Tetsu-to-Hagane

[title in Japanese]

[in Japanese], Takuo ANDO

1978 Volume 64 Issue 8 Pages 1103-1104,1246
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1103

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Experimental Study of Mass Transfer from a Sphere in Pulsating Flow

Munekazu OHMI, Tateo USUI, Yoshiro MATSUMOTO, Yoshikazu MASUYAMA

1978 Volume 64 Issue 8 Pages 1105-1113
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1105

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Mass transfer from a naphthalene sphere in a circular tube under steady and pulsating air flow at room temperature is investigated by measuring the loss in weight or the decrease in dimension of the body after a given time. Because of small mass-transfer rate, there is little difference between the results with and without the resistance due to the rate of gas flow. Under the pulsating flow, however, the resistance is taken into consideration, because air and C₁₀H₈ gas may be mixed enough. Comparison of these results with theoretical ones reported previously gives the following experimental expression:
Sh=2+ [ (0.58) ⁴+ (0.38z^0.4) ⁴] ^1/4Sc^1/3Re_p^1/2, where Sh=2γ₀k_f/D, z= (aω/U_∞) ^3/2 (a/γ₀) ^1/2, Sc=υ/D, Re_p=2γ₀U_∞/υ (a, amplitude; D, diffusivity; k_f, mass-transfer coefficient; γ₀, radius; U_∞, free stream velocity; υ, kinematic viscosity; ω, angular frequency). As z=0, this expression agrees with the experimental one for steady flow mass-transfer.
The experimental results of half sphere and local mass-transfer show that the acceleration effect of pulsating flow on the mass transfer is remarkable in the dead-water region of the sphere, where the mass transfer is small under steady flow.

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Circulation of Elements in Blast Furnace Estimated by Thermodynamics and Vapour Pressure Measurement

Yoshiyasu TAKADA, Mitsuo SUMITO, Nobuo TSUCHIYA, Kyoji OKABE

1978 Volume 64 Issue 8 Pages 1114-1123
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1114

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The circulation behaviour of Fe, Mn, Si, Mg, Zn, Na, K, S, and Cl in blast furnace is studied. The compounds of circulating elements and the region of the circulation are quantitatively estimated by thermodynamic calculations using gas compositions measured by the vertical probes at a working blast furnace. The probable vapour pressures of circulating species are quantitatively estimated by the mass spectrometric analysis of Knudsen effusates from pig iron, slag, and coke.

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On the Kinetics of Decarburization of Liquid Iron with Ar-CO-CO₂ Mixtures

Kazuo AMANO, Koin ITO, Hiroshi SAKAO

1978 Volume 64 Issue 8 Pages 1124-1132
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1124

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The decarburization rates of liquid iron have been measured in the vavious Ar-CO-CO₂ mixtures by using the levitation technique. The concentrations of carbon and oxygen change mostly along the carbonoxygen line in equilibrium with Ar-CO-CO₂ mixture under the condition that the oxide film is not formed on the surface of liquid iron. The reaction finishes at a concentration determined by P_CO₂/P_CO. The rate has been analyzed by assuming that the mass transfers between the two phases determine the overall reaction rate. The following rate equation has been obtained under the condition of n_C·n_O=constant; -n_c=P_CO₂-P_CO^*P_CO^S/K_IⁿC/RT/k_g {1+ (1+P_CO^S/K_IIγ) (P_CO^*/K_{III^n_C²}) } At the high concentration of carbon the decarburization rate is regarded to be controlled by the mass transfer in the gas boundary layer. The rate is gradually reduced, because the resistance of the mass transfer in the metal boundary layer increases and the driving force of the reaction decreases as the concentration of carbon becomes lower. The iron droplet exploded due to the formation of the oxide film on the surface at the high partial pressure of CO₂. For a short period at the beginning, the rapid reaction occurs to reduce both the concentrations toward the equilibrium line of P_CO+P_CO₂, in Ar-CO-CO₂ mixture. The reaction can be satisfactorily explained by the mechanism that C-O degassing and decarburization take place at the same time during this stage.

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Effect of Slag Composition on the Desulfurization and Dephosphorization of Molten Steel

Tomoo TAKENOUCHI, Koreaki SUZUKI

1978 Volume 64 Issue 8 Pages 1133-1142
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1133

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In order to produce steels with ultra low sulfur and phosphorus, some experiments were done to clarify the influence of slag composition on the desulfurization and dephosphorization rates. The results obtained were summarized as follows:
(1) Large rate constants for desulfurization and dephosphorization were obtained by using slags which contained Na₂O, B₂O₃, Na₂B₄O₇ or K₂O in CaO-CaF₂ base and had great reaction ability as well as fluidity.
(2) Simultaneous reaction of desulfurization and dephosphorization became possible for steels containing some oxygen, with the use of these slags.
(3) Because of the strong erosive effect of these slags, refractories should be selected according to the slag composition.

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The Mechanism of Formation of CO Blowholes during Solidification of Iron

Hiroyuki NOMURA, Kazumi MORI

1978 Volume 64 Issue 8 Pages 1143-1152
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1143

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In order to clarify the mechanism of blowhole formation, an experimental study has been made of unidirectional solidification of iron for carbon contents of the melt of 0.01 to 0.40% at a solidification rate of about 5mm/min. Critical composition for blowhole formation has been determined. Above 0.15% carbon the critical oxygen concentration is almost constant (0.0025%), while it increases with decreasing carbon content below 0.15%. A macroblowhole originates from a small blowhole formed in the interdendritic area. A model based on the equilibrium solidification suggests that the small blowhole is formed without supersaturation of carbon and oxygen in the interdendritic liquid. The growth of blowholes which proceeds at oxygen contents below the critical concentration is accounted for by the model of steady growth of cyclindrical blowholes.

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The Precipitation of AlN in Austenite and the Hardenability of Boron-Treated Steels

Kazuo YAMANAKA, Yasuya OHMORI

1978 Volume 64 Issue 8 Pages 1153-1161
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1153

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The aluminum nitride precipitation in austenite and its effect on the hardenability of low-carbon-1/2 moly bdenum boron-treated steels has been investigated. The results are as follows:
(1) The precipitation of BN occurs under non-equilibrium condition in the case of shorter austenitizing time and consequently lowers hardenability. Such non-equilibrium BN precipitates transform to AlN with increasing the austenitizing time, resulting in the recovery of hardenability.
(2) The recovery of hardenability is due to the increase of the soluble boron content accompanied by the formation of AIN.
(3) The orientation relationship between AlN and austenite is given as:
[0001] _AlN// [110] _γ-Fe growth direction
(1120) _AlN// (111) _γ-F
(1100) _AlN// (112) _γ-Fe
The degree of misfit is very small along the [0001] _AlN (// [110] _γ-Fe) direction, leading to the preferential growth of AIN along this direction.

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Temper Embrittlernent by Phosphorus and Fracture Behavior

Kazuo YAMANAKA, Yasuya OHMORI

1978 Volume 64 Issue 8 Pages 1162-1170
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1162

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Temper embrittlement and fracture behavior of Fe-C and Fe-C-Ni-Cr alloys doped with P were studied by means of grain boundary etching technique, Charpy impact tests, and low temperature tensile tests.
Grain boundary etching behavior with respect to aging time seems to correspond to the cementite precipitation at the grain boundaries together with the change of the grain boundary concentration of P. Temper embrittlement does not occur only by the grain boundary segregation of P, but needs the coexistence of alloying elements such as Ni or Cr.
Brittle fracture in temper embrittled alloys is initiated by the formation of grain boundary cracks followed by the crack propagation without arresting. Therefore, Griffith's crack such as a pearlite colony crack is not assumed to exist in the fracture of temper embrittled alloys.

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The Mechanism of Hydrogen Damage in Austenitic Stainless Steel

Shigeo NOMURA, Masayoshi HASEGAWA

1978 Volume 64 Issue 8 Pages 1171-1178
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1171

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The existence of clusterings of platelet tangled dislocations in 304 steel, produced at the grain boundary or internal interfaces by the precipitation of atomic hydrogen, was demonstrated by the transmission electron microscope. Futhermore macroscopic phenomena caused by this microscopic hydrogen defects were observed in hydrogenated stainless steel, that is, 1) the increase of flow stress 2) anomalous behavior of recovery process in hydrogen embrittlement 3) anomalous increase of intergranular corrosion loss.
The initiation sites of microcracks due to hydrogen embrittlement in austenitic stainless steel were grain boundaries or carbide interfaces, and these were the sites of hydrogen defects. The propagation process of the microcracks by hydrogen embrittlement depended on the austenitic stability to martensite transformation under tensile stress, and the interfaces of martensite lath provided the most preferential path of microcracks.

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Effects of Ni Content and Grain Size on the Martensitic Trans-formation and Deformation Behavior in 18Cr-8Ni Stainless Steels

Masakuni FUJIKURA, Tetsuo KATO

1978 Volume 64 Issue 8 Pages 1179-1188
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1179

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The effects of Ni content and grain size on the athermal and deformation-induced martensitic transformations in 18-8 austenitic stainless steels have been examined. Furthermore, their deformation characteristics, especially 0.2% proof stress (0.2PS) and flow stress at sub-zero temperatures have also been examined in terms of austenite stability. The results are as follow:
(1) Ms and Md temperatures are depressed with increasing Ni content. Ms temperatures of commercial alloys are about 130K lower than those of high-purity alloys with low interstitials. The effect of grain size on Md is larger than that of Ms.
(2) The amount of athermal martensite formed at 77°K is analysed according to Magee's equation. There seems a good agreement between observed and calculated values when grain size is 115μ. In case of smaller grain size with 36μ, however, calculated values are larger than observed ones. This disagreement may comes from the differences of Ms and the nucleation frequency at Ms.
(3) The content of deformation-induced χ' and ε' martensite depends on Ni content and tensile temperature.
(4) The change of transformation mode from γ→ε'→α'to γ→α' is observed with increasing Ni content and tensile temperature, which can be understood in terms of stacking fault energy and chemical driving force (ΔG_γ→α').
(5) Inverse dependence on temperature of 0.2% proof stress (0.2PS) does not occur in this study. The temperature dependence of 0.2PS of untransformed stable austenite is about 2.7 times larger than that of of 0.2PS of unstable austenite in which martensitic transformation intervenes before yielding of austenite.
(6) The flow stress of unstable austenite e. g. 18Cr-9Ni alloys at 93K does not follow the simple law of mixture of austenite and martensite.

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Oxide Inclusions in 19Cr-9Ni Stainless Steel Weld Metal

Hiroyuki TSUKUI, Yutaka TOGASHI, Takashi MITAMURA

1978 Volume 64 Issue 8 Pages 1189-1198
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1189

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An investigation was made of oxide inclusions in 19Cr-9Ni stainless steel weld metal which was produced using a electrode covered with lime-titania.
2MnO·SiO₂ (tephroite), MnO·SiO₂ (rhodonite), FeO·Cr₂O₃ (chromite), FeO·Ti₂O₃, Cr₂₃C₆, TiC, and TiN were identified by the X-ray analysis of the residue separated from the weld metal by ultrasonic agitating dissolution method using 14% I₂-CH₃OH solution.
The inclusion particles extracted were classified according to the size (5 μ over and under) by ultrasonic sieving method, and observed by optical microscope.
Typical inclusion particles over 5 μ were analyzed by electronprobe X-ray microanalyzer.
It was found that inclusion particles over 5 μ were mainly spheroidal MnO·SiO₂, 2MnO.SiO₂, angular SiO₂, massive SiO₂, plate-like SiO₂, rod-like Al-silicate, needle-like TiN, and stringer-like Ca-phosphate.
Inclusion particles less than 5 μ amount to about 90% of oxide inclusions, and they contain mainly Mnsilicate, FeO·Cr₂O₃, and FeO·Ti₂O₃, the size of which was 1 μ or under.

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Dependence of Temperature and Strain Rate on the Low-Cycle Fatigue Life of Type 321 Stainless Steel

Koji YAMAGUCHI, Kenji KANAZAWA, Susumu YOSHIDA

1978 Volume 64 Issue 8 Pages 1199-1208
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1199

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There are three effects, mechanical, environmental, and creep effects, on the low-cycle fatigue life of Type 321 stainless steel at high temperatures. At intermediate temperature such as 450°C, the strain rate dependence of the fatigue life is due mainly to the mechanical effect caused by the cyclic strain hardening, because the fracture mode is transgranular and creep and environmental effects seem to be negligible. At higher temperatures above 600°C, the strain rate dependence of the fatigue life is due mainly to the change of the fracture mode from a transgranular type to an intergranular type with decreasing the strain rate. This intergranular fracture mode, composed of smooth, grain boundary facets, is similar to the creep fracture mode of wedge type cracking. The wedge type crack seems not to propagate without the oxidation effect, because it is said that in vacuum test the strain rate dependence of the fatigue life is hardly observed and the fracture mode is rather transgranular. Therefore, in this case the main damaging factor is the environmental effect. On the other hand, in hold time test in tension intergranular facets covered with small dimples are observed. This intergranular fracture mode is similar to the creep fracture mode of void type cracking. The void type crack seems to propagate without being influenced by oxidation, because it is said that the hold time effect is observed even in vacuum test. In void type intergranular cracking, creep effect, that is, creep-fatigue interaction exists.

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Statistical Analysis of the Scatterings in Charpy Impact Values of the Heat Affected Zone of a Welded Low Carbon Steel

Shoichi MATSUDA, Shoichi SEKIGUCHI, Hideaki KAGEYAMA

1978 Volume 64 Issue 8 Pages 1209-1218
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1209

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In relation to clarifying the cause of the scattering of energy absorbed in Charpy transition temperature range, a study was made of finding the cleavage crack initiation site. Main results were as follows.
1) The cleavage crack always initiated at the pearlitic second phase independently of the energy level absorbed in Charpy test. Heterogeneity such as inclusions and so on did not contribute to the cleavage crack initiation.
2) The cleavage microcracks initiating at the effective grain larger than mean size could grow to final fracture, while the microcracks initiating at the smaller effective grains could not propagate.
3) Frequency of cleavage microcrack initiation was very small. It was one or two cracks per area of 0.4mm² of ductile fracture surface. On the basis of experimental results described above, statistical analysis was made. It may be concluded that Gaussian distribution of effective grain size was the direct cause of the scattering cf energy absorbed in Charpy test.

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Effect of Powder Properties on Strength of Hot Isostatic Pressed High Speed Steels

Hisashi ANDO, Akira OKAYAMA, KO SOENO, Hisasuke TAKEUCHI

1978 Volume 64 Issue 8 Pages 1219-1225
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1219

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Green and tap densities of atomized high speed steel powders (JIS SKH 57) are measured. The shapes of the powders are spherical in gas atomization and irregular in water atomization. The densities are lower in the water-atomized powders than in the gas-atomized ones. Pulverization of the water-atomized powders increases the densities. Compacting press also increases the densities of the water-atomized powders. However, the densities of the water-atomized powders are difficult to approach to the tap density of the gasatomized powders.
Hot isostatic pressing, 113 MPa is applied at 1150°C in order to sinter densely the water-atomized powders, gas-atomized powders, and their mixture. Transverse rupture strength have been investigated in the dense specimens subjected to heat-treatment for hardening. The strength level of the specimens produced by using the water-atomized powders is much higher than that of the specimens produced by using the gas-atomized powders. It is also observed that adding the gas-atomized powders to the water-atomized powders causes the decrease in strength level.
Strength level is greatly increased by hot isostatic pressing and subsequent hot forging. However, the strength level of the dense specimens of the gas-atomized powders can not be increased satisfactorily without destroying the spherical forms by giving a great forging ratio.

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The Characteristics in Composite Damping Steel Sheet and Its Application Techniques

Takesada SASAKI, Hiroshi ENDO, Tadahumi HONDA, Yoshimasa ZAMA

1978 Volume 64 Issue 8 Pages 1226-1235
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1226

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Recent Trends of Temperature Measurement in Iron and Steel Industry

Hisao SUZUKI, Jiro OHNO

1978 Volume 64 Issue 8 Pages 1236-1245
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1236

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[title in Japanese]

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

1978 Volume 64 Issue 8 Pages 1248-1252
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1248

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[title in Japanese]

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

1978 Volume 64 Issue 8 Pages 1253-1256
Published: July 01, 1978
Released on J-STAGE: March 25, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_1253

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[title in Japanese]

[in Japanese]

1978 Volume 64 Issue 8 Pages A91-A114
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A91

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[title in Japanese]

[in Japanese], [in Japanese]

1978 Volume 64 Issue 8 Pages A115-A134
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A115

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[title in Japanese]

[in Japanese]

1978 Volume 64 Issue 8 Pages A135-A158
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A135

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[title in Japanese]

[in Japanese]

1978 Volume 64 Issue 8 Pages A159-A178
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A159

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[title in Japanese]

[in Japanese]

1978 Volume 64 Issue 8 Pages A179-A198
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A179

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[title in Japanese]

[in Japanese]

1978 Volume 64 Issue 8 Pages A199-A226
Published: July 01, 1978
Released on J-STAGE: February 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.64.8_A199

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