAMANAKA

1981 Volume 67 Issue 10 Pages 1686-1695
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1686

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Metallic Resources Series-Niobium-

Masanori UEKI, Satoshi KADO

1981 Volume 67 Issue 10 Pages 1696-1707
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1696

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Recent Progress of Optical Communications

Yasuharu SUEMATSU

1981 Volume 67 Issue 10 Pages 1708-1712
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1708

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Small Experimental Apparatus for High Pressure Fluidized Bed Reduction of Pulverized Iron Ore

Yasunori NISHIKAWA, Kyoji SATO, Yoshinobu UEDA, Yoshikazu SUZUKI, Sogo ...

1981 Volume 67 Issue 10 Pages 1713-1719
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1713

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An experimental apparatus with a batch type fluidized bed reactor of 60 mm I.D. for iron ore reduction was developed. The maximum reduction temperature and H₂ pressure were 900°C and 40 kg/cm². Experiments revealed that there were many operational problems to be solved and successive improvements were made. Findings obtained during the development of the apparatus are as follows :
(1) In order to keep the gas flow and pressure constant at the reduction, the performance of inlet pressure regulators was the most important and it was better to install two independent regulators for high and low pressure ranges.
(2) In order to decrease the pressure change brought by swiching the gas flow from N₂ to H₂ at the start of the reduction, it was effective to install two independent outlet pressure regulators for N₂ and H₂.
(3) When pressurized Ar was introduced to the space in the electric furnace of external heating type to get the pressure balance with the reactor, heating efficiency of the furnace was found to decrease seriously because of enhanced heat leakage.
(4) Sufficient gas preheating was very effective for fine control of the reduction temperature in the fluidized bed and also for prevention of the sintering trouble of the reduced iron powder at higher reduction temperature.

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Temperature-dependency of Interdiffusion in Molten Fe-C Alloys

Yoshimoto WANIBE, Shoji TAKAI, Toshiharu FUJISAWA, Hiroshi SAKAO

1981 Volume 67 Issue 10 Pages 1720-1725
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1720

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In order to measure the precise interdiffusion coefficient of carbon in molten Fe-C alloys (D_c), an experiment was carried out for the carbon content of 1.353.44% at 1 4001 650°C by means of a diffusion couple method. The results are summarized as a following experimental equation ;
D_c=exp{-(12 100/T+2.568)+(1 320/T-0.554)[%C]}……(±0.12×10^-4) cm²/s and can be shown reasonable through the discussions on the temperature- and the concentration-dependencies of the coefficient.

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Dissolution Rate of Sintered MgO into Molten Fe_tO-CaO-SiO₂ Slags

Mikio UMAKOSHI, Katsumi MORI, Yasuji KAWAI

1981 Volume 67 Issue 10 Pages 1726-1734
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1726

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The sintered MgO (porosity 29.9% and 13.0%) was immersed into molten Fe_tO-CaO-SiO₂ slags at temperatures from 1 350 to 1 425°C and the dissolution rate of MgO was determined with the rotating cylinder method by measuring the decrease of the cylinder radius. Also, the section of the MgO cylinder after immersion was examined by EPMA to know the penetration of slag and the dissolution mechanism.
The results obtained are as follows :
(1) The dissolution rate of MgO was increased with the rotating speed of cylinder and with temperature, and was found to be controlled by mass transport in the boundary layer of molten slag.
(2) The change of mass transfer coefficient at 1 400°C with slag composition was correlated well to the change of kinematic viscosity of slag. Utilizing the nondimensional correlation found in literature, the values of diffusion coefficient of MgO into molten slags were estimated to be 1.0×10^-53.0×10^-5cm²/s at 1 400°C.
(3) The dissolution of MgO proceeded through the formation of (Fe, Mg)O solid solution layer at the interface and its dissolution. The penetration of slag was retarded by this dense (Fe, Mg)O layer and the depth of penetration after 560 min was only 13 mm in high porosity MgO and <1 mm in low porosity MgO.

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The Solubility of Magnesia and Ferric-Ferrous Equilibrium in Liquid Fe_tO-SiO₂-CaO-MgO Slags

Jae-Dong SHIM, Shiro BAN-YA

1981 Volume 67 Issue 10 Pages 1735-1744
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1735

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The solubility limit of magnesia and the ferrous-ferric oxide equilibrium have been measured for the Fe_tO-MgO, Fe_tO-SiO₂-MgO and Fe_tO-SiO₂-CaO-MgO slags in equilibrium of liquid iron at the temperature range from 1 550°to 1 650°C. The results obtained are summarized as follows ;
1) The solubility limit of magnesia and the ferric oxide content in Fe_tO-MgO slags are represented by the following empirical formulae.
log(wt%MgO)=-6000/T+4.21 (±0.05) 1 536°-1 660°C ……(1)
log(wt%Fe₂O₃)=3553/T-1.00 (±0.05) 1 536°-1 660°C ……(5)
2) The solubility limit of magnesia in Fe_tO-SiO₂-MgO slags has been established at the temperatures of 1 550°, 1 600° and 1 650°C. The value of Λ=Fe³⁺/Fe²⁺ in this slags decreases with increasing silica content.
3) The solubility limit of magnesia in Fe_tO-SiO₂-CaO-MgO slags decreases with increasing Fe_tO content and slag basicity, and it becomes almost constant, 6.-8. wt% in the range of basicity higher than 2(=wt%CaO/wt%SiO₂). The value of Λ=Fe³⁺/Fe²⁺ in these slags increases with increasing the slag basicity and with decreasing Fe_tO content in basic slags.

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The Distribution of Oxygen between Liquid Iron and Fe_tO-SiO₂-CaO-MgO Slags Saturated with MgO

Jae-Dong SHIM, Shiro BAN-YA

1981 Volume 67 Issue 10 Pages 1745-1754
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1745

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The equilibria of oxygen distribution between liquid iron and the Fe_tO-MgO, Fe_tO-SiO₂-MgO and Fe_tO-SiO₂-CaO-MgO slags saturated with MgO havebeen measured in the temperature range from 1 550°C to 1 650°C. The results obtained are as follows :
1) The oxygen content of metal in equilibrium with Fe_tO-MgO slags saturated with MgO is expressed by the following equation.
log[wt%O]=-5520/T+ 2.276…… ( 5 )
2) The iron oxide activity in Fe_tO-SiO₂-MgO and Fe_tO-SiO₂-CaO-MgO slags was determined at a temperature of 1 600°C, and the maximum value of the iron oxide activity was found along a line joining the orthosilicate composition with Fe_tO apex. The substitution of CaO with MgO in the slag increases the iron oxide activity.
3) In view of ionic theory, the approximate validity of regular solution model for cations were examined to formulate the thermodynamic properties of complex slag containing MgO. It was confirmed that the regular solution model was applicable to the wide range of slag composition over basic to acidic slag. The values of the interaction energy concerning MgO are as follows :
α (Fe²⁺Mg²⁺)=+3 070 α(Fe³⁺Mg²⁺)=-5 620
α (Si⁴⁺Mg²⁺)=-30 500 α(Ca²⁺Mg²⁺)=+4 500 (cal)

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State of Sulphur and Sulphur-iron Interaction in Na₂O-SiO₂ Slags

Nobuya IWAMOTO, Yukio MAKINO, Taisuke NISHIMURA

1981 Volume 67 Issue 10 Pages 1755-1762
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1755

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From the standpoint of external desulphurization, state of sulphur and sulphur-iron interaction in Na₂O-SiO₂ slags were investigated by optical absorption, electron spin resonance(ESR) and S K_α X-ray emission spectroscopies. An optical absorption was observed near 24 000 cm^-1 in the slags produced in the intermediately (Po₂=10^-5.1 atm.) and strongly(Po₂=10^-6.7 atm.) reducing atmospheres. The absorption was assigned to polysulphide ions consisting of several sulphurs. Fe³⁺-S^2- interaction was suggested from the increase of the intensity of ESR absorption near g=6.0 in the slags produced in the strongly reducing atmosphere. Chemical shift study of S K_α X-rays in the slags indicated that sulphur atoms are in the form of S⁶⁺ ions in oxidizing condition(Po₂=0.21 atm.) and in the mixed state of S⁶⁺ and S⁰ in the reducing conditions. It was concluded from these results that, in Na₂O-SiO₂ slags, polysulphide ions such as S₂^-> are formed as intermediate stage with reducing partial oxygen pressure of atmosphere. Further, it was indicated that Fe³⁺-S^2- interaction begins to occur in the vicinity of Po₂=10^-610^-7 atm.

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Formation of Smudges and Iron Oxide Film in the Course of Cold Rolling

Masao KOMAI, Satoshi FUKUYAMA, Taizo SATO, Satoshi IKETAKA

1981 Volume 67 Issue 10 Pages 1763-1769
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1763

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The effects of the cold rolling conditions on the amount of smudge has been investigated. The smudge formed on the edge of cold rolled steel sheet surface causes the dewetting of tin plate since it can not be removed by the conventional electrolytic cleaning. It is estimated that the smudge consists of iron powders and iron oxide powders, and it deteriorates palm oil. Inhomogeneous distributions of the smudge and the iron oxide film are observed in the strip width. The amount of smudge at the edge of the strip is more than twice as much as that at the center.
The results suggests that the cold rolling conditions significantly affect the amount of smudge and the iron oxide film thickness on the surface of cold rolled steel sheet.
The amount of smudge and oxide film thickness increase with the increase of rolling speed and the reduction at the final stand (stand No. 5), but are reduced by supplying the more oil at the final stand. Furthermore, the calculated temperature of the strip at the exit of roll bite suggests that the amount of smudge and oxide film thickness depends on the temperature. It is revealed that the amount of smudge and the iron oxide film thickness are reduced by adding the antioxidant additive to the rolling oil.

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Development of High Current MIG+2SAW Technique for Heavy Wall UOE Linepipes

Kiyoteru HIRABAYASHI, Tadaaki TAIRA, Hiroyuki ICHINOSE, Osamu HIRANO

1981 Volume 67 Issue 10 Pages 1770-1776
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1770

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MIG+2SAW technique has been developed for longitudinal welding process to produce the heavy wall UOE linepipes up to 50 mm in thickness.
(1) An experimented MIG+2SAW equipment is designed so that the leading electrode is DCRP for high current MIG welding and the middle and trailing electrodes are connected in Scott transformer connection for 2SAW. This equipment placing MIG and 2SAW torches on one cart can weld test plates with one-run. The arc interaction between MIG and 2SAW has hardly been observed.
(2) MIG+2SAW process is devised to disperse the heat input to decrease it per one molten pool as compared with 3SAW because a torch spacing between MIG and 2SAW is long enough and two molten pools are formed. Therefore weld metal and HAZ in the center of plate thickness by MIG+2SAW process give a better toughness than those by 3SAW.
(3) As the heat input of 2SAW on MIG+2SAW process can be lowered as compared with that of 3SAW, MIG+2SAW process consumes a fewer fluxes than 3SAW. The shielding effect of the molten slag is scarcely deteriorated because it is not overheated even if the fused flux is used. As a result the weld bead in 50 mm thickness plate is sound and slippery.

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Effect of Calcium Treatment on Stress Relief Cracking in 80kg/mm² Class High Tensile Strength Steel

Yasuhide ONO, Yoshihiro OKAMURA, Seinosuke YANO, Toshimitsu FUJII, Koi ...

1981 Volume 67 Issue 10 Pages 1777-1786
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1777

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The effects of calcium treatment on stress relief cracking were investigated in Ni-free type HT80 steels. Calcium was added into molten steel in the fountains during bottom pouring. The y-groove restraint cracking test method was primarily used as stress relief cracking test.
As a result, stress relief cracking was remarkably reduced by calcium treatment and close correlation was observed between the susceptibility to stress relief cracking and the amount of free sulphur which was calculated by (S_total-32/40Ca). The amount of free sulphur is considered to decrease by calcium treatment. This is explained mainly by the reason that stress relief crack tends to propagate along grain boundary as the surface energy of cavities in the grain boundary is decreased by the segregation of free sulphur.

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An Evaluation of Threshold Stress-intensity Factor, K_ISCC Using AE Technique

Akira NOZUE, Teruo KISHI, Ryo HORIUCHI

1981 Volume 67 Issue 10 Pages 1787-1794
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1787

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In this paper, a new method to evaluate the threshold stress-intensity factor K_ISCC by the use of acoustic emission (AE) signal analysis is proposed using the material of type 4340 steel, of which hydrogen content was controlled by the cathodic electrolytic method. In the subcritical crack growth due to hydrogen embrittlement, a linear correlation was observed between stress-intensity factor K and emission event counts N. From this relation K_ISCC was defined as a stress-intensity factor K_AE corresponding to the generation of AE events. The effects of K and threshold voltage of AE measurement on the K_ISCC were discussed in detail, and with the results of fractography it was concluded that the obtained K_ISCC corresponded to the nucleation of hydrogen induced intergranular microcrack in the maximum triaxial stress field ahead of the crack tip.

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Grain Refinement of Austenite through Reverse Transformation from Martensite in Fe-15Ni-Co-Mo-Ti Alloys

Kozo NAKAZAWA, Yoshikuni KAWABE, Seiichi MUNEKI

1981 Volume 67 Issue 10 Pages 1795-1804
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1795

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The effects of 5Mo, 15Co or 2Ti addition to Fe-15Ni-10Co-5Mo base alloy on grain refinement of reversed austenite subjected to single austenitizing were studied at heating rates between 0.083 and 100 °C/s. Grain refinement was promoted by Co or Ti addition and was suppressed by Mo addition. Grain refinement was promoted in the base, (base+15Co) and (base+2Ti) alloys at the lower heating rates, whereas it was suppressed in the (base+5Mo) alloy. Refining processes depended on chemical composition and heating rate, and were classified into the following two groups in terms of the differences in the initial stage of formation of γ grains : (1) after completion of reverse transformation, γ grains were formed due to recrystallization of γ ; and (2) during reverse transformation, γ grains were formed probably by nucleation and growth of diffusionally transformed γ. It was shown that the mechanisms of reverse transformation associated with chemical composition and heating rate played an important role in these refining processes.

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Effect of Grain Size on High Temperature Creep Properties of Hastelloy X

Yoshihiro KONDO, Takashi MATSUO, Takayuki SHINODA, Ryohei TANAKA

1981 Volume 67 Issue 10 Pages 1805-1814
Published: August 01, 1981
Released on J-STAGE: January 19, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1805

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The effect of grain size, ranged from 37 to 1220 μm, on creep behavior of Hastelloy X was studied at temperatures of 950, 1 000 and 1 050°C. A steady state creep rate, ε_s, of the alloy decreased with the increase of the grain size, reached a minimum at the grain size of 100200 μm, L_M, and increased with the increase of that. From measurements of friction stress (σ_f) and observations of microstructures, it is concluded that the increase in ε_s under a given applied stress with the decrease of the grain size is attributable to the increase of an effective stress, σ_e(=σ_a-σ_f, whereey σ_a is the applied stress). On the other hand, recrystallization induced by a high stress concentration at grain boundary triple points in the coarse-grained alloys seems to accelerate the creep. By comparing the results in the Hastelloy X with those in carbon free 17Cr-14Ni steel, it is suggested that the grain size dependence of the ε_s of the Hastelloy X having finer grains than L_M is more remarkable than that of carbon free 17Cr-14Ni steel because of the decrease of fine precipitates within grains in the former alloy, while the dependence of the alloy having coarser grains than L_M is minor than that of carbon free 17Cr-14Ni steel because of preventing the stress concentration at the triple points by the grain boundary precipitates.

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On the Change in the Internal Friction of Stainless Steels in the Fatigue Process

Haruhiko FUJITA, Manabu TANAKA, Osamu KAMIYA

1981 Volume 67 Issue 10 Pages 1815-1822
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1815

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The internal friction has been measured on the specimens of repeat-bend fatigue test with constant strain amplitude using austenitic SUS316, ferritic 11Cr-0.4Ti and semi-austenitic SUS631 steels. A discussion was then made on plastic deformation, initiation and propagation of cracks, and martensitic transformation of these steels during fatigue test.
It was considered that in 11Cr-0.4Ti and SUS316 steels the internal friction increased owing for the most part to an increase of dislocation density by the plastic deformation during fatigue test. In SUS631 steel, the internal friction increased markedly due to martensitic transformation rather in the earlier stage of fatigue. The internal friction increased more strongly owing to the initiation and propagation of cracks in these steels. The initiation and propagation of cracks in these steels was also examined by means of both optical and scanning electron microscopy.

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Determination of Small Amounts of Aluminum in Iron and Steel by X-ray Fluorescence Analysis

Minao ITO, Shoki SATO, Masanao NARITA

1981 Volume 67 Issue 10 Pages 1823-1828
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1823

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The accuracy of X-ray fluorescence analysis for determining aluminum in steel is generally poor when the aluminum content is below 0.1%. In this study, it is confirmed that the existence of inhomogeneous acid-insoluble aluminum causes the poor accuracy of X-ray fluorescence analysis. The accuracy can be improved by adding granular ferro-zirconium to molten steel when sampling. By using this method, the accuracy of determining aluminum was 0.0024% for low alloy steels and 0.0022% for stainless steels as the standard deviation obtained for a series of differences between an analytical result and a standard value. Corrections for overlapping of the chromium spectrum, and for absorption and enhancement effects of co-existent elements are not necessary for the analysis of low alloy steels, whereas these corrections are necessary for the analysis of stainless steels.

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Improvement of Higher Productivity Using Bottom Blown Converter

Toyohiko OHTA, Makoto SAIGUSA, Fumio SUDO, Tsutomu NOZAKI

1981 Volume 67 Issue 10 Pages 1829-1833
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1829

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Combustion Control by Minute Pressure Pulsation Pattern

Keiichi OHTANI, Ryuichi ODAWARA, Tomio SUZUKI, Kotaro MORIMOTO, Tooru ...

1981 Volume 67 Issue 10 Pages 1834-1841
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1834

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[title in Japanese]

[in Japanese], [in Japanese]

1981 Volume 67 Issue 10 Pages 1841-1841,1851
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1841

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Development of No-tension Control System for Bar Mill (SNTC) Based on Direct Measurement

Toshimitsu MATSUI, Yoshisuke MISAKA, Shunji OGATA, Motoho ASAKAWA, Kat ...

1981 Volume 67 Issue 10 Pages 1842-1847
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1842

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[title in Japanese]

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

1981 Volume 67 Issue 10 Pages 1860-1865
Published: August 01, 1981
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.67.10_1860

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