Tetsu-to-Hagane

[title in Japanese]

[in Japanese]

1977 Volume 63 Issue 12 Pages 1783-1784
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1783

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On the Evaluation of Mass Transfer Resistance through Gas Phase in Reduction Kinetics of Oxide Pellets

Yoichi ONO, Tadatsugu JOKO

1977 Volume 63 Issue 12 Pages 1785-1790
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1785

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The problem of how to evaluate the mass transfer resistance through the gas phase surrounding an oxide pellet during its reduction was studied experimentally. Reduction experiments were carried out in which NiO pellts were reduced by hydrogen at various flow rates between 0.5 and 8.0 Nl/min in the temperature range from 800 to 1000°C. The data were analysed by the graphical method of the so-called mixed-control plot, which was proposed in the previous paper (Trans. ISIJ, 8 (1968), p.377). It has been concluded that the gas phase resistance should include the resistance due to the mass balance which takes into account the dilution effect of produced gas as well as the gas-film diffusion resistance.

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Discrimination among Conditions at Lower Part of Blast Furnace by Distribution Ratios of Si, Mn and S between Slag and Pig Iron

Nobuo TSUCHIYA, Seiji TAGUCHI, Yoshiyasu TAKADA, Kyoji OKABE

1977 Volume 63 Issue 12 Pages 1791-1800
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1791

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At the blast furnace hearth, the equilibrium of the partitioning reactions of Si, Mn, and S between the slag and iron is proved not to be attained. Furthermore, the analytical studies of operational data and sample from working furnace indicate that Si transfer to iron occurs at the lower region above the tuyere level through SiO gas, and those of Mn to iron and S to slag occur as slag-metal reactions in the slag layer at the hearth.
The attainments of the reaction equilibrium indicate the condition of the lower part of the furnace and are expressed as follows; R_Si= (LSi/L°_Si) ·100, R_Mn= (L_Mn/L°_Mn) ·100, and R_S= (LS/L°_S) ·100, Where Li is the partitioning ratio calculated from the practical data and L°_i the equilibrium ratio. The index Rsi shows the thermal intensity around tuyere level suggesting the height of melting zone. The indices R_Mn and Rs show the oxygen influence in the hearth suggesting the amount of FeO entered as unreduced. In addition to these the iron temperature shows the thermal intensity in the hearth.
The furnace operation during a half year at Chiba Works, Kawasaki Steel Corporation has been clearly explained by the use of these indices.

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On the Dephosphorization of Hot Metal in the Ladle

Kantaro SASAKI, Yoshimichi OHKITA, Takami IKEDA, Takashi OKAZAKI, Tohr ...

1977 Volume 63 Issue 12 Pages 1801-1808
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1801

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Dephosphorization of hot metal in the ladle was investigated by mechanical stirring method with the dephosphorizing agent consisting of LD slag and Fe₂O₃ powder. The experiments were carried out both with a laboratory scale apparatus and 45t industrial ladles.
The following results have been obtained;
(1) Using LD slag with Fe₂O₃ powder, the phosphorus level of hot metal can be reduced to 20% to 40% of the initial content after 40 minutes treatment even when the slag is acidic.
(2) During the treatment, the extent of decarburization is small, although silicon and manganese are oxidized and removed from the hot metal.
(3) The low phosphorus steel, with less than 0.010%P, can be easily obtained in LD vessels starting with the dephosphorized hot metal.

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Thermodynamics of Fe_tO-P₂O₅ Slags Saturated with Solid Iron

Shiro BAN-YA, Tadao WATANABE

1977 Volume 63 Issue 12 Pages 1809-1818
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1809

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As a first step in a study of the physical chemistry of dephosphorization in steelmaking process, equilibrium measurements were made of hydrogen-steam mixtures of simple Fe_tO-P₂O₅ slags in equilibrium with solid iron in the temperature range form 1200 to 1450°C. Activities of Fe_tO and P₂O₅ in the slags were determined from the data Activity of Fe_tO negatively deviated from Raoult's law and its of P₂O₅ showed positive daviation from Henry's law. The ferrous and ferric concentrations of slags, expressed as Fe⁺³/Fe⁺², were decreased by the addition of P₂O₅.
The iso-activity lines in FeO-Fe₂O₃-P₂O₅ slags at 1600°C were calculated by applying the regular solu- tion model of Lumsden to the experimental data.

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Calculation of Spread and Elongation of Bars in Rolling Pass Sequences, Square-Oval, Square-Diamond and Round-Oval

Yoshihiro SAITO, Mikio MORIGA, Keno KATO

1977 Volume 63 Issue 12 Pages 1819-1827
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1819

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An experimental investigation of spread and elongation in the pass sequences was made by means of simulative rolling tests using plasticine as a model material and laboratory hot rolling tests of commertial steel for a wide range of geometrical conditions. Through analytical and statistical treatment of the data, it was found that in any pass sequence the spread index k defined in this paper could be expressed as a function of a newly introduced geometrical criterion US.
A calculation scheme was developed for predicting coefficient of spread β and coefficient of elongation λ in these pass-rollings by taking advantage of the k-US relations.
The accuracy of the proposed method was checked on the all experimental points of plasticine model, and it was proved that calculated values of β and λ agreed with experimential values with in ±4% in error.

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Effect of Cold Rolling by Grooved Rolls on the Formation of Cold Rolling Texture of 3% Silicon-Steels

Masuji KUMAZAWA, Yasuhiro NAKAGAWA, Tomoo SEKINE

1977 Volume 63 Issue 12 Pages 1828-1837
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1828

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In order to elucidate the mode of deformation introduced by cold rolling of grooved rolls and smooth rolls, plasticinc was used in an experiment on mass flow, and single crystals were employed to test crystal rotation.
When groove-caused protrusions were smoothed on a flatter, a mass flow was observed accompanied by rotation on the axis of groove direction. The transverse mass flow by rotations on the axis of rolling direction was particularly important for the formation of (100) [011] texture. A profound influence on the rotational system of ordinary cold rolling texture would be induced by mass flows as accompanied by rotations. Thus groove rolling is effective in the formation of (100) [011] cold rolling texture. The groove shape, groove arrangement, and groove rolling reduction are largely contributory to the formation of cold rolling texture.

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Effect of Cold Silicon by Grooved Rolls on Internal Strain of 3% Silicon Steels

Masuji KUMAZAWA, Kenzo IWAYAMA, Yozo SUGA

1977 Volume 63 Issue 12 Pages 1838-1847
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1838

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Generally, the higher the residual strain which is introduced by rolling, the more effective the development of (100) recrystallization in 3% silicon steels. In order to confirm this effect and to clarify the mode of deformation involved, an experiment was conducted on work hardening by rolling between grooved rolls.
The experimental results are as follows.
(1) As compared to ordinarily cold rolling, internal strains of about 1.3-1.5 times were obtained by groove rolling and succeeding smooth rolling.
(2) Grooved rolled specimens generally exhibit far greater hardness in their center than on the surfaces. This is due to irregular deformation from groove rolling which induces extensive internal structural change.
(3) As compared to ordinarily cold rolled steels, cold groove-rolled specimens exhibit considerable work hardening by the following rolling on the flattener of a smoothing roll. This is due to grooved-roll protrusions wedged into the matrix under flattener pressure by that is termed the wedging action.

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Effects of Grain-and Grain Boundary-Strengths on the Creep Rupture Properties of an Austenitic Heat Resisting Steel

Masaru YAMAMOTO, Ohmi MIYAGAWA, Mitsuyuki KOBAYASHI, Dai FUJISHIRO

1977 Volume 63 Issue 12 Pages 1848-1857
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1848

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This study was carried out to clarify the contribution of the grain-and the grain boundary-strengths to the creep rupture properties in a 20-11 P austenitic heat resisting steel (0.3C-0.2P-20Cr-11Ni-2Mo) having a wide variation in hardness and the configuration of grain boundaries.
The rupture life under a stress increased with the increase in hardness until it reached the maximum value at some critical hardness, but further increases in hardness led to the drop of the rupture life in spite of decrease in minimum creep rate. From the analysis of fracture behavior, it was clarified that the transition of fracture mode from ductile to brittle with increasing hardness is responsible for this variation on the rupture life. When the grain boundaries were strengthened by serration, the critical hardness shifted to higher values and the remarkable increase in the rupture life was obtained as a result of preventing the formation and the growth of cracks and cavities along grain boundaries.
This result suggests that in order to improve the rupture strength, the hardness, i. e. the strength of grains, must be increased in keeping a balance with the strength of grain boundaries depending on their configuration.

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Effects of Grain-and Grain Boundary-Strengths on the Notch Rupture Properties of an Austenitic Heat Resisting Steel

Masaru YAMAMOTO, Ohmi MIYAGAWA, Mitsuyuki KOBAYASHI, Dai FUJISHIRO

1977 Volume 63 Issue 12 Pages 1858-1867
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1858

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The notch effect on both the rupture strength and the fracture behavior was investigated in 20-11 P austenitic heat resisting steel whose hardness and configuration of grain boundaries were widely changed by heat treatments.
The notch rupture life under constant stress reached the maximum value at some critical hardness value depending on the configuration of grain boundaries. As compared with the result of smooth speimen, the critical hardness for the notched specimen was shifted to the value lower than that of the smooth one. This resulted in the notch strengthening in lower hardness region and the notch weakening in higher hardness region.
The analysis of fracture behavior suggested that stress concentration in notch root would cause the notch weakening in higher hardness region by the accelerated nucleation and propagation of grain boundary cracking, while the constraint of plastic deformation around notch root could cause the notch strengthening in lower hardness region where the ductile fracture occurred and the rupture life would be determined by strain rate. It was also shown that notch weakening of strengthening was strongly dependent on the ductility.

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Study of the Microstructures and Toughness of Steels with Precipitation-Hardening Due to Cu and NiAl

Hiroshi YADA, Mitsuo HONDA

1977 Volume 63 Issue 12 Pages 1868-1877
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1868

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Age-hardening behavior, especially related to the influence of matrix microstructures, and the resulting changes of toughness, was investigated in low-carbon Ni-containing steels with the addition of Cu and Al. Main results are as follows:
a. Age-hardening was most prominent when the matrix microstructure was bainitic.
b. Precipitates that contribute to age-hardening was concluded to be NiAl and Cu. Grobular NiAl under 100 A in diameter precipitated at dense dislocations in bainite at peak hardness.
c. In 0.15C-1.5Ni-0.5Mo steels, the amount of age-hardening increased, but the toughness was greatly impaired, with increase of the amount of Cu or Al.
d. Age-hardening and corresponding change in toughness with the addition of Cu and Al were studied in various low-carbon bainitic steels containing Ni. Among these, low carbon 6Ni-4Cr-1.5Mo-Cu-Al steels maintained fairly good toughness up to the strength level of 200kg/mm², as compared with maraging type of steels.

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Influence of MnS Inclusion on Ductility and Ductile Fracture Process of High Strength Steels

Setuo OKAMOTO, Fukunaga TERASAKI, Taturo KUNITAKE

1977 Volume 63 Issue 12 Pages 1878-1886
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1878

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The influence of MnS inclusion on ductility and ductile fracture process was investigated using quenched and tempered 70kg/mmmm2 class weldable high strength steels with a variation of sulfur content of 0.005 to 0.045wt%.
The influence of sulfur content on the tensile fracture strain and impact shelf energy was greater in the cross direction than in the longitudinal direction, and shelf energy was more affected than the fracture strain in the low sulfur level. In the case of materials with higher ductility which were tempered at higher temperatures, the influence became more pronounced. Shelf energies of 2mm V notched specimen were nearly the same as those of 2 mm deep fatigue notched and lower than those of 2mm V notched. The difference among shelf energies was independent on sulfur content.
In Charpy test, MnS inclusion affected the crack propagation rather than the crack initiation. On the other hand, in the tesile test, the true strain to crack initiation was pronouncedly affected by MnS inclusion.
The ductile fracture process of weldable high strength steels consists of two processes: relatively large void formation around inclusions which is detectable by an optical microscope, and coalescence of a void with other voids or notch or crack tip through “sheet of voids” as Rogers proposed. The size of void concerning “sheet of voids” in the present paper was very small and of electron microscopic order. A quantiative analysis made on the fracture surface proved that there existed a fairly good correlation between the shelf energy and area of small dimples due to “sheet of voids”, suggesting that the coalescence process was strongly affected by the matrix properties such as hardness, size of carbide and so on. The carbide particles larger than approximately 0.1 micron played an important role to the formation of small voids.

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Preparation of Thin Specimens of Chromium-Nickel Austenitic Steels with Various Combinations of Carbon and Nitrogen Concentration

Makoto KIKUCHI, Tohru TANAKA, Takanobu NISHIMURA, Shu-ichi TAKEDA, Ryo ...

1977 Volume 63 Issue 12 Pages 1887-1893
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1887

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A simple method, in terms of gaseous equilibration, has been developed to prepare specimens of Cr-Ni austenitic steels with various combinations of carbon and nitrogen concentration. Specimens were first nitrogenized up to the desired nitrogen concentration under the controlled nitrogen pressure with the aid of experimental studies on the activity of nitrogen in Cr-Ni austenitic steels. The nitrogenized specimens were carburized in a sealed quartz capsule, using hydrogen as a carrier and a plain carbon steel as a carbon supply. In this method, the carbon concentration in the Cr-Ni austenitic steels can be controlled within ±0.01% at the concentration level of 0.3% with very rough estimate of carbon activity in the specimen.
The method was successfully applied to a study of the effect of nitrogen on the precipitation morphology of M₂₃C₆ in a 25%Cr-28%Ni-2%Mo austenitic steel.

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Rate Equation in Multi-Interface Shell Model of Iron-Oxide Pellet Reduction

Yukiaki HARA

1977 Volume 63 Issue 12 Pages 1894-1896
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1894

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In the case that the multi-interface shell model applied to the analysis of the reduction kinetics of porous iron-oxide pellet, the rate equations take the different forms whether the resistances of intraparticle gaseous diffusion of the reactant and product species are equivalent or not.
The same type equations, which were proposed by author previously for the case the diffusion was assumed to be in molecular diffusion range and took the fairly simplified forms than those of the other case, are able to be used for the diffusion resistances are non-equivalent by adopting the modified resistance terms to the intraparticle diffusion.

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Reduction of Coke Rate and New Coking Processes Using Non-coking Coal

Toshio IKESHIMA

1977 Volume 63 Issue 12 Pages 1897-1903
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1897

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Energy Saving in Japanese Steel Industry

Tadaharu IKEDA

1977 Volume 63 Issue 12 Pages 1904-1910
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1904

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Process Development for Continnous Copper Smelting and Converting Process

Takeshi NAGANO

1977 Volume 63 Issue 12 Pages 1911-1917
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1911

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Management of the Modernized Steel Works

Masumi AIHARA

1977 Volume 63 Issue 12 Pages 1918-1925
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1918

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[title in Japanese]

[in Japanese], [in Japanese], [in Japanese]

1977 Volume 63 Issue 12 Pages 1926-1929
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1926

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[title in Japanese]

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

1977 Volume 63 Issue 12 Pages 1930-1937
Published: October 01, 1977
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.63.12_1930

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