All issues
Volume 26, Issue 6
Displaying 1-16 of 16 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kazuo Nakazawa1962 Volume 26 Issue 6 Pages 339-343
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOn three samples of 13Cr stainless steel containing 13% of chromium and 0.09%, 0.17% and 0.26% of carbon, the effect of austenitizing temperature on the Ms and Mf points and on the microstructure has been investigated and the TTT-diagrams have been established at the different austenitizing temperatures for 10 minutes in order to investigate the correlation between the austenitization and the behavior in transformation. The Ms and Mf points were measured by the dilatometric method and the process of isothermal transformation was examined by the use of hardness and microscopic tests. The Ms and Mf points become evidently lowered by dissolution of the carbide. In the pearlite transformation, the higher the austenitizing temperature rises, the longer grows the incubation period and the slower the transforming rate. Comparison of the Ms and Mf points and the TTT-diagrams of the three samples revealed the difference coming from the influence of their chemical compositions on the transformation process. These results may illustrate the dependence of the behavior in transformation mainly on the concentrations of carbon and chromium.View full abstractDownload PDF (1150K) -
Shoji Ueda, Kenji Morizane, Hidejiro Kinoshita1962 Volume 26 Issue 6 Pages 344-348
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDuring β→α transformation of a Cu-Al alloy containing about 9%Al, segregation of solute atoms was found to occur in a similar manner as the segregation which occurs during solidification of alloys. The amount of (α+δ) eutectoid caused by the segregation increased at greater rates of cooling from 975°C. A long-time annealing at 975°C, the β phase range of the alloy, resulted in large grain sizes of α phase, which caused much segregation of solute atoms. The effect of cooling rate on the amount of segregation during solid-solid transformation was compared to that of rate of solidification on the amount of the segregation during liquid-solid transformation. But the effect of α-grain size on the amount of segregated eutectoid was attributed to the rate of nucleation of α within β phase.View full abstractDownload PDF (1389K) -
Shoji Ueda, Masato Zama1962 Volume 26 Issue 6 Pages 348-352
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn Cu-Al alloy systems, segregation occurs due to the transformation of β→α in the process of cooling,because β⁄(α+β) and (α+β)⁄α solubility curves are located just at the limits of solidification range, and the diffusion of solute atoms in α phase is more difficult to occur than in matrix β phase. Even in an alloy that consists of α mono phase in equilibrium state, (α+δ) eutectoid precipitates in the grain boundary of α phase.
Using the phenomenon of this segregation, a series of alloys which satisfies the following conditions can be obtained: (1) The α-grain size remains uniform. (2) α-path in the eutectoid is constant, and (3) The length fraction of α⁄(α+δ) boundary varies. In this paper, the effects of existence of a brittle phase surrounding the ductile phase on the mechanical properties were investigated by using the alloys which were treated under the abovementioned conditions. The experimental results strictly satisfied the following formula: σ_s = σ_o + K’ [{(γ_1 - γ_2)/d}f + γ_2/d]^1/2 where, σs is the yield strength, σo is the back stress of dislocations, d is α grain size, γ1 and γ2 are measures of the strength of α⁄(α+δ) boundary and α⁄α boundary, respectively, f is the length fraction of brittle phase boundary, and K′ is constant.View full abstractDownload PDF (840K) -
Tsuneyoshi Okamoto1962 Volume 26 Issue 6 Pages 352-357
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEnquiries were made into the technique of manufacturing sheet-like bicrystals and tricrystals of aluminium and columnar tricystals of zinc having the required orientations. (1) Bicrystals of the required orientations: First, a sample of the specific shape is carved out of aluminium sheet. Then a single crystal having either a crystallographic orientation common to the two crystals which is to consitute a bicrystal or the same orientation as one of these two crystals is produced from the sample using a Bridgeman’s furnace. Finally, the single crystal is subjected to an orientation conversion treatment using two seed crystals spontaneously developing a grain boundary. (2) Sheet-like tricrystals of the required orientations: A sample of the specific shape is carved out of aluminium sheet, and subjected to a treatment similar to the above-mentioned case of bicrystals. (3) Columnar tricrystals of the required orientations: Three seed crystals are welded to the tips of sample of the proper shape, and after the seed crystals are twisted and bent so that their orientations may be brought in line with the required orientations, the sample is made into a tricrystal in a Bridgeman’s furnace. The deviation from the required orientations of the bicrystals and tricrystals thus manufactured was found to be in the vicinity of ±1°.View full abstractDownload PDF (850K) -
Tsuneyoshi Okamoto1962 Volume 26 Issue 6 Pages 357-361
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe anisotropies of the boundary energy and of the crystal boundary diffusion were studied employing tricrystal samples of Al and Zn. The obtained results may be summarized as follows: (1) The boundary energy (relative value) depends on the difference in orientation angle between the two crystals adjacent to the boundary and the maximum value is observed at the orientation angle difference of 28° for Al or 22° for Zn. (2) Read-Schockley’s theoretical relation between the boundary energy and the orientation angle difference agrees well with the experimental results, particularly well for the angle difference below 17∼18°. (3) The penetration depth of 65Zn in the boundary along the ⟨0001⟩ direction in Zn tricrystals reaches a maximum at about 30° orientation angle difference.View full abstractDownload PDF (932K) -
Teishirô Oda, Takashi Daikoku, Masaru Ikenaga, Akira Kaneko1962 Volume 26 Issue 6 Pages 362-366
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to obtain some information about sulfurizing process, specimens of mild steel (0.13%C) were treated in salt bath containing sodium cyanide, sodium thiosulfate, sodium chloride and sodium carbonate, and then were investigated by means of metallography, X-ray or electron diffraction method and X-ray probe microanalysis. The results obtained can be summarized as follows: (1) The sulfurizing process is only a sort of nitriding process and thiosulfate added has an effect to oxidize and decompose sodium cyanide and to promote, in consequence, the nitriding reaction. (2) The rate of reaction of α-iron with nitrogen was found to follow the parabolic law at temperatures between 500°C and 600°C. (3) It was also found that the rate constant of nitriding reaction was not in linear relation with the reciprocal of the absolute temperature. This fact indicates that the nitrogen concentration at interface varies with temperature. (4) Iron sulfides constituted the compound layer with cementite and iron nitrides such as Fe4N, Fe2N, etc., but the greater part of them were distributed near the surface. (5) In respect of the nitriding reaction, a similar effect is expected to be obtained if sodium cyanate (NaCNO) or potassium cyanate (KCNO) is used as a primary constituent.View full abstractDownload PDF (962K) -
Teishirô Oda, Takashi Daikoku, Akira Kaneko1962 Volume 26 Issue 6 Pages 366-370
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe nitriding process for case hardening of steel is an excellent method having many advantages, but its greatest disadvantage is that it takes a long time. Recently, the rapid nitriding method in which molten salt containing cyanate is used has been employed in practice and it has been observed that the nitrided layer obtained, after treatment of only 2 or 3 hours at temperature between 550° and 570°C by this method, did not greatly differ from that obtained by the gas nitriding method in hardness and microstructure. However, the reason why molten salt promotes the nitriding reaction has not been clarified yet. From this point of view, we investigated into the cause of promotion of nitriding in by use of molten salt, in comparison with the gas nitriding method in which NH3 gas is used. From the results obtained the following conclusions may be drawn : (1) The accelerated nitriding reaction with molten salt can be explained by considering the nitrogen concentration at interface, i.e. in the case of nitriding with molten salt containing cyanate, nitrogen concentration at interface increases linearly as nitriding temperature becomes higher. (2) The nitriding reaction can be considerably promoted, when the nitriding treatment is carried out at temperature over 530°C. (3) It is probably possible to further reduce the nitriding time, by using the salt having more nitrogen concentration than that in this experiment.View full abstractDownload PDF (627K) -
Etsujiro Yajima, Koichi Furusawa1962 Volume 26 Issue 6 Pages 370-375
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSNitrization, heretofore in use, has many advantages, viz:- the heat resistivity of hardened layer is excellent and heat treatment after nitrization is not neccesary. But the time of nitrization is very long. The affinity of Ti to nitrogen is so large that diffusion or addition of Ti may accelerate nitrization and, experiments were carried out on this point of view. The results obtained were as follows: (1) By diffusing Ti before nitriding, hard (VHN: 1450) layers were formed, but no good surface could be obtained. (2) Next, we prepared Ti-containing steels (Ti: 1.5, 5.0, 9.0%) and nitrized. The specimens, containing more than 5% of Ti, were sufficientry hardened in a short time (9∼18 hrs) by nitriding at 550∼650°C. The higher the nitriding temperature, the smaller the hardness, and the thicker the layer grows. The surface of steel free of carbon was harder, but more brittle than that of steels containing carbon. (3) Steels containing Ti and Cr were prepared and the same experiments were carried out. In this case, steels with less than 2% of Ti could not be hardened. And it was found that Cr had no effects on the surface hardness, but the surface conditions were largely improved by Cr. Hard (maximum hardness is about VHN: 1200) and thick (about 0.4 mm) layers were obtained by nitrization at 650°C for 4 hrs. The effects of nitriding temperature and carbon content were the same as in Ti-steels. The surface hardness of steels, melted in vacuum, was slightly higher than that of samples melted in air. (4) Heat-resisting tests were carried out on these specimens, the surface hardness of Ti-Cr-steels was kept unchanged by reheating at 500∼600°C, but was lowered by reheating at 700°C.View full abstractDownload PDF (866K) -
Yûnoshin Imai, Yoshizumi Nishi1962 Volume 26 Issue 6 Pages 375-380
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStudies were made on the oxidation behavior of Ni-Cr-Fe and Ni-Cr-Co alloys containing about 19% chromium. The weight loss due to the oxidation was measured, and the oxides composing the thin oxide films and the scales were identified by electron and X-ray diffraction methods, respectively. The following results have been obtained. (1) Addition of Fe up to 10% or Co up to 15% has no appreciable effect on the weight loss due to scaling on Ni-Cr alloys, at temperatures of 850° and 1000°C. (2) Three sorts of oxides, (Cr, Fe)2O3, an oxide with spinel type structure and NiO, form in the scales of Ni-Cr-Fe alloys. The formation of the last two oxides is observed at a temperature as high as 1100°C and above. (3) The phase with spinel type structure can form more easily in the scales of Ni-Cr-Co alloys than in those of Ni-Cr alloys. At a temperature as high as 1300°C, this phase and Cr2O3 grow rapidly in contrast with a low growth rate of (Ni, Co)O.View full abstractDownload PDF (700K) -
Yoshizumi Nishi1962 Volume 26 Issue 6 Pages 380-386
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStudies were made on the oxidation behavior of Ni-Cr-Mo-Al, Ni-Cr-Co-Mo-Al, Ni-Cr-Al, Ni-Cr-Fe-Al and Ni-Cr-Co-Al alloys containing about 19∼20% chromium. The weight losses due to the oxidation was measured, and the oxides composing the thin oxide films and the scales were identified by electron and X-ray diffraction methods, respectively. The following results have been obtained. (1) Addition of aluminum hinders the formation of NiOMoO3 in the scales of Ni-Cr-Mo alloys and decreases the weight loss due to scaling on them. The formation of molten phase of NiOMoO3 is retarded by aluminium addition at the temperature of oxidation resistance limit of Ni-Cr-Mo alloys. A similar effect of aluminium addition was observed in the scales of Ni-Cr-Co-Mo-Al alloy. (2) The formation of the oxide with spinel type structure and NiO is retarded in the scales of Ni-Cr-Al and Ni-Cr-Fe-Al alloys in the temperature range from 850° to 1300°C. The same behavior is observed in the scales of Ni-Cr-Co-Al alloy at a temperature as high as 1300°C.View full abstractDownload PDF (664K) -
Masanobu Miyake, Tadao Sano1962 Volume 26 Issue 6 Pages 386-390
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAs one of the basic research on the mechanism of reaction between solid and liquid metals, a kinetic study has been made on the dissolution processes of pure solid metals, Ni, Cu and Ag into liquid pure Bi. The experiments were carried out under the static and isothermal condition over a range of temperatures from 500° to 900°C in argon atmosphere, and the rate of dissolution was followed by analyzing a small sample drawn successively from the liquid solution after a predetermined time of dissolution. The obtained rates of dissolution have been found to obey unimolecular reaction law expressed in a form of n=ns{1−exp(k·S⁄V·t)}, as in the case of dissolution for these systems obtained previously in the lower range of temperatures from 300° to 500°C. The rapid rise in solution rate constants of Ni, Cu and Ag which was attributed to the change in the behavior of dissolution was observed at temperatures above 500°, 600° and 450°C, respectively. On the other hand, a remarkable change in the temperature dependence upon the experimental solubilities for Ni, Cu and Ag in liquid Bi was observed at the same temperature levels. Taking account of the correspondence of the change in solution rate constants with that of solubility, it is inferred that the rate of dissolution is determined by the diffusion process of solute atom in the effective boundary layer near the solid surface, in which the values of concentration of the dissolved metal are almost the same as that of saturation concentration.View full abstractDownload PDF (513K) -
Mamoru Nakamura1962 Volume 26 Issue 6 Pages 391-394
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSamples of vacuum-melted re-electrolysed iron were zone-refined by the floating-zone melting method in hydrogen gas, with the zone passed seven times at the velocity of 1.1 mm/min. Low-temperature resistivity measurements, quantovac analysis, and gas analysis were performed for estimating the refining effect and impurity distribution. The highest purity was found in the middle portion. This floating-zone refining method was effective for C, P and S, but we did not observe the refining effect for Mn and Si. O, N and H were eliminated effectively. The growth rate of the re-crystallized grains was markedly greater in the highest-purity part, and the ratio of the mean grain sizes of the pure and impure parts was 9:1.View full abstractDownload PDF (1058K) -
Chikao Yoshii, Katsuya Watanabe1962 Volume 26 Issue 6 Pages 395
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (166K) -
Tsutomu Iimura, Sadahiko Sekiguchi, Mutsuo Sasaki1962 Volume 26 Issue 6 Pages 396-397
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (573K) -
[in Japanese], [in Japanese]1962 Volume 26 Issue 6 Pages 398-401
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (900K) -
[in Japanese], [in Japanese], [in Japanese]1962 Volume 26 Issue 6 Pages 402-406
Published: 1962
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (789K)
- |<
- <
- 1
- >
- >|