Tetsu-to-Hagane

Steel Industry and Vacuum

Chikara HAYASHI

1984 Volume 70 Issue 7 Pages 621-627
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_621

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Fundamentals of Combustion Technique (I)

Yukio MIZUTANI

1984 Volume 70 Issue 7 Pages 628-636
Published: May 01, 1984
Released on J-STAGE: February 16, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_628

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Characterization of Passive Films on Stainless Steels Using Modern Surface Analysing Techniques

Katsuhisa SUGIMOTO

1984 Volume 70 Issue 7 Pages 637-649
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_637

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Emission Spectrometry with Inductively Coupled Plasma as Light Source

Tsutomu TAKAHASHI, Osamu KUJIRAI

1984 Volume 70 Issue 7 Pages 650-656
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_650

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Melting Model of Iron Ore Sintering

Shun SATO, Takazo KAWAGUCHI, Minoru ICHIDATE, Mayumi YOSHINAGA

1984 Volume 70 Issue 7 Pages 657-664
Published: May 01, 1984
Released on J-STAGE: February 16, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_657

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A fundamental study was carried out on melting process and its primary controlling factors in the iron ore sintering. Melting properties of sinter feed were evaluated by the volume ratio of the melted portion to the substantial solid of sinter, "melting ratio". From sinter pot test, the corelation between the melting ratio and the sinter operational conditions was studied. The melting process in sintering depended on the holding time in high-temperature zone, are particle size, its chemical composition, and porosity after dehydration. On the basis of the obtained information, a model simulation of sinter melting process was developed and was discussed by comparing the observed values and the calculated ones by the model. The calculated values were in good agreement with the observed values. This melting model for sintering process can be applied to the estimation of sinter feed and analysis of sinter quality.

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Evaluation of Softening Properties of Sinter and Gas Flow in the Blast Furnace

Teruhisa SHIMODA, Koichi KURITA, Yuji IWANAGA

1984 Volume 70 Issue 7 Pages 665-671
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_665

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The softening test under the simulated conditions in a real blast furnace and the gas permeability test through the softened sinter were carried out. An attempt was made to express the pressure drop through the softened sinter bed by the pressure drop equation including the terms of first- and second-order of velocity.
From the view point of blast furnace operation, high temperature properties of sinter were evaluated by applying the test results to the mathematical gas flow model.
The main results obtained are as follows.
1) When the gas flow resistance obtained from the softening test at high temperatures is increased, the radial gas flow in the cohesive zone becomes predominant and the permeability in the blast furnace becomes worse.
2) When the high temperature properties of sinter become worse, the formation of inverse V-shaped cohesive zone prevents the increase of the total gas pressure loss in the blast furnace.

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Manganese Equilibrium between Molten Iron and MgO-saturated CaO-Fe_tO-SiO₂-MnO-P₂O₅ Slags

Hideaki SUITO, Ryo INOUE

1984 Volume 70 Issue 7 Pages 672-679
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_672

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Manganese distribution between liquid iron and MgO-saturated CaO-Fe_tO-SiO₂-MnO slags containing P₂O₅ or S has been obtained in the temperature range from 1550° to 1650°Cby use of magnesia crucibles. The manganese distribution ratio was found to increase with increasing SiO2 content and decreasing temperature. The close relationship between activity coefficients of MnO or equilibrium quotient k_Mn(=(%MnO)/{[%Mn]· (%Fe_tO)}) and the slag basicity B (=[(%CaO)+0.3(% MgO)]/[(% SiO₂)+(%P₂O₅)]) value was observed.

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Refining Characteristics of Stainless Steel in Top and Bottom Blown Converter

Tsuyoshi KAI, Fumio HOSHI, Yoshioki KAMIDATE, Tetsuya YAMAGAMI

1984 Volume 70 Issue 7 Pages 680-686
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_680

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The refining characteristics of stainless steel in top and bottom blown converter was studied by using a 45 ton LD converter in LD-VAC process where the bottom was equipped with two tuyeres blowing Ar and N₂ gases. The results obtained are as follows:
1) The perfect mixing time (τ_s) shown in eq. (2) is effectively available to evaluate agitating and mixing characteristics of the top and bottom blown converter even in the refining of stainless steel through the consideration on the relations between [C] and (Cr₂O₃) at blow end and the carburization rate. The index of BOG is also available to use even if the oxide mainly formed is not FeO but Cr₂O₃.
2) The refining characteristics are improved by the top and bottom blowing when the rate of bottom blowing gas increase up to 0.06 Nm³/t·min at which τ_s is corresponding to 60 sec. The apparent partial pressure P_CO becomes 0.9 to 1.0 and the C-O reaction seems to be equilibrium. On the other side, the apparent P_CO in the conventional top blowing converter is more than unity and the reaction as a whole melt seems not to be equilibrium.
3) Nitrogen can sufficiently be used as a agitating gas, although the amount of ten to twenty percent of blowing nitrogen is absorbed into melt.

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Improvement of Surface Quality of Continuously Cast Stainless Steel Slabs

Hidemaro TAKEUCHI, Shogo MATSUMURA, Takashi YANAI, Yasunobu IKEHARA

1984 Volume 70 Issue 7 Pages 687-693
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_687

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The effect of continuous casting conditions on surface quality of austenitic stainless steel slabs have been investigated in order to roll slabs without surface conditioning.
Development of new continuous casting techniques such as high frequency-short stroke mould oscillation, low viscosity-carbonless mould powder, tundish refractories, one piece immersion nozzle and so on, made it possible to improve slab surface quality and to roll slabs without surface conditioning.

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Development of Air-atomizing Mist Nozzles and Mist Cooling System for Continuous Casting

Masashi MITSUTSUKA, Yozo FUKUHISA, Makoto WAKE, Masaki OKAJIMA, Nagao ...

1984 Volume 70 Issue 7 Pages 694-700
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_694

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The use of air atomizing mist nozzle for the secondary cooling of continuous casting machine results in the following advantages over the conventional water spray nozzle: less longitudinal surface cracks and higher temperature of cast slabs, wide control range of cooling, and prevention of nozzle cloggings. The air injection to the water spray nozzle is also good for preventing nozzle cloggings.
The authors have developed a few types of air atomizing nozzles and their application techniques, including the air injection technique, for the secondary cooling system of the slab casters.
Discussed here are structual and fluidic features of the newly developed mist nozzles and the air injection type water spray nozzle with reference to some technical points concerning the new cooling system and the operational results.

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Toughness Deterioration of 13Cr-3.8Ni Cast Steel in the Process of Tempering

Yoshitaka IWABUCHI

1984 Volume 70 Issue 7 Pages 701-708
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_701

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In order to explain the toughness degradation of 13Cr-3.8Ni cast steel due to tempering, a systematic study on the effect of heating temperature and subsequent cooling on mechanical properties has been, carried out. When as quenched martensite is tempered, toughness reaches a minimum at about 550°C and increases with increasing temperature, and then decreases above 650°C as the result of thermal deformation of austenite reverted into martensite during cooling from tempering temperature. The low toughness at about 550°C seems to be due to temper embrittlement. In addition, it is observed that the toughness is deteriorated with the increase of strength when the specimen is cooled at slow rates after tempering.

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The Effect of Microstructure on the Toughness and High-temperature Strength of 0.2C-3Ni-3Mo Precipitation Hardening Hot Work Alloy Tool Steel

Toshio OKUNO

1984 Volume 70 Issue 7 Pages 709-716
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_709

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The effects of microstructure on toughness and high temperature strength of the 0.2C-3Ni-3Mo steel were investigated.
(1) The granular upper bainite structure, which was obtained by quenching at the rate of the half temperature time of 60 min, provides the following differences in properties compared with the martensite structure.
(a) After tempering at 400°C;
(i) The plane strain fracture toughness was lower but the difference was small. (ii) The fatigue crack propagation rate was smaller. (iii) The uniform elongation in tensile testing was higher.
(b) After tempering at precipitation hardening temperature of 550600°C, the plane strain fracture toughness and Charpy impact value were lower but the differences were small.
(c) The high-temperature strengths at the temperature higher than 600650°C were higher.
(2) Followings are microstructural factors relating to the above three behaviors ((a)(c)), respectively.
(a); (i) Larger effective grain size. (ii) Formation of excessively stable retained austenite located both along grain boundaries and in grains. (iii) Suppressed precipitation of M₃C.
(b); (i) Not a large increase of tendency of carbide precipitation along the grain boundaries of prior austenite. (ii) Existing of retained austenite to some extent.
(c); Suppressed agglomeration of M₂C carbides to higher temperature.
(3) This steel is superior in room temperature toughness and inferior in high temperature strength to the 0.2C-3Cr-W-Mo-V-Co steel.

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The Effects of Microstructure and Texture on Toughness of Control-rolled Steel Bars

Yasuhiro MAEHARA, Fukukazu NAKASATO, Yasuya OHMORI, Fukunaga TERASAKI

1984 Volume 70 Issue 7 Pages 717-724
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_717

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Texture and mechanical properties of low carbon microalloyed steel bars control-rolled in an oval/round process have been studied. Strength can be increased by decreasing rolling temperature without any ductility loss. This can be explained in terms of the refinement of ferrite grains as well as the work hardening by rolling in the γ/α duplex phase region. Ductile /brittle transition temperature (VTS) in Charpy impact test is also remarkably decreased by lowering rolling temperature, e. g, VTS<-196°C for the material with the finishing rolling temperature of 644°C. Such a marked improvement of toughness mostly arises from the refinement of microstructure although a significantly strong texture development promotes the occurrence of separations as well. The main and suborientations of texture developed are an unusual {100} <001> and a {111}{211} <011>, respectively. Fractographic examinations revealed that cleavage cracks either perpendicular to rolling direction or parallel to the rolling plane initiate within relatively coarse grains of the cube orientation elongated to rolling direction and that the propagation of such cracks is arrested by the surrounding extremely fine grained area of different orientations such as {111}{211} <011>. The initiation of separations cannot be explained by the CHAO'S model considering the plastic anisotropy due to the above textures.

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Recrystallization Behaviour of Al and Al-Ti Containing 17Cr Ferritic Stainless Steel during Hot Rolling

Mitsuo ISHII, Hirofumi YOSHIMURA, Michio WAKAMATSU, Tadashi SAWATANI

1984 Volume 70 Issue 7 Pages 725-732
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_725

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To investigate the recrystallization behaviour of Al and Al-Ti containing 17Cr ferritic stainless steel during hot rolling, the precipitation behaviour of AlN and Ti(C, N) in heated east slab was examined, and then wedge shaped specimens taken from the slab were hot rolled at 1173K to 1453K in single pass manner and hardness test and optical microscopic observation were conducted. The results are as follows.
When heating the slab of Al containing steel, AlN precipitates most easily at about 1273K; this gives the nose in precipitation behaviour.
With Al-Ti containing steel, almost all of Ti precipitated as Ti (C, N) in the as-solidified state, and this prevented precipitation of AlN.
The Al containing steel hot rolled at relatively lower heating temperature near 1173K exhibited deformation structure with deformation bands. The deformation band initiated at ferrite grain boundaries and dispersed AlN precipitates. The deformation structure changed into partial recrystallization structure with raising heating temperature to 1273K and increasing rolling reduction. In relatively higher heating temperature, recovery structure which contained many fine sub-boundaries was attained. Therefore the nose in recrystallization behaviour existed at near 1273K. It is considered that recrystallization structure is statically formed after hot rolling and recovery structure is dynamically formed in hot rolling.
Nearly the same results were obtained in Al-Ti containing steel. A peculiarity was found of the Al-Ti containing steel in structural changes during hot rolling, that is relatively coarse recrystallized grains existed in the recovered structure. This is considered attributable to dynamical recrystallization.

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Antioxidation Mechanism of an Oxidation Inhibitor Composed of Refractory Powder-SiO₂-Al-Synthetic Mica-Colloidal Silica-Coking Bond

Hisao ODASHIMA, Minoru KITAYAMA, Shigeyoshi MAEDA

1984 Volume 70 Issue 7 Pages 733-740
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_733

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Antioxidation mechanism of a newly developed oxidation inhibitor composed of a refractory powder-SiO₂-aluminum-synthetic mica-colloidal silica-coking bond has been investigated.
During heating, the metallic silicon is formed after the reduction by the metallic aluminum of both mullite (3Al₂O₃·2SiO₂) containing in refractory powder and SiO₂. This is oxidized again so as to change gradually to protective amorphous SiO₂ layer which acts as an excellent diffusion barrier to oxigen from atmosphere. Aluminum, in turn, is oxidized to form the protective films composed of α-Al₂O₃ and FeO·Al₂O₃. In addition, a spinel (FeO·Al₂O₃) prevents effectively the formation of low melting fayalite (2FeO·SiO₂), and consequently the protective films remain stable even after prolonged heating at high temperatures.
On the other hand, a lot of pores are formed by the volume reduction due to the melting of aluminum, the oxidation of aluminum and the reduction of SiO₂, by which the diffusion of Fe²⁺ and O^2- is effectively inhibited.

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Effects of S and Mn Contents on Pitting Resistance of 18-8 Stainless Steel

Kikuo TAKIZAWA, Yasuhiko SHIMIZU, Yoshihiro HIGUCHI, Imao TAMURA

1984 Volume 70 Issue 7 Pages 741-748
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_741

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The effects of S and Mn contents on pitting corrosion behavior of 18-8 stainless steel have been studied by means of anodic polarization and immersion test in chloride media. The main results obtained are summarized as follows:
In 3% NaCl solution at 0 and 30°C, pitting potential (V'c₁₀₀) had tendency to become less noble with the increase in S content. This tendency, however, could not be found for the specimens containing S above about 0.01%. On the other hand, V'c₁₀₀ continuously became less noble with the increase in Mn content. In 3% NaCl solution at 70°C or 3% NaCl acidic (HGl) solution at 30°C, V'c₁₀₀ depended on S and Mn contents, and it became noble with the decrease in those elements. In 10% FeCl₃·6H₂O solution at 25°C, the frequency of occurrence or the density of pits increased with the increase of the quantity of sulfide inclusions. On the other hand, the growth tendency of pits depended on the Mn/S ratio, and anodic reaction of specimen was retarded with decrease of the ratio. In all of the specimens, the pit initiation site, was sulfide inclusion/metal interface in the pitting potential region in NaCl and FeCl₃·6H₂O solution, and pit grew preferentially into the metal matrix.

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[title in Japanese]

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

1984 Volume 70 Issue 7 Pages 761-763
Published: May 01, 1984
Released on J-STAGE: June 30, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.70.7_761

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