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Volume 30, Issue 10
Displaying 1-18 of 18 articles from this issue
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Nobumitsu Kitashima1966 Volume 30 Issue 10 Pages 899-905
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCavitation damages for f.c.c. type materials as well as hcp type materials were experimentally studied. These results were discussed, together with those of b.c.c. type materials described in a previous report. The results obtained are as follows:
(1) On the damaged regions of f.c.c. type materials, slip bands and work hardening phenomena were observed, and there appeared cracks along the slip bands. These facts indicate that the fracture due to cavitation for this type of materials was of the shear type. (For b.c.c. type materials, a cleavage type fracture was observed.)
(2) For f.c.c. type materials, the amount of reduction in weight was greater in small grain specimens than in large grain ones.
(3) Wedge-shaped cracks and work hardened layers were observed in the damaged regions of titanium and of zinc specimens. Slip bands were also observed in the damaged regions of titanium specimens, but they were scarcely seen in zinc ones.
(4) The amount of reduction in weight was greater in b.c.c. type materials than in f.c.c. type ones for the same initial hardness. The rate of increase in the weight reduction with the amplitude were greater in b.c.c. type materials than f.c.c. type ones. From these results, it seems that the resistance of f.c.c. type materials against cavitation erosions were inherently superior to that of b.c.c. type materials.
(5) The superiority of f.c.c. type material would be explained in terms of the work hardening rate of f.c.c. type materials and the difference in the number of slip systems.View full abstractDownload PDF (1342K) -
Yasushi Miyamoto1966 Volume 30 Issue 10 Pages 905-909
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe nucleation of tin electrodeposits on the cold rolled steel sheets with various surface conditions was studied in a solution containing stannous sulfate and sulfuric acid. It was found that the nucleus of electrodeposit on the rolled surface developed from the uneven edge caused by rolling, while it appeared at random on the buff-polished surface. On the surface with a crystal structure caused by etching after polishing, the electrodeposit developed at the grain boundary at a low current density and in the crystal grain at a high current density. On the surface with carbide caused by etching after polishing, the electrodeposit concentrated at carbide at a high current density and at random at a low current density.
In this case, when the specimen was dipped in the electrolyte for several seconds before electrodeposition, the electrodeposit developed except on carbide irrespective of current density.
These results show that the nucleation is greatly affected by the unevenness of the steel sheet surface, carbide, etc. It is assumed that the different behaviors of nucleation under various current densities and treating conditions are caused by the non-uniformity of characteristics of the passive layer exsisting on the surface before electrodeposition.View full abstractDownload PDF (2037K) -
Eiji Fukushima1966 Volume 30 Issue 10 Pages 910-915
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSConsiderable numbers of studies have been done on the peculiar oxidation of zirconium and its alloys, mostly by measuring the weight increase during oxidation and the oxygen concentration gradient in the substrate. In order to obtain a better understanding of the oxidation of zirconium and its alloys, it is more adequate to separate the total weight increase into the formation of oxide scales and the oxygen solution into the substrate. The growth of oxide scales is estimated from the measurement of the electric capacity. The relative importance of the oxide scale formation in the total oxidation is investigated and a consideration is given to the substantial function of oxygen solution into the substrate.
Main results of this study are as follows: (1) The oxidation of zircaloy-2 at 600°∼800°C is proportional to the cubic root of oxidation time until the breakaway occurs. (2) According to the electric capacity measurement of specimens, the increase of the oxide scale thickness is also neatly proportional to the cubic root of oxidation. (3) The higher the oxidation temperature, the more oxygen dissolves into the substrate. (4) According to the radio-chemical analysis of the amount of oxygen dissolved in the substrate at 800°C, the contribution of the oxide scale formation to the total weight gain is 93 to 95% in the initial period of oxidation (within 70∼100 min). Thereafter, the contribution of the dissolved oxygen increases rapidly and that of the oxide scale formation does not increase so much.View full abstractDownload PDF (1273K) -
Nobujiro Takamoto, Toshio Katagiri, Kyoko Fujii1966 Volume 30 Issue 10 Pages 915-920
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAs the first step to study the boronizing of metals with BCl3 and H2, some fundamental experiments were carried out to prepare BCl3 according to the following reaction:
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By reacting gaseous chlorine with homogeneous and porous material which was obtained by sintering a mixture of H3BO3 and C with a stoichiometric composition corresponding to equation (1), BCl3 could be easily prepared and BCl3 was obtained with the rate of about 1 mol/hr at a Cl2 flow rate of 1.9 mol/hr. It was found that contact time [NA0W⁄F]lim was about 1 [(kg-sintered material)×hr/(kg-Cl2)] at 900°C and decreased with increasing reaction temperature and that the apparent activation energy of this reaction was about 11 kcal/mol. From the result of chemical analysis, the purity of the obtained BCl3 was determined to be 99.8 wt%.View full abstractDownload PDF (1491K) -
Shirô Sato, Yasuo Fukuda1966 Volume 30 Issue 10 Pages 920-925
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe phenomenon of cracking or embrittlement of chromium copper (Cu-1%Cr) rods during tempering was investigated. By a detailed inspection of the cracked or embrittled rods, the following results were obtained. (a) Cracking or embrittlement was due to the presence of voids along the grain boundary. (b) Internal stress prevailed in the drawn rod. (c) Cracks or voids were formed during tempering near the surface of the drawn rod where tension stress existed. Isothermal tempering tests of the drawn rod by rapid heating revealed that the cracks or voids would be formed when the internally stressed rod was kept in the temperature range from 300°C to 800°C for more than a certain period. The embrittling test under bending stress was also made to ascertain the effect of the factors affecting the embrittlement. From the results of these tests, it was made clear that the following factors were responsible for the embrittlement: (i) Existence of high tension stress, (ii) holding for more than a certain period in the temperature range from 300° to 800°C at which voids are formed, and (iii) large grain size. It may be concluded that the embrittling phenomenon of chromium copper during tempering is essentially consistent with that of α brass during annealing which is identified with the cavitation phenomenon of metals in the creep test at elevated temperatures.View full abstractDownload PDF (1963K) -
Shirô Satô, Yasuo Fukuda1966 Volume 30 Issue 10 Pages 925-929
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper deals with the mechanism of the grain size effect on the susceptibility to the embrittlement of α-brass during annealing. The creep and creep rupture tests were conducted at 300°C on cold rolled specimens of 70-30 brass of different grain size (0.03∼0.50 mm) under different stresses.
The results obtained were as follows:
(1) Elongation (εc) in ruptured specimens or elongation (ε′) required to embrittle the specimens decreased with grain size (L). The products of L and εc or L and ε′ showed constant values in a wide range of grain size.
(2) This can be explained by taking into account the relation that the length of grain boundary sliding (Δs) is nearly proportional to grain size L under a constant elongation: Δs=α·ε·L⁄cosθ, where α is the contribution of grain boundary sliding to the overall elongation, ε is the overall elongation, and θ is the angle between the stressing direction and the sliding direction.
(3) Same experiments were conductedon on cold worked aluminium brass which is empirically known to be sensitive to the embrittlement during annealing. The value of L·εc or L·ε′ of the aluminium brass was nearly 1/3 of that of 70-30 brass.
(4) The application of these results to the phenomenon of embrittlement encountered in the brass mill gives a satisfactory explanation for the remarkable effect of grain size on this phenomenon.View full abstractDownload PDF (1497K) -
Hideo Saitô, Hiroaki Morita1966 Volume 30 Issue 10 Pages 930-935
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe electrical resistivity and the thermal expansion were measured with the iron-aluminium alloys containing 9.75 to 11.66 weight per cent aluminium which were subjected to the isothermal treatment at temperatures between 200°C and 300°C or cooled to −183°C from the quenched state, the K-state and the Fe3Al-ordered state. It was found that the alloys containing more than 10.65 per cent aluminium, which exhibit the characteristics of the K-state at room temperature, transformed into the Fe3Al phase after passing through the K-state during the isothermal treatment. Further, it was also observed that the amount of the K-state in the alloys containing 10.5 to 10.9 per cent aluminium decreased at −183°C, and the alloys with more than 10.9 per cent aluminium showed the characteristics of the Fe3Al phase at that temperature. Therefore, it can be concluded that the K-state observed at room temperature is essentially of the Fe3Al superstructure. However, the alloys containing less than 10.5 per cent aluminium retained the K-state even at −183°C. The difference in the nature between the alloys containing more and less than 10.5 per cent aluminium remains to be clarified.View full abstractDownload PDF (1847K) -
Ôhiko Kammori, Mitsuyoshi Ikeda1966 Volume 30 Issue 10 Pages 935-940
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe rational analysis of M.Fe, FeO, Fe3O4 and Fe2O3 in an iron scale was carried out using a magnetic separator. From microscopic observations, it was found that the mixed layer of fine particles of FeO and Fe3O4, existed as the third layer in the scale produced by heating iron in air. Therefore, as a part of FeO was not dissociated from Fe3O4 by the magnet on separation, the following method of calculation was proposed.
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\ oindentwhere M.Fe is Fe determined by the mercuric chloride method, T.Fe is Fe determined by the potassium permanganate method, ΣFe(II) is Fe determined by a potassium permanganate titration after dissolving a sample in hydrochloric acid in an atomosphere of carbon dioxide, T.Fe′ is Fe in the part attracted by a magnet, and which is determined by the potassium permanganate method, ΣFe (II)′ is Fe in the part attracted by a magnet which is determined by the same manner as at ΣFe(II).
By this means, M.Fe, FeO, Fe3O4 and Fe2O3 in synthetic samples were determined within the absolute error of 1% and a good reproducibility was obtained in the result of analysis of the iron scale.View full abstractDownload PDF (1556K) -
Sakae Takeuchi, Naomi Obata1966 Volume 30 Issue 10 Pages 941-946
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSProperties of ThCl4 were studied by means of X-ray powder diffraction, pressure measurement by the Burdon gauge and gravimetric analysis by a thermobalance. To prevent the hygroscopic chloride from hydration, all samples were treated in dry atmosphere.
The X-ray pattern of ThCl4 powder prepared by chlorination showed a body-centered tetragonal type, in good agreement with the known structure as anhydrous chloride. But in the case of the vapor pressure measurement below 900°C, a markedly irreversible change in pressure was observed on heating and cooling, and retained gas of considerable pressure was found even at room temperature. On gravimetric analysis of tetrachloride in vacuum, a weight loss of 6∼10% was seen below 400°C, where sublimation of chloride was scarcely observed. After sublimation proceeded above 500°C, the weight loss finally ceased and an insoluble residue was formed. Moreover, the gas release of H2O and HCl, and the formation of ThOCl2 and ThO2 were confirmed in the course of heating the ThCl4 powder in vacuum.
It is considered from the above results that body-centered tetragonal ThCl4 is not of the anhydrous but the hydrated phase containing a considerable amount of H2O in the crystalline state. Anomalous behaviors of ThCl4 can be attributed to dehydration and hydrolysis. In the course of stndies, the phase of ThOCl2 was identified and its X-ray diffraction data was established.View full abstractDownload PDF (2145K) -
Sakae Takeuchi, Naomi Obata1966 Volume 30 Issue 10 Pages 946-952
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVacuum sublimation of ThCl4 was carried out in order to prepare anhydrous chloride. Properties of the sublimation product and the process conditions were also investigated. According to the chemical analysis and melting point measurement, the product was undoubtedly ThCl4, but its X-ray diffraction pattern was quite different from that of the body-centered tetragonal structure formerly confirmed as the crystal structure of ThCl4.
Results of the present work proved that the known tetragonal phase ThCl4(I) may be regarded as hydrated chloride, and the newly-found phase ThCl4(II) to be anhydrous chloride. On vacuum heating of ThCl4(I), its released gas and solid residue due to dehydration and hydrolysis were observed. On the contrary, ThCl4(II) was free from such a behavior. In spite of vacuum sublimation, the product was again ThCl4(I) if the released gas from starting chloride was not effectively evacuated. ThCl4(II) could only be prepared by vacuum sublimation under highly dried atmosphere.
The diffraction data of ThCl4(II) suggested its crystal structure to be of the orthorhombic system. The lattice constants obtained were a=11.18 Å, b=5.93 Å and c=9.09 Å. The tetragonal data previously known was obtained by using samples prepared by sublimation in a glass capillary, where a highly dried atmosphere could hardly be attained and probably the product was nothing but hydrated ThCl4(I).View full abstractDownload PDF (2102K) -
Kazuo Tsuya, Noriyoshi Aritomi1966 Volume 30 Issue 10 Pages 952-958
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMolybdenum ingots, which are electron beam melted without any additions, are not ductile at room temperature and liable to intergranular fracture under a low stress. The purposes of this experiment are (1) to investigate the variations in ductility of some kinds of molybdenum ingots which are electron beam melted with C, B, Zr and Ti, respectively, and (2) to make a study of the mechanisms for the improvement of their ductility by melting with the additional elements. By means of bend tests, measurements of intergranular fracture stresses and observations of fracture surfaces, following results were obtained. (1) The ductility of molybdenum ingots at room temperature was improved by electron beam melting with the optimum amounts of C, B and Ti, respectively. However, the addition of Zr did not improve the ductility of ingots. (2) The improvement in ductility was dependent on the strengthening of grain boundaries. (3) Judging from fractographic observations, it was considered that in the cases of C and B additions, the intergranular fracture strength was increased by the suitable amounts of intergranular precipitates. In the case of Ti addition, it was assumed that grain boundaries were strengthened by eliminating the segregation of some harmful impurities at grain boundaries. (4) In conclusion, the degree of improvement in ductility of molybdenum ingots by additional elements depends on the two opposite effects of the added elements, i.e., the lowering of ductility of matrix and the strengthening of grain boundary.View full abstractDownload PDF (2293K) -
Yukio Ohba1966 Volume 30 Issue 10 Pages 958-964
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh purity iron has been produced from reelectrolytic iron by the hydrogen reduction method and the zone refining method. The effects of interstitial impurities, testing temperature and plastic deformation on k in the Petch relation have been investigated using these kinds of pure iron, and the physical meaning of k has been made clear.
kL (k for lower yield stress) of an electrolytic iron containing 70 ppm C and N is independent of the testing temperature. This result suggests that kL of the electrolytic iron is a measure of stress which is necessary for the athermal generation of dislocations from sources in or near grain boundaries. kP.L. (k for proportional limit) of a decarburized iron containing 3 ppm C and N is very small as compared with kL of the electrolytic iron at room temperature, but is comparable with kL at −78°C. It is suggested that when dislocation pinning due to atmospheres of C and N is weak, yielding occurs by unpinning and kp.L. of the decarburized iron is a measure of the Cottrell locking. The change in kF (k for flow stress) with strain is also discussed.View full abstractDownload PDF (2270K) -
Kazumi Ogino, Akira Adachi1966 Volume 30 Issue 10 Pages 965-970
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe contact angle between molten metal and slag was measured by the shape of the molten slag on the molten metal surface, and the interfacial properties—contact angle, interfacial tension, work of adhesion and spreading coefficient—between molten pure metals (silver, copper and nickel) or alloys (nickel-copper and copper-siliver) and molten aluminate slag (CaO-MgO-Al2O3) were investigated.
In the pure metal-slag system these interfacial properties regularly changed in the order of silver, copper and nickel. It is considered that the variation of the interfacial properties from metal to metal may be related to the polarizing power of the metal.
In the alloy-slag systems the interfacial properties changed smoothly with the composition of the alloy.View full abstractDownload PDF (2041K) -
Katsuhisa Sugimoto, Yoshinobu Sawada, Susumu Morioka1966 Volume 30 Issue 10 Pages 971-977
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAnodic polarization behaviours of pure aluminum and SAPs have been investigated in various halide solutions with a potentiostat. Effects of various factors on the anodic polarization curves and the pitting potential such as solution pH and compositions of materials have also been discussed. The results obtained are summerized as follows: (1) There is almost no difference in anodic polarization behaviour between 99.49%Al and SAP. The Al2O3 content in SAP does not give any considerable effect on the pitting potential. (2) In neutral aqueous solutions, 99.99%Al shows a limiting current range on the anodic polarization curves between corrosion potential and pitting potential, but this limiting current range does not appear on the curves for 99.49%Al and SAP because of approximation of the corrosion potential to the pitting potential. (3) Pitting potentials measured potentiostatically are not affected by the solution pH and compositions of materials tested below pH 6, but they shift towerd a noble direction with increasing pH values from 6 to 12.4. (4) Hysteresis is observed on the anodic polarization curves when the anodic current increases or decreases. This results from the change in pH value of the solution near the electrode during electrolysis.View full abstractDownload PDF (2563K) -
Katsuhisa Sugimoto, Yoshinobu Sawada, Susumu Morioka1966 Volume 30 Issue 10 Pages 977-984
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPitting dissolution behaviours of 99.99%Al, 99.49%Al and SAP 71 (9.8%Al2O3) in weak alkaline aqueous solutions of NaCl (pH\fallingdotseq10.7) have been investigated by measuring the anodic current vs. time curves which were obtained using two different potentiostatic immersion methods, hysteresis curves of anodic polarization and potential decay curves after interrupting the pitting dissolution. The effects of temperature on the pitting dissolution have also been discussed. The results obtained are summerized as follows: (1) Pitting potentials by means of the potentiostatic immersion methods are about −0.50 V (vs. N.H.E.) for both 99.99%Al and SAP 71 and are the same as those obtained galvanostatically. (2) The solution pH near the electrode becomes lower and a solution layer with some pH value is formed near the electrode with development of the pitting corrosion. (3) Effects of temperature on the pitting potential are not observed, and the pitting dissolution is accelerated with increasing temperature. (4) The dissolution rate at the anodic limiting current range is of the zero order reaction and its apparent activation energy is 6.0×103 cal/mole. The reaction order estimated from the pitting dissolution velocity after 6∼18 min is of the 1st order and the apparent activation energy for this reaction is 8.2×103 cal/mole.View full abstractDownload PDF (2654K) -
Seita Sakui, Kimiko Sato, Tsutomu Mori1966 Volume 30 Issue 10 Pages 984-989
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWhen magnesium single crystals of 99.99% purity were prestrained at a low temperature (e.g. −196°C) and subsequently deformed at a high temperature (e.g. room temperature), both the yield drop in the stress-strain curve and the propagation of Lüders bands were observed. The effects of the prestraining and retesting temperatures as well as low temperature annealing treatments were studied. It was shown that the sharp yielding was not due to the strain aging induced by impurity diffusion but due to the work softening. Microcopic observations showed that the surface markings of the work softened region consisted of broad, concentrated slip bands whereas the region which was not work softened had sharp slip markings. No cross slip was observed. It is suggested that the work hardening at low temperatures is due to the immobile character of the jogs created during deformation. Annihilation of the jogs through their movement along dislocations under applied stress with the aid of thermal fluctuation at high temperatures is proposed as a possible mechanism to explain the work softening in magnesium.View full abstractDownload PDF (2507K) -
Akira Isaka, Yasushi Matsumoto, Makoto Sugihara1966 Volume 30 Issue 10 Pages 990-994
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWhen the ferrites are cooled slowly from a high temperature, there are changes in the composition and formation of inhomogenious layers with the gain or loss of oxygen from or to the ambient atmosphere. Therefore, the magnetic properties are not merely determined by the proportion of initial ingredients. The permeability versus temperature curves of MnZn ferrites, before and after grinding the surface of specimens, were measured and ferrous ion contents on the internal and the surface layer were chemically analyzed. From these data, the relation between the distribution of ferrous ion content in MnZn ferrites and the oxygen per cent versus temperature during the cooling processes was discussed.View full abstractDownload PDF (1530K) -
Gorô Itô, Seiichi Ikeda1966 Volume 30 Issue 10 Pages 995-1000
Published: 1966
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidation behaviors of iron and aluminium alloys containing up to 13.65% of aluminium in carbon dioxide gas at the temperature of 500°∼900°C under a pressure of 10 kg/cm2 were studied. The results of experiments were summerized as follows:
(1) The alloys showed a better oxidation resistance with increase in aluminium content at the testing temperature of 500°C. However, at 600°C, the oxidation rate increased, especially for the alloys containing up to 10% aluminium.
(2) This phenomenon is attributed to internal oxidation of aluminium observed in the alloys containing 8.26∼10.46% aluminium.
(3) The internal oxidation of the alloys containing more than above 8% aluminium was not observed at 700°C, and hence the oxidation rate was slower than at 600°C. At 800°C, the oxidation rate further decreased as compared with that at 700°C, but the rate again increased at 900°C.
(4) The oxide film of the alloys containing more than 8.26% aluminium tested at 600°C comprised Fe3O4 and FeO, but the co-existence of Fe3O4 and α-Fe2O3 was found at 700°C, and only the formation of α-Fe2O3 was detected at 800°C. At 900°C α-Al2O3 was observed together with FeO·Al2O3. These changes in the composition of surface oxide films could well explain the effect of testing temperatures on the oxidation rate of the alloys mentioned above.
(5) The creep resistance of iron-aluminium alloys decreased with the concentration of aluminium.View full abstractDownload PDF (2139K)
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