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Volume 46, Issue 10
Displaying 1-13 of 13 articles from this issue
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Hitoshi Taimatsu, Hiroyuki Kaneko, Yoshinori Uetani, Fumitada Nakatani1982 Volume 46 Issue 10 Pages 951-956
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPartial pressures of oxygen in commercial Ar, N2 and CO2 gases were measured in an oxygen concentration cell of the type: Ar, N2 or CO2|ZrO2+CaO| air. The concentration of oxygen in a gas with no leakage and the leak rate of oxygen were determined by analysis of the dependence of the measured partial pressure of oxygen on the gas flow rate. The results showed that trace amounts of oxygen in Ar or N2 gas cylinders could be easily determined by use of a compact gas-tight system in which the leak rate of oxygen was in the order of 10−12 m3·s−1 up to about 1100 K. Above 1100 K, the leak rate of oxygen was increased steeply with increasing temperature due to the permeation of oxygen across a solid electrolyte. The temperature dependence of the measured partial pressure of oxygen in a CO2 gas was interpreted by considering the reaction of CO2=CO+1⁄2O2 in the cell. Therefore, the determination of trace amounts of oxygen lower than 10−4%O2 in inert gases can be accomplished firstly by eliminating gas leakage from the surroundings and gas generation from the inner wall of the system, i.e., by using leaklight system, and secondly by reducing permeable oxygen across a solid electrolyte, e.g., by operating an oxygen concentration cell at still low temperature.View full abstractDownload PDF (452K) -
Kazumi Ogino, Hitoshi Taimatsu, Fumitada Nakatani1982 Volume 46 Issue 10 Pages 957-962
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface tensions of liquid Co-O and Co-Fe-O alloys and the contact angles between liquid Co-O and Co-Fe-O alloys, and Al2O3 substrates were measured in Ar+H2+H2O mixtures at 1873 K by the sessile drop method. Solidified Co-O and Co-Fe-O alloys/Al2O3 substrates interfaces were examined by the metallographic observation and EPMA survey.
Main results obtained were as follows:
(1) The surface tensions of liquid Co-O and Co-Fe-O alloys decreased remarkably with addition of a small amount of oxygen, and were independent of the iron content when the oxygen content was less than about 0.06 mass%.
(2) Excess surface concentration of oxygen in the surface layer of liquid Co was 17×10−6 mol/m2 in agreement with the reported values in the liquid Fe-O and Ni-O system, suggesting that the arrangements of the adsorbed oxygen on the surfaces of liquid Ni, Co and Fe were analogous to one another.
(3) The wettabilities of Al2O3 by liquid Co-O and Co-Fe-O alloys increased with increasing oxygen content, especially in iron-rich alloys. This change in the wettability with the iron content is considered to be due to the difference in the affinity for oxygen between cobalt and iron.View full abstractDownload PDF (498K) -
Kazuhiro Yoshihara, Kazuyoshi Nii1982 Volume 46 Issue 10 Pages 963-972
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface composition of SUS 321 stainless steel at high temperatures was observed in vacuum with Auger electron spectroscopy.
The precipitation of titanium carbide was found on the surface of SUS 321. The thickness of precipitated titanium carbide layer increased in proportion to the square root of annealing time and became about 0.05 μm after heated at 1100 K for 432 ks. The precipitated titanium carbide was not replaced by the most surface active element sulfur, and remained stable on the surface. The precipitated layer, however, was not even and had many holes about 1 μm in diameter. The bottom of a hole was SUS 321, on which phosphorus, oxygen and sulfur segregated. As the annealing time was prolonged, these segregants were replaced one by one in the order of the surface activity, and finally the most surface active element, sulfur, remained on the bottom of the hole. Moreover, sulfur diffused over the outside of the hole.
The titanium carbide precipitated on the surface was not removed by the argon ion sputtering (acceleration voltage; 3 kV, current density; 0.6 A/m2) at 1100 K. This was because titanium and carbon were supplied to the surface at sufficient velosity by the diffusion during the sputtering at high temperature.
The precipitation of titanium carbide on the surface occurred according to the following processes: (1) The titanium and carbon which had been dissolved in the bulk diffused onto the surface of the stainless steel. (2) The titanium carbide which had been precipitated in the bulk dissolved because the concentration of titanium and carbon fell under their solubility limits in the bulk. (3) The titanium and carbon diffused onto the surface which was exposed to vacuum. (4) The titanium and carbon recombined into titanium carbide and precipitated on the surface. The growth rate of the thickness of the precipitated layer was controlled by the diffusion of titanium and carbon in the precipitated titanium carbide.
Thermodynamic consideration based on the Gibbs dividing surface model showed that the compound which was precipitated in the bulk came out onto the surface in order to decrease the strain and the interface energies.View full abstractDownload PDF (842K) -
Ken Tohma1982 Volume 46 Issue 10 Pages 973-979
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo investigate the intergranular corrosion mechanism in Al-Mn alloys, galvanostatic anodic dissolution in chloride solutions of Al-Mn alloys containing 0.4 to 1.2 mass percent of manganese and electrochemical polarization measurements in AlCl3 solution on the alloys and on Al-Mn compounds have been carried out. Pitting types of localized dissolution were observed after galvano-static anodic dissolution in the alloys quenched after solution treatment at 873 K, while, distinct intergranular dissolution occurred after reheating at 673 K. Iron and other impurities in the alloys accelerated the intergranular attack. According to EDXS on an Al-Mn alloy thin foil the amount of manganese in solid solution was much lower along grain boundaries than in the grain bodies in the alloys susceptible to the attack, while pitting potential increased with increasing manganese content. With these results it could be concluded that intergranular corrosion of Al-Mn alloys occurred due to selective dissolution of a manganese depleted zone along a grain boundary which could be formed with precipitation on the grain boundary. Surface observation after galvanostatic anodic dissolution in acidified chloride solution was usefull also in Al-Mn alloys as a rapid estimation of the intergranular corrosion susceptibility.View full abstractDownload PDF (1367K) -
Akira Chiba1982 Volume 46 Issue 10 Pages 980-985
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe isothermal transformation of ferrite to austenite in a carbon-free Fe-8.0 mass%Cr alloy at temperatures above A3 has been investigated quantitatively. The main results are as follows:
(1) Austenite preferentially nucleates at ferrite grain boundary corners and grows with a constant velocity in all directions.
(2) The nucleation sites are saturated in the early stage of transformation.
(3) The isothermal transformation behaviour of austenite can be expressed by the Johnson-Mehl type equation, and the reaction exponents have a value about 3 for all transformation temperatures.
(4) The kinetics are in good agreement with Cahn’s theory of grain boundary nucleated reactions.View full abstractDownload PDF (1007K) -
Takao Kozakai, Toru Miyazaki1982 Volume 46 Issue 10 Pages 986-992
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMicrostructural changes near the coherent spinodal line during ageing in Fe-18.5 and 19.2 at%Mo alloys were investigated by means of transmission electron microscopy.
A mixed microstructure of the ⟨100⟩ modulated structure and the plate-shaped Mo-riched zones was observed in the alloys aged at a temperature just above the coherent spinodal temperature, Ts. With further ageing this morphological distinction became obscure and consequently the modulated structure appeared. When the alloy was aged at a higher temperature, the plate-shaped zones were only nucleated on the {100} matrix plane, while the ageing at a temperature just below Ts only produced a typical ⟨100⟩ modulated structure. A series of results implies that the microstructures produced near Ts become continuously inhomogeneous with increase of ageing temperature, which has been proposed by Binder.View full abstractDownload PDF (1645K) -
Masahiro Sakai, Katsuya Watanabe1982 Volume 46 Issue 10 Pages 993-999
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMonofilament composites were prepared by Ni electrodeposition on the commercial SiC fibers. Having been subjected to thermal cycle between 473 K and up to 1273 K, the composites were investigated by SEM observations.
Cavities were formed at SiC/Ni interface and developed as the thermal cycle proceeded. The rate of reaction between SiC and Ni decreased with increasing the number of cycle irrespective of the amount of cavities.
The results obtained are discussed in terms of thermal stress which arises from the difference in thermal expansion between SiC fiber and Ni. A mechanism of grain boundary sliding in Ni phase at high temperatures is proposed to the cavity formation and interfacial debonding.View full abstractDownload PDF (776K) -
Hakaru Masumoto, Michio Kikuchi, Takafumi Nakayama1982 Volume 46 Issue 10 Pages 999-1004
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe thermal expansion, magnetic properties, lattice constants, hardness and workability were measured for Mn-Ge based ternary alloys cooled at various rates after homogenizing at 1100 K for 10.8 ks.
In the thermal expansion curves of Mn-20 and 22%Ge based ternary alloys containing Co or Ni less than 5% and 10%Fe, the Néel temperature of the ε-phase clearly appeared, showing the Invar characteristic below the temperature. The zero region of the thermal expansion coefficient at room temperature is widened by Fe addition, while it is narrowed by Ni or Co addition.
The temperature dependence of the magnetization of the ternary alloys shows almost the same behaviour as that of binary alloys. The ε-phase showing the antiferromagnetism at room temperature is stable for the addition of the third elements.
The vickers hardness of Mn-20%Ge-Fe alloys is lowered about 100 from the value of 500 of binary alloys by some Fe addition, keeping a constant value of 400 up to 10%Fe.
The machinability and forgeability of the ternary alloys in the ε-phase are better than those of the binary alloys.View full abstractDownload PDF (482K) -
Hirobumi Okabe, Hideo Ike, Eiji Tsuji1982 Volume 46 Issue 10 Pages 1004-1009
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been made on the oxidation behaviours of Fe-14Cr alloys with 0.1, 0.3 and 0.6 mass%Ti at temperatures between 1073 and 1373 K in atmospheric oxygen. The Ti addition has increased the isothermal oxidation resistance in every alloy. The amount of Ti content at which the highest resistance is shown in the system has been found to be around 0.1 mass%. The 0.6 mass%Ti alloy has shown the lowest resistance, but this alloy is still far more oxidation resistant than the base alloy. In every alloy the internal oxidation of Ti has occurred, the degree of which being dependent on the amount of Ti added. Cavity formation at the scale/alloy interface has been observed only in 0.3 mass%Ti alloy.View full abstractDownload PDF (800K) -
Kiyoshi Yokogawa, Seiji Fukuyama, Kiyokatsu Kudo1982 Volume 46 Issue 10 Pages 1009-1017
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMechanical properties of commercial pure iron (JIS:SUY) have been investigated in 9.91 MPa hydrogen and argon at 773 K. Results obtained are as follows:
(1) Tensile and creep properties in hydrogen are observed to decrease with proceeding the hydrogen attack in comparison with those in argon.
(2) The largest decrease in mechanical properties by hydrogen attack is obtained by constant loading test.
(3) An incubation period in hydrogen attack is observed under no loading condition, but not under loading condition by acceleration of decarburization.
(4) Internal pressures in bubbles formed by decarburization are estimated by using the equation given by Shewmon, and the effect of stress on the growth of bubbles is discussed.View full abstractDownload PDF (1432K) -
Tadashi Yamada1982 Volume 46 Issue 10 Pages 1017-1022
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn tube extrusion, a billet of larger diameter than the tube diameter is generally used, and in this case an extrusion machine of larger capacity is required and the extruded tubes are subjected to relatively large thickness deviation. As a method overcoming these disadvantages, the Raflo Process to extrude large tubes by using smaller billets has been proposed, but details have not been reported. The author has carried out a basic study of this process. This paper is concerned with the disc extrusion as the first stage deformation in the Raflo Process.
Billets of pure lead, 30 mm in diameter and 100 mm in length were used. Disc extrusion was carried out to a thickness t0, 1 or 2 mm, in which the extrusion force and the limiting diameter for disc spread, Dmax, were measured. Both the die inlet profile radius, r, and the plate angle, θ, at the center were varied.
A minimum extrusion force was observed at r=1 mm for both t0=1 and 2 mm. The largest values of Dmax are 60 mm for t0=1 mm and 100 mm for t0=2 mm. Although there is little effect of θ on Dmax, the extrusion force shows maximum value at θ=0° for both t0=1 and 2 mm. Regarding thickness variation in extruded discs, the disc thickness decreases with the distance from the center regardless of r. Thus, the limit of diameter for each required disc thickness have been evaluated.View full abstractDownload PDF (718K) -
Tadashi Yamada, Yukio Matsumoto1982 Volume 46 Issue 10 Pages 1023-1029
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn a previous report, the limiting diameter of an extruded disc has been described. In the present study, experiments were conducted on tube extrusion by the Raflo Process, in which the extrusion force and the thickness deviation in extruded tubes were measured. Tubes with a diameter of 60 mm were extruded from billets of pure lead with a diameter of 30 mm. The required thickness was set at 2, 3 or 4 mm. When a radius of die outlet profile, R, is increased, the extrusion force decreases due to a decrease in bending resistance at the die outlet. With an increase in the required thickness, t0, the extrusion force also decreases. The ratio of tube thickness to required thickness, t⁄t0 varies with R. Thickness deviation of an extruded tube is nearly zero. However, the optimum condition for t=t0 varies with t0, and the smaller R⁄t0 is required with an increase in t0.
For comparison with the Raflo Process, tubes of the same size were extruded by two other methods; the extrusion blanking process and the inverse extrusion process. The extrusion force is slightly larger in the extrusion blanking process than in the Raflo Process, whereas the inverse extrusion process requires extrusion force several times larger. Both in the extrusion blanking process and in the inverse extrusion process, it is difficult to make the mandrel and the die center coincident with each other. Therefore, tubes extruded by these two processes involve large thickness deviation in comparison with those by the Raflo Process. Thickness deviation in extruded tubes is particularly distinctive in the extrusion blanking process.View full abstractDownload PDF (442K) -
Yoshio Hasegawa, Shinsaku Hanasaki, Masanori Yasutomi, Takashi Muromac ...1982 Volume 46 Issue 10 Pages 1029-1035
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper describes crystallographically the cutting mechanism in cutting a single crystall of Al with a conical shape tool. A milling machine was used in the experiment. The tool was fastened to a steel wheel mounted on an arbor and the workpiece was set on the table. Only one circular arc groove was formed on a surface of Al single crystall (001) or (011). Effects of the crystal orientation on cutting forces and the deformation are studied.
Main results obtained are as follows:
(1) Cutting forces varied depending upon the crystall orientation; when (001) plane was cut in the direction of [110], they are large. In case of (011)[100] and (011)[01\bar1], they are small. In other cases, they are medium.
(2) If the cutting direction was crystallographically unsymmetrical, the deformation was unsymmetrical and the side force (FS) occurred.
(3) When the cutting direction was (001)[110], the cutting efficiency (γ) took a maximum value of about 0.6 and in other case it was 0.2-0.4.
(4) According to the obsevation of deformed zone around the tool by the quick-stop technic of cutting, there were three types of deformation corresponding to the relative orientation between crystal and cutting direction;
(a) Type in which the displaced material is separated into the right and the left against the cutting direction.
(b) Type in which the displaced material is put aside either to the right side or to the left one.
(c) Type in which the displaced material is concentrated in front of the tool.View full abstractDownload PDF (821K)
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