Refine your search:     
Report No.
Search Results: Records 1-20 displayed on this page of 68

Presentation/Publication Type

Initialising ...


Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...


Initialising ...


Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

A Study on convection in molten zone of aluminum alloy during Fe/Al resistance spot welding

Iyota, Muneyoshi*; Matsuda, Tomoki*; Sano, Tomokazu*; Shigeta, Masaya*; Shobu, Takahisa; Yumoto, Hirokatsu*; Koyama, Takahisa*; Yamazaki, Hiroshi*; Semba, Yasunori*; Ohashi, Haruhiko*; et al.

Journal of Manufacturing Processes, 94, p.424 - 434, 2023/05

 Times Cited Count:1 Percentile:84.05(Engineering, Manufacturing)

Journal Articles

Relationship between internal stress distribution and microstructure in a suspension-sprayed thermal barrier coating with a columnar structure

Yamazaki, Yasuhiro*; Shinomiya, Keisuke*; Okumura, Tadaharu*; Suzuki, Kenji*; Shobu, Takahisa; Nakamura, Yuiga*

Quantum Beam Science (Internet), 7(2), p.14_1 - 14_12, 2023/05

Journal Articles

Actual stress analysis of small-bore butt-welded pipe by complementary use of synchrotron X-rays and neutrons

Suzuki, Kenji*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa; Morooka, Satoshi

Zairyo, 72(4), p.316 - 323, 2023/04

Journal Articles

Direct energy conversion using Ni/SiC Schottky junction in $$^{237}$$Np and $$^{241}$$Am gamma ray regions

Fukuda, Tatsuo; Kobata, Masaaki; Shobu, Takahisa; Yoshii, Kenji; Kamiya, Junichiro; Iwamoto, Yosuke; Makino, Takahiro*; Yamazaki, Yuichi*; Oshima, Takeshi*; Shirai, Yasuhiro*; et al.

Journal of Applied Physics, 132(24), p.245102_1 - 245102_8, 2022/12

 Times Cited Count:0 Percentile:0(Physics, Applied)

Direct energy conversion has been investigated using Ni/SiC Schottky junctions with the irradiation of monochromatized synchrotron X-rays simulating the gamma rays of $$^{237}$$Np (30 keV) and $$^{241}$$Am (60 keV). From current-voltage measurements, electrical energies were obtained for both kinds of gamma rays. The energy conversion efficiencies were found to reach up to $$sim$$1.6%, which is comparable to those of a few other semiconducting systems reported thus far. This result shows a possibility of energy recovery from nuclear wastes using the present system, judging from the radiation tolerant nature of SiC. Also, we found different conversion efficiencies between the two samples. This could be understandable from hard X-ray photoelectron spectroscopy and secondary ion mass spectroscopy measurements, suggesting the formation of Ni-Si compounds at the interface in the sample with a poor performance. Hence, such combined measurements are useful to provide information that cannot be obtained by electrical measurements alone.

Journal Articles

A Study on stress measurement of weld part using double exposure method

Suzuki, Kenji*; Kura, Komoe*; Miura, Yasufumi*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Kajiwara, Kentaro*; Shobu, Takahisa

Zairyo, 71(12), p.1005 - 1012, 2022/12

This paper describes a stress measurement from a welded part of an austenitic stainless steel using synchrotron X-rays. Difficulty measuring the X-ray stress of the welded part is caused by the broadening of the diffraction spot in the radial and circumferential directions. The bending strains of the rectangular bar made of the welded part were measured using synchrotron white X-rays and the double exposure method. To improve the energy resolution, monochromatic synchrotron X-ray of 70 keV was used. The diffraction pattern showed the sharp arc like a pattern from texture material. The diffraction profile was obtained from the integral of the diffraction intensity in the direction of the circumference. The diffraction angle was determined using the double exposure method. As a result, the distribution of the residual stresses of the welded part could be measured.

Journal Articles

Stress measurements of quasi-coarse grained material using double exposure method with high-energy monochromatic X-rays

Suzuki, Kenji*; Yamada, Minami*; Shiro, Ayumi*; Shobu, Takahisa; Toyokawa, Hidenori*; Saji, Choji*

Zairyo, 71(4), p.347 - 353, 2022/04

We have already succeeded in the residual stress of aluminum alloys using the double exposure method (DEM) with 30 keV synchrotron radiation X-rays. However, the DEM has not be applied in the range of high-energy synchrotron X-rays. In this study, the stress measurements of a shrink-fitted ring using the DEM with synchrotron monochromatic X-rays beyond about 70 keV were performed. A CdTe pixel detector and a CCD camera were used as a detector. The shrink-fitted specimen of SUS304 was quasi-coarse grains of 43 micro-meters, and the diffraction rings were spotty. Despite quasi-coarse grains, it was possible to measure the stresses of the shrink-fitted specimen using the DEM. As a result, the DEM is excellent method to measures the stress for coarse grained materials. In addition, it is better to make the length between the detection positions longer to improve precision of the DEM. On the other hand, it was ineffective to increase the positions of detection.

Journal Articles

Feasibility study of magnetic-domain observation by means of non-resonant magnetic X-ray diffraction

Inami, Toshiya*; Shobu, Takahisa; Ishii, Kenji*

IEEE Transactions on Magnetics, 57(3, Part2), p.6400105_1 - 6400105_5, 2021/03

 Times Cited Count:0 Percentile:0(Engineering, Electrical & Electronic)

Journal Articles

Double-exposure method with synchrotron white X-ray for stress evaluation of coarse-grain materials

Suzuki, Kenji*; Shiro, Ayumi*; Toyokawa, Hidenori*; Saji, Choji*; Shobu, Takahisa

Quantum Beam Science (Internet), 4(3), p.25_1 - 25_14, 2020/09

It is difficult to evaluate stress by the strain scanning method using a conventional diffractometer and a point detector since the two-dimensional diffraction pattern of a material composed of coarse grains does not have a ring but a spotty. To solve this problem, we proposed a double exposure method using a two-dimensional detector and monochromatized X-rays. In this study, we have developed a technique to apply that technique to white X-rays. The diffraction obtained by irradiating white X-rays for a material with of coarse grains becomes a Laue spot. Therefore, we have carried out developing a CdTe pixel two-dimensional detector that can limit the energy to be detected, and we evaluated the stress using that detector. As a result, we succeeded to measure the strain distribution of a bending specimen made to austenitic stainless steel. In the future, we would like to improve this technology and apply it to actual machine materials.

Journal Articles

Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.

Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01

 Times Cited Count:1 Percentile:14.68(Materials Science, Multidisciplinary)

We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm$$^-1$$ and an overlapped shoulder around 0.7 nm$$^-1$$. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.

Journal Articles

Stress measurement of coarse grains using double exposure method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi*

Zairyo, 68(4), p.312 - 317, 2019/04

Materials after thermal processing such as welding often have coarse grains. To understand the residual stress after processing is very important from the viewpoint of the soundness of the structure. In this study, we proposed a double exposure method that combines a two-dimensional detector and high-energy synchrotron radiation as an X-ray stress measurement method for materials with coarse grains, and confirmed its practicality. As a result of measuring the residual stress of the plastic bending specimen and the indentation specimen of the aluminum alloy (A5052), the effectiveness of this measurement method was clarified because the residual stress distribution was in good agreement with the finite element analysis.

Journal Articles

Intergranular strains of plastically deformed austenitic stainless steel

Suzuki, Kenji*; Shobu, Takahisa

E-Journal of Advanced Maintenance (Internet), 10(4), p.9 - 17, 2019/02

In materials with an elastic anisotropy, a stress difference is generated between crystals when plastic deformation occurs, and it is known that this is deeply involved in material fracture. In this study, the residual stress for load direction in the plastically deformed material was investigated for each crystal orientation using the high-energy synchrotron radiation diffraction method. As a result, it was found that the residual stress is a tensile residual stress at an index with a high X-ray elastic constant (Young's modulus obtained for each diffraction surface) and a compressive residual stress at an index with a low X-ray elastic constant. We believe that this result will be useful for the technique of controlling the crystal orientation like the texture as improving the material strength.

Journal Articles

Evaluation of welding residual stresses using diffraction spot trace method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Advanced Materials Research, 996, p.76 - 81, 2014/08

 Times Cited Count:0 Percentile:0

Journal Articles

Stress evaluation in material with coarse grains using area detector

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Zairyo, 63(7), p.527 - 532, 2014/07

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 bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. 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.

Journal Articles

Internal stress measurement of weld part using diffraction spot trace method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Materials Science Forum, 777, p.155 - 160, 2014/02

 Times Cited Count:3 Percentile:83.17

Journal Articles

Residual stresses of water-jet peened austenitic stainless steel

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi

Zairyo, 62(7), p.437 - 442, 2013/07

The specimen material was austenitic stainless steel, SUS316L. The residual stress was induced by water-jet peening. The residual stress was measured using the 311 diffraction with conventional X-rays. The measured residual stress showed the equi-biaxial stress state. To investigate thermal stability of the residual stress, the specimen was aged thermally at 773 K in air to 1000 h. The residual stress kept the equi-biaxial stress state against the thermal aging. Lattice plane dependency of the residual stress induced by water-jet peening was evaluated using hard synchrotron X-rays. The residual stress measured by the soft lattice plane showed the equi-biaxial stress state, but the residual stress measured by the hard lattice plane did not. In addition, the distributions of the residual stress in the depth direction were measured using a strain scanning method with hard synchrotron X-rays and neutrons.

Journal Articles

Residual stresses in dissimilar metal joint by multi-pass welds

Suzuki, Kenji*; Yamagishi, Aoi*; Nishikawa, Satoru*; Shobu, Takahisa

Hozengaku, 11(2), p.91 - 98, 2012/07

In this study, a residual stress distribution in a dissimilar plate butt-welded joint was simulated by a thermo-elastic finite element method. The base metal was the austenitic stainless steel SUS316L. The other base metal was nickel super-alloy NCF600, and the weld metal was the alloy 82 (YNiCr-3). The dimensions of the plate butt-welded joint were a width of 200 mm, a length of 250 mm and a thickness of 25 mm. The welding joint was fabricated by TIG welding with 22 passes. For comparison, the residual stress distribution for the similar butt-welded joint of SUS316L was simulated as well as the dissimilar welded joint. According to the simulated results, there was not the difference in the thermal field between the similar and the dissimilar welded joints. The residual stress distribution in the similar welded joint became symmetrical to the welding center after removal of the weld bead. For the dissimilar welded joint, the peak of the residual stresses moved to the NCF600 side a little. The residual stress level of the dissimilar welded joint was large compared with the similar welded joint. The residual stress of the welding direction was larger than that of the transverse direction.

Journal Articles

Evaluation of internal stresses using area detectors

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Toyokawa, Hidenori*

Hozengaku, 11(2), p.99 - 106, 2012/07

An area detector technique has to be applied to the strain scanning method for materials with coarse grains. A new rotating slit system was designed for a 2-dimensional (2D) detector strain scanning method. The rotating slit system can focus the 2D detector on the center of the goniometer, and the gauge volume is made by the rotating slit system. The stress measurements were examined with the rotating slit and 2D detector. The measured diffraction spots shifted for the 2D strain scanning. The magnitude of the shift of the diffraction spot was very large as compared with the shift due to the strain. This phenomenon was caused by interaction between the gauge volume and the coarse grain. That is a coarse grain effect. To overcome the coarse grain effect, we propose a diffraction spot trace method (DSTM), which is constructed by the rotating slit and the PILATUS detector. The bending stress distribution of the coarse grain aluminum alloy was measured by DSTM. The measured stress was consistent with the applied stress.

Journal Articles

Residual micro-stresses in austenitic stainless steel due to high strain rate

Suzuki, Kenji*; Tanabe, Yuji*; Shobu, Takahisa

Hozengaku, 10(1), p.57 - 63, 2011/04

Austenitic stainless steel (SUS316L) was used as specimen material, and the plate specimens were deformed plastically with a wide range of strain rates (6.67$$times$$10$$^{-5}$$ $$sim$$ 6.70$$times$$10$$^{2}$$/s). The residual micro-stress for each lattice plane was measured with hard synchrotron X-rays. The residual macro-stress due to tensile deformation depended on strain rate. The residual micro-stresses varied from tension to compression, depending on the diffraction elastic constant. The soft lattice plane had tensile residual stress, and the hard lattice plane had compressive residual stress. The higher the strain rate, the smaller the difference in residual micro-stresses. The residual micro-stresses of the surfaces preened with the laser-preening or water-jet-preening were examined. Both surfaces had exhibited large compressive residual stress. The residual micro-stress on the peened surfaces showed a tendency opposite to residual micro-stress due to tensile deformation.

Journal Articles

Relaxation process of residual stress induced by laser peening

Akita, Koichi; Miyashita, Daisuke*; Takeda, Kazuya*; Oya, Shinichi*; Shobu, Takahisa; Sano, Kenji*; Saito, Toshiyuki*

Nihon Zairyo Gakkai Dai-44-Kai X Sen Zairyo Kyodo Ni Kansuru Shimpojiumu Koen Rombunshu, p.46 - 50, 2010/07

Relaxation process of surface compressive residual stress during tensile or compressive loading on a laser peened aluminum alloy was investigated. The residual stress was measured by X-ray, synchrotron and neutron diffractions and analyzed by a finite element method. The relaxation process clarified in this study was described as follows. When the tensile loading was increased, plastic deformation was occurred at the tensile residual stress region that existed inside of the material to be balanced with the surface compressive residual stress. On the other hand, when the compressive loading was applied, the plastic deformation was started at the maximum compressive residual stress region located just beneath the surface. Because the plastic deformation of the inside of the material induced the redistribution of the residual stress in the sample, the surface compressive residual stress was relaxed prior to the surface yielding.

Journal Articles

Internal stress in EB-PVD thermal barrier coating under heat cycle

Suzuki, Kenji*; Shobu, Takahisa

Materials Science Forum, 638-642, p.906 - 911, 2010/01

68 (Records 1-20 displayed on this page)