Tetsu-to-Hagane

Structure and Properties of Nanocrystalline Materials

Yoshikiyo OGINO

1994 Volume 80 Issue 11 Pages 807-812
Published: November 01, 1994
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_807

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Control of Pouring Molten Charge out of a Levitation Type Cold Crucible

Kenji ANDO, Kazuhiko IWAI, Shigeo ASAI

1994 Volume 80 Issue 11 Pages 813-818
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_813

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A new method for pouring a molten charge out of a levitation type cold crucible has been proposed. In the new method, the charge is taken out through the bottom-hole of the crucible by changing the magnetic field which results in the break-down of the mechanical balance among magnetic pressure, hydrostatic pressure and the pressure due to surface tension. Pouring the charge out of the crucible was demonstrated by changing the distance between the coil and the crucible. A new technique which can fix the shape of the molten charge in the crucible has been proposed. By using this technique, the elongation of the charge shape predicted by the numerical analysis was confirmed and whether the charge contacted with the crucible was examined. In the experiment, the small temperature difference between the molten charges before and after pouring was observed and the large super heat in the poured metal was available.

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Prediction of Annual Production Rates of Crude Steel in Various Countries by a Modified Logistic Function

Minoru SASABE, Hidekiyo ITAKURA

1994 Volume 80 Issue 11 Pages 819-824
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_819

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Annual production rates of crude steel of various countries in future are estimated by the following procedure : First, real production rates are corrected by a regular procedure. Then equations of relationship between the corrected production rate and the year are expressed by regression of a logistic equation. Estimated production in various countries can be obtained by subtracting the difference of the corrected and the real productions from the regressed amount.
For examples of results, the maximum production rate of Japan in future can be estimated as 120Mt/y. It is also suggested that annual production rate under depression in near future can be estimated.

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Activities of the Constituents in FeO·Cr₂O₃-MgO·Cr₂O₃-MgO·Al₂O₃Spinel Solid Solution

Mitsutaka HINO, Ken-ichi HIGUCHI, Tetsuya NAGASAKA, Shiro BAN-YA

1994 Volume 80 Issue 11 Pages 825-830
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_825

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The activity of iron chromite in solid FeO·Cr₂O₃-MgO·Cr₂O₃-MgO·Al₂O₃ spinels, saturated with (Cr, Al)₂O₃, was determined at 1573 K, by the equilibrium of iron dissolved into liquid silver in the spinel crucible with CO-CO₂gas mixture, to clarify the thermodynamic properties of chromium ores used in ferrochromium industry.
The phase relation between (Cr, Al)₂O₃and FeO·Cr₂O₃-MgO·Cr₂O₃-MgO·Al₂O₃spinel phase was studied, and the solubility of (Cr, Al)₂O₃ in FeO·Cr₂O₃MgO·Al₂O₃, MgO·Cr₂O₃-MgO·Al₂O₃ and FeO·Cr₂O₃-MgO·Cr₂O₃-MgO·Al₂O₃ spinel phases was found to be small.
The activity of FeO·Cr₂O₃ in FeO·Cr₂O₃-MgO·Cr²O₃-MgO·Al₂O₃spinel solid solution coexisted with (Cr, Al)₂O₃shows negative deviation from ideality. It was observed that the spinel solid solution took regular solution behavior, and α-function of each pseudo-binary in FeO·Cr₂O₃-MgO·Cr₂O₃-MgO·Al₂O₃system was determined as follows;
α_{FeO·Cr₂O₃-MgO·Al₂O₃}=-92, 000(J),
α_{MgO.Cr₂O₃-MgO·Al₂O₃}=-30, 000 (J)

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Mathematical Analysis on the Upper Limit of Cooling Rate in Casting on the Basis of One-dimensional Semi-infinite Model

Kazumi YASUDA, Hiroyuki KAJIOKA

1994 Volume 80 Issue 11 Pages 831-836
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_831

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Cooling rate is an important index to estimate solidification structure or property of cast products.
In order to evaluate the upper limit of the cooling rate in near net shape casting processes of various kinds, heat conduction in the semi-infinite region with and without solidification was calculated analytically. On the basis of Neumann's solution for the semi-infinite region (y>0) initially at constant temperature U with the surface (y=0) maintained at zero for the subsequent time (t>0), cooling rate was calculated for the cases in which location, time or temperature was fixed respectively.
The results are as follows.
(1) In case of cooling without solidification, the maximum cooling rate at any fixed location takes place at the constant temperature 0.92U independent of the thermal characteristics. While in case time is fixed, the maximum cooling rate occurs at another constant temperature of 0.68U.
(2) In case of cooling with solidification, cooling rate is determined by location, time and the dimensionless parameter Ya, which is the ratio between sensible and latent heat, And for any kind of metal the maximum cooling rate at any fixed location or time appears just behind the solidification front. Approximate equations for the maximum cooling rate are proposed.

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General Method for Solidification and Cooling Analysis of a Cast in a Mold through a Linear Heat Flow Model

Kazumi YASUDA, Hiroyuki KAJIOKA

1994 Volume 80 Issue 11 Pages 837-842
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_837

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It has been difficult to get an analytical solution for temperature distribution in a solidifying and cooling process in a mold of continuous casting machine, because of multi-layered heat resistance between solidification front and water cooling surface of a mold ; solidified shell/ melt or solidified powder/ air gap/ mold coating/ mold metal and cooling water. Numerical methods, which are inconvenient to get a perspective of the total system, have been the only measure to analyse processes.
The object of this research is to present a new general method to analyse a mold cooling system.
The authors proposed a new concept "quasi-steady state", and defined a new standard function "cast function" as a solution of a linear heat flow model. They established a new precise general method to analyse a mold cooling system. As a result it has become possible to express explicitly temperature at arbitary location and time in the casting and cooling system.
They also made a comparison among this method and other model methods.

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Application of Bake Hardenable Tinplate to 2 Piece Can

Kuniaki MARUOKA, Tsuyoshi KAWANO, Yasuhiko YAMASHITA

1994 Volume 80 Issue 11 Pages 843-848
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_843

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The possibility was fundamentally investigated, that the demand to light weight DWI can could be satisfied by bake-hardenable and thin gauge tinplate which had excellent DWI formability at the stage of DWI forming before baking and had high pressure resistance after baking due to such bake-hardenability as automotive steel sheets.
At first, change of mechanical property of continuous annealed tinplate with controlled amount of solute carbon due to forming was experimentally investigated by simulating DWI forming by cold rolling. Such tinplate showed increase of yield strength due to bake-hardening following cold rolling corresponding to bottom forming, and that was expected to improve dome pressure resistance. At the same time, since tensile strength of bake-hardenable tinplate cold rolled up to 70% was not higher than that of conventional tinplate, DWI formability of bake-hardenable tinplate was expected to be equivalent to that of conventional one.
Then model cans were experimentally manufactured from 2 types of tinplate, and the improvement of dome pressure resistance in bake-hardenable tinplate was proved.
Finally it was discussed that dome was fully reinforced by structural design and that the burst of dome was considered a kind of plastic collapse.

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Effects of Hot Rolling and Descaling Condition on Red Scale Defects Formation

Hikaru OKADA, Tomoki FUKAGAWA, Haruhiko ISHIHARA, Atsuki OKAMOTO, Masa ...

1994 Volume 80 Issue 11 Pages 849-854
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_849

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Red scale defects usually observed in high Si hot rolled strip were reproduced in a laboratory 3 stand tandem mill. The effects of hot rolling and descaling condition on the strip surface color and scale structure were examined.
Irrespective of Si content in steel, the hot rolled strip surface became red when the scale thickness before rolling was above 20μm and the rolling temperature was below 900°C. It was found that surface part of the scale (mainly FeO) was broken to powder by the hot rolling at the temperature below 900°C. The red scale of Fe₂O₃ was formed by the oxidation of powdered scale during cooling. Thick scale formed during slab soaking was completely removed by hydraulic descaling before rolling in low Si steel, whereas that was not removed in high Si steel. This remained scale caused the red scale defects after rolling and cooling. The application of obtained results to the hot strip mill production of red scaleless strip was discussed.

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Diffusible Hydrogen Behavior in Pre-strained High Strength Steel

Nobukazu SUZUKI, Nobuyuki ISHII, Yutaka TUCHIDA

1994 Volume 80 Issue 11 Pages 855-859
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_855

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Diffusible hydrogen behavior in pre-strained high strength steel was investigated by use of a newly developed hydrogen content determining method for better understanding of delayed fracture.
Pre-straining up to 4.2% formed a new hydrogen trapping site in the steel. When hydrogenerated in a 0.1N HCl solution, hydrogen content in the steel increased with the amount of pre-straining. The trapping site resulted from prestraining was removed by aging at 200°C.
During the hydrogenation of the 4.2% pre-strained specimen, hydrogen content in the steel increase in accordance with Fick's law.
The decrease of hydrogen content in the specimen pre-strained, hydrogenated, then held at room temperature cannot be explained by a single diffusion rate. This phenomenon can be better explained by assuming that hydrogen in the lattice and trapping sites diffuse independently without showing local equilibrium.

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Fatigue Fracture for Bead-formed Sheet of Austenitic Stainless Steel

Takashi KATSURAI, Tatsumi TOZAWA, Hajime KATO, Yoshimasa TAKAYAMA

1994 Volume 80 Issue 11 Pages 860-865
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_860

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A metallic gasket for the cylinder head of the automobile engine is made of an austenitic stainless steel sheet. It commonly has a press-formed bead which seals the high pressure gas in the combustion chamber. Because the fatigue characteristics of the sheet with the bead do not correspond to those of the plain sheet without bead, it is not easy to judge the suitability of the materials for the metallic gasket. We investigated the fatigue behavior for the sheet with the bead, especially the number of crack origins and the fatigue crack propagation rate. As a result, the fatigue strength at the number of 10⁶ cycles was not dependent on the mean stress but the stress amplitude. In addition, the discrepancy between the fatigue characteristics of the sheets with and without the bead resulted from fine wrinkle-like bands of plastic deformation which occurred at a part of bead profile foot during the bead-forming.

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Influence of Al Addition on Resistivity and Phase Constitution of Quenched Ti-5Fe Alloy

Masahiko IKEDA, Shin-ya KOMATSU, Takashi SUGIMOTO, Kiyoshi KAMEI, Koic ...

1994 Volume 80 Issue 11 Pages 866-870
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_866

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Previous results on β quenched Ti-215%(mass%) Fe alloys suggested that the volume fraction of athermal ω phase (ω_ath) was maximum in the Ti-5%Fe alloy. In present work, influence of Al addition to the Ti-5%Fe alloy on the formation of ω_ath has been investigated by resistivity and hardness measurement, X-ray and electron diffractometry in the β quenched state.
In alloys containing up to 8%Al, optical microscopy reveals single phase structure, and only β phase is detected by X-ray diffraction.
Resistivity monotonously increases with Al content. Resistivity ratio between liquid nitrogen and room temperature, ρ_LN/ρ_RT, shows a maximum at 6%Al, at which hardness shows a minimum.
Room temperature electron diffraction pattern due to athermal ω phase is changed by the Al addition from clear spots to diffuse scattering.
Similarly as the case of Ti-20V-Al, it is considered that the added Al dissolves substitutionally into β Ti-5%Fe lattice, lowers starting and finishing temperatures of athermal ω phase formation, ω_S and ω_f, and then decreases volume fraction of athermal ω phase at room temperature.

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International Trend on Global Warming Issue

Yotaro OHNO

1994 Volume 80 Issue 11 Pages N558-N563
Published: November 01, 1994
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.80.11_N558

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