Establishment of Mass-production Technology and Supply System on High-grade Lime and Dolomite
Hyoza YOSHIZAWA
pp. 1273-1280
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オンライン版ISSN: | 1883-2954 |
冊子版ISSN: | 0021-1575 |
発行機関: | The Iron and Steel Institute of Japan |
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30 Dec. (Last 30 Days)
Hyoza YOSHIZAWA
pp. 1273-1280
Masao SERIZAWA
pp. 1281-1287
Hideyuki YOSHIMOTO
pp. 1288-1296
抄録
[in Japanese]
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鉄と鋼 Vol.75(1989), No.10
鉄と鋼 Vol.73(1987), No.1
鉄と鋼 Vol.75(1989), No.10
Katsuya NAKAYAMA
pp. 1303-1308
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鉄と鋼 Vol.75(1989), No.10
鉄と鋼 Vol.73(1987), No.1
鉄と鋼 Vol.75(1989), No.10
Keiji IBA
pp. 1316-1322
Takeaki MURAYAMA, Yoichi ONO
pp. 1323-1328
抄録
A method of determination of the rate parameters (chemical reaction rate constant, effective diffusivity in the product layer and effective diffusivity in the reaction zone) and Thiele's modulus included in ISHIDA-WEN's model is proposed. With this method, those parameters can be determined easily from reduction data. This method was examined by being applied to the reduction curve calculated by ISHIDA-WEN's model and the experimental data of gaseous reduction of iron oxide pellets. This method was useful especially in the case of smaller value of Thiele's modulus.
Nobukazu SHIGEMATSU, Hikoya IWAI
pp. 1329-1336
抄録
The dense wustite plates containing SiO2 and CaO were reduced isothermally in H2 gas stream over a temperature range of 670 to 930°C. The wustite samples used in this work consist of FeO phase dissolving SiO2 and CaO, Fe-Ca olivine and dicalcium silicate. It was clear that the reduction rate of the samples was affected mainly by the additives dissolved in FeO phase and slightly by the complex oxides. By the presence of very small amount of SiO2 dissolved in FeO phase the reduction was promoted at temperatures above 800°C and retarded at temperatures below 730°C. The reduction was promoted very much by the presence of dissolved CaO over a temperature range of this work. It was recognized that the effect of these dissolved oxides on the reduction rate originated from their effect on the morphology of the reduced iron.
Nobuaki OHARA, Shinya NUNOUE, Eiichi KATO
pp. 1337-1342
抄録
The effects of CaO, MgO, MnO and SiO2 on the activity coefficient of P2O5 in dilute solution of P2O5 in FetO were determined at 1370°C by the use of a mass spectrometer-Knudsen cell combination. The activity of P2O5 was determined by the use of the following chemical equilibrium. Iron vapor in equilibrium with solid iron was used as internal standard.
PO ( g )+ P2O5( in slag ) = 3PO2(g)
aP2O5 = K·P3PO2PPO=K'·(I+PO2/I+Fe)3(I+PO/I+Fe)
The interaction parameters have been calculated from the activity coefficient of P2O5 with the aid of the least square method. The obtained results are as follows.
εCaOP2O5 = - 23 ± 3 εMgOP2O5 = - 20 ± 2
εMnOP2O5 = - 13 ± 1 εSiO2P2O5 = - 4 ± 1
These interaction parameters are for dilute solution of P2O5 in FetO.
Masahiro HIRASAWA, Kazumi MORI, Masamichi SANO, Asao HATANAKA, Yuhji SHIMATANI, Yoshimitsu OKAZAKI
pp. 1343-1349
抄録
Kinetic studies have been made on the rate of reaction between molten slag and metal with gas-injection stirring. The explored reaction is oxidation of Si in molten Cu by FeO in a Li2O-SiO2-Al2O3-FeO slag taking place under the condition of rate-controlling by Si transport in the metal phase. Kinetic experiments were done at 1250°C. The slag-metal bath was stirred by Ar gas injected through a nozzle located at the crucible bottom. The apparent metal-side mass-transfer coefficients of Si, kSi', are calculated from the kinetic data. Relations between kSi' and experimental conditions (gas flow-rate, Vg ; metal depth, hM; slag depth, hsl ; crucible diameter, dc) have been investigated.
kSi' is found to increase generally with increasing Vg. The dependence of kSi' on the gas flow-rate varies at certain gas flow-rates denoted by Vg* and Vg**.In the low Vg range (Vg<Vg* : Region I), kSi' is proportional to ( Vg/dc2)1/2. In the medium Vg range (Vg* <Vg<Vg** : Region II), the effect of the increase in gas flow-rate on kSi' is cosiderably smaller than in Region I. In the high Vg range (Vg>Vg**: Region III), the extent of the increase in kSi' with Vg increases again. It is also found that kSi' increases with metal depth, hM, below a transitional depth, hM*. Above the transitional metal depth hM*, kSi' becomes independent of hM. Examinations have been performed of the influence of slag depth, hsl, on kSi' in Regions I and II. In Region I, kSi' is independent of hsl. In Region II, kSi' decreases with the decrease of slag depth.
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鉄と鋼 Vol.78(1992), No.5
鉄と鋼 Vol.77(1991), No.10
鉄と鋼 Vol.79(1993), No.5
Masahiro HRASAWA, Kazumi MORI, Masamichi SANO, Yuhji SHIMATANI, Yoshimilsu OKAZAKI
pp. 1350-1357
抄録
A theoretical analysis has been made on the metal-side mass-transfer in a slag-metal reaction system with gas-injection stirring. Considerations have been given of the fluid flow in the vicinity of the slagmetal interface. On the basis of a theory of turbulence phenomena, metal-side mass-transfer coefficients are derived as functions of gas-injection stirring conditions. The theoretical equations are rearranged to dimensionless correlation equations.
The mass-transfer data obtained by the authors for molten slag-Cu reaction system of Si oxidation by FeO at 1250°C and the available data of model studies at low temperature (aqueous solution-amalgam system at room temperature and molten salt-molten Pb system at 450°C) are correlated successfully by the equations obtained in the present study. It is found that the dimensionless correlation equations obtained in the present study are applicable to the data of ladle desulfurization, as far as the rate is controlled by the mass-transfer in the metal phase.
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鉄と鋼 Vol.75(1989), No.10
鉄と鋼 Vol.73(1987), No.1
鉄と鋼 Vol.75(1989), No.10
Hiroyasu YAMAMOTO, Jun HASHIMOTO, Teruhide NIDOME, Toshiyuki SHIRAISHI, Takashi ASAMURA
pp. 1358-1365
抄録
In order to achieve the high productivity in a continuous tandem cold mill, the control system of forward slip ratio has been developed by the use of a supply device of rolling lubricant, which works in quick response to the lubricant flow and concentration.
In the calculation model of this control system, the method which modifies BLAND & FORD'S equation with a slide factor for calculation of friction coefficients is used to estimate negative values of forward slip ratio in addition to positive values. As for the supply device of rolling lubricant, emulsion stability and particle size distribution of lubricant obtained by a static mixer are equivalent to those by a convenient device. A high-speed and stable rolling without chattering can be realized by controlling the supply amount of rolling lubricant in the present control system of forward slip ratio.
Takashi FUJIMOTO, Kazushi BABA, Kazuo ARAI, Teruyuki NAKANISHI, Junjiro YAMASAKI
pp. 1366-1372
抄録
Kawasaki Steel has recently developed computer control techniques for a 4-tandem mill with grooved rolls at the billet mill in Mizushima Works.
These techniques consist of set-up and dynamic control functions. The purpose of set-up control is to decide the manipulating variables (roll gap, roll revolution) which cause material dimensions to achieve the aimed value by means of the mathematical models. We have developed such presice models as to be applied to on-line control. On the other hand, the purpose of dynamic control is to achieve uniform sectional dimensions along the length of the material. Development has also been made on the new sectional profile control technique to utilize dynamic roll gap control, firstly as a grooved mill.
As the result of these application, the dimensional accuracy of the product has been significantly improved in the mill.
Yasuhiro MAEHARA, Kunio YASUMOTO, Hiroshi TOMONO, Yasuya OHMORI
pp. 1373-1380
抄録
Effect of thermo-mechanical history during cooling from solution treatment temperature of 1 300°C on the ductility at 800°C at a strain rate of 10-3 s-1 of low carbon low alloy steels has been investigated by means of hot tensile test in relation to surface cracking of continuously cast (CC) slabs. The ductility evaluated by reduction in area of the specimens directly cooled to the deformation temperature is largely reduced by the slow strain rate deformation especially in Nb steels, since ductile intergranular fracture of austenite easily occurs because of the dynamic precipitation of NbC and/or AlN within the matrix as well as on the grain boundaries. By decreasing the cooling rate or by isothermal holding at around 1 100°C, the ductility is significantly improved and the fracture mode changes into transgranular ductile, because the dynamic precipitation is much reduced by the depletion of preciptating elements due to nucleation and coarsening of the precipitates in these processes. This however takes extremely long time to achieve the coarsening of the precipitates in conventional CC process and is not practical. In order to accelerate this phenomenon the effect of the prior deformation was examined and the optimum conditions suitable for CC process were determined. In the case of continuous cooling the predeformation larger than 5% should be applied at temperatures around 1 050°C at strain rates larger than 10-2 s-1. The ductility of the specimens predeformed at lower temperatures can also be improved by employing the subsequent reheating process.
Kunio YASUMOTO, Yasuhiro MAEHARA, Tsuneaki NAGAMICHI, Hiroshi TOMONO
pp. 1381-1388
抄録
Surface cracking and the effect of predeformation on the cracking of continuously cast (CC) low carbon low alloy steel slabs have been studied by means of hot bending tests simulating a practical CC and the direct rolling process using the as-cast thin slabs. Two kinds of cracking, i. e., fine transverse cracks in microalloyed steels due to carbonitride precipitation during slow strain rate deformation of 10-3 s-1 and severe cracks in low carbon Al-killed steels due to sulfide precipitation during high strain rate deformation of 10 -1 s -1were easily simulated by the deformation in low temperature γ region. The both kinds of cracking were markedly suppressed by the slight predeformation on the slab surface during cooling to the deformation temperature. Since γ grain size was not changed by the predeformation, these results can be explained in terms of precipitation behavior of carbonitride or sulfide in each case. That is, the precipitates formed by the predeformation can grow into coarse particles during the cooling stage, resulting in marked suppression of fine precipitation which causes large ductility loss in the subsequent bending process.
Takashi ARAI, Toshiharu KOBAYASHI, Takehiko ITAGAKI, Kisaburo KOIKE, Nobuo SAKUMA
pp. 1389-1396
抄録
For improving endurance temperature of superalloys, an investigation was carried out into mould conditions of vacuum casting procedure and into fabrication conditions of tungsten fibre reinforced cobalt-base superalloys.
Creep testing was performed for the test-pieces, which were prepared by the method found to be the optimum in the above experiment. The tungsten wire was 1 mm in diameter and the matrix alloy was X-45 or its modification with respect to tungsten content. The fibre content was 50%. The strength of the composites was considerably lower than that expected from the combination of the wire and the matrix when the tungsten content in the matrix was low. This was due to the partial dissolution of the wire into the molten alloy during casting.
The effect of the thermal degradation of the wire during fabrication on the strength of the composite decreased with the increase in testing period, because the rate of decrease in the wire strength was smaller for the wire which had once experienced a high temperature as compared with the wire which had not. Although nickel-induced recrystallization was not observed, growth of reaction zones as well as formation and growth of voids proceeded during creep testing. Their effect on the strength of the composite was possible.
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鉄と鋼 Vol.73(1987), No.2
鉄と鋼 Vol.76(1990), No.7
鉄と鋼 Vol.76(1990), No.5
Mitsuo NIINOMI, Ikuhiro INAGAKI, Toshiro KOBAYASHI
pp. 1397-1404
抄録
The instrumented Charpy impact test and dynamic fracture toughness test are carried out on variously heat treated Ti-6Al-2Sn-4Zr-6Mo alloy, and the effect of microstructure on toughness under impact loading is examined.
In equiaxed α structural specimens, Charpy absorbed energy (Et) value increases with the increase of solution treatment temperature below 1 123 K, and then decreases with increase of solution treatment temperature above 1 123 K. Et value is strongly influenced by the cooling rate after solution treatment. In equiaxed α structural specimens, the tendency of the change in dynamic fracture toughness (Jd) with solution treatment temperature is similar to that of Et value. However, the degree of the change in Jd value and the effect of cooling rate after solution treatment on Jd value are significantly small. Et and Jd values are remarkably large in acicular structural specimens which are furnace cooled after solution treatment in the β region. In acicular α structural specimens, Et and Jd values increase with the increase of prior β grain size. However, in equiaxed α structural specimens, Et value rather decreases with increase of prior β grain size although Jd value increases. Et and Jd values increase with the increase of the roughness of fracture surface.
Mitsuo NIINOMI, Kenzi SUZUKI, Toshiro KOBAYASHI
pp. 1405-1412
抄録
The effect of various heat treatments on the behavior of the hydrogen embrittlement of Ti-6Al-2Sn-4Zr-6Mo alloy, and the relation between hydrogen embrittlement and microstructural factor was investigated.
In the case of the specimens which were air cooled after solution treatment in the (α+β) region, the width of hydrogen embrittled fracture surface, which corresponded to the hydride formation zone, and the hydrogen embrittlement ratio increased with the increase of solution treatment temperature, namely the decrease of the areal percentage of primary α. On the other hand, in the case of the specimens which were water quenched after solution treatment in the (α+β) region, the opposite tendency was observed. In the case of solution treatment temperature higher than 1 173 K, the width of hydrogen embrittled fracture surface and the hydrogen embrittlement ratio increased in the order of furnace cooled, water quenched and air cooled specimens after a solution treatment with the same treatment temperature. The hydrogen embrittlement ratio was lower and the width of hydrogen embrittled fracture surface was wider in the specimens which were solution treated in the β region than that in those which were solution treated in the (α+β) region with the same cooling condition after solution treatment.
Michihiko FUJINE, Masanao NARITA, Fumikichi MOGI
pp. 1413-1418
抄録
The application of ICP-AES method was investigated for the rapid analysis of impurities in titanium and it's alloy. Elements for analysis were Mn, Cu, Ni, Cr, Mo, Sn, Zr, Fe, Y, Al and V. Good results were obtained by using titanium as an internal standard, which were enough preferable to the precision and the accuracy in the comparison with chemical analysis.
After the acid decomposition of metal sample (0.5 g) and fuming of H2SO4, the solution is diluted to 100 ml with water for the ICP determination.
The detection limits in the present method are 0.0001% for Mn and Y, 0.001% for Cu, Ni, Cr, Mo, Zr, Fe and Al, and 0.01% for Sn and V, which mostly show better results than those of widely used analysis. In the determination of Ti-6Al-4V alloy, however, corrections are needed according to the contents of V and Al.
Takashi SUGIHARA, Keizi SAITO, Akihiro GODA, Toshihiko HATA
pp. 1419-1424
抄録
In the emission spectrometric analysis of steels, the influence of surface structure and microstructure on an analytical result and its prevention were investigated. The followings were obtained.
(1) The analytical precision was markedly influenced by the presence of surface oxidized layer but not by the surface roughness.
(2) Microstructural effect on analytical results was found to be due to the unusual emission caused by preferential discharge into pearlite. This effect was remarkable in the analysis of carbon.
(3) The preferential discharge was improved by the rapid formation of electrical discharge hardening layer, which was achieved by the prolonged preburn time or the discharge with high energy spark.
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ISIJ International Vol.64(2024), No.14
ISIJ International Vol.64(2024), No.15
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