材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
40 巻 , 448 号
選択された号の論文の20件中1~20を表示しています
  • 江良 正直, 村田 英幸, 筒井 哲夫, 斎藤 省吾
    1991 年 40 巻 448 号 p. 1-7
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 池尻 忠夫
    1991 年 40 巻 448 号 p. 8-14
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the deterioration of synthetic resin caused by low voltage high current arc, it is considered that arc behaves inherently as a heat source. So, the arc resistance is usually evaluated from the viewpoint of deterioration by the equivalent heat source.
    In this paper, several new test methods including the modified one by the equivalent heat source were examined to evaluate effectively the arc resistance of insulating materials. From the combined use of these test methods, the right evaluation of arc resistance seems possible.
    As the new test methods, the arc resistance test by a gasoline torch lamp, the rotary type one by chemical flame, the arc resistance one by an instant infared heating apparatus among others were employed.
    The comparison of the experimental results by these test methods was made, and it was observed in all cases that the resins such as silicone-glass and melamine-glass laminates showed high arc resistance and the resins such as PVC and phenol resins showed low arc resistance.
  • 北村 辰雄, 菊池 潮美, 小岩 昌宏
    1991 年 40 巻 448 号 p. 15-20
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Pb-Sn eutectic alloys were deformed in compression at room temperature in the as-cast condition. The microstructural change during deformation and nonuniform deformation with boundary sliding were investigated in a metallographic point of view.
    Boundary sliding occurred mainly at the interface between colonies in the initial deformation stage. Dynamically recrystallized grains were formed at the colony boundaries and developed into matrix with increasing strain. In the lamella structure region, lamella structures were destabilized and changed to equiaxed grains of Pb and Sn phases during deformation. In the massive structure region, equiaxed subgrains were formed by deformation in the large grains of Pb and Sn phases. These processes to make equiaxed structure are very important for as cast Pb-Sn eutectic to deform superplastically according to grain boundary sliding.
  • 中馬 丞, 広橋 光治, 大釜 敏正, 笠原 康弘
    1991 年 40 巻 448 号 p. 21-26
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Bamboo is a natural unidirectional fiber-reinforced material and so it is mechanically anisotropic. In this study, the relationship between the Young's modulus in the tangential direction of cylindrical wall within internode and the volume fraction of bundle sheathes Vf or the specific gravity ρ was investigated on two samples of Mousou bamboo. The experimental results obtained are as follows:
    (1) The Young's modulus in the tangential direction ET increased parabolically from the inner bark toward the outer bark in the cylindrical wall for both of the samples, and had a tendency of relative increase with height.
    (2) ET could be approximated by the next equation.
    ET=(1-C)Ef·Em/Ef(1-Vf)+Em·Vf+C{Ef·Vf+Em(1-Vf)}
    where, Ef and Em are Young's moduli of bundle sheathes and parenchyma, respectively. C is the ratio (0≤C≤1) of a parallel model.
    (3) The variation of specific gravity ρ among samples became large with increasing Vf when compared at the same Vf level. This is because the cell diameter of parenchyma differs with samples and the specific gravity increased with decreasing cell diameter of parenchyma.
    (4) An approximate equation was established between ET and Vf. Consequently, ET could be evaluated by the measurement of ρ by means of the linear relationship between Vf and ρ.
  • 友田 陽, 龍福 進, 朴 敏
    1991 年 40 巻 448 号 p. 27-33
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of fcc (γ)→hcp (ε) martensitic transformation on the tensile deformation behavior of Fe-Mn, Fe-Mn-Si and Fe-Mn-Co alloys was investigated. The amount of ε martensite formed during deformation was drastically increased by the addition of Si or Co which lowers the Neel temperature. On the other hand, the Si addition was revealed to suppress the γ→ε transformation by cooling.
    A positive temperature dependence of 0.2% proof stress resulting form the γ→ε a transformation was found above Ms temperature commonly in these three alloy systems. This phenomenon became more pronounced according to an increase in γ strength by Si solid solution and/or dislocation (ausforming) hardening. A pre-existing ε plate was found to be a strong barrier for further plastic flow, so that a high work hardening was produced. Therefore, the tensile property vs. temperature relation for the alloys examined were well understood by considering the linked influences of softening and hardening due to the deformation induced γ→ε transformation. Although the shape of the true stress vs. true strain curve accompanying the γ→ε transformation became unusual one particular to the so-called TRIP (transformation induced plasticity), ductility was not enhanced so much.
  • 夏目 喜孝, 宮川 進
    1991 年 40 巻 448 号 p. 34-39
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    To investigate the opening and closing behaviors of fatigue cracks on the surface of 1/2CT specimen of high-speed tool steel SKH51, the contact stress σc1 between the two opponent fracture surfaces was determined by X-ray stress measurements in the vicinity of fatigue crack tip at Kmax=8.9MPam1/2 and Kmax=15.4MPam1/2 during the loading process. The results obtained are summarized as follows.
    The residual stress on the fatigue fracture surface was found to be given as the sum of three components; the tensile stress component σr1, resulting from the monotonic plastic zone dimension, the compression stress component -σr2, resulting from the cyclic plastic zone dimension, and the compression component -σr3, resulting from the contact compression zone dimension under the fracture surface. The effect of -σr3 was especially large in the low stress intensity factor range, and consequently the residual stress on the fracture surface became compressive.
  • 宮川 進, 夏目 喜孝, 児玉 昭太郎
    1991 年 40 巻 448 号 p. 40-45
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    To investigate the applicability of the residual stress model used for the fatigue fracture surface of high hardened material SKH51 to the middle and low hardened materials, the residual stresses on the fatigue fracture surfaces of the quench-and-tempered SK-5 or SNCM439 and the annealed S15C were examined. The results obtained are summarized as follows. The residual stress on the fatigue fracture surfaces σr was found to be given by the sum of the same three components as that for the high hardened material; the tensile stress component, σr1, the compression stress component -σr2 and the compression component -σr3. The contribution of -σr3 was especially large in the low stress intensity factor range, and the residual stress on the fracture surface showed various distributions due to the variations of -σr2 and -σr3.
  • 荒谷 眞一, 荻納 淑, 高津 学
    1991 年 40 巻 448 号 p. 46-50
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    In oder to investigate the crack propagation characteristics of thermally tempered glass, its fracture pattern has been studied by using disk samples having various diameters. The peculiar point, in which the fragment density changed discontinuously itself, was observed, and it was coincided with a point of the collision between the fracture front and the elastic wave from the edge of the glass plate, assuming the fracture velocity being 1.5×103m/sec and the elastic wave 3.3×103m/sec. The occurrence of spline depended upon the tensile value, two principal stresses, the initial fracture energy and the interaction with elastic wave and fracture front.
  • 矢川 元基, 吉村 忍, 菱田 博俊
    1991 年 40 巻 448 号 p. 51-57
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper is concerned with experiments as well as numerical analyses on thermal fatigue crack growth of Type 304 stainless steel, which is one of candidate materials for the first wall of fusion reactors, under hydrogen ion (H+) beam irradiation.
    In the experiments, a surface-cracked plate specimen set in a vacuum chamber of 10-6 torr was irradiated repeatedly with 25keV H+ beam pulse of normal distribution, whose peak value and time duration were about 2MW/m2 and 1sec in every 45sec, respectively. During the irradiation, temperature on the specimen surface reached 800-900 degree C. After several hundreds of irradiation cycles, the specimen was cooled down and broken along a cracked plane. Crack growth of about 1mm was observed on the fracture surface.
    To evaluate such a fatigue crack growth behavior, nonlinear fracture mechanics analyses were performed based on the three-dimensional thermal conduction and thermal elasto-plastic finite element analyses. The temperature dependence of material properties was taken into account. The nonlinear fracture mechanics parameter adopted here was the ΔJ-integral considering thermal effects.
    The crack extension amount Δa was estimated using the calculated ΔJ value and several experimental data on fatigue crack growth in literature. It is shown that the present estimation scheme can predict the fatigue crack growth phenomena under ion beam irradiation with an accuracy of a factor 4, in spite of the FEM analyses ignoring micro damage effects of irradiation.
  • 田中 芳雄, 朴 吉煥
    1991 年 40 巻 448 号 p. 58-64
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    The thermal load due to the frictional heat in a material during the two-dimensional sliding contact between a hard indenter and a brittle material is theoretically shown to relax the tensile stress induced by the mechanical load in the surface layer of the material behind the indenter. This implies that the plastic deformation which generally occurs only by a sharp indenter appears even by a much blunter indenter without any elastic cracking. In this paper, the indenter's transition radius was defined as the critical radius which distinguishes the occurence of the first plastic deformation from the elastic cracking as the first damaging event. In the analysis, both the fracture criterion and the yield criterion were employed. It was shown that the transition radius Rc increased steeply and then slowly with an increase in sliding speed V. The both speeds which give Rc to increase steeply and slowly varied depending on thermal diffusivity κ and thermal constant M=α·E/{2·(1-ν)·ρ·C} (where, α: coefficient of expansion, E: Young's modulus, ν: Poison's ratio, ρ: density, C: specific heat) as well as their relative values. The above speeds were almost the same for Si3N4, Al2O3, and glass, but they were much higher for SiC.
  • 杉山 好弘, 浅見 克敏, 黒岩 秀樹
    1991 年 40 巻 448 号 p. 65-71
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the case that the matrix-microstructure of ductile cast iron was changed into the single-phase of bainite by austempering it from γ phase region (full-austempering), the fatigue crack propagation resistance decreased considerably in the low ΔK region as compared with that of the as-cast material. In this paper, the effect of austempering from (α+γ) phase region (partial-austempering) was investigated to improve the fatigue crack propagation resistance of ductile cast iron. Fatigue tests were carried out at a stress ratio, R=0.1.
    The matrix-microstructure consisting of the dual-phase of ferrite and pearlite in the as-cast material was changed into the dual-phase of ferrite and bainite by partial-austempering, and the fatigre crack propagation resistance of the partial-austempered material was higher than that of the as-cast material in the entire ΔK region. The improvement of fatigue crack propagation resistance was due to the increase of crack closure which was induced by the roughness of the fracture surface and the formation of the oxide deposits. Furthermore, it was found that the static tensile properties might be improved by partial-austempering.
  • 森 要, 大塚 昭夫
    1991 年 40 巻 448 号 p. 72-76
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    The characteristics of mode II fatigue crack growth were investigated in air and in 3.5% saltwater on 7075-T6 aluminum alloy specimens extracted in the L-T and T-L orientations. The tests in saltwater were made under free corrosion and under application of anodic and cathodic potentials.
    The mode II crack growth rates in saltwater were higher than those in air, regardless of the applied potential, in the higher ΔKII region for L-T orientation. Almost no effect of saltwater and applied potential was found in the da/dNKII relation for T-L orientation. A comparison between the behaviors of mode II and mode I fatigue crack growth was also made.
  • 廣瀬 明夫, 松廣 克之, 湖東 雅弘, 小林 紘二郎
    1991 年 40 巻 448 号 p. 77-83
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of the fiber-matrix chemical reaction which occurs during thermal exposure on the tensile strength of a SiC/Ti-6Al-4V composite was studied. The tensile strength of the composite decreased with an increase in the fiber-matrix reaction zone thickness. Especially, a drastic degradation occurred when the reaction zone thickness exceeded 1μm. The strength of the fibers extracted from the composite also decreased as the fiber-matrix reaction proceeded. This degradation in the fiber strength was caused by the surface roughness of the fiber due to the fiber-matrix reaction. The strength of the composite was approximately identical with the value estimated from the ROM (Rule of Mixture) using the strengths of the matrix and the extracted fibers.
    It was assumed from the observation of fracture surfaces of the composite and AE analysis during the tensile test that a fiber-matrix reaction zone debonding occurred before failure of the fiber. Therefore, it is concluded that the degradation in strength of the composite by thermal exposure can be attributed not to a notch effect of cracking in the reaction zone, but to the decrease in strength of the fiber itself.
  • 堀田 紀好, 加納 源太郎, 高沢 知生
    1991 年 40 巻 448 号 p. 84-88
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Double-layered gas diffusion electrodes with a fixed gas supplying-layer have been prepared by hot-pressing using hydrophobic acetylene black; AB(I), semi-hydrophobic acetylene black; AB(II), AB(II) with manganese oxide (mixture of Mn5O8 and Mn3O4), active carbon, and active carbon with AB(I) as reaction-layer materials, and their oxygen-reduction performance was examined in 6M KOH solution. The electrodes consisting of AB(II), AB(II) with manganese oxide, and active carbon with AB(I) exhibited a stable and good pclarization behavior throughout experiments, because of a favorable wettability which was effective to hold stable three phase boundaries, i.e., oxygen dissolving sites in the reaction-layer. In addition, as active carbon and particularly manganese oxide particles had a high electrochemical activity and HO-2 ion decomposition ability, a most excellent oxygen-reduction performance was found in the electrode containing manganese oxide, which was followed by the electrode consisting of active carbon with AB(I). On the other hand, the electrode consist of AB(I) or active carbon only gave a poor performance, because of a little or an excessive electrolyte penetration into the reaction-layer by which the formation of three phase boundaries was limited.
  • 渡辺 豊, 庄子 哲雄
    1991 年 40 巻 448 号 p. 89-95
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    2.25Cr-1Mo steel is one of heat resistant materials used most widely in fossil power plants as a header and a boiler tube. The most important phenomenon in material deterioration of 2.25Cr-1Mo steel during a long term operation is carbide coarsening. Carbide coarsening causes such changes in mechanical properties as softening or reduction both of creep strength and of toughness.
    In this paper, a new nondestructive method for detection and evaluation of these material degardations in 2.25Cr-1Mo steel by means of an electrochemical technique is described. The main results obtained are as follows.
    (1) A degree of material degradation can be evaluation by the peak value of current density (ΔIp) obtained by the anodic polarization measurement. Since ΔIp corresponds to the rate of selective dissolution of coarse carbides M6C, the amount of M6C carbides can be evaluated quantitatively by ΔIp.
    (2) ΔIp shows a good correlation with ΔFATT. Hence, the toughness reduction can be nondestructively estimated by ΔIp measurement.
    (3) ΔIp can be regarded as a representative parameter showing the decrease in Mo concentration in grains caused by M6C (Mo-rich) carbide coarsening. ΔIp shows a good correlation with hardness change ΔHv. Based on this interrelation, the degree of softening can be nondestructively estimated.
    (4) The L.M.P. value of materials used in actual plants can be estimated by ΔIp measurement. Hence, the actual operational temperature can be estimated from the operation period with high accuracy.
  • 田中 啓介, 峰 典明, 鈴木 賢治, 川瀬 良一
    1991 年 40 巻 448 号 p. 96-101
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Alumina ceramics was coated on mild steel by a detonation gun with different quantities of detonation gas, and the residual stress in the coated film was measured by using the X-ray diffraction from the (844) plane of γ-alumina by Cu-Kα radiation. The mechanical Young's modulus increased with decreasing amount of cracks and pores in the coated film made under a larger quantity of detonation gas. The X-ray Young's modulus was larger than the mechanical one because the strain measured by X-rays was the average of crystalline phases. The residual stress measured by X-rays was tension and distributed uniformly in the coated film. The tensile residual stress was smaller for the coat made with larger gas quantity. It was rather insensitive to the film thickness and also to the surface grinding.
  • 貞廣 孟史, 栗田 広明, 今村 昭嗣
    1991 年 40 巻 448 号 p. 102-108
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    The characteristics of TiN film coated on WC-Co alloy by CVD process were studied as a function of surface roughness of the substrate which was prepared by grinding and re-sintering after ground. It was found that the orientation of TiN film decreased with increasing surface roughness of substrate. The residual stress of TiN film determined by X-ray stress measurement was tensile and that of WC phase in substrate was compressive. The critical load at scratch tests increased with increasing thickness of TiN film and surface roughness of substrate. The half value breadth in WC phase showed good correlation with the critical load at the scratch test.
  • 佐藤 彰, 黒部 利次
    1991 年 40 巻 448 号 p. 109-113
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Thin diamond blades are widely used for the precision slicing of electronic parts such as a magnetic head. It is well known that the elasticity of the blade has a great influence on the machining characteristics of work-pieces, i.e. chipping and residual stress. In this paper, a simple measuring method for the blade elasticity has been developed. From the comparison of this method with the conventional ones such as a vibrating reed method, it was found that the newly-developed method is capable of evaluating the elasticity of blade very well. Furthermore, from the results by the vibrating reed method, the effects of concentration and grain size on the blade elasticity were examined.
  • 池尻 忠夫
    1991 年 40 巻 448 号 p. 114-119
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
    Many tracking resistance tests of synthetic resin have hitherto been proposed, but no satisfactory test method has been derived because of the complication of tracking phenomena. In this paper, a new tracking resistance test was tried under the adequate consideration of various previous tests. In the test, commercial frequency A.C. voltage was applied between two electrodes with the maximum secondary voltage in high voltage transformer being 15kV and the capacity of transformer 1.5kVA. The progress of carbonized track from only one electrode was taken into consideration and the other electrode was floated. Under this electrode arrangement, the variation of length of track was measured by changing the applied voltage, the electrode gap length, etc. Test samples wetted thinly and uniformly with the mixture of 0.1% NH4Cl solution and 0.5% sodium dodecinyle benzen sulphonate solution were used. The length of carbonized track in the experiment was examined from the view point of tracking resistance. The results agreed reasonably well with those by the previous tracking test methods, confirming the applicability of the present method.
  • 岩崎 高明
    1991 年 40 巻 448 号 p. 120-126
    発行日: 1991/01/15
    公開日: 2009/06/03
    ジャーナル フリー
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