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Journal Articles

Deformation mechanism of a strong and ductile maraging steel investigated using ${it in situ}$ X-ray synchrotron diffraction

Li, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*

International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06

 Times Cited Count:0 Percentile:72.54(Engineering, Mechanical)

In order to clarify the strength properties of Co-free maraging steel, ${it in situ}$ tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.

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:72.41(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

In-operando measurement of internal temperature and stress in lithium-ion batteries

Hirano, Tatsumi*; Maeda, Takehiro*; Murata, Tetsuyuki*; Yamaki, Takahiro*; Matsubara, Eiichiro*; Shobu, Takahisa; Shiro, Ayumi*; Yasuda, Ryo*; Takamatsu, Daiko*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 11(1), p.49 - 57, 2023/02

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

Heat-induced structural changes in magnesium alloys AZ91 and AZ31 investigated by in situ synchrotron high-energy X-ray diffraction

Liu, X. J.*; Xu, P. G.; Shiro, Ayumi*; Zhang, S. Y.*; Shobu, Takahisa; Yukutake, Eitaro*; Akita, Koichi*; Zolotoyabko, E.*; Liss, K.-D.*

Journal of Materials Science, 57(46), p.21446 - 21459, 2022/12

 Times Cited Count:0 Percentile:21.52(Materials Science, Multidisciplinary)

Journal Articles

Crystallinity in periodic nanostructure surface on Si substrates induced by near- and mid-infrared femtosecond laser irradiation

Miyagawa, Reina*; Kamibayashi, Daisuke*; Nakamura, Hirotaka*; Hashida, Masaki*; Zen, H.*; Somekawa, Toshihiro*; Matsuoka, Takeshi*; Ogura, Hiroyuki*; Sagae, Daisuke*; Seto, Yusuke*; et al.

Scientific Reports (Internet), 12, p.20955_1 - 20955_8, 2022/12

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

We evaluated Laser-Induced Periodic Surface Structure (LIPSS) crystal structures using the stress imaging station at BL22XU of JAEA-BL on SPring-8. Crystallization of LIPPS was used different two types laser these are Ti:Sapphire laser (wavelength: 800 nm) and MIR-FEL (mid-infrared free electron laser, wavelength 11.4 $$mu$$m). These lasers are different in the laser pulse structure and the wavelength. We investigated on the effects of formed LIPSS crystallization using different kind of laser. Measured synchrotron X-ray energy is 30 keV and beam size is 20 $$mu$$m. Detector of diffracted X-ray is two-dimensional detector (PILATUS300K, DECTRIS). LIPSS formed using Ti:Sapphire laser has deformed structure with good crystallinity. LIPSS formed using MIR-FEL has dislocation or fault without structural stress. These results show depending on select of laser forming LIPPS structure. These information becomes important a point of the functional application of LIPSS.

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

Study of hierarchical deformation mechanism in LPSO-type magnesium alloys using diffraction method

Shiro, Ayumi*; Shobu, Takahisa; Hagihara, Koji*; Watanabe, Masashi*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 10(5), p.438 - 446, 2022/10

no abstracts in English

Journal Articles

Influence of pulse duration on mechanical properties and dislocation density of dry laser peened aluminum alloy using ultrashort pulsed laser-driven shock wave

Yoshida, Masayuki*; Nishihata, Itsuki*; Matsuda, Tomoki*; Ito, Yusuke*; Sugita, Naohiko*; Shiro, Ayumi*; Shobu, Takahisa; Arakawa, Kazuto*; Hirose, Akio*; Sano, Tomokazu*

Journal of Applied Physics, 132(7), p.075101_1 - 075101_9, 2022/08

 Times Cited Count:2 Percentile:76.55(Physics, Applied)

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

${it In situ}$ observation of recrystallization of aluminum single crystals using synchrotron radiation monochromatic X-rays

Shiro, Ayumi*; Shobu, Takahisa; Okada, Tatsuya*

Zairyo, 71(4), p.354 - 360, 2022/04

Recrystallization process of an aluminum (Al) single crystal was observed in situ using synchrotron X-rays. Al single-crystalline samples were deformed in tension along a $$<$$111$$>$$ direction to a strain of 8%, and were subsequently annealed at 753 K. The changes in the shape and intensity of diffraction spots were analyzed using a two-dimensional detector. A diffraction spot from the deformation matrix had three peaks which reflected a sub-grained microstructure of the sample. The ${it in situ}$ observation during annealing unveiled the appearance of diffraction spots from a recrystallized grain at 330.8 s. As the diffraction spots from the recrystallized grain became larger, the diffraction spots from the deformation matrix gradually disappeared. The application of the X-ray topography method revealed the crystal orientation variation in a recrystallized grain in order of 0.001 degree.

Journal Articles

Dissolution and precipitation behaviors of zircon under the atmospheric environment

Kitagaki, Toru; Yoshida, Kenta*; Liu, P.*; Shobu, Takahisa

npj Materials Degradation (Internet), 6(1), p.13_1 - 13_8, 2022/02

 Times Cited Count:1 Percentile:21.52(Materials Science, Multidisciplinary)

Journal Articles

${it In situ}$ synchrotron radiation observation of deformation and annealing processes of aluminum single crystal

Shiro, Ayumi*; Okada, Tatsuya*; Shobu, Takahisa

Mechanical Engineering Journal (Internet), 8(6), p.21-00106_1 - 21-00106_8, 2021/12

The objective of the present study was to carry out ${it In situ}$ observations of deformation and annealing processes of aluminum single crystals using a synchrotron radiation X-rays at SPring-8. Al single-crystalline samples having a 111 orientation parallel to the longitudinal direction were grown by a Bridgman method. The samples were deformed in tension to a nominal strain of 0.08 at room temperature using an in-line tensioning apparatus. Post-deformation annealing at 480 $$^{circ}$$C was subsequently carried out in the same apparatus. A two-dimensional detector was used to detect multiple diffracted beams from the sample during the deformation and annealing processes. The volume irradiated by the X-ray beam was found to be composed of three regions having a small orientation difference, which was attributable to sub-grained microstructures of the sample. Detailed analyses of a diffraction spot intensity showed that the sub-grained microstructures were surpassed by dislocated microstructures with the increase in the tensile strain. During the post-deformation annealing, diffraction spots from a recrystallized grain first appeared at 180 s after the temperature reached 480 $$^{circ}$$C. Coexistence of diffraction spots from the deformation matrix and recrystallized grain lasted only for about 22 s in the irradiated volume. The migration rate of the boundary between the deformation matrix and recrystallized grain was estimated to be of the order of several micrometers/s.

Journal Articles

Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*

Tetsu To Hagane, 107(9), p.760 - 768, 2021/09

 Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Evaluation of internal strain distribution of dissimilar laser welding using high energy X-rays

Shobu, Takahisa; Shiro, Ayumi*; Muramatsu, Toshiharu*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 9(5), p.318 - 323, 2021/08

Laser welding has already been put into practical use for various metal materials because the irradiation area is very small and the control is easy. In this study, we evaluated strain, stress, deformation, etc. near the processing affected area by high-energy synchrotron radiation X-ray diffraction method, which is one of the problems of laser welding of different materials that are expected to be put into practical use. As a result of internal deformation measurement of the bonding of dissimilar materials of copper and iron, it was confirmed that the copper side with a high coefficient of linear expansion was hardly deformed, strong tensile strain on the iron side, and a plastic deformation region on the heat-affected zone. In addition, a retained austenite phase, which is thought to be caused by the mixture of copper, was observed in the plastic deformation region of iron, and further problems were clarified in the evaluation of material strength in the mixed metallic materials.

Journal Articles

Internal strain distribution of laser lap joints in steel under loading studied by high-energy synchrotron radiation X-rays

Shobu, Takahisa; Shiro, Ayumi*; Kono, Fumiaki*; Muramatsu, Toshiharu; Yamada, Tomonori; Naganuma, Masayuki; Ozawa, Takayuki

Quantum Beam Science (Internet), 5(2), p.17_1 - 17_9, 2021/06

The automotive industries employ laser beam welding because it realizes a high energy density without generating irradiation marks on the opposite side of the irradiated surface. Typical measurement techniques such as strain gauges and tube X-rays cannot assess the localized strain at a joint weld. Herein high-energy synchrotron radiation X-ray diffraction was used to study the internal strain distribution of laser lap joint PNC-FMS steels (2- and 5-mm thick) under loading at a high temperature. As the tensile load increased, the local tensile and compressive strains increased near the interface. These changes agreed well with the finite element analysis results. However, it is essential to complementarily utilize internal defect observations by X-ray transmission imaging because the results depend on the defects generated by laser processing.

Journal Articles

Effects of stress and plastic strain on hydrogen embrittlement fracture of a U-bent martensitic steel sheet

Shibayama, Yuki; Hojo, Tomohiko*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Matsuno, Takashi*; Akiyama, Eiji*

ISIJ International, 61(4), p.1322 - 1329, 2021/04

 Times Cited Count:3 Percentile:30.42(Metallurgy & Metallurgical Engineering)

Journal Articles

Effects of residual stress on hydrogen embrittlement of a stretch-formed tempered martensitic steel sheet

Nishimura, Hayato*; Hojo, Tomohiko*; Ajita, Saya*; Shibayama, Yuki*; Koyama, Motomichi*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Akiyama, Eiji*

ISIJ International, 61(4), p.1170 - 1178, 2021/04

 Times Cited Count:3 Percentile:30.42(Metallurgy & Metallurgical Engineering)

297 (Records 1-20 displayed on this page)