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Volume 40, Issue 3
Displaying 1-17 of 17 articles from this issue
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Hideo Abe, Fumie Togawa, Yoshie Ohashi1976 Volume 40 Issue 3 Pages 201-205
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPreliminary experimental results are given for the changes in thermoelectric power and resistivity of 99.999%-purity copper at −78.3°C by cold drawing, annealing in vacuum, and quenching. From the Nordheim-Gorter plots, the apparent thermoelectric powers due to dislocations and solute oxygen atoms are found to be +2.2 μV/deg and −2.0 μV/deg, respectively.View full abstractDownload PDF (438K) -
Osamu Akisue1976 Volume 40 Issue 3 Pages 206-211
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate the origin of the recrystallized grains with preferred orientation in low carbon steel sheets, the regions of twisted crystal lattice resulting from the blocking of dislocation slip during cold-rolling were examined. The rotation rates for various orientations were mathematically deduced. The cold-rolling deformation was assumed to progress under the plane-strain condition and by operation of the ⟨111⟩ pencil glide system. The {554}⟨225⟩ preferred orientations in the recrystallization texture of the niobium-added steel rotate about the ⟨110⟩ axes inclined ±60° from the rolling direction towards {211}⟨011⟩ with increasing cold reduction. The rotation rate of the preferred orientation in the recrystallization texture was found to coincide with that of the twisted region calculated on the basis of the above theory. It is concluded that the {554}⟨225⟩ type recrystallization texture in the niobium-added steel develops from the regions of heavily twisted lattice.View full abstractDownload PDF (469K) -
Kazuo Suzuki, Tetsuo Fujiwara, Susumu Usui1976 Volume 40 Issue 3 Pages 211-218
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relations among oxidation resistance, thermal shock resistance and metallurgical structure parameters of WC-20% Co sintered alloys with different WC-grain sizes (3.8–14 micron-m) were investigated by means of oxidation tests in air at temperatures of 750 to 850°C, and using a newly developed thermal shock test apparatus. To evaluate the thermal shock resistance of these alloys, tests were carried out using an electro-spark discharge apparatus and measuring the total length of thermal crack produced 0.05 mm below the sparking surface. Structure parameters of WC-20% Co alloys were measured with the photomicrographs quantitatively.
The results obtained are as follows:
(1) Oxidation process of WC-20% Co alloy is controlled by the OXIDE/METAL interfacial reaction. It obeys a linear law which has an apparent activation energy of 42.1 kcal/mol.
(2) Oxidation resistance of these alloys depends mainly upon the cobalt content, which exists on the oxidation front surface, and upon the WC-grain size in the sintered structure.
(3) Thermal shock resistance increases with increase in WC-grain size.View full abstractDownload PDF (1643K) -
Takashi Nishimura, Minoru Nishigaki, Shitoshi Ohtani1976 Volume 40 Issue 3 Pages 219-226
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAging characteristics of the beta metastable titanium alloys Ti-15Mo-5Zr and Ti-15Mo-5Zr-3Al were investigated with detailed aging treatments by means of the tensile test, hardness measurement, microstructure observation and the X-ray diffraction method.
In the as-solution treated condition, the strength decreased with increasing solution temperature and the relationships between the yield strength (YS kg/mm2) and the beta grain diameter (d mm) were given as follows:
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The optimum solution temperature for the aged material was beta transus for Ti-15Mo-5Zr and 50°C below the beta transus for Ti-15Mo-5Zr-3Al, as the finer beta grains gave the good tensile properties after heat treatment.
In the Ti-15Mo-5Zr alloy solution treated at the beta transus and aged at 400°C, the maximum age hardening and the minimum value in ductility were observed for each aging time. It was found from the X-ray diffraction results that these phenomena were related to the omega phase precipitation. In this alloy, the alpha phase precipitation led to the decrease in tensile strength and the increase in ductility. In the Ti-15Mo-5Zr-3Al alloy the omega phase precipitation during aging was suppressed by aluminum addition and the age hardening was related to the amount of the alpha phase strengthened by aluminum. The largest age hardening was observed after heat treatment at 425 to 450°C. Therefore, the mechanical properties were controlled by the omega and the alpha precipitation in the Ti-15Mo-5Zr alloy and mainly by the alpha precipitation in the Ti-15Mo-5Zr-3Al alloy. The tensile properties obtained by the optimum heat treatment conditions are as follows:
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The notched tensile test, the impact test and the fatigue test showed that the Ti-15Mo-5Zr-3Al alloy hardened by the alpha precipitation was superior to the Ti-15Mo-5Zr alloy hardened by the omega precipitation as a commercial alloy, with good combinations of strength, ductility, toughness and fatigue property.View full abstractDownload PDF (990K) -
Katuo Saito, Takeo Hikage1976 Volume 40 Issue 3 Pages 227-235
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA dilute solid solution of copper containing silicon up to 2.30 wt% was internally oxidized in the temperature range from 700 to 1000°C. The effects of holding time, solute concentration, and holding temperature on the internal oxidation structure was investigated. The product of the solubility N0 and the diffusibity D0 of oxygen has been obtained in the above temperature range. The results obtained are as follows: (1) The shape of oxides formed in the internal oxidation/unoxidation zone boundary is spherical and a few particles coalesced. In the internal oxidation zone, besides the boundary and its neighborhood, the oxide shape is spherical only. As the silicon concentration increases, the shape of oxide at the boundary changes from spherical to dendritic. (2) The thickness of the adhesive copper layer on the specimen surface is proportional to the content of oxygen diffused into the specimen. (3) The activation energy determined from the product N0D0 decreases with increase in silicon concentration. Solute concentration dependence of the activation energy corresponds with the change in oxide shape from spehrical to dendritic.View full abstractDownload PDF (1677K) -
Minoru Nobuki, Atsushi Oguchi1976 Volume 40 Issue 3 Pages 236-239
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA quenched and tempered high carbon steel containing about 1%C was tested in tension or in bending under hydrostatic pressures up to 13000 kg/cm2 at room temperature in order to make clear the influence of hydrostatic pressure on the fracture stress of brittle material. The results obtained are as follows: (1) When the fracture stress σf is represented by an equation σf=αP+σf0, the values of α and σf0 were measured to be about 0.82 and 104.5 kg/mm2 for the tensile test and about 0.76 and 159.6 kg/mm2 for the bending test. Where α, P and σf0 are a constant, the ambient pressure under a compressive stress which takes a positive sign, and the fracture stress at atmospheric pressure, respectively. (2) The value of σf0 measured in the bending test was approximately one and half times larger than that obtained in the tensile test. It seems that the fracture occurs following the theory of Weibull for the fracture of the material containing cracks. (3) The value of α was observed between 0 and 1. This seems to be due to the fact that the fracture occurs essentially according to the maximum principal stress theory and, in the actual material, the probability of fracture at the surface crack becomes larger under a hydrostatic pressure than that at atmospheric pressure.View full abstractDownload PDF (403K) -
Hakaru Masumoto, Kiyoshi Watanabe, K\={o}nosuke Inagawa1976 Volume 40 Issue 3 Pages 240-243
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe magnetic properties of Co-0∼35 at%Ir alloys of the perfect hcp crystal structure type were studied by use of a magnetic balance and a pendulum-type magnetometer, and the following results were obtained; The crystal magnetic anisotropy energies of hcp type Co-Ir alloys rapidly decreased with increase in Ir concentration. The magnetic moment \barμ per atom in these alloys decreased linearly with increase in Ir concentration, and the concentration dependence of \barμ, d\barμ⁄dq, in the hcp alloys was −2.59μB/Ir, being lower in absolute value than −2.95μB/Ir in fcc type Co-Ir alloys. If the magnetic moments of Co and Ir are constant for all compositions, the magnetic moment of Ir for the hcp Co-Ir alloys is −0.87μB, that for the fcc Co-Ir alloys being −1.20μB.View full abstractDownload PDF (289K) -
Masamichi Miki, Yoshitsugu Amano1976 Volume 40 Issue 3 Pages 243-251
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPrecipitation process of Cu-30%Ni-1∼3%Al alloys during aging at 500°C or 600°C after water quenching from 1050°C, and characteristics of the nodule formed by grain boundary reaction in these alloys were investigated by means of optical and electron microscopy, hardness measurement and X-ray diffraction.
The results obtained were as follows:
(1) At 500°C, hardening occurred in two stages and the maximum values in hardness were not still obtained after aging for 2×104 min. At 600°C, the hardness increased monotonously and reached their maximum after 1000 min aging.
(2) The lines of θ phase and the side bands were observed from the early stage of aging on X-ray diffraction patterns. The structure of the θ phase was ordered fcc.
(3) In the transmission electron micrographs, the modurated structure were observed at the early stage of aging.
(4) The mode of precipitation in the alloys was of the discontinuous type: α super-saturated solid solution→modurated structure→equilibrium α phase+equilibrium θ phase with composition of a extent from (Ni0.67Cu0.33)3Al to (Ni0.85Cu0.15)3Al.
(5) Fine structure inside the nodule grew and changed gradually during aging, and a granular θ phase was observed at the latter stage of aging.
(6) The hardness inside the nodule changed in nearly the same way as that inside the grain.View full abstractDownload PDF (1816K) -
Atsumi Ohno, Tetsuichi Motegi, Kenichi Nagai1976 Volume 40 Issue 3 Pages 251-256
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is known that when the degree of undercooling of a molten alloy increases, the solidified structure alters from equiaxed structure to columnar dendrites and finally to fine granular structure. In order to know the process of these structure changes with the increase of degree of undercooling, the solidification phenomenon and solidification structures of 99.99% Sn and Sn-Bi alloys undercooled at various degrees were observed. The maximum undercooling obtained in this experiment was about 27°C of Sn-4% Bi alloy.
With small degree of undercooling, the separation of necked-crystals which finally form an equiaxed zone from the container wall was clearly observed. As the degree of undercooling was increased, the separation of crystals stopped to form a stable solid skin on the container wall to produce the columnar dendrites. When the degree of undercooling was further increased, the fine grains were formed by the partial remelting of the necked dendrite arms.View full abstractDownload PDF (883K) -
Ichiya Endo, Yasuaki Morioka, Shunji Itoh1976 Volume 40 Issue 3 Pages 256-263
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-Si alloy powders containing 3∼13 wt% T.Si (total silicon) were prepared by water atomization. These powders as water-quenched were annealed at 900°C for 3 hr in H2 gas. Their phase transformation and sintering behavior were studied by means of X-ray diffraction and dilatometric measurement.
The results are summarized as follows;
(1) The oxygen content of the powders decreases with increasing Si content. When T.Si content is less than 5 wt%, the oxidized surface layer of the powders is abundant with Fe2SiO4.
(2) When alloyed Si content is less than 5 wt%, the structure of both quenched and annealed powders is exclusively a disordered α-phase. When alloyed Si content exceeds 5 wt%, the ordered α1-phase begins to appear. The average degree of order of the quenched powders with 5∼7 wt% alloying Si is lower than that of the annealed ones. When alloyed Si content is more than 7 wt%, only α1-phase can be recognized.
(3) The lattice constant of the quenched powders with less than 5 wt% alloyed Si is smaller than that of the annealed powders. When alloyed Si content is more than 7 wt%, almost the same lattice constants of the quenched and annealed powders are obtained.
(4) The order-disorder transformation temperature obtained by the measurement of lattice constant corresponds to that of the phase transitions of α1↔α+α1 or α1↔α2. In this experiment, however, the ordered α2-phase (B2 type) cannot be observed.
(5) The compacts from powders with a rich α1-phase present a liquid phase during the sintering process at a comparatively low temperature below 1200°C. When alloyed Si content is above 4.5 wt%, abnormal behavior of dilatation is observed at a temperature corresponding to the order-disorder transformation of α1→α+α1 or α1→α2.View full abstractDownload PDF (765K) -
Seita Sakui, Taku Sakai1976 Volume 40 Issue 3 Pages 263-269
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of grain size on the tensile deformation behavior of high-purity polycrystalline iron was studied over the temperature range from 25 to 900°C, by means of a newly devised equipment with which the metallic materials could be quenched by hydrogen gas immediately after hot tensile deformation at various strain rates from 1 to 10−7 l/sec. The following characteristics of high temperature deformation behavior of pure iron were observed above 500°C where the effect of the blue-brittleness phenomena disappeared: (1) the steady state flow, (2) no grain size dependence of flow stress in high strain range, and (3) the marked increase in total elongation and the decrease in strain at tensile strength.
The relation between the grain size and yield stress or flow stress at a given strain was approximately represented by the Hall-Petch equation from 25 to 800°C. The temperature dependence of yield stress originates from the temperature dependence of friction stress (σi) and of grain size effect (Ky·D−1⁄2). The Ky⁄σi-ratios were almost constant (0.18±0.02) between 400 and 800°C, and this fact indicates the yield stress largly depends upon the grain size even at 800°C. The temperature dependence of σi was similar to that of the yield stress of iron single crystal.
The grain size dependence of flow stress shows a complicate behavior with the change of temperature and strain. This behavior is explained qualitatively in terms of the work hardening model rather than the dislocation pile-up model. The grain size dependence of steady state flow stress was hardly observed. This seems to be due to the fact that a uniform subgrain size was produced at high temperature and high strain range regardless of the initial grain size.View full abstractDownload PDF (584K) -
Akinori Matsuda1976 Volume 40 Issue 3 Pages 270-275
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress-strain curves for crystals deformed by a shearing method matching the applied stress with a slip system vary significantly in terms of the shearing plane and direction. The present studies were conducted by observation of the dislocation structures in crystals deformed by shear in order to examine the work hardening behavior of iron single crystals.
When the shearing plane was aligned with the (112) plane, three-stage hardening occurred in the crystals. On the other hand, for crystals sheared on the (101) plane, the stress-strain curves showed the parabolic type. However, the dislocation structures were similar for crystals sheared both on the (112) and (101) planes. The distribution of dislocation in crystals was inhomogeneous; The cell structures having the cell wall approximately parallel to ⟨111⟩ developed. The three-stage hardening process for crystals sheared on the (112) plane depended markedly on shearing direction. These changes for hardening with shearing direction may have a close connection with the formation of cell structure in crystals. In the crystals sheared at 77°K, where the stress-strain curves showed the parabolic type for both (101) and (112) shearing planes, the dislocation arrangements in crystals were uniform and screw dislocation was predominant.
The relationship between the shear stress and the reciprocal of the spacing of screw dislocation was linear. This result suggests that the work hardening at low temperatures was closely related with the interaction of screw dislocations.View full abstractDownload PDF (727K) -
Hiroyasu Araki, Yoshinori Fujimura1976 Volume 40 Issue 3 Pages 275-282
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo clarify a recrystallization process in (α+γ) two-phase stainless steels, the structural change with annealing was studied on three kinds of two phase specimens with 25%Cr and different nickel contents and also on three kinds of single phase specimens with 20∼30%Cr, which were cold rolled 75% in reduction followed by heating mainly for 1 hr. The results obtained are as follows. (1) Shape of a hardness-temperature curve for the two-phase specimen was greatly different from that for the single phase specimen. That is, considerable hardening due to 475°C brittleness prior to softening and furthermore another hardening was observed in the midst of softening. (2) Recrystallization process as well as its temperature in each phase of the two-phase specimen was different from each other. That is, in the α phase small recrystallized grains were observed after subgrains had been formed by recovery, but in the γ phase subgrains were hardly observed below the temperature where the recrystallized grains began to appear. (3) In the α phase, there was little difference in the temperature where subgrains began to form and in the beginning and ending temperatures of recrystallization for both the two-phase and single phase specimens. (4) In the two-phase specimen σ and γ phases were formed from the recrystallized α phase. The temperature where these phases were again transformed into the α phase became higher as the nickel content increased and at higher nickel contents it was fairly higher than the ending temperature of recrystallization in the γ phase. (5) Structural change with annealing in cold rolled high Cr-low Ni two-phase specimens can be regarded as being started form the recovery, followed by the formation of the recrystallized structure in the α phase at the same temperature as in the high Cr single phase specimens, and then the appearance of fine recrystallized grains and a gradual progress of recrystallization in the γ phase follow. Besides, the σ and γ phases are easily formed in the recrystallized α phase, which makes the ending temperature of softening considerably higher than that of recrystallization in the γ phase.View full abstractDownload PDF (1178K) -
Toshio Shimoo, Naofumi Saino, Hiroshi Kimura, Masao Kawai1976 Volume 40 Issue 3 Pages 282-288
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study was carried out to investigate the rate of nitrogen removal from carbon saturated iron melted with lime-alumina slag in an atmosphere of argon.
The content of nitrogen in metal decreases rapidly, and then the behavior N3−, CN−, C22−, Fe2+ in slag and Al in metal becomes complicated. The rate of nitrogen removal is shown by the second-order reaction. The apparent activation energy is 69.8 kcal/mol. The rate of nitrogen removal is accelerated with increasing activity of lime in slag and decreasing weight of the slag added. From a mass balance for nitrogen, it is clear that the amount of nitrogen transferred to the slag is less than that removed from metal. It is supposed that the reaction of nitrogen removal proceeds on the basis of the transfer of nitrogen from metal to slag and to CO bubbles evolved at the slag-metal interface, and that the rate of nitrogen removal is controlled by certain chemical reactions.View full abstractDownload PDF (828K) -
Kenzo Igaki, Minoru Isshiki1976 Volume 40 Issue 3 Pages 289-296
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to obtain high purity iron from chloride solution, a purification process by anion exchange and solvent extraction in hydrochloric acid medium has been developed. The purification by anion exchange consists of two steps, elution of FeCl2 and elution of FeCl3. Solvent extraction was carried out by using methyl-isobuthyl-ketone after anion exchange. The purified ferric chloride solution was evaporated to dryness in air, oxidized and thereafter reduced by Pd-purified H2.
Iron wire specimens 0.5 mm in diameter were obtained and then purified by wet H2, dry H2 and vacuum treatment. Electrical resistivity was measured on wire specimens at 4.2 K to obtain the residual resistivity ratio. Effectivity of each purification step was confirmed and the purified iron showed RRRH* of 1580. Elution of FeCl3 can be repeated easily and is known to be very effective, and the sample, purified through 2 passes of FeCl3 elution after FeCl2 elution, showed RRRH of 2600.
*RRRH; the residual resistivity ratio obtained by using the minimum resistivity under the application of longitudinal magnetic field of 750 Oe.View full abstractDownload PDF (693K) -
Fumio Morito, Yoichi Ishida, Masao Kato1976 Volume 40 Issue 3 Pages 296-305
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDislocations in Al-1.0 and 4.4%Mg alloys creep-tested in the temperature range 350 to 400°C and the stress range 0.6 to 4.4 kg/mm2 were investigated by transmission electron microscopy to understand the mechanism of high temperature creep.
Dislocations were viewed parallel to [100] and [110] directions under two-beam diffraction conditions where one of the low index planes {111}, {200} and {220} was diffracting most strongly. The Burgers vector of the matrix dislocations was analyzed by using the micrographs. They were all of the a⁄2 [110] type and no a [100] dislocation was observed. All the six a⁄2 [110] dislocations are distributed almost uniformly. The matrix dislocation ended at three-fold dislocation nodes forming a loosely connected three-dimensional network. The dislocations were neither purely edge nor purely screw. They did not lie on any of the slip planes.
It is concluded that creep deformation of Al-Mg solid solution alloys at elevated temperatures are based on the “partly climb and partly glide” motion of mixed-type matrix dislocations forming a three-dimentional network.View full abstractDownload PDF (1252K) -
Noboru Yahata, Fusao Hayama1976 Volume 40 Issue 3 Pages 306-313
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor annealed S43C and SK5 carbon steels, optical and electron microscopy, X-ray and XMA techniques have been used to examine the metallurgical changes, hardening, oxidation and residual stresses taking place in the surface layer during the steady wear process. Wear experiments have been carried out with a pin-on-ring type wear testing apparatus under the unlubricated sliding condition in air.
The results obtained are as follows:
(1) With increase in carbon content, the wear decreases only in the range of low and moderate sliding speeds.
(2) When the average temperature of the sliding surface exceeds about 200°C, the seizure occurs and the wear tends to increase considerably in both S43C and SK5 carbon steels.
In this case, the tensile stresses are induced at or near the surface parallel to the sliding direction.
(3) In S43C carbon steel, oxide fragments which cover thickly the sliding surface are sometimes buried in the surface layer as in the case of mild steel.
(4) Depending on the sliding speed, the transformed phases with light eching or non-eching characteristics are in the form of a patch or uniform and continous layer. In the former there is usually a distinct demarcation between the transformed phase and the substrate, but in the latter there is always a transition layer between them.View full abstractDownload PDF (1891K)
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