"鉄と鋼"をより魅力あるものに
田中 良平
pp. 3-4
Readers Who Read This Article Also Read
Tetsu-to-Hagané Vol.67(1981), No.1
Tetsu-to-Hagané Vol.67(1981), No.2
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ONLINE ISSN: | 1883-2954 |
PRINT ISSN: | 0021-1575 |
Publisher: | The Iron and Steel Institute of Japan |
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田中 良平
pp. 3-4
Readers Who Read This Article Also Read
Tetsu-to-Hagané Vol.67(1981), No.1
Tetsu-to-Hagané Vol.67(1981), No.2
森田 善一郎, 槌谷 暢男, 原 行明
pp. 34-34,92
Readers Who Read This Article Also Read
Tetsu-to-Hagané Vol.67(1981), No.1
Tetsu-to-Hagané Vol.67(1981), No.2
Hisashi KISHITAKA, Sen-ichi HARIMAYA
pp. 54-62
Shichiro NOJIRI
pp. 63-69
Nobuya SHINOZAKI, Katsumi MORI, Yasuji KAWAI
pp. 70-79
Abstract
The rate of oxidation of manganese in liquid iron by slag was investigated by measuring the change of manganese and oxygen contents of liquid iron covered with FetO(+MnO)-CaO(+MgO)-SiO2 slag in a magnesia crucible. Experiments were carried out with slags of basicity(=(CaO+MgO)/SiO2) from 0.37 to 1.49 and FetO content from 24 to 75 wt% at 1600°C.
The oxidation reaction of manganese proceeded comparatively slowly except at the initial period and the equilibrium between liquid iron and slag was not attained within 60 min.
The experimental results were interpreted by the rate equation derived from the assumption that the reaction rate was controlled by the transfer of Mn, O, (MnO) and (FeO) in the boundary layers and the driving force of the reaction varied with proceeding of the reaction. The effect of FetO content of slag on the reaction rate was observed more clearly in the driving force than in the mass transfer coefficient.
The effect of slag basicity on the reaction rate was not clear.
Hiroyuki NOMURA, Yoshio TARUTANI, Kazumi MORI
pp. 80-87
Abstract
A mathematical model with special respect to peritectic transformation has been given on formation of negative segregation zone during uni-directional solidification of iron alloys. The model has been developed for the case of equilibrium solidification and nonequilibrium one.
The analysis predicts that solute-depleted band is formed in the vicinity of the section of area reduction. The reduction ratio of cross section and carbon concentration are suggested to influence the intensity of the segregation. It is concluded that the negative segregation is caused by mass flow of solute-rich liquid in the interdendritic region to feed solidification contraction.
Hiroyuki NOMURA, Yoshio TARUTANI, Kazumi MORI
pp. 88-92
Abstract
In order to clarify the mechanism of formation of negative segregation zone, an experimental study has been done on uni-directional solidification of iron with carbon contents of 0.09 to 0.25% and the solidification rate of about 6mm/min. Melting and solidification of iron were done in crucibles with an abrupt change of cross-sectional area. Solute-depleted band is formed in the vicinity of the section of area reduction. Extent of negative segregation is larger for phosphorus than carbon. Reasonable agreement of prediction of the model with experiment has been obtained.
Katsuo KINOSHITA, Hidenari KITAOKA, Toshihiko EMI
pp. 93-102
Abstract
Effects of high withdrawal rates, fluid mold slags, and mold taper on the occurrence of breakouts or surface cracks of the strand cast slabs have been evaluated by using an elasto-plastic stress analysis model previously developed.
The model has made it possible to predict the air-gap formation, and hence hot spot formation at the corner portion of the shell/mold boundary as well as the stress mode in the shell. Choice has been made of casting conditions which can minimize the hot spot formation and yield compressive stress in the shell.
Commercial scale casting experiments carried out on a Voest type straight mold and a Mannesmann type curved mold have confirmed that the chosen conditions are effective to prevent the breakout and crack formations of the shell.
A mechanism of the formation of longitudinal corner cracks and longitudinal facial-cracks has also been discussed.
Koichi TASHIRO, Shiro WATANABE, Ikujiro KITAGAWA, Itaru TAMURA
pp. 103-112
Abstract
Influence of hot top and mould design on the formation of central porosities and loose structure in heavy forging ingot was analyzed by using finite element method. The results of analysis were compared with those of sectioning investigation of 100t and 135t ingots, and the influence of mould and hot top design on the internal defects has been made clear quantitatively.
The result shows that the geometry of hot top and mould design plays most important role on the manufacture of sound heavy ingots. The central porosities and loose structure are liable to increase when the rate of vertical solidification at the centerline of ingot exceeds the value of about 10mm/min., and the defects are strengthened at the area where the rate of solidification is accelerated.
For 0.25%C-3.5%Ni-Cr-Mo-V steel ingot, "A" segregation begins to form when the rate of transverse (horizontal) solidification decreases to the value of about 0.8mm/min.
Kiyohiko FUJITA, Takao YAMAGUCHI
pp. 113-122
Abstract
When the color temperature is strictly defined, it is classified into "color temperature", "distribution temperature", and "two-color temperature", but these have often been referred to simply as color temperature, without distinguishing them exactly.
In this paper, these three color temperatures will be regarded as distinctive, and the definition and the respective determination methods of these three color temperatures will be proposed. From the viewpoint of measuring the color temperatures mentioned above, some new types of radiators will be defined, based on the characteristics of spectral radiation of the radiator, and then the correlation of each color temperature and the true temperature will be discussed.
When the spectral emissivity of metals (εM(λ, T)) is assumed to be in a linear relationship with wavelength λ, i.e. εM(λ, T)=aλ+b (where a μm-1 and b are constant), each of the color temperatures can be expressed as a function of a/b.
Thus, each of the color temperatures for various a/b values is calculated by the determination methods proposed in this paper, and the correlations with each of the other color temperatures and the true temperature of metals are shown. It is checked up whether the assumption mentioned above is reasonable with tungsten, whose wavelength dependency of spectral emissivity is known. Moreover, the color temperature of liquid iron is treated.
Kenji CHIJIIWA, Yotaro HATAMURA, Nobuki HASEGAWA, Yoshiyuki TANABE
pp. 123-132
Abstract
Simulation of horizontal 2-stands rolling by plasticine, for compressive rolling and tensile rolling, is carried out. The following items are clarified:
(i) Deformation of side face, upper face and transverse section of workpiece and distribution of principal strain-rate and slipping velocity against rolls.
(ii) Forces and torques acting on rolls and rolling energy.
(iii) Distribution of pressure, circumferential frictional stress and axial frictional stress acting on the surfaces of rolls.
(iv) Distribution of internal stress in workpiece.
Then the above experimental results are analysed, and the following facts become clear:
(i) All the stress measurements are made with enough accuracy.
(ii) Distribution of principal strain-rate and others coincide well with the measured stress distributions.
(iii) Compressive rolling is effective to eliminate the tensile stress in the neighborhood of the surface of workpiece. Thensile rolling slightly reduces rolling energy.
Natsuo HATTA, Jun-ichi KOKADO
pp. 133-142
Abstract
A mathematical model is proposed for the mill arrangement equivalent to semi continuous type in a hot strip mill. The rolling schedule is arranged so that a slab is rolled from 230 mm into 60 mm in bar thickness by reversibly three passes roughing and 60 mm into 1.2 mm, 2.0 mm and 2.5 mm in final thickness by seven passes finishing. The possibility of rolling in this case is analytically examined in due consideration of slab weight, temperature change, rolling power, rolling capacity and rolling speed. As a result, the rolling of the comparably heavy slab with 30 t/m in unit weight is enabled, and the temperature condition is sufficiently fulfilled. The length of the rolling mill line can be geometrically shortened very much in comparison with the case of other type hot strip mill.
Chiaki OUCHI, Tetsuya SAMPEI, Isao KOZASU
pp. 143-152
Abstract
The effects of hot rolling condition and chemistry of the steels on the onset temperature of γ-α transformation after hot rolling were investigated using the thermal analyzer developed for measurment of Ar3 temperature after hot rolling. The changes of Ar3 temperature and austenitic microstructure with the reheating temperature, the rolling temperature and the rolling reduction were investigated in the Si-Mn and Nb-bearing steel. These results were analyzed based on the changes of the effective interfacial area per unit volume(SV) that included the recrystallized or unrecrystallized γ grain boundary and deformation band as a nucleation site for ferrite. Although the SV value increased with the refinement of recrystallized γ grain or the increase of rolling reduction below recrystallization temperature of austenite, the latter resulted in much greater rise of Ar3 temperature in Nb steel. This was considered to be due to the reduction of the amount of dissoluted Nb atom around the grainboundary or deformation band through the strain induced precipitation of Nb(CN).
The effects of chemistry and the plate thickness on Ar3 temperature after controlled rolling were studied in the large number of the steels with the different chemistry, and the relation of Ar3 temperature and each element was quantitatively established based on the multiple regression analysis.
Yuzo ODA, Minoru KONAKA
pp. 153-158
Abstract
A new method of quantitative electron probe microanalysis was proposed. By this method the precise measurements of chemical composition can be done without measuring intensity of background which was expressed by the additive property of intensities of continuous X-rays irradiated from each element in the sample. A computor programming of the quantitative analysis was made and the results of the computation could be graphic out by a plotter.
The present method was applied to analysis of various alloys, and it was found that the results obtained through the use of this method have been fairly good having the accuracy of 0.03% in relative error.
Hisao FUJIKAWA, Junichiro MURAYAMA, Nobukatsu FUJINO, Taishi MOROISHI, Yuji SHOJI
pp. 159-168
Abstract
As high temperature oxidation resistance of a 19Cr-13Ni-3.5Si steel is usually inferior to that of SUS 310S steel, yttrium, rare earth metals and other active metals are often added in the steels to improve the oxidation resistance.
The authers have experienced that some 19Cr-13Ni-3.5Si steels show excellent resistance to high temperature oxidation. Therefore, high temperature oxidation behaviors of 19Cr-13Ni-3.5Si steels containing 0.0001 to 0.012% sulfur have been investigated by means of isothermal and cyclic heating at temperature up to 1 200°C. It has been found that sulfur existing as an impurity in steels shows very harmful influence on high temperature oxidation resistance of 19Cr-13Ni-3.5Si steels. The steels containing extra low sulfur less than 0.001% show more excellent resistance to high temperature oxidation than SUS 310S steel, and moreover, the addition of calcium in the steels containing sulfur less than 0.001% is beneficial. It has also been found that the nonmetallic compounds containing sulfur consist of the Ca-Al-Mg-O-S in the steels with sulfur less than 0.001%, and transform into MnS with an increase of sulfur content in the steels. It is suggested that MnS compounds have harmful influence on high temperature oxidation resistance of 19Cr-13Ni-3.5Si steels.
Besides, high temperature oxidation behaviors of 19Cr-13Ni-3.5Si steels containing various amounts of sulfur were clarified.
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Tetsu-to-Hagané Vol.72(1986), No.11
Hisao FUJIKAWA, Junichiro MURAYAMA, Nobukatsu FUJINO, Taishi MOROISHI
pp. 169-177
Abstract
It was published in the previous paper that a small amount of sulfur existing as an impurity in the steels has the harmful effect on the high temperature oxidation resistance of 19Cr-13Ni-3.5Si austenitic stainless steels.
In the present study, the high temperature oxidation behaviors of 19Cr-13Ni-3.5Si steels containing extra low sulfur (0.0004%S) and high sulfur (0.012%S) have been observed from the initial oxidation state in the temperature range of 800°to 1 200°C, and the oxide scales formed on these steels have been studied by means of microscope, EPMA, fluorescent X-ray analyzer, scanning Auger analyzer, IMMA and so on.
The steel containing extra low sulfur uniformly forms the protective oxide scales consisting of corundumtype oxide (mainly Cr2O3) and SiO2 which is accumulated at the metal-Cr2O3 interface by heating at high temperatures, and shows the excellent oxidation resistance. On the other hand, in the steel containing high sulfur, MnS compounds near the surface dissolve during heating at higher temperatures than 800°C change into Cr-Mn-O compounds. Therefore, the chromium-depleted zone is formed around the compounds, and sulfur concentrates around the compounds on the steel surface. These portions form the nonprotective spinel-type oxide containing mainly iron, and the other portions form the protective corundum-type oxide. However, the corundum-type oxide is attacked by the rapid growth of the spineltype oxide formed around MnS compounds, and the oxidation resistance of the steel containing high sulfur is extremely lowered.
From the above results, the mechanism of high temperature oxidation of 19Cr-13Ni-3.5Si steels with extra low sulfur and high sulfur has been discussed.
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Tetsu-to-Hagané Vol.73(1987), No.1
Tetsu-to-Hagané Vol.71(1985), No.2
Tetsu-to-Hagané Vol.70(1984), No.5
Toshio TAKAMATSU, Yasuo OTOGURO, Kazuhide SHIOTSUKA, Katsukuni HASHIMOTO
pp. 178-187
Abstract
Influences of impurities, alloying elements and grain refining elements were investigated systematically in relation to high temperature strength and temper embrittlement of 21/4 Cr-1Mo steel which was widely used for high temperature chemical equipments such as a desulphurization reaction vessel of heavy oil.
The following results were obtained.
1) The degree of the temper embrittlement increased remarkably with increasing the amount of impurites such as P, Sb and Sn. It was also larger with higher C content, cooling rate at quench and strength level. However, relative ratio of their degree of the embrittlement among various impurities was nearly constant.
2) Effective element for high temperature strength was generally harmful to temper embrittlement.
3) Steels with fine grain size had less susceptibility to temper embrittlement than those with coarse grain size. Accordingly, addition of grain refining elements such as Ti, Nb, Te and Al decreased the susceptibility.
4) Rare earth elements lowering the content of P on grain boundaries decreased the susceptibility.
5) Both high strength at elevated temperature and less susceptibility to temper embrittlement was obtained with steel containing a combination of Ti, B and REM.
Naoki TONA
pp. 188-191
小林 一彦, 西尾 浩明, 月橋 文孝, 檀 武弘, 加藤 嘉英, 郡司 好喜, 古君 修, 新谷 紀雄, 長井 寿, 金尾 正雄, 河淵 靖, 徳山 幸夫, 菊池 実, 名村 夏樹, 新村 哲生
pp. 205-210
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