Tetsu-to-Hagane

Progress in Heavy Industries; in the Past 30 Years and in the Future

Yoshinori SAIGA

1989 Volume 75 Issue 7 Pages 1069-1077
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1069

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Progress in Laser Materials Processing

Muneharu KUTSUNA

1989 Volume 75 Issue 7 Pages 1078-1092
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1078

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Progress of R & D on Metallurgical Cokemaking in Japan after the World War II

Yoshiaki MIURA

1989 Volume 75 Issue 7 Pages 1093-1103
Published: July 01, 1989
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1093

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Fatigue of Titanium Alloys

Kuninori MINAKAWA

1989 Volume 75 Issue 7 Pages 1104-1111
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1104

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Functional Thin Films by Electroless-plating Method

Application to High-density Magnetic Recording Media

Tetsuya OSAKA, Hiroshi MATSUBARA

1989 Volume 75 Issue 7 Pages 1112-1118
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1112

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Impurity Analysis of Fine Ceramics

Toshio ISHIZUKA

1989 Volume 75 Issue 7 Pages 1119-1125
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1119

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Effects of Atmosphere, Temperature, Pressure and Holding Time on Solid State Bonding of Ni-Al₂O₃ System

Kiyoshi NOGI, Hiroyuki NAKANISHI, Toshinori SAKAMAKI, Kazumi OGINO

1989 Volume 75 Issue 7 Pages 1126-1131
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1126

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Solid state joining between Ni and Al₂O₃ was carried out under various experimental conditions.
Main results are as follows;
Bonding strength depended on atmosphere, bonding time, bonding temperature, and bonding pressure.
Bonding strength in a reducing atmosphere is higher than in an inert atmosphere and in an air atmoshere.
The higher the bonding temperature, the higher the bonding strength.
Desirable bonding time and clamping pressure are 3.6 ks and c.a. 2.5 MPa, respectively.
The experimental conditions which produced the maximum bonding strength (86 MPa) were at 1673 K, in a reducing atmosphere, 3.6 ks of bonding time, and 3 MPa of clamping pressure.

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Dephosphorization of Granular High-carbon Ferromanganese in Reducing Conditions

Tohru MATSUO, Takami IKEDA

1989 Volume 75 Issue 7 Pages 1132-1138
Published: July 01, 1989
Released on J-STAGE: January 19, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1132

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Granular high-carbon ferromanganese was dipped into molten Ca-CaCl₂, Mg-MgCl₂ and Ca-NaCl flux under argon atmosphere and dephosphorization was investigated in a laboratory scale test.
1. Dephosphorization of more than 90% could be achieved with all kinds of flux investigated, by the treatment at 10001050°C for 2 h.
2. It is considered that the high dephosphorization rate was obtained by the penetration of the flux into the high-carbon ferromanganese granules through micro-cracks, and the penetration shortened the diffusion distance and increased the interfacial area for dephosphorization. In addition, highly segregated phosphorus in granules accelerated the dephosphorization.

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Numerical Analysis of the Gas Flow and Combustion Reaction in Converter

Masaki MABUCHI, Haruo KOKUBU, Hakaru NAKATO, Tsutomu NOZAKI

1989 Volume 75 Issue 7 Pages 1139-1145
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1139

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The mathematical model for numerical analysis of the gas flow and combustion reaction in a converter is developed by taking into account of the equilibrium reaction of CO-CO₂-O₂ gas mixture at a given temperature. The effect of molten steel bath shape, thermal condition of side wall and operation conditions on the combustion ratio is clarified by the calculation on the mathematical model.
The model is compared by the evaluation of the combustion ratio between calculated value and observed one. By considering the depression of molten steel bath and the heat flow to side wall, the high temperature gas region above 2250 K in the converter is found to appear near molten steel bath surface.

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Development of CO Gas Bottom Blowing Process in Combined Blowing Converter and Its Characteristics in Metallurgical Reaction

Yasuo KISHIMOTO, Syuji TAKEUCHI, Yoshiei KATO, Tetsuya FUJII, Hisashi ...

1989 Volume 75 Issue 7 Pages 1146-1153
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1146

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In order to use CO gas purified from off gas of a converter as a bottom blowing gas in combined blowing converter, the metallurgical characteristics brought by bottom injected CO gas were examined in a 5 t test converter. There was no appreciable difference in metallurgical reactions between CO gas and N₂ or Ar gas.
In the case of CO gas blowing, decrease in the partial pressure, P_co, cannot be expected in comparison with that in the case of N₂ or Ar blowing. Nevertheless, decarburization and deoxidation were observed during rinsing and concentrations of oxygen and carbon after rinsing reduced to those in equilibrium with 0.6 atm of CO. These phenomena cannot be explained by the effect of P_co reduction by bottom blowing gas. On the basis of the experimental results, a new reaction model was proposed by considering the oxygen potential in slag. The model can reasonablly explain the experimental results.
Commercial use of CO gas has been started since 1985 in 180 t combined blowing converter at Mizushima Works, and satisfying results have been obtained.

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Effect of Water Temperature on Cooling Capacity in Water Cooling of Hot Steels

Masashi MITSUTSUKA, Keiji FUKUDA

1989 Volume 75 Issue 7 Pages 1154-1161
Published: July 01, 1989
Released on J-STAGE: January 19, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1154

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In water cooling of hot steels, a cooling capacity (H) is influenced by water temperature(θ_w). The authors analyzed the effect of water temperature on the cooling capacity by using the data of authors' and other reseachers' experiments. The coefficient of water temperature Rb [°C^-1], which is the contribution factor of water temperature to the cooling capacity, is defined as Rb=[H(θ_b+Δθ)-H(θ_b-Δθ)]/[H(θ_b)×2·Δθ], where θ_b and Δθ are basic temperature and temperature difference from θ_b, respectively. By introducing the idea of Rb, the effect of θ_w on H in many experiments has been analysed systematically. The mian results obtained are as follows:
1) The values of R_{θ_b,5} (θ_b:30, Δθ:5), which correspond to the typical temperature of cooling water in production mills, exist within the range of -0.01 to -0.02°C^-1. This result means that the values of H change_??_(1 to 2)% with ±1°C variation of θ_w.
2) The absolute R_{θb, 5} -value of laminar coolings is larger than that of spray coolings.
3) It seems that the values of Rb are influenced by sizes and surface conditions of a steel to be cooled, flow conditions of cooling water on a cooled surface, and so on.

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Bonding Strength and Microstructure of Bonding Interface of Hot Rolled Titanium Clad Steel

Takashi FUKUDA, Yoshinori SEINO

1989 Volume 75 Issue 7 Pages 1162-1169
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1162

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In order to produce a titanium clad steel plate by hot rolling process, the effect of insert metal, rolling conditions and oxidation of clad surface on the bonding strength and the microstructure of bonded zone were investigated. The following results were obtained.
(1) The titanium clad steel inserted with ultra-low carbon steel, exhibits satisfactory bonding strengths, ductilities and weldabilities.
(2) The bonding strength is dominated by the thickness of Fe-Ti intermetallic compound produced at bonding interface and the degree of interdiffusion between Fe and Ti. High bonding strengths with very small scatter band can be obtained in the thickness range of Fe-Ti compound of 0.2 to 0.3μm.
(3) A lower bonding strength due to the oxidation on the surface to be bonded is not caused by the oxidized layer but mainly by the remarkable growth of intermetallic compound and, secondarily, by the formation of voids between Ti and steel.

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Rapid Melting and Solidification of Fe-3% C-2% Si Alloy Using cw CO₂ Laser

Jun KUROBE, Hiroshi SAKUTA, Yasunori MIYATA, Toshio SUZUKI, Yukio ICHI ...

1989 Volume 75 Issue 7 Pages 1170-1177
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1170

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The surface of Fe-3% C-2% Si alloy was rapidly melted and solidified using cw 250 W CO₂ laser. The absorptivity of the alloy was estimated by comparing the values of melt depth and width of spot-melted specimens to those by FEM analysis. The determined value of absorbtivity was 50%. The relation between secondary arm spacing and average cooling rate calculated for spot-melted specimens was obtained. Using the relation, average cooling rates of scan-melted specimens were estimated to be 2×10⁵ K·s^-1 at maximum.

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Effect of Controlled Rolling and Cooling on the Spheroidization Behavior of Medium Carbon Steel

Yutaka KANETSUKI, Masaaki KATSUMATA, Hiroharu SAWADA

1989 Volume 75 Issue 7 Pages 1178-1185
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1178

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The medium carbon steels have been used for structural parts. In process to make these parts, spheroidization treatment has been applied to obtain good cold forgeability. In this study, the effect of controlled rolling and cooling process on the spheroidization behavior of medium carbon steel has investigated using hot deformation simulater and actual rolling process. Following results were obtained.
(1) By controlling the cooling rate immediately after controlled rolling to be 10°C/s, the dynamicaly recrystallized fine austenite grains did not show further grain growth and transformed to fine ferrite-pearlite microstructure. This microstructure revealed high volume fraction of ferrite compared with coarse austenite grains.
(2) During the spheroidization treatment, fine ferrite-pearlite microstructure showed rapid spheroidization.
(3) The bars controlled rolled and cooled by actual rolling process showed good upsetting limit.
It has been discussed that rapid sheroidization is caused by enhanced reaustenitization occurred at ferrite-pearlite interphase boundary and increased carbon content in pearlite phase due to the increasing of ferrite volume fraction.

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The Effect of Carbon on α'→γ Reversion of Metastable Austenitic Stainless Steels

Kouki TOMIMURA, Manabu OKU, Setsuo TAKAKI, Youichi TOKUNAGA

1989 Volume 75 Issue 7 Pages 1186-1192
Published: July 01, 1989
Released on J-STAGE: January 18, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1186

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The effects of carbon on reversion behavior of metastable austenitic stainless steel were investigated using a 16.2% Cr- 8.8% Ni- 0.11% C steel by means of transmission electron microscopy and magnetic analysis. The steel used almost transforms to lath martensite (α') from austenite (γ) by 90% cold rolling.
The results are as follows:
(1) The steel completely reverses on 923 K-10 s annealing. However, isothermal α' is produced on subsequent aging at room temperature (290 K) in case of more than 0.1 ks in 923 K isothermal annealing, and also at 900 K and above in 0.6 ks isochronal annealing.
(2) In case of 923 K annealing, carbide precipitation occurred in preference to reversion. The carbide tends to retard a martensitic reversion and accelerate a diffusional reversion inversely.
(3) The grain size of γ reversed by a diffusional reversion at 923 K annealing is 0.2 μm dia. The carbide is very effective for refining grain by reversion.

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Recrystallization and Hot Tensile Behaviour of Single Phase Stainless Steels

Yasunori TORISAKA, Toshio SUZUKI, Yasushi WATANABE, Matsuo MIYAGAWA

1989 Volume 75 Issue 7 Pages 1193-1200
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1193

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This study is aimed to investigate the recrystallization for grain refinement and the hot tensile behaviour of single phase stainless steels, namely ferritic Fe-17Cr(SUS430), austenitic Fe-18Cr-8Ni(SUS304) and Fe-25Cr-20Ni(SUS310) so as to examine their possibilities of superplasticity.
The influence of reduction in area and annealing conditions on static recrystallization was investigated. Subsequently, m value and total elongation were measured for evaluation of superplasticity, after hot tension tests were carried out for recrystallized stainless steels sheet at various temperatures below the recrystallization temperature and with various strain rates.
A critical working reduction in area required for recrystallization was about 25% for SUS430, a few % for SUS304 and 20% for SUS310. The fine grain size was obtained under the optimum recrystallization condition for SUS310, though it was not obtained for the other two types of stainless steels.
Among single phase stainless steels, only SUS310 with the recrystallized fine grain size showed superplastic behaviour and its maximum elongation exceeded 200% at 1088 K with the initial strain rate of 4.2×10^-4s^-1.

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Stress Corrosion Cracking Susceptibility and Cracking Criteria of 13 Cr Martensitic Stainless Steels in Neutral Chloride Solution at Room Temperature

Toshinori OZAKI, Yuichi ISHIKAWA

1989 Volume 75 Issue 7 Pages 1201-1208
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1201

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Hydrogen embrittlement of 13Cr martensitic stainless steel was evaluated in 3% NaCl solution at room temperature using slow strain rate technique (SSRT) and step loading constant load SCC test with simultaneous electrochemical measurements. Under SSRT conditions pits formed during plastic deformation may become the crack initiation site and dissolution of newly created slip steps causes enrichment of the solution in the pit, and thus providing the environment dispensable for hydrogen embrittlement cracking. Hydrogen embrittlement susceptibility represented by I_SCC increases with increasing hardness of the steel and decreasing crosshead speed. However hydrogen embrittlement susceptibility disappears at hardness lower than HV 235. Susceptibility index determined by step loading SCC test (σ_B-σ_SCC)/σ_B relates well with I_SCC. This relation is quite useful for determining the design stress of 13Cr martensitic stainless steel components. Furthermore modified AISI414 stainless steel (Ni and Mo addition) exhibits a slightly higher resistance against hydrogen embrittlement.

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Embrittlement Factors in High-Cr Ferritic Heat Resisting Steels

Kentaro ASAKURA, Yasushi KOUBUCHI, Toshio FUJITA

1989 Volume 75 Issue 7 Pages 1209-1216
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1209

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Heating brittleness of dual phase δ-ferrite/martensite steel and single phase martensite steel was investigated. In order to clarify the heating embrittlement factor for these steels, Charpy impact testes, transmission electron microscopy and determination of precipitates were carried out using specimens tempered at 700°C and 800°C and reheated at 550 and 650°C for 10²10⁴ h.
In the case of dual phase steel, the embrittlement of the materials and the rise of the ductile-brittle transition temperature were caused by the precipitation of Fe₂Mo, while the embrittlement of the single phase martensite steel was due to the increase in the number of M₂₃C₆ precipitates. In both steels, the increase in the transition temperature was found to be correlated to the total amount of the precipitates. When the precipitates were small enough, the toughness of the materials of heating embittlement could be recovered by means of heating at 800°C. On the other hand, when the precipitates grew over 200nm, the toughness could not be recovered.

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Effect of Soaking Treatment of Continuously Cast Bloom on Manganese Segregation of High-Carbon Steel Wire Rod

Ikuo OCHIAI, Hiroshi OHBA

1989 Volume 75 Issue 7 Pages 1217-1224
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1217

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A study has been made on the diffusion behavior of manganese in the macrosegregation spots of continuously cast bloom during soaking treatment prior to bloom rolling in order to reduce the martensite structure, which is caused by manganese segregation and reduces the wire drawability, in Stelmor-cooled high-carbon steel wire rod. Eutectoid steel samples (SWRS80B) sawed off from the middle part of a 300mm×500mm continuously cast bloom were heated at 1573 K for 0.5 to 5 h and the manganese concentration profiles were measured with EPMA.
(1) Manganese microsegregation peaks (concentration peaks) were substantially annihilated by a soaking treatment of 1573 K×1 h, even though calculations based on the previously reported diffusion constant of manganese in austenite predicted the presence of high microsegregation peaks after a soaking treatment of 1573 K×5 h.
(2) The difference between the experimental and the calculated results in the diffusion rate of manganese decreased with increase in the strain of hot rolling, and thus approximately the same diffusion constant as previous works was obtained for wire rod.
(3) It is thought that the excess vacancies, which are generated by the pores existing in the macrosegregation spots of continuously cast bloom, accelerate the volume diffusion, and thereby the soaking treatment of the continuously cast bloom has the industrial significance for the reduction of manganese microsegregation, as well as carbon and phosphorus segregation.

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Clean Room for Analytical Laboratory

Yasushi NAKAMURA

1989 Volume 75 Issue 7 Pages 1225-1229
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1225

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A Japanese Steel Company and the English Language

Tony DEAMER

1989 Volume 75 Issue 7 Pages 1230-1232
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1230

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[title in Japanese]

[in Japanese], [in Japanese]

1989 Volume 75 Issue 7 Pages 1235-1236
Published: July 01, 1989
Released on J-STAGE: June 19, 2009

DOIhttps://doi.org/10.2355/tetsutohagane1955.75.7_1235

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