巻号一覧
39 巻, 6 号
選択された号の論文の17件中1～17を表示しています
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中村 森彦, 津谷 和男1975 年 39 巻 6 号 p. 553-559
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーIn order to clarify the effect of preloading on fracture strength of notched specimens, measurements were made on the fracture load at liquid nitrogen temperature and its dependence on preloads given at various temperatures using V-Charpy specimens of low strength steel with various notch root radii and flank angles and standard V-Charpy specimens prestrained uniformly in tension. The results obtained were as follows.
(1) When specimens were preloaded at lower temperature than −140°C or when they had small notch root radii, the fracture load increased with increase in tensile preload, while the fracture load decreased with increase in compressive preload. (2) When specimens were preloaded at higher temperature than −100°C or when they had relatively large notch radii, the fracture load were insensitive to the compressive preload. (3) The size of a plastic deformation zone at the root of the notch produced by preloading was independent of preloading temperature under the same notch geometry. An attempt to explain the above results was made in terms of (i) the residual stress, (ii) the work-hardening, and (iii) the internal damage such as microcracks induced in a plastic deformation zone near the root of the notch produced by preloading.抄録全体を表示PDF形式でダウンロード (697K) -
中村 森彦, 津谷 和男1975 年 39 巻 6 号 p. 559-565
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe effects of preloading on the fracture strength of notched (or cracked) specimens have so far been discussed in terms of the effects of residual stress at the tip of the notch produced by a plastic zone. In this paper, the effect of work-hardening, another important factor associated with the plastic zone, was investigated experimentally and theoretically. Measurements were made on fracture stress and critical COD of Fe-3.12%Si deep-notched specimens indented at the notch tip by the Brinell hardness tester. The results obtained were as follows. (1) In specimens subjected to only one indentation at the notch tip, which produced the work-hardening and the compressible residual stress, the fracture stress increased with indentation load at room temperature and 100°C, but the critical COD increased only at 100°C. (2) In specimens subjected to two indentations near the notch tip, which produced the work-hardening and the tensile residual stress, the fracture stress showed a maximum value with decreasing distance between the two indentations. A similar tendency was found on the critical COD at 100°C. (3) At room temperature the critical COD was not sensitive to the indentation load in both specimens, contrary to the results on fracture stress. Theoretical analysis based on the BCS model was made on the effects of the work-hardening region produced at the tip of the notch, and the result was then applied to the explanation of the present experimental results.抄録全体を表示PDF形式でダウンロード (631K) -
上條 栄治1975 年 39 巻 6 号 p. 566-570
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe thermal stability and stabilizing treatments of cadmium oxide particles in silver-cadmium oxide alloys produced by internal oxidation were examined by a thermobalance method.
In order to determine the relation between the thermal stability and contact erosion, the amount of erosion was mearsured with an electro magnetic contactor.
The results are summarized as follows.
(1) The thermal stability of the cadmium oxide particles depends mainly upon the position of these particles, i.e. the oxygen pressure at that point.
(2) The excellent thermal stability of these particles in the inner part of the alloy is obtained by heat treatment in an oxygen atmosphere whose pressure is increased to reach the inner part after the first internal oxidation.
(3) It is considered that the cadmium oxide in the silver matrix is substoichiometoric, and its formula is CdO1−x where X increases continuously from the outer surface to the inner part.
(4) The contact performance, especially the contact erosion, is improved by the heat treatment which produces the thermally stable cadmium oxide particles in the silver matrix.抄録全体を表示PDF形式でダウンロード (402K) -
津野 勝重, 清水 久雄1975 年 39 巻 6 号 p. 570-575
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーIn order to achieve higher field homogeneity than 10−6 in an air gap of electromagnet, pole tips have to be made of magnetically uniform. The residual magnetization distributions at the pole faces were measured and compared with the signals of high resolution NMR which were observed under the correction of magnetic field by a current shim. The following relations must be satisfied for all areas of pole face except near the edge, in order to attain the higher field homogeneity than 2×10−9 in a space of 4 mmφ.
(This article is not displayable. Please see full text pdf.)
\ oindentWhere Hr(R) and Hr(φ) are the radial and directional components of measured residual magnetization, R and φ the radial distance and the angle from the top of the pole tip, and A2, A4 and C1, the coefficients of inhomogeneities calculated as to fit for the measured values.抄録全体を表示PDF形式でダウンロード (490K) -
上原 重昭, 木村 啓造1975 年 39 巻 6 号 p. 576-581
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーEffects of the quenching temperature on the structures and mechanical properties of Zr-2.5%Nb alloys containing up to 0.3%Ru were studied by opitical and electron microscopy, tensile tests and vickers hardness tests.
In the specimens quenched from the β range or higher temperatures in the α+β range, a martensitic structure was observed. In the twinned martensite plate, (10\bar11) internal-twins were mainly observed with a portion of (10\bar12) internal-twins and dislocations. But in the untwinned martensite plate, internal-twins could not be observed.
In the structure quenched from the temperatures in the α+β range, it was observed that as the quenching temperature decreases, the amount of the α phase increases and the retained β or ω phase occurs at the specified temperatures.
In specimens of furnace-cooled and air-cooled from the β range, parallel plate-like α and basketweave α structures were observed, respectively.
Quenching from the β range or higher temperatures in the α+β range, the tensile strength shows almost a constant value. Further, the decreasing of quenching temperatures shows complicated changes in tensile properties. The minimum and maximum values of tensile strength were observed in relation to the quenched structures of the α with the retained β phase and of the α phase with the quenched ω phase, respectively. In a specimen quenched below 780∼790°C, yield phenomenon was observed in the stress-strain curve.抄録全体を表示PDF形式でダウンロード (606K) -
森 勉, 堀江 正明1975 年 39 巻 6 号 p. 581-588
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーTwo step aging (stress aging and free aging) has been carried out on single crystals of iron-nitrogen solid solutions. It has been confirmed that the stress orienting effect of α′′ precipitates (Fe16N2) is due to preferential nucleation on a particular habit plane of α′′ which is favored by the stress. A critical nucleus of α′′ which can grow spontaneously at 100°C is estimated to have not more than 30 nitrogen atoms. Growth kinetics of α′′ has been determined by measurement of length change which is induced by growth of preferentially nucleated α′′ during the stress aging and has been shown to have the time exponent 2.抄録全体を表示PDF形式でダウンロード (1035K) -
沖 憲典, 増田 順一, 羽坂 雅之1975 年 39 巻 6 号 p. 589-595
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe kinetics of ordering in Fe-Al alloys with about 25 at%Al is investigated both theoretically and experimentally. The kinetic equations which express the time variation of the degrees of order in B2 and DO3 structures are obtained by taking into account the direct interchange of atoms between the first and the second nearest neighbors. The experimental results of X-ray diffraction on isothermal annealing or slow cooling of these alloys are reproduced satisfactorily by the theoretical rate equations.
The ordering in DO3 type is influenced substantially by the atomic interchange between the second nearest neighbors. The B2 type ordering takes place so rapidly that the quenching from a disordered phase can not prevent the ordering. An oscillatory change of the degree of order in the B2 structure is expected from the calculation in the isothermal annealing.抄録全体を表示PDF形式でダウンロード (549K) -
増本 剛, 中谷 功, 梅村 文夫1975 年 39 巻 6 号 p. 595-600
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーSingle crystals of ferromagnetic semiconductor CdCr2S4 were grown by improved methods based on the vapor-liquid transport method. The crystallographic properties were investigated, and the magnetic properties were measured for each single crystal obtained. Then we discussed the relation between the wide scatter of the magnetic property in each single crystal and the deviation from stoichiometry in the compound. The results are summarized as follows:
(1) Using CdS and CrCl3 pellets both in the mole ratio 2:1, CdCr2S4 single crystals which were octahedral up to 4 mm on the edge were grown by vapor-liquid transport for 4 days with the temperatures of the feed end, 985°C, and of the growth end, 950°C. When the starting CrCl3 pellet was wound with a platinum ribbon, octahedral CdCr2S4 single crystals of about 5 mm on the edge were obtained.
(2) In each single crystal obtained, Curie constant C and paramagnetic Curie temperature θ were found to show rather wide scatter from 3.40 to 4.50 emu·deg/mol and from 140 to 165 K, respectively. This seems to be caused by the difference in the degree of deviations from stoichiometry in individual samples.抄録全体を表示PDF形式でダウンロード (791K) -
村田 威雄, 高橋 賢一, 増本 健1975 年 39 巻 6 号 p. 600-605
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーIn order to investigate the creep properties of ferritic Fe-Cr (25∼45 wt%Cr) alloys aged at 475°C, tensile creep tests have been carried out at 475°C. The results obtained are summarized as follows:
(1) With increasing aging time, the instantaneous creep strain and the rupture strain decrease. The creep rate decreases very much by the aging treatment and the creep rates of the aged alloys are estimated to be as low as 10−3∼10−4 of the values of the unaged ones.
(2) In specimens crept after aging, tangled dislocations, cells, deformation twins and straight screw dislocations are found. It is thought that the straight screw dislocations are introduced by the preferred motion of the edge component of mobile dislocations which take place due to the recovery of the tangled dislocation structure, during the creep deformation, and this recovery is controlled by the self-diffusion in the chromium-rich phase.
(3) A remarkable decrease in the creep rate by the aging treatment can be correlated with a decrease of self-diffusion coefficient in chromium-rich phase in which the chromium content increases with increasing aging time.抄録全体を表示PDF形式でダウンロード (795K) -
薬師寺 正雄, 近藤 喜之, 松本 弘司, 岡本 平1975 年 39 巻 6 号 p. 606-608
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe hardness on (010)θ of the primary cementite in a hyper eutectic iron-cementite alloy prepared by means of directional solidification was measured at elevated temperatures up to 700°C, and its temperature dependence was investigated. The results obtained are as follows:
(1) The hardness H of the cementite decreased with increasing temperature T, in accordance with the Ito-Shishokin’s relationship, i.e., H=Ae−BT, except the discontinuous decrease at 200∼250°C.
(2) The temperature range of 200∼250°C where the hardness decreased discontinuously corresponded to that of its Curie temperature. The hardness of pure nickel also showed a similar behavior at the Curie temperature. It was supposed, therefore, that the anomaly found on the hot hardness of cementite at 200∼250°C was related to the transformation from a ferromagnetic to a paramagnetic state.
(3) The slope of the log hardness-temperature curve changed at about 470°C, which is within the range of 0.5∼0.8Tm, where Tm is the melting point, reported for various intermetallic compounds.抄録全体を表示PDF形式でダウンロード (297K) -
桑野 範之, 緒方 勲, 江口 鉄男1975 年 39 巻 6 号 p. 609-614
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe dependence of lattice parameter on quenching temperature was investigated for α phase of Cu-Al alloys of various compositions. The experimental results showed that the lattice parameter reaches its maximum value at the quenching temperatures of 400∼500°C as predicted from the behavior of other physical properties, and that the maximum deviation of lattice parameter of the quenched alloy from that of the slow-cooled one is approximately 0% for 5.1 at%, 0.008% for 10.2 at%, 0.02% for 14.8 at% and 0.028% for 18.6 at% Al alloy. These changes in lattice parameter are attributed to the existence of short range order (SRO).
The relation between lattice parameter and SRO parameter was analyzed by the following two different methods: the elastic model developed by Rudman to include strain relaxation due to SRO, and the nearest-neighbor interaction approximation developed by Dienes, in which the interaction between atoms is described by a quadratic function of interatomic distance. It was concluded that the latter method is satisfactorily applicable to the case of α Cu-Al alloys.抄録全体を表示PDF形式でダウンロード (497K) -
高田 潤, 亀井 康夫, 清水 真人, 足立 正雄1975 年 39 巻 6 号 p. 615-620
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーInternally oxidized iron alloys and α-Fe were deformed at 650∼850°C. And some activation parameters were obtained. Stress exponents, apparent activation energies and activation volumes were similar to those of α-Fe. High temperature deformation of these alloys is controlled by lattice diffusion. In these alloys, the average internal stresses were slightly higher than in α-Fe. The effective stress exponent of the average dislocation velocity was 2∼3 and had slight temperature dependence.抄録全体を表示PDF形式でダウンロード (434K) -
当摩 建, 吉永 日出男, 諸住 正太郎1975 年 39 巻 6 号 p. 621-625
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーIn order to identify the mechanism of high-temperature deformation of pure metals, internal stresses are measured by the stress transient dip test on fcc copper, bcc iron and vanadium, and hcp titanium.
The extrapolation method proposed in the previous paper is applied in determining the critical stress for deformation stagnation in order to minimize the error produced by the recovery during measurements, and it is found in the fcc and bcc metals that the contribution of internal stress to applied stress is nearly 100%. This shows that the deformation mechanism in these metals is recovery-controlled. In hcp titanium, however, the contribution of frictional stress is found to be appreciable in a higher stress range (i.e. higher strain rate range).
Further, the cause underlying the discrepancies between the data reported hitherto concerning the internal stress during creep is discussed and concluded to be due to the recovery effect during measurements.抄録全体を表示PDF形式でダウンロード (410K) -
吉永 日出男, 当摩 建, 諸住 正太郎1975 年 39 巻 6 号 p. 626-634
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーIn order to examine the idea that the high-temperature deformation of pure metals is recovery-controlled, strain rate change tests and stress relaxation tests have been performed using vanadium, aluminium, copper and α-iron.
The work hardening rate without the recovery effect, h, and the recovery rate, r, are determined at a given deformation state by a stress relaxation test. Slopes of the stress-strain curve immediately after the strain rate change can be calculated from the values of h and r. The calculated slopes agree well with the experimentally determined slopes. The activation energy for recovery determined from stress relaxation tests agrees approximately with the activation energy for self-diffusion. Transmission electron microscopic observations on vanadium suggest that the stress change Δσ accompanying a rapid strain rate change is related to the local variation of the dislocation density.
From these results, it is discussed that the high-temperature deformation of these pure metals can be understood by the recovery-controlled mechanism.抄録全体を表示PDF形式でダウンロード (944K) -
丹羽 直毅, 大久保 忠恒1975 年 39 巻 6 号 p. 635-642
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe process of a “cup and cone” fracture was studied in tough-pitch copper round bar specimens pulled in tension by using a stiff loading device. The stiff loading device provided an accurate load vs elongation curve well beyond the steep load drop point. Longitudinal sections of specimens strained to various points on a load vs elongation curve were examined by a light microscope. In specimens used, voids with inclusions elongated along the wrought direction were observed before straining. Before the first steep load drop, void growth and void coalescence were observed, resulting in the formation of weakened regions near the center of the necked region. After the steep load drop point, this type of fracture was completed through three stages. (1) A few small cracks were formed simultaneously by connecting weakened zones. This corresponds to the so-called “break-point”. Then, connecting these small cracks, a large central crack was formed. On a load vs elongation curve, the load dropped rather steeply. (2) The central crack grew gradually in a zig-zag way toward the outer surface, and a narrow region of heavy deformation and void formation extending from the crack tip to the outer surface was formed, while the load dropped slowly. (3) When this region reached the outer surface, the region failed immediately resulting in the total separation of the specimen. Therefore, the second steep load drop occurred. Stress wave emission was observed during the internal development of the “cup and cone” fracture. The emission was thought to be associated with the formation and growth of cracks.抄録全体を表示PDF形式でダウンロード (1594K) -
財満 鎮雄, 森下 定1975 年 39 巻 6 号 p. 642-647
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe orthogonal hot machining tests are carried out to confirme the adaptability of hot machining for high silicon aluminium alloys. The heating temperature at starting time of the tests are changed in the range of −60∼300°C and the influences of heating temperature on the cutting mechanism of these alloys are investigated from the viewpoints of cutting resistance, change of shear angle, cutting ratio, growth of the built-up edge, roughness of the cut surface and others. The results are summarized as follows:
With increasing heating temperature, the cutting resistance decreases distinctly, but both the cutting ratio and shear angle increase slightly. At heating temperatures over 300°C, there seems no difference due to the material between 13 and 19%Si alloys. In the case of 13%Si alloys, the formation of the built-up edge is conspicuous, but the size of the built-up edge is reduced with increasing heating temperature, and with the disappearance of the built-up edges at 200∼300°C, the cut surface is remarkably improved. In the case of 19%Si alloys, the formation of the built-up edge is seldom observed and value of surface roughness is small, so the influences of heating temperature on the cut surface become very little.抄録全体を表示PDF形式でダウンロード (795K) -
小野寺 龍太, 豊島 清三1975 年 39 巻 6 号 p. 648-656
発行日: 1975年
公開日: 2008/04/04
ジャーナル フリーThe formation of voids and the ductile fracture behavior in tension of low carbon steels and decarburized steels were studied using light and electron microscopy. Many microcracks which were associated with inclusions or carbides were observed on the sections of specimens prior to ductile fracture, but these changed into voids by repetition of etching and polishing. Sections of specimens containing central fissure seem to show the ductile fracture preceded by the propagation of “microcracks”. But after the repeated etching and polishing, these “microcracks” changed into void coalescence. When the substance between microcracks in decarburized specimen was thrusted with a pin, it fell into a void which had been concealed under it.
It is reasonable to consider from the above results that “microcracks” observed on the section of a specimen in the process of ductile fracture are not real cracks but gaps between the matrix and the lid which covered void during polishing. Then we conclude that the mechanism of ductile fracture of a low carbon steel is a process of void coalescence.
In fractograph, the dimple pattern of coarse grained decarburized steel was coarser than that of the fine grained specimen. It appears that the grain boundaries play an important role in expanding small voids during the process of void coalescence.抄録全体を表示PDF形式でダウンロード (2189K)
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