材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
63 巻 , 7 号
選択された号の論文の12件中1~12を表示しています
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論文
  • 田中 啓介, 所 昇平, 小池 祐基, 江上 登, 秋庭 義明
    2014 年 63 巻 7 号 p. 514-520
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    The X-ray diffraction method is used to measure the residual stress in injection-molded plates of short-fiber reinforced plastics (SFRP) made of crystalline thermoplastics, polyphenylene sulphide (PPS), reinforced by carbon fibers with 30 mass%. Based on the orientation of carbon fibers, injection molded plates can be modeled as three-layered lamella where the core layer is sandwiched by two skin layers. The stress in the matrix in the skin layer was measured by Cr-Kα radiation by the sin2ψ method. Since the X-ray penetration depth is shallow, the state of stresses measured by X-rays in FRP can be assumed to be plane stress. The X-ray measurement of stress in carbon fibers was not possible because of high texture. A new method was proposed to evaluate the macrostress in SFRP from the measurement of the matrix stress. According to micromechanics analysis of SFRP, the matrix stresses in the fiber direction, σ1m and perpendicular to the fiber direction, σ2m, and shear stress τ12m can be expressed as the functions of the applied (macro) stresses, σ1A, σ2A, τ12A as follows: σ1m = α11σ1A + α12σ2A, σ2m = α21σ1A + α22σ2A, τ12m = α66τ12A, where α11, α12, α21, α22, α66 are stress-partitioning coefficients. Using skin-layer strips cut parallel, perpendicular and 45° to the molding direction, the stress in the matrix was measured under the uniaxial applied stress and the stress-partitioning coefficients of the above equations were determined. Once these relations are established, the macrostress in SFRP can be determined from the measurements of the matrix stresses by X-rays. Microscopic phase stresses due to the mismatch of the thermal expansion coefficient between matrix and fiber was negligible in X-ray stress measurement of the skin layer.
  • 冨永 真, 秋庭 義明
    2014 年 63 巻 7 号 p. 521-526
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    For the X-ray stress measurement in the region which has a steep stress gradient such as the neighborhood of a crack, a smaller irradiation area is required to estimate highly precise stresses. However, the reduction of the irradiated area brings a decrease in diffraction intensity and spotty diffraction pattern. In the conventional X-ray stress measurement using a scintillation counter, 1000 grains within the irradiated area and the oscillation method are recommended. However, for the sin2ψ method using a two-dimensional detector, effect of measurement conditions is not clear yet. In the present study, the effects of the oscillation condition and irradiated area on the accuracy of the stress measured by the sin2ψ method were investigated. For the oscillation effect, θ angle was more effective than χ angle. For the two-dimensional detector, the decrement of the number of grains required for accurate stress determination corresponded to the increase of the area of the detector. The stress distribution near a crack was able to be measured with the collimator diameter of 0.3 mm or more with enough accuracy for 2024-T3. It was suggested that actual stress could be evaluated by the reverse analysis of measured average stresses.
  • 鈴木 賢治, 菖蒲 敬久, 城 鮎美, 張 朔源
    2014 年 63 巻 7 号 p. 527-532
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    The spiral slit-system and DSTM (diffraction spot trace method) are under development in order to evaluate internal stresses of materials with coarse grains. The spiral slit-system was improved so that the length of the gauge volume is independent of the diffraction angle. The bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. The distribution of the measured bending stress coincided with the applied bending stress. As a result, it was proved that the combination of the advanced spiral slit-system and the DSTM is useful for the internal stress measurement of materials with coarse grains. The welded specimen of a Mg-alloy plate was prepared by melt-run with TIG welding. The residual stress map in the cross-section of the specimen was made using the DSTM. On the other hand, the residual stresses of the welded specimen were simulated by a finite element method. The measured residual stresses were similar to the simulated results, and the residual stresses due to extrusion were measured also using the DSTM. Therefore, the DSTM is suitable for the stress measurement of weld parts.
  • 柴野 純一, 梶原 堅太郎, 塚本 拓也, 河合 紘和, 三浦 節男, 張 朔源, 菖蒲 敬久
    2014 年 63 巻 7 号 p. 533-538
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    A ductile damage progress of an aluminum single crystal with the prior activity of the single slip system under tensile loading was verified by a profile analysis using white X-ray obtained in BL28B2 beam line of SPring-8. In this study, the aluminum single crystal of the purity 6N was used as a specimen prepared in I-type geometry for tensile test. A notch was introduced into one side of the center of a parallel part of the specimen by the wire electric discharge machining. White X-ray beam, which has 50 μm in both height and width, was incident into the specimen on the Bragg angle θ of 3 degrees using energy dispersive X-ray diffraction technique. The specimen was deformed by elongation in the direction of 45° to [111] and [110] crystal orientations, respectively, and a diffraction profile of the white X-rays from Al220 plane was analyzed. In profile analysis, an instrumental function was defined in consideration both of a divergence by slits and a response function peculiar to the energy dispersive method. The Gauss component of integral breadth related to non-uniform strain and the Cauchy component of integral breadth related to crystallite size were determined by eliminating the broadening by the instrumental function from the diffraction profile of white X-rays. As a result, dislocation density increased as ductile damage progressed, but it was relatively low near the notch. The influence of a release of the strain energy by a ductile damage progress was expected. The characteristics of ductile damage progress near the notch of the aluminum single crystal with a prior activity of a single slip system under the tensile loading were clarified from the distribution of dislocation density.
  • 八代 浩二, 鈴木 大介, 佐野 正明, 石黒 輝雄, 三井 由香里, 坂本 智明, 伊藤 友美, 片桐 隼人
    2014 年 63 巻 7 号 p. 539-544
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    For the application to the structure part of the magnesium alloy, material evaluations such as mechanical strength, fatigue property and property of stress corrosion cracking are necessary. Therefore, the X-ray stress measurement that is Non-destructive inspection is effective technique. However, there are few reports that described X-rays stress measurement about magnesium alloy. The report considered about X-ray elastic constant and stress constant in detail is not found. In this report, X-ray elastic and stress constants of rolled AZ61 magnesium alloy were measured. As result, by removing surface layer that has anelastic behavior and considering texture of specimen, X-ray elastic and stress constants can be measured. The X-ray elastic constants of AZ61 magnesium alloy in as received specimens were 41.2 GPa by using 1014 diffraction and 39.9 GPa by using 1015 diffraction.
  • 湯村 友亮, 前口 貴治, 栗村 隆之
    2014 年 63 巻 7 号 p. 545-550
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    In order to verify stability of residual stress improvement effect of peeing for mitigation of stress corrosion cracking in components of PWR plant, relaxation behavior of residual stress induced by water jet peening (WJP) on surface of alloy 600 weld metal (alloy 132) was investigated by in-situ X-ray residual stress measurement under thermal aging and stress condition considered for actual plant operation. Surface residual stress change was observed at the early stage of thermal aging at 360℃, but no significant further stress relaxation was observed after that. Applied stress below yield stress does not significantly affect stress relaxation behavior of surface residual stress. For the X-ray residual stress measurement, X-ray stress constant at room temperature for alloy 600 was determined experimentally with several surface treatment and existence of applied strain. The X-ray stress constant at elevated temperatures were extrapolated theoretically based on the X-ray stress constant at room temperature for alloy 600.
  • 伊原 涼平, 望月 正人
    2014 年 63 巻 7 号 p. 551-556
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    Residual stress is important factor for stress corrosion cracking (SCC) that has been observed near the welded zone in nuclear power plants. Especially, surface residual stress is significant for SCC initiation. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and residual stress distribution due to surface machining is varied by the subsequent butt welding. In previous paper, authors reported that residual stress distribution generated by bead on plate welding after surface machining has a local maximum residual stress near the weld metal. The local maximum residual stress shows approximately 900 MPa that exceeds the stress threshold for SCC initiation. Therefore, for the safety improvement of nuclear power plants, a study on the local maximum residual stress is important. In this study, the effect of surface machining and welding conditions on residual stress distribution generated by welding after surface machining was investigated. Surface machining using lathe machine and bead on plate welding with tungsten inert gas (TIG) arc under various conditions were conducted for plate specimens made of SUS316L. Then, residual stress distributions were measured by X-ray diffraction method (XRD). As a result, residual stress distributions have the local maximum residual stress near the weld metal in all specimens. The values of the local maximum residual stresses are almost the same. The location of the local maximum residual stress is varied by welding condition. It could be consider that the local maximum residual stress is generated by same generation mechanism as welding residual stress in surface machined layer that has high yield stress.
  • 坂井田 喜久, 稲山 朝仁, 矢代 茂樹
    2014 年 63 巻 7 号 p. 557-562
    発行日: 2014/07/15
    公開日: 2014/07/20
    ジャーナル フリー
    A chromium-molybdenum steel composed of 0.20 mass% carbon was used as a starting material. Two kinds of specimens having different case depths were made by carburizing and quenching. Using the scanning electron microscope, the crystallographic information was measured on the cross-sectional hardened layer by electron backscattering diffraction method. The kernel average misorientation, Θ, of the inverse pole figure were calculated from the carburized surface to the interior of each specimen. The area-average, Θmean, was compared to the case depth and the cross-sectional residual stress distribution measured by x-ray. As a result, the area-average of the hardened layer was larger than that of the interior of specimen after heat treatment. The estimated depth of the increment in the Θmean found to accord to the case depth and be proportional to the depth in which large compressive residual stress was distributed on the gradually polished surface. Therefore, the case depth and eigen strain distribution that induce the compressive residual stress can be indirectly estimated by electron backscattering diffraction method.
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