| TODA HIROYUKI | Last modified date：2024.04.18 |
Professor /
Strength of Materials /
Department of Mechanical Engineering /
Faculty of Engineering
Presentations
| 1. | F. Shuo，戸田裕之，藤原比呂, Surrogate-based Optimization for Fatigue Crack Initiation Behavior in Ti-6Al-4V Alloy, 日本鉄鋼協会 第187回春期講演大会, 2024.03. |
| 2. | H. Toda, Y. Wang, J. Tang, M. Yamaguchi, T. Tsuru, K. Shimizu, H. Fujihara, K. Hirayama, K. Ebihara, Hydrogen embrittlement and its prevention in Al-Zn-Mg alloys, Materials Research Meeting 2023, 2023.12. |
| 3. | K. Shimizu, S. Tsuchiya, H. Toda, H. Fujihara, M. Uesugi, A. Takeuchi, Y. Kamada, Development of hydrogen-resistant Al-Zn-Mg-Cu alloys by T-phase precipitation and trace element addition, Materials Research Meeting 2023, 2023.12. |
| 4. | J. Tang, Y. Wang, H. Fujihara, K. Hirayama, K. Shimizu, H. Toda, Stress corrosion cracking of high strength Al-Zn-Mg-Cu alloy with Mn-rich dispersoid and T(Al2Mg3Zn3) Phase, Materials Research Meeting 2023, 2023.12. |
| 5. | Y. Wang, N. Adachi, H. Fujihara, Y. Todaka, H. Toda, Hydrogen embrittlement of ultra-fine-grained Al-Zn-Mg-Cu alloys processed by high pressure torsion, Materials Research Meeting 2023, 2023.12. |
| 6. | H. Fujihara, H. Toda, K. Ebihara, M. Uesugi, A. Takeuchi, Influence of internal and external hydrogen accumulation behavior on stress corrosion cracking behavior in Al-Zn-Mg alloy, Materials Research Meeting 2023, 2023.12. |
| 7. | K. Hirayama, M. Doi, H. Toda, H. Fujihara, K. Shimizu, Analysis of hydrogen embrittlement mechanism in Al-Zn-Mg alloy by TEM observation, Materials Research Meeting 2023, 2023.12. |
| 8. | H. Toda, C. Koga, H. Fujihara, A. Takeuchi, M. Uesugi, K. Ishikawa, Multi-modal measurements of 3D crystallographic transformation behaviour in TRIP steel, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 9. | H. Fujihara, H. Toda, K. Ebihara, M. Kobayashi, M. Uesugi, A. Takeuchi , Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloy via multimodal 3D image-based analysis, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 10. | R. Higa, H. Fujihara, H. Toda, K. Ebihara, M. Kobayashi , Influence of crystal plasticity and hydrogen diffusion under stress on intergranular crack propagation in Al-Zn-Mg alloy, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 11. | K. Shimizu, S. Tsuchiya, H. Toda, H. Fujihara, M. Uesugi, A. Takeuchi, Y. Kamada, Deformation and fracture behavior of T-phase precipitated Al-Zn-Mg alloys under hydrogen influence using synchrotron imaging, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 12. | J. Tang, Y. Wang, H. Fujihara, K. Hirayama, K. Shimizu, H. Toda, Stress corrosion cracking of high strength Al-Zn-Mg-Cu alloy with mnrich dispersoid and T phase, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 13. | K. Horikawa, M. Hino, K. Shimizu, H. Toda, M. Hoshino, K. Uesugi, 3D measurement of internal microstructures of Al-Zn-Mg based alloy with Ni-P plating by means of synchrotron X-ray CT, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 14. | Y. Wang, J. Tang, H. Fujihara, N. Adachi, Y. Todaka, A. Takeuchi, M. Uesugi, H. Toda, Hydrogen embrittlement of ultra-finegrained Al-Zn-Mg-Cu alloys processed by high pressure torsion, ATEM-iDICs '23（The Advanced Technology in Experimental Mechanics and International DIC Society Joint Conference 2023）, 2023.10. |
| 15. | H. Fujihara, H. Toda, K. Ebihara, M. Kobayashi, K. Shimizu, A. Takeuchi, M. Uesugi, Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloys by multimodal 3D image-based simulation, IHC2023（International Hydrogen Conference 2023）, 2023.09. |
| 16. | A. Ahmed, S. Lee, T. Tsuchiya, K. Matsuda, K. Nishimura, N. Numomura, H. Toda, K. Hirayama, K. Shimizu, M. Yamaguchi, T. Tsuru, M. Itakura, Microstructure observation of Al-Zn-Mg alloy with high Mg content, Thermec’2023（International Conference on Processing & manufacturing of advanced Materials）, 2023.07. |
| 17. | Y. Wang, B. Sharma, Y. Xu, K. Shimizu, H. Fujihara, H. Toda, Role of T phase in the hydrogen embrittlement suppression for Al-Zn-Mg-Cu alloys, IHC2023（International Hydrogen Conference 2023）, 2023.09. |
| 18. | K. Shimizu, Y. Wang, H. Fujihara, H. Toda, M. Yamaguchi, M. Uesugi, A. Takeuchi, Prevention of hydrogen embrittlement in Al-Zn-Mg alloys by dispersion of novel phases, IHC2023（International Hydrogen Conference 2023）, 2023.09. |
| 19. | A. Ahmed, S. Lee, T. Tsuchiya, K. Matsuda, K. Nishimura, N. Numomura, H. Toda, K. Hirayama, K. Shimizu, M. Yamaguchi, T. Tsuru, M. Itakura, Observation of microstructure morphology in Al-Zn-Mg alloy with low Zn/Mg ratio, 日本金属学会春期（第172回）講演大会, 2023.03. |
| 20. | A. Ahmed, S. Lee, T. Tsuchiya, K. Matsuda, K. Nishimura, N. Numomura, H. Toda, K. Hirayama, K. Shimizu, M. Yamaguchi, T. Tsuru, M. Itakura, Microstructure observation of Al-Zn-Mg alloys with low Zn/Mg ratio, 軽金属学会第143回秋期大会, 2022.11. |
| 21. | H. Toda, M. Yamaguchi, T. Tsuru, K. Shimizu, H. Fujihara, K. Hirayama, K. Ebihara, K. Matsuda, Hydrogen embrittlement in Al-Zn-Mg alloys: Semi-spontaneous interfacial decohesion of precipitates, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 22. | K. Nishimura, K. Matsuda, N. Nunomura, T. Namiki, S. Lee, W. Higemoto, T. Tsuru, T. Matsuzaki, I. Watanabe, K. Shimizu, H. Toda, Solute-hydrogen binding energies in aluminum studies by Muon spin relaxation method, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 23. | T. Tsuru, K. Shimizu, M. Yamaguchi, M. Itakura, K. Ebihara, A. Bendo, K. Matsuda, H. Toda, Hydrogen trapping and quasi-cleavage fracture in Al-Zn-Mg alloy, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 24. | S. Lee , T. Tsuchiya, K. Uttaraksa, K. Hirao, K. Matsuda, K. Nishimura, N. Nunomura, H. Toda , K. Hirayama , K. Shimizu , M. Yamaguchi, T. Tsuru, M. Itakura, TEM observation of the interface between the β phase and Al matrix in Al-Mg-Si alloy, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 25. | R. Ono, K. Shimizu, Y. Kamada, H. Toda, H. Fujihara, A. Takeuchi, Effect of high temperature aging on hydrogen embrittlement in 7XXX alloys, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 26. | K. Shimizu, H. Toda, H. Fujihara, K. Hirayama, M. Yamaguchi, A. Takeuchi, Prevention of hydrogen embrittlement via preferential hydrogen partitioning to particles, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 27. | Y. Wang, B. Sharma, Y. Xu, K. Shimizu, H. Fujihara, K. Hirayama, A.Takeuchi, M. Uesugi , H. Toda, Improved resistance to hydrogen embrittlement by switched age-hardening precipitates for high-strength aluminum alloys, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 28. | R. Higa, H. Fujihara, H. Toda , K. Ebihara , M. Kobayashi , T. Mayama, Multi-modal 3D image-based simulation of initiation of hydrogen embrittlement in Al-Zn-Mg alloy, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 29. | H. Fujihara, H. Toda, K. Ebihara, M. Kobayashi, A. Takeuchi, M. Uesugi, Influence of hydrogen accumulation behavior under stress on hydrogen embrittlement in Al-Zn-Mg alloy with multi-modal 3D image-based analysis, ICAA18（The 18th International Conference on Aluminium Alloys）, 2022.09. |
| 30. | Y. Suzuki, H. Toda, A. Takeuchi, Hard X-ray schlieren microscopy and its application to computer tomography, International Conference on X-ray Microscopy, 2022.06. |
| 31. | B. Sharma, Y. Wang, H. Fujihara, K. Shimizu, K. Hirayama, A. Takeuchi, M. Uesugi, H. Toda, Hydrogen embrittlement prevention in Al-Zn-Mg by Sn addition, 軽金属学会第142回春期大会, 2022.05. |
| 32. | 比嘉良太，藤原比呂，戸田裕之，小林正和，平山恭介，清水一行，海老原健一, Al-Zn-Mg合金における水素脆化亀裂発生挙動のマルチモーダル3Dイメージベース解析, 軽金属学会第142回春期大会, 2022.05. |
| 33. | 福田祐輝，藤原比呂，平山恭介，戸田裕之，竹内晃久，上椙真之, 7075アルミニウム合金の金属間化合物粒子の水素誘起損傷挙動の統計学的解析, 軽金属学会第142回春期大会, 2022.05. |
| 34. | 山口翔吾，戸田裕之，藤原比呂，平山恭介，竹内晃久，上椙真之, Al-Zn-Mg合金における水素脆化亀裂の結晶学的発生挙動のメタモデル解析, 軽金属学会第142回春期大会, 2022.05. |
| 35. | S. Lee, T. Tsuchiya, K. Uttarasak, K. Hirao, K. Matsuda, K. Nishimura, N. Nunomura, H. Toda, K. Hirayama, K. Shimizu, M. Yamguchi, K. Ebihara, M. Itakura, T. Tsuru, Microstructure observation of β-phase in aged at 673K and as cast Al-Mg2Si alloys, 軽金属学会第142回春期大会, 2022.05. |
| 36. | V. Tubei, H. Toda, A. Takeuchi, M. Uesugi, Three-dimensional time evolution behavior of short fatigue crack morphology and crack closure in Ti-6Al-4V alloy assessed using high-energy imaging type CT, TMS 2022 Annual Meeting & exhibition, 2022.03. |
| 37. | M. Yamaguchi, T. Tsuru, K. Ebihara, M. Itakura, Hydrogen Trapping Energy at Incoherent Boundary in Aluminum Alloy: First-Principles Calculations, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 38. | T. Tsuru, K. Shimizu, M. Yamaguchi, M. Itakura, K. Ebihara, A. Bendo, K. Matsuda, H. Toda, Hydrogen-accelerated cleavage in high strength aluminium alloys, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 39. | H. Fujihara, H. Toda, K. Ebihara, M. Kobayashi, A. Takeuchi, M. Uesugi, S. Yasuda, Influence of hydrogen accumulation behavior under stress on hydrogen embrittlement in Al-Zn-Mg alloy, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 40. | S. Lee, K. Takemoto, T. Tsuchiya, K. Matsuda, K. Nishimura, N. Nunomura, H. Toda, H. Gao, K. Hirayama, K. Shimizu, M. Yamaguchi, K. Ebihara, M. Itakura, T. Tsuru, Effect of hydrogen on precipitation behavior in low Zn/Mg ratio Al-Zn-Mg alloy, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 41. | K. Nishimura, K. Matsuda, N. Nunomura, T. Namiki, S. Lee, W. Higemoto, T. Tsuru, T. Matsuzaki, I. Watanabe, K. Shimizu, H. Toda, Hydrogen Trapped Sites in Al-Mg and Al-Cu alloys studied by Muon Spin Relaxation Method, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 42. | H. Toda, M. Yamaguchi, T. Tsuru, K. Shimizu, K. Hirayama, K. Ebihara, K. Matsuda, Hydrogen embrittlement mechanism of Al-Zn-Mg alloys: semi-spontaneous interfacial decohesion, MRM2021 (Materials Research Meeting 2021), 2021.12, [URL]. |
| 43. | V. Tubei, H. Toda, K. Hirayama, M. Hassanipour, A. Takeuchi, M. Uesugi, Application of High Energy Imaging CT to Investigate Local 3D Short Fatigue Crack Closure Behavior in Ti-6Al-4V Alloy, 3DMS2021(The 5th International Congress on 3D Materials Science), 2021.06. |
| 44. | V. Tubei, H. Toda, M. Hassanipour, K. Hirayama, A. Takeuchi, M. Uesugi, Three-dimensional observation of complex short fatigue crack morphology and variation in crack closure behavior using nano-tomography, 第6回マルチスケール材料力学シンポジウム, 2021.05. |
| 45. | H. Toda, K. Hirayama, K. Shimizu, K. Uesugi, A. Tkauchi, Application of high-resolution X-ray tomography to hydrogen embrittlement in aluminium, ICAA17 (The 17th International Conference on Aluminium Alloys), 2020.10. |
| 46. | K. Hirayama, Y. Sek, H. Toda, M. Uesugi, A. Takeuchi, Direct measurement of internal stress of particle in Al-Si alloy using fine beam XRD, ICAA17 (The 17th International Conference on Aluminium Alloys), 2020.10. |
| 47. | M. Hassanipour, S. Watanabe, H. Li, K. Hirayama, H. Toda, A. Takeuchi, K. Uesugi, A surrogate approach to reveal microstructural mechanisms controlling the 3D short crack growth in a Ti-6Al-4V alloy, 14th World Conference on Titanium (Ti 2019), 2020.06. |
| 48. | K. Shimizu, H. Toda, K. Hirayama, H. Fujihara, K. Uesugi, A. Takeuchi, Influence of Hydrogen Partitioning on Deformation and Fracture Behavior in Al-Zn-Mg Alloys, TMS 2020 Annual Meeting & Exhibition, 2020.02. |
| 49. | V. Tubei, H. Toda, K. Hirayama, A. Takeuchi, M. Uesugi, Investigation of 3D short fatigue crack closure behavior in Ti-6Al-4V alloy using high energy imaging CT, 軽金属学会第138回春期大会, 2020.01. |
| 50. | H. Fujihara, H. Toda, K. Shimizu, A. Takeuchi, K. Uesugi, Assessment of hydrogen accumulation behavior in Al-Zn-Mg alloys during deformation, Euromat 2019 (European congress and exhibition on advanced materials and processes 2019), 2019.09. |
| 51. | K. Shimizu, H. Toda, H. Su, H. Fujihara, K. Uesugi, A. Takeuchi, Influence of hydrogen partitioning on deformation and fracture behavior in Al-Zn-Mg alloys, Euromat 2019 (European congress and exhibition on advanced materials and processes 2019), 2019.09. |
| 52. | H. Toda, K, Hirayama, H. Su, K. Shimizu, O. Takakuwa, A. Takeuchi, K. Uesugi, Recent progress in high resolution X-ray tomography at high X-ray energies, PRICM 10(The 10th Pacific Rim International Conference on Advanced Materials and Processing), 2019.08. |
| 53. | V. Tubei, M. Hassanipour, S. Watanabe, K. Hirayama, H. Toda, A. Takeuchi, K. Uesugi, Assessment of 3D short crack closure in Ti-6Al-4V alloy utilizing synchorotron X-ray microtomography, 合同学術講演会, 2019.06. |
| 54. | V. Tubei, M. Hassanipour, S. Watanabe, K. Hirayama, H.Toda, A. Takeuchi, K. Uesugi, Assessment of 3D short crack closure in Ti-6Al-4V alloy utilizing synchrotron X-ray micro-tomography, 14th World Conference on Titanium, 2019.06. |
| 55. | M. Hassanipour, S. Watanabe, H. Li, K. Hirayama, H. Toda, A. Takeuchi, K. Uesugi, Assessment of predominant microstructural features controlling 3D short crack growth behavior via a surrogate approach in Ti-6Al-4V, Titanium 2019 (The 14th World Conference on Titanium), 2019.06. |
| 56. | V. Tubei, M. Hassanipour, K. Hirayama, H, Toda, A. Takeuchi, K. Uesugi, Assessment of 3D short crack closure in Ti-6Al-4V alloy utilizing synchrotron X-ray microtomography, Titanium 2019 (The 14th World Conference on Titanium), 2019.06. |
| 57. | ベンド アルテニス, 土屋大樹, 李昇原, 松田健二, 西村克彦, 布村紀男, 戸田裕之, 平山恭介, 清水一行, 山口正剛, 海老原健一, 板倉充洋, 都留智仁, 西川知志, 柴田果林, Microstructure evolution of hydrogen charged and subsequently aged Al-Zn-Mg alloy, 日本金属学会第164回春期講演大会, 2019.03. |
| 58. | M. Hassanipour, S. Watanabe, K. Hirayama, H. Toda, H. Li, K. Uesugi, A. Takeuchi, Complex 3D microstructure and short crack growth correlation by a surrogate model in Ti-6Al-4V, TMS 2019 (148th Annual Meeting & Exhibition), 2019.03. |
| 59. | D. Fu, H. Toda, H. Su, K. Hirayama, K. Uesugi and A. Takeuchi, 4D characterization of the stress corrosion cracking behavior in Al-10Mg aluminium alloy via synchrotron X-ray tomography, 29th International Ocean and Polar Engineering Conference, ISOPE 2019, 2019.01. |
| 60. | V. Tubei, H. Toda, K. Hirayama, A. Takeuchi, M. Uesugi, Assessment of 3D short crack closure in Ti-6Al-4V alloy utilizing synchrotron X-ray microtomography, 第101回軽金属学会九州支部例会, 2019.01. |
| 61. | M. Hassanipour, S. Watanabe, K. Hirayama, H. Li, H. Toda, A. Takeuchi, K. Uesugi, Transitional effect of 3D microstructural features on short crack growth behavior in Ti-6Al-4V alloy, M&M2018材料力学カンファレンス, 2018.12. |
| 62. | V. Tubei, M. Hassanipour, S. Watanabe, K. Hirayama, H. Toda, A. Takeuchi, K. Uesugi, Assessment of 3D short crack closure in Ti-6Al-4V alloy utilizing synchrotron X-ray microtomography, 日本機械学会 M&M2018材料力学カンファレンス, 2018.12. |
| 63. | H. Toda, H. Su, K. Shimizu, H. Fujihara, K. Hirayama, A. Takeuchi, K. Uesugi, Assessment of hydrogen embrittlement via in-situ imaging techniques in high Zn Al-Zn-Mg alloys, ECF22(22nd European Conference on Fracture), 2018.08. |
| 64. | H. Toda, K. Hirayama, K. Shimizu, K. Uesugi, Application of high-resolution X-ray tomography to hydrogen embrittlement in aluminium, THERMEC'2018, 2018.07. |
| 65. | H. Fujihara, H. Toda, K. Shimizu, A. Takeuchi, K. Uesugi, Assessment of hydrogen accumulation behavior in stressed Al-Zn-Mg aluminum alloys by means of Kelvin force microscopy, ICAA16 (The 16th International Conference on Aluminium Alloys), 2018.06. |
| 66. | K. Shimizu, H. Toda, H. Gao, K. Uesugi, A. Takeuchi, Hydrogen-induced strain loclization and nano-voids in an Al-Zn-Mg alloy, ICAA16 (The 16th International Conference on Aluminium Alloys), 2018.06. |
| 67. | 蘇航, 清水一行, 戸田裕之, 上杉健太朗, 竹内晃久, イメージベース解析による高Zn Al-Zn-Mg-Cu合金における水素分配挙動の評価, 日本鉄鋼協会第175回春季講演大会, 2018.03. |
| 68. | 蘇航, 戸田裕之, 清水一行, 上杉健太朗, 竹内晃久, 水素分配制御に基づくAl-Zn-Mg合金の力学特性最適化, 日本機械学会九州支部第71期総会, 2018.03. |
| 69. | H. Toda, K. Shimizu, H. Gao, K. Hirayama, 4D hydrogen embrittlement behaviour in high strength aluminium alloy, TMS 2018 Annual Meeting & Exhibition, 2018.03. |
| 70. | Hassanipour Meysam, 渡邉信太, 戸田裕之, 上杉健太朗, 竹内晃久, Ti-6Al-4V合金における微小疲労亀裂伝播に及ぼす3Dミクロ組織の影響, 軽金属学会第133回秋季講演大会, 2017.11. |
| 71. | H. Toda, Optimization of fatigue resistance of Al-Si alloys via reverse 4D materials engineering, The 14th Asian Foundry Congress, 2017.11. |
| 72. | M. Hassanipour, S. Watanabe, H. Toda, K. Uesugi, A. Takeuchi, Ti-6Al-4V合金における微小疲労き裂伝播挙動に及ぼす 3 次元ミクロ組織の影響, M&M2017材料力学カンファレンス, 2017.10. |
| 73. | 蘇航, 戸田裕之, 上杉健太朗, 竹内晃久, 坂口信人, 渡辺良夫, Influence of intermetallic particles on the hydrogen partitioning and embrittlement in Al-Zn-Mg-Cu aluminum alloys, 日本金属学会第161回秋期講演大会, 2017.09. |
| 74. | H. Li, D. Seo, H. TODA, R. Batres, Optimization of ductile fracture of aluminum via reverse 4D materials engineering, 日本金属学会 第160回春期講演大会, 2017.03. |
| 75. | H. Toda, K. Shimizu, H. Gao, K. Hirayama, 4D hydrogen embrittlement behaviour in high strength aluminium alloy, 14th International Conference on Fracture, ICF 2017, 2017.01, X-ray microtomography technique was used to observe hydrogen-induced strain localization, nano void formation and brittle fracture behaviour in a model Al-Zn-Mg ternary alloy. The alloy exhibited remarkable hydrogen embrittlement during an ordinary tensile test due to hydrogen uptake during its electro discharge machining. Very sharp cracks of about 1-2 m in CTOD were initiated and propagated after characteristic intense strain localization is observed, which we measured in a series of tomographic volumes by tracking tens of thousands of microstructural features. It is noteworthy that hydrostatic expansion was observed where the strain localisation was observed. This expansion was attributable to the formation of high density nano voids by utilizing the ultra-high magnification X-ray microscopy at a synchrotron radiation facility combined with STEM-HAADF observation.. |
| 76. | H. Su, H. Toda, R. Masunaga, K. Uesugi, A. Takeuchi, Y. Watanabe, Hydrogen induced strain localization in Al-Zn-Mg-Cu aluminum alloys, 14th International Conference on Fracture, ICF 2017, 2017.01. |
| 77. | H. Toda, K. Hirayama, M. Kobayashi, A. Takeuchi, K. Uesugi, Assessment of damage behavior of aluminum using diffraction-amalgamated grain boundary tracking technique, 2017 MRS Fall meeting, 2017.01. |
| 78. | M. S. Bhuiyan, H. Toda, K. Uesugi, A. Takeuchi, N. Sakaguchi, Y. Watanabe, Influence of hydrogen on crack propagation behavior in 7XXX aluminum alloys, 2016 International Hydrogen Conference, 2016.09. |
| 79. | K. Shimizu, H. Toda, K. Sasaki, K. Uesugi, A. Takeuchi, 3D/4D hydrogen embrittlement behavior in Al-8.4Zn-1.0Mg alloys, 2016 International Hydrogen Conference, 2016.09. |
| 80. | S. Gennai, M. Teranishi, O. Kuwazuru, M. Kobayashi, H. Toda, Relationship between microscopic fatigue life of inclusions and its geometrical property in cast aluminum alloys, Asian-Pacific Conference on Fracture and Strength 2016, 2016.09. |
| 81. | M. Teranishi, K.Matsumura, S. Gennal, O. Kuwazuru, M. Kobayashi, H. Toda, Image-based finite element elasto-plastic analysis of cast aluminum alloy including Si particles and intermetallic compounds, Asian-Pacific Conference on Fracture and Strength 2016, 2016.09. |
| 82. | H. Fujihara, H. Toda, K. Shimizu, A. Takeuchi, K. Uesugi, Hydrogen trapping behavior in Al-Zn-Mg alloys, The 9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 9), 2016.08. |
| 83. | H. Su, H. Toda, R. Masunaga, K. Uesugi, A. Takeuchi, N. Sakaguchi, Y. Watanabe, 3D strain mapping applied to hydrogen embrittlement in Al- Zn-Mg-Cu aluminum alloys, The 9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 9), 2016.08. |
| 84. | K. Tanaka, H. Toda, K. Hirayama, A. Takeuchi, K. Uesugi, Stress analysis on internal particles in Al-Si alloy using X-ray diffraction amalgamated grain boundary tracking, The 9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 9), 2016.08. |
| 85. | M. Kobayashi, A. Kouno, T. Matsuyama, H. Toda, H. Miura, O. Kuwazuru, 3D characterization of inhomogeneous deformation in grain microstructure of alminum alloy, 3DMS2016, 2016.07. |
| 86. | H. Toda, H. Li, D. Seo, R. Batres, O. Kuwazuru, Optimization of microstrucutre via 3D image-based simulation, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 87. | K. Hirayama, H. Toda, K. Uesugi, A. Takeuchi, Evaluation of cristallographic deformation behavior in aluminium alloy by means of diffraction-amalgamated grain-boundary tracking(DAGT) technique, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 88. | A. Takeuchi, K. Uesugi, H. Toda, M. Kobayashi, High-rexolution X-ray computed tomography at SPring-8 and improvements of imaging properties, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 89. | O. Kuwazuru, M. Teranishi, K. Matsumura, S. Gennai, M. Kobayashi, H. Toda, Image-based finite element analysis for fatigue of cast aluminum alloy, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 90. | A. Hosokawa, H. Toda, R. Batres, O. Kuwazuru, M. Kobayashi, H. Li, H. Yakita, Image-based finite element analysis of ductile fracture via hydrogen pore mechanism in an aluminum alloy, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 91. | K. Hirayama, H. Toda, K. Uesugi, A. Takeuchi, Evaluation of crystallographic deformation behavior in aluminium alloy by means of diffraction-amalgamated grain-boundary tracking (DAGT) technique, The 3rd International Congress on 3D Materials Science 2016, 2016.07. |
| 92. | K. Hirayama, H. Toda, K. Uesugi, A. Takeuchi, Assessment of deformation behavior in aluminum alloy with diffraction-amalgamated grain-boundary tracking (DAGT) technique, 15th International Conference on Aluminium Alloys (ICAA 15), 2016.06. |
| 93. | D. Seo, H. Toda, H. Li, R. Baters, K. Uesugi, A.Takeuchi, Microstructure of optimization for damage evolution in ductile deformation by R4ME methology, 15th International Conference on Aluminum Alloys (ICAA 15), 2016.06. |
| 94. | H. Toda, M. Kobayashi , K. Hirayama, Application of diffraction-amalgamated grain-boundary tracking to deforming aluminium polycrystals, THERMEC 2016, 2016.05. |
| 95. | R. Yamada, H. Toda, Y. Besel, K. Uesugi, A. Takeuchi, Damage behavior of micro segregation in Al-Si alloy by use of phase contrast imaging, 72nd World Foundry Congress, WFC 2016, 2016.05. |
| 96. | 蘇航, 益永涼平, 戸田裕之, 上杉健太朗, 竹内晃久, 坂口信人, 渡辺良夫, 3D strain mapping applied to hydrogen embrittlement in Al-Zn-Mg-Cu aluminum alloys, 日本金属学会 第158回春期講演大会, 2016.03. |
| 97. | R. Yamada, H. Toda, Y. Besel, K. Uesugi, A.Takeuchi, Damage behavior of micro segregation in Al-Si alloy by use of phase contrast imaging, 72nd World Foundry Congress, WFC 2016, 2016.01, Some segregation in casting alloys are microstructural defects and degrade mechanical properties of the alloys. Therefore it is important to understand the influence of the distribution of segregation regions on fracture behavior. In this study, tensile test was carried out on an Al-Si cast alloy. Three-dimensional (3D) in-situ observation of its tensile fracture behavior was performed by means of the synchrotron X-ray computed tomography (CT) technique. Some segregation regions have similar density to that of the matrix. Phase retrieval processing, which is one of the phase contrast imaging techniques, enables us to distinguish such segregations based on X-ray CT tomographic images. Fracture path was identified by comparing unfractured and fractured 3D volumes. Grey values of each voxel in CT images correlate to the density of the material after the phase retrieval processing. Examining grey values of voxels on the extracted fracture path, it was found that fracture occurred preferably around the segregation part with high density.. |
| 98. | K. Hirayama, H. Toda, K. Uesugiand A. Takeuchi, Evaluation of crystallographic deformation behavior in aluminium alloy by means of diffraction-amalgamated grain-boundary tracking (DAGT) technique, The 3rd International Congress on 3D Materials Science 2016, 2016.01. |
| 99. | K. Hirayama, H. Toda, K. Uesugi, A. Takeuchi, Assessment of deformation behavior in aluminum alloy with diffraction-amalgamated grain-boundary tracking (DAGT) technique, 15th International Conference on Aluminium Alloys (ICAA15), 2016.01. |
| 100. | D. Seo, H. Toda, H. Li, R. Baters, K. Uesugi, A.Takeuchi, Microstructure of optimization for damage evolution in ductile deformation by R4ME methology, 15th International Conference on Aluminum Alloys (ICAA15), 2016.01. |
| 101. | 蘇航, 戸田裕之, 上杉健太朗, 竹内晃久, 坂口信人, 渡辺良夫, Growth behavior of hydrogen micro pores in Al-Zn-Mg-Cu alloys during high temperature exposure, 軽金属学会第129回秋期講演大会, 2015.11. |
| 102. | Bhuiyan Md Shahnewaz, 戸田裕之, 多田雄貴, 上杉健太朗, 竹内晃久, 坂口信人, 渡辺良夫, Hydrogen assisted damage and fracture behaviors in high strength 7XXX aluminum alloys, 軽金属学会第129回秋期講演大会, 2015.11. |
| 103. | H. Li, H. Toda, R. Batres, D. Seo, Microstructural optimization in reverse 4D materials engineering, 2015.10. |
| 104. | K. Hirayama, H. Toda, Y. Tanabe, T. Shimoji, K. Tanaka, M. Kobayashi, K. Uesugi, A. Takeuchi, Plastic deformation behavior of aluminum alloy investigated means of diffraction-amalgamated grain-boundary tracking (DAGT) technique, International Conference on Advanced Technology in Experimental Mechanics 2015 (ATEM' 15), 2015.10. |
| 105. | H. Toda, Assessment of damage behavior of aluminum using diffraction-amalgamated grain-boundary tracking technique, EUROMAT 2015, 2015.09. |
| 106. | 蘇航, 戸田裕之, 上杉健太朗, 竹内晃久, Growth behavior of hydrogen micro pores in Al-Zn-Mg-Cu alloys during high temperature exposure, 日本金属学会 第157回秋期講演大会, 2015.09. |
| 107. | H. Toda, Origin of ductile fracture in aluminium alloys, IUTAM Symposium on Plastic localization and ductile failure, 2015.03. |
| 108. | H. Su, H. Toda, K. Uesugi, A. Takeuchi, Y. Suzuki, Growth behavior of hydrogen micro pores in Al-Zn-Mg-Cu alloys during high temperature exposure, Materials Science and Technology Conference and Exhibition 2015, MS and T 2015, 2015.01. |
| 109. | K. Shimizu, H. Toda, K. Sasaki, K. Uesugi, A. Takeuchi, Optimization of hydrogen embrittlement in Al-Zn-Mg alloys, Materials Science and Technology Conference and Exhibition 2015, MS and T 2015, 2015.01. |
| 110. | V.A. de Souza, O. Kuwazuru, M. Kobayashi, H. Toda, Experimental and numerical investigation on the chronology of fatigue damage in cast aluminum alloy using microtomography CT, image processing and image-based finite element analysis, International Symposium on Plasticity, 2015.01. |
| 111. | 戸田 裕之, T. Kamiko, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Diffraction–amalgamated grain boundary tracking technique, The 2nd International Congress on 3D Materials Science 2014, 2014.06. |
| 112. | 戸田 裕之, F. Tomozato, R. Harasaki, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Single-distance phase retrieval for DP structures in steels, The 2nd International Congress on 3D Materials Science 2014, 2014.06. |
| 113. | H. Li, H. Toda, K. Uesugi, A. Takeuchi, Y. Suzuki and M. Kobayashi, Application of diffraction-amalgamated grain boundary tracking to fatigue crack propagation behavior in high strength aluminum alloy, The 2nd International Congress on 3D Materials Science (3DMS 2014), 2014.06. |
| 114. | Hui Li, Hiroyoki Toda, Kentaro Uesugi, Akihisa Takeuchi, Yoshio Suzuki, Masakazu Kobayashi, Application of Diffraction-Amalgamated Grain Boundary Tracking (DAGT) to fatigue crack propagation behavior in high strength aluminum alloy, 2nd International Congress on 3D Materials Science, 3DMS 2014, 2014.01, The fatigue crack propagation behavior in an Al-Zn-Mg-Cu alloy was investigated by amalgamating X-ray diffraction (XRD) with grain boundary tracking (GBT). The integrated technique, Diffraction-Amalgamated Grain Boundary Tracking (DAGT), provides new possibilities for mapping grain morphologies and crystallographic orientations in three-dimension (3D). 3D crack morphologies at different propagation stages in the bulk of metallic materials were successfully obtained by using Synchrotron Radiation X-ray Microtomography (SRCT). Using 2D slices of the 3D crack, the crack length increment was measured to calculate the crack growth rate which varies significantly. Typical crack morphology, such as crack tilt, is detected by the observation of 2D tomographic slice image. The observed interaction between fatigue crack and polycrystalline microstructures can be analyzed in 3D. Through this synthesis of techniques, DAGT, a detailed direct assessment of microstructure and crack propagation behaviors has been achieved.. |
| 115. | Yusuke Yamamoto, Mineo Asano, Hideo Yoshida, Masakazu Kobayashi, Hiroyuki Toda, Effect of micro-voids on crack initiation and propagation in bending deformation of Al-Mg-Si alloy sheet, 14th International Conference on Aluminium Alloys, ICAA 2014, 2014.01. |
| 116. | Masakazu Kobayashi, Yuuki Kawamura, Soutaro Ueno, Hiroyuki Toda, Hiromi Miura, Measurement of local plastic deformation in aluminum alloy by means of X-ray 3D imaging technique, 11th International Conference on Technology of Plasticity, ICTP 2014, 2014.01, To understand the local deformation behavior is very important for improvement of deformability in aluminum alloys which possess poor deformation limit in comparison with steels. However, measurement of local deformation in the interior of metal is not sufficiently carried out. In this study, the development of local plastic strain is measured by means of X-ray 3D imaging technique, i.e. high-resolution synchrotron X-ray microtomography. The marker tracking method, which is based on 3D image processing in volumetric image, is developed for obtaining local strains in 3D. Deformation behaviour is particularly different in individual grains. It was found that grains with different orientations deform maintaining harmony by shear deformation.. |
| 117. | C. Schlacher, C. Béal, C. Sommitsch, Hiroyuki Toda, P. Mayr, Study of creep damage in creep exposed martensitic high chromium steel weldments, 7th International Conference on Advances in Materials Technology for Fossil Power Plants, 2014.01, Precipitation, grain-boundary and sub-boundary hardening are the most important strengthening mechanisms in creep resistant martensitic high chromium steels. In recent years, a design concept for the stabilisation of the microstructure (precipitates, grain boundaries and martensitic lath structure) by addition of boron and nitrides was developed. This so called MARBN steel (MARtensitic steel strengthened by Boron and Nitrogen) combines boron strengthening (solid solution strengthening) with nitride strengthening (precipitation strengthening). Welding trials showed no uniform formation of a fine grained region in the heat affected zone HAZ, which is considered critical for creep strength due to Type IV cracking. First creep test results of crosswelds are very promising. In this work, an improved MARBN steel was developed and investigated. Uniaxial creep tests of base material as well as of welded joints have been carried out at 650°C up to 25.000 hours at different stress levels. The creep strength of base material and that of welded joints was analysed and the evolution of damage was investigated using synchrotron micro-tomography and electron back scatter diffraction in order to understand the creep damage mechanism. The combination of long-term creep testing data with a 3-D damage investigation by using synchrotron μCT allows a completely new view on the basic failure mechanisms at elevated temperatures in the heat affected zone of welded joints.. |
| 118. | C. Gupta, H. Toda, C. Schlacher, P. Mayr, C. Sommitsch, K. Uesugi, Y. Suzuki, A. Takeuchi, M. Kobayashi, Study of creep damage in a 10.86% Cr heat resistant steel using synchrotron X-ray microtomography, Stainless Steel Centenary Symposium, SSCS 2013, 2013.10, Synchrotron X-ray micro-tomography (SR-μCT) scans have been carried out on sample coupons extracted from fracture specimens of a 10.86% Cr heat resistant steel exposed to creep deformation at 873K over stresses of 120, 150 and 180 MPa. The 3D cavitation characteristics in terms of void volume fraction, number density and size distribution as a function of the applied stress has been determined by quantitative analysis of reconstructed tomography slice datasets. The relationship between heterogeneous spatial distributions of creep voids and variation in rupture life has been explored in terms of microstructural specific nucleation sites during the onset of creep embrittlement.. |
| 119. | 戸田 裕之, F. Tomozato, R. Harasaki, D. Seo, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, 3D/4D high resolution observation in steels, 8th Pacific Rim International Congress on Advanced Materials and Processing, 2013.08. |
| 120. | Y. Tanabe, 戸田 裕之, T. Kamiko, Y. Suzuki, A. Takeuchi, K. Uesugi, M. Kobayashi, Assessment of crystallographic deformation behaviors in aluminum alloy using diffraction-amalgamated grain boundary tracking technique:, the 8th Pacific Rim International Congress on Advanced Materials and Processing, 2013.08. |
| 121. | C. Schlacher, C. Sommitsch, P. Mayr, C. Gupta, Hiroyuki Toda, K. Usegi, Y. Suzuki, Creep and damage investigation of improved 9%Cr steel welded joints, 9th International Conference on Trends in Welding Research, 2013.07, Due to accelerated creep damage, martensitic 9%Cr welded joints fail prematurely in the fine-grained heat affected zone (FGHAZ). These failures in the FGHAZ are categorized as "Type IV cracking". In recent years, boron containing 9% Cr steels have been developed that suppress the FGHAZ formation in order to avoid Type IV cracking and that have increased crossweld creep strength. The advanced alloying concept is based on the balanced addition of boron and nitrogen. Creep tests of 9Cr3W3CoVNbBN steel crosswelds have been carried out up to 17000 hours at 650°C. The crossweld creep strength was analyzed and the damage evolution in crosswelds was investigated using synchrotron micro-tomography of creep exposed welded joints. Additionally, the microstructure of the crossweld specimens was investigated using optical and scanning electron microscopy and electron backscatter diffraction. Creep void formation along the original prior austenite grain boundaries, at a certain distance to the weld fusion line, in the heat affected zone was observed. Electron backscatter diffraction images revealed the incomplete suppression of grain refinement along the prior austenite grain boundaries. These newly formed small grains have been identified as the main reason for the increased creep void formation in this area.. |
| 122. | 戸田 裕之, H. Oogo, H. Tsuruta, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Long-unnoticed origin of ductike fracture in aluminium alloys, 13th International Conference on Fracture, 2013.06. |
| 123. | H. Toda, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, 3D/4D strain mapping using in-situ X-ray microtomography, 2012 Annual Conference on Experimental and Applied Mechanics, 2013.01, X-ray microtomography (XMT) has been utilized for observing deformation, damage and fracture behaviors in structural materials. In-situ observation using XMT provides a unique possibility to access time evolution behaviors at a microscopic level. Local strain mapping is enabled by image-processing a series of three-dimensional (3D) images by particle tracking technique. Procedures for tracking microstructural features which have been developed by the authors, are reviewed in this article. Local crack driving forces can be measured from discrete crack tip displacement fields as well as simple 3D strain mapping. Recent extension to crystallographic measurements is also introduced.. |
| 124. | H. Toda, P. C. Qu, S. Ito, M. Kobayashi, K. Uesugi, 3D/4D observation of the micro-mechanism of blister deformation, 70th World Foundry Congress 2012, WFC 2012, 2012.12, The creep deformation behaviors of a die-casting aluminum alloy with a blister were investigated in the present study, by using a combined methodology of in-situ three-dimensional observation via the high resolution synchrotron X-ray computed tomography (CT), and an image-based numerical simulation method, in which the real morphology of the blister was considered. The high density micro-pores were observed in the samples exposed at high temperatures. It was found that the coarsest pore grew into a blister and produced an extrusion on the sample surface. It was also found that the deformation of the blister along the direction parallel to the sample surface was tensile, while it was compressive along the direction perpendicular to the sample surface. This is correspondent to the phenomenon of the micro-pores' coalescence along the direction parallel to the sample surface observed in the experiment.. |
| 125. | Hiroyuki Toda, Darren Leclere, Takanobu Kamiko, Yoshio Suzuki, Akihisa Takeuchi, Kentaro Uesugi, Masakazu Kobayashi, Development of diffraction-amalgamated grain-boundary tracking technique and its application to polycrystalline metals, Developments in X-Ray Tomography VIII, 2012.12, By amalgamating a transmission X-Ray diffraction (XRD) experiment with grain boundary tracking (GBT) that has been developed by the present authors by combining the X-ray micro-tomography (CT) and the gallium-enhanced grain boundary visualization techniques, a novel method which provides accurate crystallographic information of individual grains during deformation has been created. The developed technique, which is called diffraction-amalgamated grain boundary tracking (DAGT) technique, is non-destructive for in-situ characterizing of bulk materials, which allows for close to deformation and fracture analysis of metals. Employing near field XRD analysis with a thin collimated X-ray beam, the algorithms developed for DAGT identifies which diffraction spots are related to which grain; consequently, providing a description of the misorientation between grains. DAGT also realizes micron-level analysis of grain morphologies and local stain distribution in 3-dimensions (3D) on the basis of CT observation, enabling the crystallographic interpretation of localized deformation without being affected by blurring of diffraction spots caused by deformation. An Al-3mass%Cu alloy was used for demonstration purpose.. |
| 126. | M. Kobayashi, 戸田 裕之, Y. Suzuki, K. Uesugi, A. Takeuchi, High resolution synchrotron X-ray microtomography for investigation of local deformation and fracture in materials , 2012 Energy Materials Nanotechnology, 2012.11. |
| 127. | 戸田 裕之, Time-resolved 3D measurements of mechanical behaviours in aluminium alloys, Asian Forum on Light Metals 2012, 2012.11. |
| 128. | H. Toda, M. Kobayashi, R. Batres, K. Shimizu, O. Kuwazuru, A new concept breakthrough in materials development: reverse 4D materials engineering, Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11, シンクロトロン放射光を用い て得た膨大な4D画像を『粗視化』し、簡単な幾何学パラメーターで現象を説明すること、およ び得られた4D画像を用いて行うイメージベースシミュレーションによるミクロ組織最適化の 二つを組み合わせ、「リバース4D材料エンジ ニアリング」なる材料開発プロセスの構想を得た。この基調講演では、その内容に関して講演した。この手法を用いれば、従来の「設計→試作 →製品」とは逆の、「設計←評価・解析←製品」という流れ（『リバース』というゆえん）により、「試作⇔評価」といった時間とコストのか かるプロセスを経ずに、高能率、短時間、高精度で構造材料設計が可能になる。. |
| 129. | H. Hoshino, C. Gupta, 戸田 裕之, M. Kobayashi, C. Schlacher, C. Sommitsch, P. Mayr, K. Uesugi, A. Takeuchi, Y. Suzuki, Creep cavitation damage in 9-12% Cr tempered martensitic steels investigated using synchrotron, Proc. ISAEM 12, 2012.11. |
| 130. | M. Sugiyama, Y. Shinohara, S. Takebayashi, M. Kobayashi, 戸田 裕之, 3D characterization techniques finding in several critical volume dimensions, Proc. ISAEM 12, 2012.11. |
| 131. | M. Kobayashi, 戸田 裕之, D. J. LeClere, T. Kamiko, K. Uesugi, A. Takeuchi, Y. Suzuki, Development of new crystallographic orientation measurement in 3D space: diffraction-amalgamated grain-boundary tracking (DAGT), Proc. ISAEM 12, 2012.11. |
| 132. | D. Seo, F. Tomizato, 戸田 裕之, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Spatial resolution of synchrotron X-ray microtomography for transition metals, 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11. |
| 133. | D. Seo, F. Tomizato, 戸田 裕之, K. Uesugi, A. Takeuchi, Y. Suzuki, M. Kobayashi, Spatial resolution of synchrotron X-ray microtomography for transition metals, Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11, これまで、鉄鋼材料のX線 による3D/4Dイメージングは、空間分解能が理論分解能より1～2桁低く、実用にはならなかった。この研究では、大型放射光施設SPring-8の活用と様々な撮像条件の最適化により、鉄鋼でもほぼ理論分解能での撮像が可能に なった。これは、主にはこれまで知られていなかったX線前方散乱による大きな悪影響を避けることで達成された。この研究の成果により、鉄鋼材料でも、熱処理や加工時の組織変化、変形・破壊・疲労破壊などの3D/4Dその場観察やその解析が可能になった。. |
| 134. | M. Kobayashi, 戸田 裕之, D. J. LeClere, T. Kamiko, K. Uesugi, A. Takeuchi, Y. Suzuki, Development of new crystallographic orientation measurement in 3D space: diffraction-amalgamated grain-boundary tracking (DAGT), Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11. |
| 135. | M. Sugiyama, Y. Shinohara, S. Takebayashi, M. Kobayashi, 戸田 裕之, 3D characterization techniques finding in several critical volume dimensions, Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11. |
| 136. | H. Hoshino, C. Gupta, 戸田 裕之, M. Kobayashi, C. Schlacher, C. Sommitsch, P. Mayr, K. Uesugi, A. Takeuchi, Y. Suzuki, Creep cavitation damage in 9-12% Cr tempered martensitic steels investigated using synchrotron, Proceedings of the 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2012.11. |
| 137. | H. Toda, D. J. LeClere, T. Kamiko, Y. Suzuki, A. Takeuchi, K. Uesugi, M. Kobayashi, Development of diffraction-amalgamated grain-boundary tracking technique and its application to polycrystalline metals, Proceedings of SPIE, 2012.08, 我々は、シンクロトロン放射光を用いて得た3D/4D画像の内部に多数のミクロ構造が見えることを利用し、各画像間でミクロ組織特徴点（粒子など）を高精度に追跡する技術（ミクロ組織追跡法）を発案して開発した。その後、これを応用し、結晶粒の3D/4D観察を行うことができる結晶粒界追跡法、さらにこれに結晶方位マッピングを加えたX線回折援用結晶粒界追跡法を相次いで提案し、実現している。機械材料の変形・破壊の評価では、SEM-EBSP（電子線後方散乱回折）法や各種TEM（透過型電子顕微鏡）観察が多用される。発表手法は、これら2D（二次元）情報を3D/4Dに拡張できる、唯一かつオリジナルな技法である。. |
| 138. | C. Gupta, 戸田 裕之, M. Kobayashi, C. Schlacher, C. Sommitsch, P. Mayr, K. Uesugi, Y. Suzuki, A. Takeuchi, An understanding of embrittlement in structural materials using 3D/4D characterisation methods, 1st International conference on 3D Materials Science 2012, 2012.07. |
| 139. | C. Sclacher, P. Mayr, F. M. Martin, C. Gupta, 戸田 裕之, K. Uesugi, Y. Suzuki, C. Sommitsch, Investigation of creep damage in Martensitic 9-12% Cr Steel using Synchrotron X-ray Micro-tomography, 1st International conference on 3D Materials Science 2012, 2012.07. |
| 140. | 戸田 裕之, C. Gupta, D. Leclare, T. Kamiko, M. Kobayashi, K. Uesugi, A. Takeuchi, Y. Suzuki, Diffraction Amalgamated Grain Boundary Tracking (DAGT) technique applied to Al-3mass% Cu, 1st International conference on 3D Materials Science 2012, 2012.07. |
| 141. | Z. A. Shamsudin, 戸田 裕之, K. Uesugi, Y. Suzuki, M. Kobayashi, Damage evolution behavior of Al-Mg alloys during high temperature deformation, 12th International Conference on Creep and Fracture of Engineering Materials and Structures, 2012.05. |
| 142. | P. C. Qu, 戸田 裕之, S. Ito, M. Kobayashi, K. Uesugi, Image-based numerical analysis of the creep deformation of hydrogen micro-pores in a die-cast aluminum alloy, World Foundry Congress 2012, 2012.04. |
| 143. | 戸田 裕之, P. C. Qu, S. Ito, M. Kobayashi, K. Uesugi, 3D/4D observation of the micro-mechanism of blister deformation, World Foundry Congress 2012, 2012.04. |
| 144. | DARREN JOHN LECLERE, 神子貴信, 戸田裕之, 小林正和, 鈴木芳生, 竹内晃久, 上杉健太朗, Diffraction-Amalgamated Grain-Boundary Tracking (DAGT) technique applied to deformed polycrystaline Al-alloy, 日本金属学会, 2012.03. |
| 145. | L. Zellmer, F. Zeismann, Y. Motoyashiki-Besel, A. Brueckner-Foit, M. Kobayashi, 戸田 裕之, Investigation of the microstructure in the vicinity of a fatigue crack in in-depth direction in a ferritic-martensitic steel, EBSD 2012, 2012.01. |
| 146. | DJ. LeClere, T. Kamiko, Y. Mizuseki, H. Toda, M. Kobayashi, Y. Suzuki, A. Takeuchi, K.Uesugi, CombiningGrainBoundaryTrackingandXRDfor3-DimensionalGrainMappingofDeformedPolycrystallineAl-alloy, 日本金属学会, 2011.11. |
| 147. | Gupta Chiradeep, M. Kobayashi, T. Fijioka, H.Toda, StudyofHydrogenEmbrittlementinAl7075usingSR-microCT, 日本金属学会, 2011.11. |
| 148. | 戸田 裕之, D.J. LeClere, M. Kobayashi, Y. Suzuki, A. Takeuchi, K. Uesugi, Combining grain boundary tracking and XRD for 3-dimensional grain mapping of deformed polycrystaline Al-alloy , HEXD-MM, 2011.10. |
| 149. | Hiroyuki Toda, Kentaro Uesugi, Yoshio Suzuki, Masakazu Kobayashi, 3D/4D strain mapping using in-situ X-ray microtomography, 8th International Conference on Advances in Experimental Mechanics: Integrating Simulation and Experimentation for Validation, 2011.10, X-ray microtomography (XMT) has been utilized for the in-situ observation of various structural materials under external disturbance such as loading. In-situ XMT provides a unique possibility to access the three-dimensional (3D) character of internal microstructure and its time evolution behaviours non-destructively, thereby enabling advanced techniques for measuring local strain distribution. Local strain mapping is readily enabled by processing such high-resolution tomographic images either by the particle tracking technique or the digital image correlation technique. Procedures for tracking microstructural features which have been developed by the authors, have been applied to analyse localised deformation and damage evolution in a material. Typically several tens of thousands of microstructural features, such as particles and pores, are tracked in a tomographic specimen (0.2 - 0.3 mm 3 in volume). When a sufficient number of microstructural features is dispersed in 3D space, the Delaunay tessellation algorithm is used to obtain local strain distribution. With these techniques, 3D strain fields can be measured with reasonable accuracy. Even local crack driving forces, such as local variations in the stress intensity factor, crack tip opening displacement and J integral along a crack front line, can be measured from discrete crack tip displacement fields.. |
| 150. | A. Hosokawa, D. S. Wilkinson, J. Kang, M. Kobayashi, 戸田 裕之, The role of work hardening and secondary void formation on void coalescence in model materials investigated by X-ray computed tomography, ATEM'11, 2011.09. |
| 151. | D. Wilkinson, A. Hosokawa, J. Kang, E. Maire, 戸田 裕之, Application of X-ray tomography to the study of void growth and coalescence during ductile fracture, ATEM'11, 2011.09. |
| 152. | P. Qu, 戸田 裕之, H. Zhang, Y. Sakaguchi, L. Qian, K. Uesugi, Assessment of complicated fatigue crack propagation in an Al-Mg-Si alloy, ATEM'11, 2011.09. |
| 153. | F. Zeismann, B. Bode, Y. Motoyashiki-Besel, 戸田 裕之, A. Bruckner-Foit, Observation of crack path in a dual phase steel and crystallographic orientation in the vicinity of the crack in 3D, ATEM'11, 2011.09. |
| 154. | 戸田 裕之, Y. Sakaguchi, K. Sakai, K. Uesugi, Y. Suzuki, M. Kobayashi, Assessment of localised deformation ahead of crack-tip via X-ray microtomography, ATEM'11, 2011.09. |
| 155. | A. Hosokawa, D.S. Wilkinson, J. Kang, E. Maire, M. Kobayashi, H. Toda, Influences of stress triaxiality and work hardening on void growth and coalescence studied by x-ray tomography, International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), 2011.09. |
| 156. | M. Kobayashi, H. Toda, A. Takeuchi, K. Uesugi, Y. Suzuki, Characterization of inhomogeneous deformation behavior in a flexible graphite sheet by synchrotron radiation microtomography, International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), 2011.09. |
| 157. | P. Qu, H. Toda, H. Zhang, Y. Sakaguchi, L. Qian, K. Uesugi, Assessment of Complicated Fatigue Crack Propagation in an Al-Mg-Si alloy, International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), 2011.09. |
| 158. | Frank Zeismann, Benjamin Bode, Yasuko Motoyashiki-Besel, Hiroyuki Toda, Angelika Bruckner-Foit, Observation of crack path in a dual phase steel and crystallographic orientation in the vicinity of the crack in 3D, International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11), 2011.09. |
| 159. | Essam A. Rashed, Hiroyuki Toda, Toshihiro Sera, Akira Tsuchiyama, Tsukasa Nakano, Kentaro Uesugi, Hiroyuki Kudo, Towards a high-resolution local tomography using statistical iterative reconstruction, 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2011, 2011.01, Synchrotron radiation (SR) x-ray micro-CT is an effective method for high-resolution imaging of small objects with several applications in biology and industry. However, the detector field of view is tiny, which limits the sample size to a few millimeters. When the sample size is larger than the limited field of view, reconstructed images, using conventional methods, known to suffer from DC-shift and low-frequency artifacts. This problem is known as local tomography or interior problem. In this paper we introduce a statistical iterative image reconstruction method to eliminate image artifacts produced from local tomography. The proposed method can be used in several SR imaging applications to enable a high resolution of the scanned object while preserving the image quality from artifacts produced due to the local tomography problem.. |
| 160. | Z. A. Shamsudin, H. Toda, M. Kobayashi, K. Koyama, K. Ichitani, Y. Suzuki, K. Uesugi, M. Nakazawa, Y. Aoki, Healing behavior of hydrogen micro pores during cold plastic deformation, Materials Science and Technology Conference and Exhibition 2010, MS and T'10, 2010.12, The healing behaviors of hydrogen micropores in an Al-Mg alloy during cold plastic deformation was observed using X-ray microtomography. Local strain distribution during deformation was determined by measuring the displacement of artificially dispersed Pb particles. Our result shows that under uniform applied compressive load, the local strain distribution in the sample is significantly inhomogeneous which induces complex healing behaviors of micropores during deformation. The shrinking behavior of micropores can be explained as a function of local compressive strain. Some micropores are re-initiated by heating in position identical to those before their annihilation during plastic working even after large strain has been applied after annihilation. There were no apparent effects of local compressive strain on annihilation and re-initiation behaviors. It can be concluded that application of 60% compressive load used in this study is not sufficient enough to heal the micropores completely.. |
| 161. | Hiroyuki Toda, Masakazu Kobayashi, Kentaro Uesugt, Yoshio Suzuki, Hydrogen micro pores in cast aluminum alloys, 69th World Foundry Congress 2010, WFC 2010, 2010.12, According to our extensive 3-D non-destructive observations for various kinds of cast aluminum alloys, high-density micro pores have been identified to exist in all of the aluminum alloys except pure aluminum. The observation has been performed with the largest synchrotron radiation facility in the world, SPring-8. Growth/shrink and formation! annihilation behaviors of each micro pore are tracked during heat treatments and a plastic forming process. It has been clarified from the quantitative analysis of 3-D images that the micro pores exhibit the Ostwald ripening during the heat treatments. It has been found that considerable amount of hydrogen contained in the cast aluminum alloy is trapped in micro pores, while it is quite limited in a pure aluminum. Various efforts have been reported to eliminate such micro pores. Annihilation behaviors of micro pores under shot peening are demonstrated in 3-D. Since usually the porosity acts as fatigue crack initiation sites and fatal defects under tension, this information would be beneficial also from an industrial point of view. We also reports how mechanical properties of the cast aluminum are degraded due to the existence of micro pores in this review paper. Especially it is noteworthy that the ductile fracture of aluminum alloys is dominated by micro pore growth in addition to particle damage that is conventional text-book knowledge. Copyright. |
| 162. | M. Kobayashi, H. Toda, Y. Kawai, M. Nakazawa, Y. Aoki, K. Uesugi, Y. Suzuki, Three-dimensional plastic strain mapping technique for X-ray micro-tomography, Materials Science and Technology Conference and Exhibition 2010, MS and T'10, 2010.12, Recently, X-ray micro-tomography has been utilized for characterization of deformation and fracture behaviors in materials. The micro-tomography that is available in the synchrotron facility can reveal the existence of particles and crack in about 1 μm resolution. In this study, three-dimensional mapping technique has been developed to observe inhomogeneous plastic deformation affected by metallurgical microstructures in small specimen. Marker-tracking method with predicting marker position was produced to obtain strain in inhomogeneously and highly deformed region. The model that simulates tensile test was produced with taking actual deformation pattern into consideration. Evaluation of ratios of success tracking and tracked marker showed good performance of the developed method. The prediction of marker position after deformation was very effective in tensile deformation with necking. Almost 100% ratios of success tracking and tracked marker were indicated not only in homogeneous deformation up to 10% strain but also in inhomogeneous deformation up to 5% strain.. |
| 163. | 戸田裕之, 3D/4D X-ray tomography imaging and its application to materials science and engineering, 東北大学(中国・瀋陽）招待講演, 2010.10. |
| 164. | 戸田裕之, 3D/4D X-ray tomography imaging and its application to materials science and engineering, 中国科学院金属研究所(中国・瀋陽）招待講演, 2010.10. |
| 165. | 戸田裕之, 3D/4D X-ray tomography imaging and its application to materials science and engineering, 燕山大学(中国・秦皇島）招待講演, 2010.10. |
| 166. | LeClere Darren J, Y. Okawa, H. Toda, M. Kobayashi, Y. Suzuki, A. Takeuchi, K. Uesugi, Novel combination of 3DXRD and Grain boundary tracking for grain mapping of a polycrystalline Al-alloy, 日本金属学会, 2010.09. |
| 167. | Qiang Zhang, Hiroyuki Toda, Masakazu Kobayashi, Yoshio Suzuki, Kentaro Uesugi, Three dimensional microstructure characterization of an Al-Zn-Mg alloy foam using synchrotron X-ray microtomography, 7th Pacific Rim International Conference on Advanced Materials and Processing, PRICM-7, 2010.08, Synchrotron X-ray microtomography (SPring-8, Japan) has been used for the microstructure characterization in a closed cell Al-Zn-Mg alloy foam. Some sophisticated microstructure features, such as micropores and intermetallic particles inside the cell wall, were visualized and quantified three dimensionally(3D) by the high-resolution phase contrast imaging technique. By microtomographies tuned to energies above and below the Zn K-absorption edge, the 3D quantitation of Zn distribution was obtained using subtraction imaging technique. It has been clarified that the Zn distribution was inhomogeneous in the cell wall of the foam. And the agglomeration of Zn-bearing particles was confirmed to induce the brittle fracture of cell wall. The distributions of Ti and Ca in the foam were also visualized by subtraction method. The current tomographic techniques provide novel solutions for the 3D microstructure analysis in the highly inhomogeneous foam materials.. |
| 168. | Qu Pengcheng, Toda Hiroyuki, Zhang Hui, Sakaguchi Yuji, Assessment of 3-D fatigue crack propagation behaviors in an aluminum alloy via image-based numerical simulation, 材料学会, 2010.05. |
| 169. | Mitsuru Nakazawa, Masakazu Kobayashi, Hiroyuki Toda, Yoshimitsu Aoki, High accuracy analysis method for 3D nanoscale deformation / fracture characteristics inside a material, 2010.01, To evaluate internal thorough material characteristics in deformation, we proposed an analysis method which obtains displacement vectors of dispersed particles between deformation from nano-order 3D-CT images. In this paper, we introduce an improved approach to achieve more robust matching and eliminate the need to tune some parameters. To confirm the effectiveness of the improved approach, virtual tensile tests are carried out. Precision is achieved more than 99% at every matching between adjacent load steps.. |
| 170. | Mitsuru Nakazawa, Masakazu Kobayashi, Hiroyuki Toda, Yoshimitsu Aoki, A proposal of a method to analyze 3D deformation / fracture characteristics inside materials based on a stratified matching approach, 35th Annual Conference of the IEEE Industrial Electronics Society, IECON 2009, 2009.12, In the past, deformation / fracture (D/F) characteristics, defined as load-deformation relationships until the materials are fractured, have been analyzed and evaluated on the surface from milli- to micro-scale. The D/F characteristics are affected by more than ten thousand micro-scale internal structures like air bubbles (pores), impurity particles and cracks in 1mm 3; therefore, it is required to analyze nano-scale D/F characteristics inside materials. In this paper, we propose an analysis method by obtaining displacement vectors of impurity particles from nano-order 3D-CT images. A problem of matching over ten thousand impurity particles between deformation is solved by a stratified matching.. |
| 171. | Koji Sakamoto, Shunsuke Ishimitsu, Takeshi Oda, Yasuhiro Sugiyama, Hiroyuki Toda, Analysis the relation between material structure and auditory impression, 2009 4th International Conference on Innovative Computing, Information and Control, ICICIC 2009, 2009.12, At present, audio insulators are statically evaluated using a sine wave, whereas they need to be dynamically evaluated using musical sound. In this study, we present a dynamic evaluation method using musical sound. Furthermore, we constructed insulators with layers of aluminum waste material and various materials. And we examined various characteristics of the insulators in addition to their damping characteristics. In the results, we were able to confirm the damping characteristics of insulators using their integrals of the power spectrum for peaks at 200 to 300[Hz] and 350 to 450[Hz]. Moreover, we confirmed that envelope curve for the impulse response of insulators have various characteristics and conveyed a sound impression.. |
| 172. | P.C.Qu, H.Toda, Y.Sakaguchi, M.Kobayashi, K.Uesugi, 3D observation and image-based simulation of fatigue crack propagation in an Al-alloy, 日本金属学会, 2009.09. |
| 173. | P.Qu, H.Toda, H.Zhang, L.Qian, M.Sakaguchi, M.Kobayashi, K.Uesugi, 3D Obsergation and image-based simulation of Fatigue crack Propagation in an Al-Mg-Si alloy THERMEC'2009, THERMEC'2009, 2009.08. |
| 174. | M. Kobayashi, H. Toda and K. Uesugi, Three-dimensional Visualization and Analysis of Grain Deformation by means of Synchrotron Radiation THERMEC'2009, THERMEC'2009, 2009.08. |
| 175. | Mitsuru Nakazawa, Yoshimitsu Aoki, Masakazu Kobayashi, Hiroyuki Toda, 3D image analysis for evaluating internal deformation/fracture characteristics of materials, 2008 19th International Conference on Pattern Recognition, ICPR 2008, 2008.12, In the past, D/F characteristics, load-deformation relationships until the materials are fractured, have been analyzed on the suiface. The D/F characteristics are affected by more than ten thousand micro-scale internal structures like air bubbles (pores), cracks and particles; therefore, it is required to analyze nano-scale D/F characteristics inside materials. In this paper, we propose a method that automatically obtains the corresponding relations ofthe particles from nano-order 3D-CT images at each deformation stage. The particles are deformation-proof and may have different geometries. First of all, some big particles are considered as landmarks and matched between pre- and post-deformation. The results oflandmark matching make it easy to match many remaining particles and pores.. |
| 176. | P. Qu, H. Toda, H. Zhang, L. Qian, M. Sakaguchi, M. Kobayashi, K. Uesugi, 3D image-based analyses of fatigue crack propagation in an Al-Mg-Si alloy, Materials Science and Technology Conference and Exhibition, MS and T'08, 2008.12, 3D fatigue crack opening and propagation behaviors in an Al-Mg-Si alloy have been inyestigated in this study. A combined methodology of an in-situ 3D crack visualization via the synchrotron X-ray CT and image-based numerical simulation which takes into account real crack morphology has been applied for the study. The complex crack morphology has been observed and many essential features of the crack and its opening/propagation inside the material have been identified. Typical example would be the complex deformation behaviors in the region where two crack segments lying on different horizontal planes overlap each other. The image-based numerical simulation was performed to investigate the interactions of two overlapping crack segments and their influences on the region next to overlapping region. The combined methodology of the in-situ 3D crack visualization and the image-based numerical simulation has been demonstrated to be powerful and feasible in revealing and understanding various fracture phenomena inside materials.. |
| 177. | H. Zhang, P. C. Qu, Y. Sakaguchi, H. Toda, M. Kobayashi, K. Uesugi, Y. Suzuki, Three-dimensional characterization of fatigue crack propagation behavior in an aluminum alloy using high resolution X-Ray microtomography, Materials Science and Technology Conference and Exhibition, MS and T'08, 2008.12, Synchrotron X-ray microtomography has been used for the in-situ observation of three-dimensional (3D) fatigue crack propagation of an aluminum alloy. Local crack growth rates were calculated at different positions along specimen thickness. Crack observation revealed that crack propagation was frequently retarded in local region where crack overlapped crack segments exist. Propagation of cracks into overlapped region was strongly constrained due to stress shielding. Observation of crack propagation process indicated that the overlapped crack segments generally corresponds to the potion of twisted crack. Crack tip opening displacement was measured and it was found that crack opening was larger in single planar crack than that in crack overlapping region.. |
| 178. | Y. Ohkawa, M. Kobayashi, 戸田 裕之, T. Kobayash, K. Uesugi, Y. Suzuki, Three-dimensional analysis of grain deformation behavior in Al-Cu alloy by high-resolution X-ray computed tomography, ISAEM 08, 2008.11. |
| 179. | 戸田 裕之, M. Kobayashi, K. Uesugi, Y. Suzuki, K. Koyama, K. Ichitani, Applications of advanced 3D/4D imaging techniques to aluminum alloys , 2008 AFLM, 2008.11. |
| 180. | P. Qu, 戸田 裕之, H. Zhang, L. Qian, Y. Sakaguchi, M. Kobayashi, K. Uesugi, 3D observation and image-based simulation of fatigue crack propagation in an Al-Mg-Si alloy, ISAEM 08, 2008.11. |
| 181. | M. Kobayashi, 戸田 裕之, K. Uesugi, 3D/4D deformation and fracture analysis by tracking microstructural features in high-resolution computed tomography, ISAEM 08, 2008.11. |
| 182. | K. Shimizu, 戸田 裕之, M. Kobayashi, T. Kobayashi, K. Uesugi, Y. Suzuki, 3-D chemical concentration mapping via Kedge subtraction imaging, ISAEM 08, 2008.11. |
| 183. | Yoshikazu Ohkawa, Masakazu Kobayashi, Hiroyuki Toda, Toshiro Kobayashi, Masakazu Kobayashi, Kentaro Uesugi, Yoshio Suzuki, Three-Dimensional Analysis of Grain Deformation Behavior in Al-Cu Alloy by High-Resolution X-ray Computed Tomography, 4th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2008.11. |
| 184. | Kazuyuki Shimizu, Hiroyuki Toda, Masakazu Kobayashi, Toshiro Kobayashi, Masakazu Kobayashi, Kentaro Uesugi, Yoshio Suzuki, 3-D Chemical Concentration Mapping via Kedge Subtraction Imaging, 4th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2008.11. |
| 185. | Pengcheng Qu, Hiroyuki Toda, Hui Zhang, Lihe Qian, Yuuji Sakacuchi, Masakazu KOBAYASHI, Kentaro UESUGI, 3D observation and image-based simulation of fatigue crack propagation in an Al-Mg-Si alloy, 4th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2008.11. |
| 186. | H. Toda, Y. Takami, M. Kobayashi, T. Kobayashi, Y. Aruga, T. Takagi, Y. Suzuki, K. Uesugi, 3-D Microstructural characterization of cell wall in a high strength aluminium foam, 5th International Conference on Porous Metals and Metallic Foams, MetFoam 2007, 2008.11, X-ray microtomography has been applied to characterize inhomogeneous microstracture and micro structure/property relationships in a cast Al-Zn-Mg alloy foam. 3-D distribution of Zn, Ca, Ti and H2 (i.e. pore) are visualized by capturing 3-D images just below and above the K-edge of Zn and then subtracting them from each other. It has been clarified that the distributions of alloying elements were inhomogeneous throughout the material. Brittle fracture of a cell wall appeared to be induced by the existence of Zn-rich intermetallic particles with segregated Ca. It has also been confirmed that coarse Ti-bearing particles, which are residual foaming agent added to alloy melts, remained intact during the deformation. Overall, the approach taken in this study has provided highly effective ways to characterize microstructure/properties relationships in such highly heterogeneous materials.. |
| 187. | 戸田裕之, 4D quantitative analysis for cracked medium, 1st Workshop on Micro- and Nano-tomography 兼 第8回X線マイクロ・ナノトモグラフィー研究会, 2008.11. |
| 188. | T. Nishimura, H. Toda, T. Kobayashi, M. Kobayashi, K. Uesugi, Y. Suzuki, Change in microstructure of Al-Si-Cu casting alloys during high-temperature solution, The 10th Asian Foundry Congress Final Program and Abstract Booklet, 2008.05. |
| 189. | 戸田 裕之, M. Kobayashi, Synchrotoron X-ray micro- and nanotomography , ICCES 08, 2008.03. |
| 190. | Masakazu Kobayashi, Hiroyuki Toda, Tomomi Ohgaki, Kentaro Uesugi, David S. Wilkinson, Toshiro Kobayashi, Yuji Kawai, Yoshimitsu Aoki, 3-D high-density strain mapping procedure based on high-resolution CT, 5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006, 2007.12, A tracking procedure for the high-resolution X-ray computed tomography (CT) has been developed in order to measure 3-D local strain within a deforming material in high-density. A dispersion-strengthened copper alloy model sample with alumina particles, which contains micropores, was visualized by the synchrotron radiation CT. The pores observed in reconstructed CT volumes were used as tracking markers. The developed tracking method using a set of matching parameters, which classifies matched, pended and rejected markers, exhibited high ratio of success tracking. Furthermore, the ratio was improved by applying the spring model method, which is one of the particle image velocity (PIV) methods utilized in the field of the fluid mechanics, to the pended markers. The method based on the image analysis of CT imaging volumes provides us 3-D high-density strain mapping.. |
| 191. | Mitsuru Nakazawa, Yoshimitsu Aoki, Hiroyuki Toda, Masakazu Kobayashi, Yuji Kawai, 3D image analysis for evaluating internal deformation / fracture characteristics of materials, Optomechatronic Computer-Vision Systems II, 2007.12, In the past, all methods that understand deformation / fracture (D/F) characteristics have been limited on the surface indirectly. D/F characteristics are affected by micro-scale structural features like air bubbles (pores), cracks and micro-detects; therefore, they need to be analyzed inside. In this paper, we propose a system which automatically obtains the corresponding relations between pre- and post-D/F pores. Our system enables analyzing 3D, local, high-accuracy D/F characteristics. Experiments proved its effectiveness.. |
| 192. | H. Toda, M. Kobayashi, K. Uesugi, D. S. Wilkinson, T. Kobayashi, 3D strain mapping inside materials by microstructural tracking in tomographic volumes, 3rd International Conference on Computational Methods and Experiments in Material Characterisation 2007, 2007.12, X-ray absorption microtomography has been employed to trace the physical displacement of internal microstructural features in order to obtain local strain distribution inside materials. The number of microstructural features visible by means of state-of-the-art synchrotron radiation microtomography sometimes reaches into the tens of thousands or more in ordinary structural materials. It implies that high-density strain mapping is enabled if such large-scale tracking is accurately performed. The present paper describes a method to accurately track microstructural features by utilising the information on the size, shape and gravity centre of microstructural features together with the spring model particle tracking algorithm and exploratory registration using macroscopic deformation pattern. A model material which contains artificially introduced micro-pores has been prepared and used for the investigation. It has been clarified that almost perfect tracking is realised if the procedure is adequately applied to 3D image data sets. 3D internal strain mapping is also demonstrated and correlated to the localised ductile fracture of the model material.. |
| 193. | Tomomi Ohgaki, Hiroyuki Toda, Kentaro Uesugi, Toshiro Kobayashi, Koichi Makii, Toshiaki Takagi, Yasuhiro Aruga, Application of local tomography technique to high-resolution synchrotron X-ray imaging, 5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006, 2007.12, X-ray CT method is a kind of nondestructive inspection, but has strong limitation in sample size due to a small field of view (FOV). The higher the resolution, the smaller FOV is, mainly due to the element number of available detectors commercially. Therefore, sample machining is more or less necessary so that the sample size is fit within the small FOV in the case of the high-resolution observation. Local tomography technique enables a high resolution reconstruction of small region of interests within a sample without the sample machining. In this study, we have evaluated the size effects of aluminum foam samples in terms of the 3D image quality by the local tomography techniques.. |
| 194. | M. Nakai, M. Niinomi, T. Akahori, N. Ohtsu, H. Nishimura, H. Toda, H. Fukui, M. Ogawa, Hard-ceramic layer formed on Ti-29Nb-13Ta-4.6Zr and Ti-6Al-4V ELI during Gas Nitriding, 6th Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6, 2007.12, The surface of Ti-29Nb-13Ta-4.6Zr (TNTZ) subjected to gas nitriding at 1023-1223 K was investigated in comparison with the conventional biomedical titanium alloy, Ti-6Al-4V ELI (Ti64). After gas nitriding, the microstructures near the surface of these alloys were observed by optical microscopy, X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. In both alloys, two titanium nitrides (TiN and Ti2N) are formed and the a phase precipitated by gas nitriding. Furthermore, oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO 2 is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding.. |
| 195. | M. Kobayashi, Y. Takayama, H. Kato, H. Toda, In-situ SEM/EBSP analysis during annealing in a pure aluminum foil for capacitor, 5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006, 2007.12, In-situ SEM/EBSP analysis has been performed during the evolution of the cube texture in a pure aluminum foil. In general, foils for capacitor are manufactured in an industrial process of casting, homogenizing, hot rolling, cold rolling (CR), partial annealing (PA), additional rolling (AR) and final annealing (FA). The foil samples after CR or AR in the process were analyzed by the SEM/EBSP technique at a constant temperature which was step-heated repeatedly by 10-20K from a room temperature to 623K or 598K. In a CRed sample, cube ({001}〈100〉) grains begin to grow preferentially at 503K to cover the sample. On the other hand, in a sample subjected to PA at 503K and AR, cube grains coarsened rapidly and preferentially at more than 533K in contrast to other oriented small grains remaining their sizes. Further, intragranular misorientation analysis revealed that the misorientation, which corresponds to dislocation density or strain, was much smaller in cube grains than in S ({123}〈634〉) and Cu ({112}〈111〉) ones.. |
| 196. | L. Li, H. Toda, T. Ohgaki, M. Kobayashi, T. Kobayashi, K. Uesugi, Y. Suzuki, Wavelet-based local region-of-interest reconstruction for synchrotron radiation X-ray microtomography, Materials Science and Technology Conference and Exhibition, MS and T'07 - "Exploring Structure, Processing, and Applications Across Multiple Materials Systems", 2007.12, Synchrotron radiation X-ray microtomography is becoming a uniquely powerful method to non-destructively access three-dimensional internal microstructure in a metallic material, with a resolution of 1-micrometer or less. The tiny field of view of the detector, however, requires that the sample has to be strictly small, which would limit the practical applications of the method such as in-situ experiments. In this paper, a wavelet-based local tomography algorithm is proposed to recover a local region of interest inside a large object only using the local projections, which is motivated by the locality property of wavelet transform. Local tomography experiment for an Al-Cu alloy is carried out at SPring-8, the third-generation synchrotron radiation facility in Japan. The proposed method readily enables the high-resolution observation for a large specimen, by which the applicability of the current microtomography would be promoted to a large extent.. |
| 197. | 戸田 裕之, T. Kobayashi, Aluminum-based heavily deformed in-situ composite, 10th ICAM, 2007.10. |
| 198. | H. Toda and T. Kobayashi, Aluminum-based heavily deformed in-situ composite, The 10th International Conference on Advanced Materials, 2007.10. |
| 199. | H.Toda, Y.Takami, M.Kobayashi, T.Kobayashi, Y.Aruga, T.Takagi, Y.Suzuki, K.Uesugi, 3-D Microstructural Characterization of Cell Wall in a High Strength Aluminium Foam, The 10th International Conference on Advanced Materials, 2007.10. |
| 200. | H. Toda, M. Kobayashi, K. Uesugi, D.S. Wilkinson and T. Kobayashi, 3-D strain mapping inside materials by microstructural tracking in tomographic volumes, The 10th International Conference on Advanced Materials, 2007.10. |
| 201. | M.Nakai, M.Niinomi, T.Akahori, Y.shinozaki, H.Toda, S.Itsuno, N.Haraguchi, Y.Itoh, T.Ogasawara, T.Onishi, Mechanical properties of porous Titanium filled with polymethyl-methacrylate for biomedical applications, Proceedings of International Conference on Advanced Technology in Experimental Mechanics 2007, 2007.09. |
| 202. | M.Kobayashi, H.Toda, T.Ohgaki, K.Uesugi, D.S.Wilkinson, T.Kobayashi, Y.Kawai, Y.Aoki, Measurement of 3-D strain distribution based on tracking of microstructural features in high-resolutioin SR-CT image, Proceedings of International Conference on Advanced Technology in Experimental Mechanics 2007, 2007.09. |
| 203. | H.Toda, S.Yamamoto, K.Uesugi, M.Kobayashi, T.Kobayashi, 3-D measurement of crack-tip opening displacement along crack front line via synchrotron microtomography, Proceedings of International Conference on Advanced Technology in Experimental Mechanics 2007, 2007.09. |
| 204. | M. Nakai, M. Niinomi, T. Akahori, Y. Shinozaki, 戸田 裕之, S. Itsuno, N. Haraguchi, Y. Itoh, T. Ogasawara, T. Onishi, Mechanical properties of porous Titanium filled with polymethyl-methacrylate for biomedical applications, ATEM '07, 2007.09. |
| 205. | M. Kobayashi, 戸田 裕之, T. Ohgaki, K. Uesugi, D.S. Wilkinson, T. Kobayashi, Y. Kawai, Y. Aoki, Measurement of 3-D strain distribution based on tracking of microstructural features in high-resolutioin SR-CT image, ATEM '07, 2007.09. |
| 206. | 戸田 裕之, S. Yamamoto, K. Uesugi, M. Kobayashi, T. Kobayashi, 3-D measurement of crack-tip opening displacement along crack front line via synchrotron microtomography, ATEM '07, 2007.09. |
| 207. | H.Zhang, H.Toda, M.Kobayashi, T.Kobayashi, Y.Suzuki, K.Uesugi, Three-dimensional investigation of steady state fatigue crack closure via high-resolution synchrotron X-ray microtomography, 日本金属学会, 2007.09. |
| 208. | M. Nakai, M. Niinomi, T. Akahori, Y. Shinozaki, H. Toda, S. Itsuno, N. Haraguchi, Y. Itoh, T. Ogasawara, T. Onishi, Development of Fabrication Process of Poyous Titanium and Polymethylmethacrylate (PMMA) Composite Biomaterial, Ti-2007 Science and Technology, proceedings of the 11th World Conference on Titanium (JIMIC5), 2007.06. |
| 209. | L.Q.Li, H.Toda, T.Ohgaki, M.Kobayashi, T.Kobayashi, K.Uesugi, WeveWabelet-based local region-of-interest reconstruction for synchrotron radiation X-ray microtomography, 日本金属学会, 2007.03. |
| 210. | L. Qian, H. Toda, K. Uesugi, M. Kobayashi, T. Kobayashi, 3D image-based modeling of ductile fracture in an aluminum alloy using synchrotron X-ray CT images, 6th Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6, 2007.01, Traditional computational models always assume idealized crack geometry. However, actual crack geometry is very complex in real materials and thus, those simulations do not realistically represent the actual loading conditions of a real crack. In this paper, three-dimensional (3D) image-based simulation was performed to investigate the fracture behavior of an aluminum alloy, and the model takes into account the real crack geometry based on the 3D images of the crack. Accordingly, many essential features of fracture can be identified and interpreted, and some new insight into fracture behavior in real materials can be offered.. |
| 211. | T. Kobayashi, H. Toda, Strength and fracture of aluminium alloys, 5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006, 2007.01, Synchrotron X-ray microtomography has been utilized for the 3D characterisation of microstructure of aluminium foams. A combination of phase contrast imaging technique and several application techniques, such as local area tomography, microstructural gauging and in-situ observation, has enabled the assessment of microstructural effects on compressive deformation behaviours. It has been clarified that ductile buckling of a cell wall occurs regardless of any of the above microstructural factors in the case of a pure aluminium foam, while rather brittle fracture of a cell wall is induced by the existence of coarse micro-pores independently of the intermetallic particles and the grain boundary in the case of Al-Zn-Mg alloy foams. When cooling rate during foaming is high, however, lower energy absorption might be attributable to the significant amount of residual foaming agent particle and its inhomogeneous distribution. These tendencies are also confirmed by 3D strain mapping by tracking internal microstructural features.. |
| 212. | T. Ohgaki, Y. Takami, H. Toda, T. Kobayashi, Y. Suzuki, K. Uesugi, K. Makii, T. Takagi, Y. Aruga, Three-dimensional zinc mapping inside aluminum foams using synchrotron X-ray microtomography, 6th Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6, 2007.01, Three-dimensional zinc mapping based on X-ray K-edge scanning has been performed. By microtomographies with energies above and below the K-absorption edges of the elements, the concentration distribution of the elements is evaluated during in-situ experiments, respectively. It is found that the Zn concentration distribution during the heat treatment was changed inside the cell wall of the aluminum foams and it has been homogenized. Also several precipitated phase transformation can be three-dimensionally visualized by the CT-method tuning X-ray energies.. |
| 213. | Mitsuru Nakazawa, Yoshimitsu Aoki, Yuji Kawai, Masakazu Kobayashi, Hiroyuki Toda, 3D image analysis for evaluating internal deformation / fracture characteristics of materials, IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, 2006.12, In order to understand deformation / fracture characteristics, many measurement methods have been proposed and developed. Almost all methods, however, have been limited on the surface indirectly due to insufficient resolution. Recently, third-generation synchrotron radiation facilities have enabled observations with high resolution. Therefore, the 3D mapping of structural features like air bubbles (pores) have been attempted to understand local deformation / fracture characteristics in some materials using the X-ray computed tomography (CT). However, there are some issues and one of them is long processing time. In this paper, we propose a system which can measure a 3D, local, high-accuracy deformation / fracture characteristic by obtaining the strain distribution. Experiments have proved its effectiveness.. |
| 214. | Shin Yamamoto, Hiroyuki Toda, Lihe Qian, Tomomi Ohgaki, Masakazu Kobayashi, Toshiro Kobayashi, Kentaro Uesugi, Assessment of damage and fracture behaviors in a cast aluminum alloy via In-situ synchrotron microtomography, 10th International Conference on Aluminium Alloys, (ICAA-10), 2006.12, High resolution phase contrast imaging technique has been applied to obtain clear crack images together with the detailed of microstructural features in a cast aluminum alloy. Crack opening/closure, crack extension and damage evolution in the vicinity of a crack-tip is observed three-dimensionally (3-D). 3-D image analysis is performed to evaluate void initiation and growth near the crack-tip. The information on physical displacement of each microstructural feature ¡s provided for analyzing local crack driving forces at crack front. This technique has been identified to provide a unique possibility to quantitatively interpret the 3-D cracking behavior in bulk materials.. |
| 215. | T. Akahori, M. Niinomi, Hiroyuki Toda, H. Fukui, H. Ogawa, Fatigue properties of beta-type titanium alloy for biomedical applications under various fatigue conditions, Materials and Processes for Medical Devices Conference 2005, 2006.12, Tensile, plain and notch fatigue properties of a β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), which was subjected to various thermomechanical treatments, were investigated in order to judge its potential for biomedical applications. Microstructures of TNTZ aged at 723 K for 259.2 ks after cold rolling and those aged at 723 K for 259.2 ks after solution treatment are composed of a precipitated a phase in the β phase. However, microstructures of TNTZ aged at 598 and 673 K for 259.2 ks after cold rolling and aged at 598 K and 673 K for 259.2 ks after solution treatment are composed of a precipitated ω phase and precipitated α and ω phases in the β phase, respectively. Futher, the tensile strengths of TNTZ aged after solution treatment and those aged after cold rolling decrease with an increase in the aging temperature, although the elongation shows the reverse trend. TNTZ composed of the ω phase or the ω and a phases in the β phase shows a tensile strength of arout 1000 MPa or more. On the other hand, plain fatigue strengths of TNTZ aged after solution treatment and those of TNTZ aged after cold rolling increase with the aging temperature. In particular, TNTZ aged at 723 K after cold rolling exhibits the highest fatigue strength in both the low- and high-ycle fatigue life regions. Futher, the fatigue limit, which is about 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI conducted with aging, which is one of the representative α+β-type titanium alloys for biomedical applications. The notch fatigue strengths of TNTZ aged at stress concentration factors of 2 and 6 decrease by 30%-40% and 50%-60%, respectively, as compared with the plain fatigue strengths in the low-cycle fatigue life region. Futher, the notch fatigue limits range from 450 to 490 MPa and from 220 to 300 MPa, respecitvely; an exception to this is TNTZ aged at 598 K after cold rolling, which has a high volume fraction of the ω phase. Single- and multi- fatigue cracks initiate at the bottom of the notch at stress concentration factors of 2 and 6, respectively.. |
| 216. | Hiroyuki Toda, T. Kobayashi, M. Niinom, T. Akahori, T. Sakai, Improvement of mechanical properties by high temperature solution treatment in an aluminum casting alloy, 23rd ASM Heat Treating Society Conference, 2006.12, The authors have realized that solution treatment may be possible at a higher temperature than that by the conventional air furnace if a fluidized bed furnace is utilized. In this study, solution treatment temperatures close to binary or ternary eutectic temperatures were used for a JIS AC4CH cast aluminum alloy. Mechanical properties were tested with internal microstructures such as micro-pores and intermetallic compound particles then being correlated using high resolution computed tomography. It is clarified that the solution treatment at the ternary eutectic temperature brings the improvement of strength by about 15.7 % for a relatively short solution treatment time (typically about 1/10 of the conventional condition by an air furnace) . On the other hand, the solution treatment at the binary eutectic temperature causes significant degradation by coalescence of micro-pores forming crack-like pores. These behaviors can be assessed by visualizing internal microstructures using the high resolution computer tomography (hereafter, CT). Overall, the combination of the superior heating furnace with the state-of-the-art temperature control and sophisticated visualization technique may enable the improvement of mechanical properties in aluminum cast alloys.. |
| 217. | Hiroyuki Toda, Keisuke Minami, Masakazu Kobayashi, Kentaro Uesugi, Akihisa Takeuchi, Toshiro Kobayashi, Observation of precipitates in aluminum alloys by sub-micrometer resolution tomography using fresnel zone plate, 10th International Conference on Aluminium Alloys, (ICAA-10), 2006.12, An X-ray microtomography combined with hard X-ray imaging microscopy, that potentially has a spatial resolution of the order of 10 to 100 nm, has been applied to the three-dimensional observation of internal microstructural features in overaged Al-Ag alloys. A Fresnel zone plate is used as an objective with a magnification of 49.3 times. Imaging of resolution test patterns has indicated spatial resolutions of around 180 and 200 nm in the vertical and horizontal directions, respectively. This paper reports the first impression of the microstructural imaging by means of such a high-resolution imaging microtomography. Precipitate microstructures are readily observed and quantified in terms of volume fraction and orientation. Conventional microtomography with a simple projection geometry is also applied for comparison purpose at the highest resolution level currently available at a third generation synchrotron facility. It would appear that the present technique provides a unique potential to observe the 3-D geometry and spatial distribution of nanoscopic features inside samples that are several orders of magnitude thicker than thin-foil specimens for TEM observation.. |
| 218. | T. Ohgaki, L.Q. Li, Y. Takami, 戸田 裕之, T. Kobayashi, K. Uesugi, Visualization of 3D microstructure in porous metal materials at K-edge X-ray absorption by local tomography, 1st Workshop of the Asia/Oceania Forum for Synchrotron Radiation Research Program Book, 2006.11. |
| 219. | Lihe Qian, Hiroyuki Toda, Kentaro Uesugi, Masakazu Kobayashi, Toshiro Kobayashi, 3-D In-situ Visualization and Image-based Simulation of Ductile Fracture in an Al-Si Alloy, 日本金属学会, 2006.09. |
| 220. | H. Zhang, H. Toda, H. Hara, K. Uesugi, M. Kobayashi, T. Kobayashi, D. Sugiyama, N. Kuroda, 3D Characterization of Fatigue Crack Propagation in a Cast Al Alloy using High Resolution Synchrotron Microtomography, 日本金属学会, 2006.09. |
| 221. | Zuldesmi, S. Mitsuo, T. Akahori, M. Nakai, H. Toda, T. Fukui, O. Michiharu, Effect of Aging Treatment on Mechanical Properties of Cast Beta Type Titanium Alloy for Dental Applications, 日本金属学, 2006.09. |
| 222. | L. Qian, 戸田 裕之, K. Uesugi, T. Ohgaki, M. Kobayashi, T. Kobayashi, 3D visualization of ductile fracture using synchrotron X-ray computer tomography, 16th ECF, 2006.07. |
| 223. | 戸田 裕之, T. Ohgaki, M. Kobayashi, T. Kobayashi, K. Uesugi, K. Maki, T. Takagi, Y. Aruga, Application of synchrotron X-ray microtomography to aluminium foams, International Porous Metals Symposium, 2006.05. |
| 224. | Zuldesmi, M. Niinomi, T. Akahori, M. Ogawa, Effect of Aging Treatment on Mechanical Properties of Cast Beta Type Titanium Alloy for Dental Applications, 軽金属学会, 2006.05. |
| 225. | L. Qian, H. Toda, T. Ohgaki, K. Uesugi, M. Kobayashi, T. Kobayashi, 3D visualization of ductile fracture using synchrotron X-ray computer tomography, 16th European Conference of Fracture, 2006.01. |
| 226. | L.Qian, H.Toda, T.Ohgaki, K.Uesugi, M.Kobayashi, T.Akahori, M.Niinomi, and T.Kobayashi, 3D quantitative investigation of ductile fracture in cast Al alloys using synchrotron X-ray microtomography, 日本金属学会, 2005.09. |
| 227. | L. Qian, 戸田 裕之, S. Nishido, T. Kobayashi, M. Niinomi, T. Akahori, Assessment of crack growth behaviours of practical aluminum alloys via numerical simulation, NAFEMS World Cong. 2005, 2005.05. |
| 228. | Toshikazu Akahori, Mitsuo Niinomi, Hisao Fukui, Michiharu Ogawa, Hiroyuki Toda, Improvement in fatigue characteristics of newly developed beta type titanium alloy for biomedical applications by thermo-mechanical treatments, Selected Papers Presented at the Materials Science and Technology 2004 Meeting: Titanium for Biomedical, Dental, and Healthcare, 2005.05, Tensile and plain fatigue properties of β type titanium alloy, Ti-29Nb-13Ta-4.6Zr, which underwent various thermo-mechanical treatments, were investigated in order to judge its potential for biomedical applications. Microstructures of Ti-29Nb-13Ta-4.6Zr (TNTZ) aged directly at 723 K for 259.2 ks after cold rolling and TNTZ aged at 723 K for 259.2 ks after solution treatment are composed of precipitated α phase in β phase. While, microstructures of TNTZ aged directly at 598 K and 673 K for 259.2 ks after cold rolling and aged at 598 K and 673 K for 259.2 ks after solution treatment are composed of precipitated ω phase, and precipitated α and ω phases in β phase, respectively. Tensile strength of aged TNTZ after solution treatment and aged TNTZ after cold rolling decreases with increasing aging temperature although the elongation shows the reverse trend. TNTZ composed of ω phase or ω and α phases in β phase shows the tensile strength of around 1000 MPa or more. Young's moduli of aged TNTZ after solution treatment and aged TNTZ after cold rolling decrease with increasing aging temperature. TNTZ conducted with solution treatment has the lowest Young's modulus of around 60 GPa. Fatigue strengths of aged TNTZ after solution treatment and aged TNTZ after cold rolling increase with increasing aging temperature. In particular, TNTZ aged directly at 723 K after cold rolling shows the greatest fatigue strength in both low cycle fatigue life and high cycle fatigue life regions, and the fatigue limit, which is around 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI conducted with aging, which is one of representative α + β type titanium alloys for biomedical applications.. |
| 229. | J. J. Ahn, H. Toda, M. Niinomi, T. Kobayashi, T. Akahori, K. Uesugi, True-3D strain mapping for assessment of material deformation by synchrotron X-ray microtomography, Review of Progress in Quantitative Nondestructive Evaluation, 2005.04, Downsizing of products with complex shapes has been accelerated thanks to the rapid development of electrodevice manufacturing technology. Micro electromechanical systems (MEMS) are one of such typical examples. 3D strain measurement of such miniature products is needed to ensure their reliability. In the present study, as preliminary trial for it 3D tensile deformation behavior of a pure aluminum wire is examined using the synchrotron X-ray microtomography technique at Spring-8, Japan. Multipurpose in-situ tester is used to investigate real-time tensile deformation behavior of the Al wire. Tensile tests are carried out under strokes of 0, 0.005, 0.01 and 0.015mm. It measures 3D local deformation of a region of interest by tracking a relative movement of a pair of particles at each point. Local deformation behavior of the Al wire is identified to be different from macroscopic deformation behavior. It may be closely associated with underlying microstructure.. |
| 230. | N. Sakaguchi, M. Niinomi, T. Akahori, J. Takeda, 戸田 裕之, Super elastic behavior observation in Ti-Nb-Ta-Zr system alloy for biomedical applications, 4th Asian Int. Sympo. Bio. Appl., 2004.11. |
| 231. | Y. L. Zhon, M. Niinomi, H. Toda and T. Akahori, Aging Response of Martensite a” and Resulting Mechanical Properties of Ti-Ta Alloys for Biomedical Applications, 日本金属学会, 2004.09. |
| 232. | Tomokazu Masuda, Hiroyuki Toda, Toshiro Kobayashi, Notch effects on impact tensile properties in A6061-T6 aluminum alloy, Designing, Processing and Properties of Advanced Engineering Materials: Proceedings on the 3rd International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2004.07, The strain rate sensitivity of a A6061-T6 aluminum is examined as a function of triaxial stress. The triaxial stress state is changed by changing the notch acuity of notched specimens. Under the high strain rate conditions, increasing triaxiality increases flow stress. Plastic constraint factor decreases in notched specimens under high strain rate conditions. Reduction-of-area in notched specimen increases with increasing strain rate. The relaxation of plastic constraint takes place under high strain rate in the notched specimens. The effects of triaxial stress and strain rate on the fracture surfaces are discussed.. |
| 233. | Hiroyuki Toda, Toshiro Kobayashi, Up-grade recycle by consolidating aluminum cutting chip under severe plastic deformation, Designing, Processing and Properties of Advanced Engineering Materials: Proceedings on the 3rd International Symposium on Designing, Processing and Properties of Advanced Engineering Materials, 2004.07, Cutting chip is, generally, remelted for recycling solely as raw materials. In terms of microstructures, however, the cutting chip may be identified utilizable due to highly accumulated strain during its formation. In this study, aluminium chips are consolidated by cold severe plastic deformation so that their highly deformed microstructure is utilized for strengthening. After a preliminary investigation in which a variety of cutting processes and conditions are examined to find the optimum one for the present purpose, the aluminium chips have been successfully consolidated by a combination of pressing and swaging. The consolidated chips exhibit superior strength to a wrought alloy together with finer microstructure when compared at a same applied strain. In addition, a simple method is demonstrated effective to eliminate the undesirable effects of oxide film on the surface of the chips, which inevitably causes debonding during loading.. |
| 234. | Lihe Qian, S. Nishido, H. Toda, T. Kobayashi, Numerical Simulation of Fracture Behavior of Model Al-Si Alloys, 軽金属学会, 2004.05. |
| 235. | Hiroyuki Toda, Toshiro Kobayashi, Damage behaviours of various coarse Al-Fe-Si particles in model wrought alloys, Thermec 2003 Processing and Manufacturing of Advanced Materials, 2003.01, Al-Fe(-Si) model wrought alloys are prepared which are cast at three different cooling rates on a laboratory scale. In-situ SEM observation of tensile tests has been used to observe damage behaviours of coarse intermetallic compound (IMC) particles; AlmFenSip and AlmFe which are usually observed in practical wrought aluminium alloys. Particular attention is given to the chemical composition, size and aspect ratio of each broken particle. AlFeSi particles close to Al8Fe2Si1 and Al10Fe3Si3 are formed by metal mold and Graphite mold castings, respectively, and AlFeSi particles with various composition ratios are formed by furnace cooling, then being transformed into AlFe3 by subsequent long exposure at 858 K. Almost all of the AlFeSi particles formed during the metal and Graphite mold castings remain intact, while other AlFeSi and AlmFe particles are damaged extensively. Factors affecting the in-situ strengths of the particles are discussed.. |
| 236. | Tomokazu Masuda, Toshiro Kobayashi, Lei Wang, Hiroyuki Toda, Effects of strain rate on deformation behavior of A6061-T6 aluminum alloy, Thermec 2003 Processing and Manufacturing of Advanced Materials, 2003.01, The strain rate sensitivity of A6061 aluminum is examined as a function of aging condition. The triaxial stress is changed by notched specimen. Increasing triaxiality under high strain rate condition increases flow stress and size of void. No difference of the mechanical properties is found for the results between peakaged and overaged specimens under different strain rates. Plastic constraint factor under high strain rate with notched specimen decreases. The voids initiation, growth and coalescence under high strain rate are promoted by notch, then, the formation of cup-cone type failure takes place. This is accompanied by a concomitant increase in reduction of area with increasing strain rate. The effects of triaxial stress and strain rate on the fracture surfaces are also discussed.. |
| 237. | Nasir Hayat, Hiroyuki Toda, Toshiro Kobayashi, Noboru Wade, Experimental investigations of fatigue characteristics of AC4CH cast aluminum alloys fabricated through rheocast and squeeze cast methods, Aluminium Alloys 2002 Their Physical and Mechnaical Properties: Proceedings of the 8th International Conference ICAA8, 2002.12, This study investigates the fatigue characteristics of AC4CH cast aluminum alloys fabricated through the semi-solid metal (rheocasting) process by employing the inclined cooling plate technique with a wide range of spherical α size (38-160 μm) and compares with those of the conventional squeeze casting. Rheocasting process employing an inclined cooling plate is based on the crystal separation theory. The results of measured microstructural parameters indicate that aspect ratio and size of eutectic Si and size of intermetallic compound decrease with the decrease in primary α size. The fatigue strength increases with decreases in primary α size and the material with the minimum primary α size (i.e. 38μm) shows 11.3% higher fatigue strength at 107 cycles than that of the squeeze cast material. Although difference in damage accumulation behaviors during tensile loading is quantified by the in-situ studies, however, it does not seem to have discernable effect on the fatigue properties. The Si and intermetallic compound particles remain almost intact below 250 MPa and 200 MPa respectively in all of the materials and damage evolution occurs at the lowest stress level in the squeeze cast material. Moreover, the maximum fraction of the damaged particles depends upon the primary α size and reaches the maximum with the minimum primary α size. The crack growth rates through each phase indicate that the main difference between the rheocast and the squeeze cast material is in the crack propagation across the grain boundaries with the other regions having almost comparable crack propagation rates in the same as well as between different materials. The fact that even decrease in grain size does not lead to the impressive improvement in fatigue strength can not be attributed to the difference in grain structure according to quantitative investigation of misorientation angles between neighboring grains utilizing a scanning electron microscope equipped with electron backscattered diffraction pattern facility.. |
| 238. | Nasir Hayat, T. Kobayashi, H. Toda, W. Lei, Effects of gas bubbling conditions on the grain refinement in AC4CH cast aluminium alloy, 日本金属学会, 2002.11. |
| 239. | 戸田 裕之, T. Kobayashi, Shape memory alloy particles dispersed titanium composites, Mater. Cong. 2002, 2002.04. |
| 240. | Hiroyuki Toda, Toshiro Kobayashi, In-situ strengths of various coarse intermetallic particles in wrought aluminum alloys, Aluminium Alloys 2002 Their Physical and Mechnaical Properties: Proceedings of the 8th International Conference ICAA8, 2002.01, Al-Mg-Si, Al-Fe-Si and Al-Fe model alloys are cast at three different cooling rates. In-situ SEM observation of tensile tests has been used to characterize the strength levels of various coarse intermetallic compound (IMC) particles such as Mg2Si, AlmFenSip and AlmFe which are usually observed in practical aluminum alloys. Particular attention is given to the chemical composition, size and aspect ratio of each broken panicle. AlFeSi particles close to Al8Fe2Si 1 and Al10Fe3Si3 are formed by metal mold and Graphite mold castings, respectively and AlFeSi panicles having various composition ratios are formed by furnace cooling, which are transformed into AlFe3 by subsequently being exposed at 858 K. Almost all of the AlFeSi particles formed during the metal and Graphite mold castings remain intact, while Mg2Si, AlmFe and other AlFeSi panicles are damaged extensively. In-situ strength levels of the damaged particles are also estimated utilizing Eshelby inclusion method.. |
| 241. | V.A.Mosneaga, T. Kobayashi, H. Toda, Fracture Toughness of Weldments in Al-Si-Mg Alloys, 日本金属学会, 2001.08. |
| 242. | 戸田 裕之, Shape memory alloy particles dispersed titanium composite, Proceedings of the International Symposium on Smart Materials and Structural Systems, JSME, Fukui, 2001.08. |
| 243. | 戸田 裕之, Shape memory alloy particles dispersed titanium composite, Proceedings of the International Symposium on Smart Materials and Structural Systems, JSME, Fukui, 2001.08. |
| 244. | 小林俊郎, 戸田裕之, 橋詰貴志, Design and fabrication of shape memory alloy actuated titanium matrix composites, 日本MRS, 2000.12. |
| 245. | 戸田 裕之, Proceedings of International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2000, Las Vegas, U.S.A., Effects of coarse intermetallic particles on fracture toughness of wrought aluminum alloys, 2000.10. |
| 246. | 戸田 裕之, Proceedings of International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2000, Las Vegas, U.S.A., Effects of coarse intermetallic particles on fracture toughness of wrought aluminum alloys, 2000.10. |
| 247. | T. Hashizume, T. Kobayashi, 戸田 裕之, Design and evaluation of TiNi particle dispersed titanium matrix composite, 12th Symposium of The Materials Research Society of Japan, 2000.06. |
| 248. | 戸田 裕之, Fracture and toughness of MMCs, Proceedings of the 10th IKETANI Conference on Materials Research toward the 21st Century, 2000.06. |
| 249. | 戸田 裕之, Fracture and toughness of MMCs, Proceedings of the 10th IKETANI Conference on Materials Research toward the 21st Century, 2000.06. |
| 250. | V.Mosneaga, T.Kobayashi and H.Toda, Effects of age-hardening on the mechanical properties of 6061 Al alloy processed by ECAP, 日本金属学会, 2000.03. |
| 251. | Hiroyuki Toda, Akihiro Takahashi, Toshiro Kobayashi, Effects of damaged coarse inclusion particles on mechanical properties of wrought aluminum alloys, The 7th International Conference ICCA7 - 'Aluminium Alloys: 'Their Physical and Mechanical Properties', 2000.01, In-situ SEM observation of fracture toughness tests has been used to characterize the fracture behavior of a wrought aluminum alloy. Particular attention is given to in-situ fracture strength of the coarse inclusions associated with this alloy. The fracture domain of CuAl2 and Al2CuMg particles with respect to the main crack is also investigated. Crack propagation is conducted by ductile failure of matrix ligaments between the fractured particles and the main crack, thereby producing slight crack deflection. Coarse Al3Zr and Al3Ti particles even adjacent to the fracture surface remain intact, while CuAl2 and Al2CuMg particles are extensively damaged ahead of a crack-tip. A combination of HRR singularity and Eshelby type internal stress analysis is used to estimate the in-situ strength values of various inclusion particles. It is concluded that the fracture strength of the inclusion particles has strong dependence on diameter. For example, it decreases from 740 to 500 MPa for the Al2CuMg. By decreasing the volume fraction of the coarse inclusions larger than 3μm from 2.2 to 1.2% by applying various heat and thermo-mechanical treatments, 0.2% proof stress, fracture toughness and crack propagation resistance of the alloy are remarkably improved without sacrificing ductility.. |
| 252. | Toshiro Kobayashi, Naoya Inoue, Shigeki Morita, Hiroyuki Toda, On the accuracy of measurement and calibration of load signal in the instrumented Charpy impact test, The 1999 Symposium on 'Pendulum Impact Testing: A Century of Progress', 2000.01, Significant variation in measured load of an instrumented Charpy impact test is observed if specimen materials or sizes are changed from the standard specimen. Load calibration factors for different materials and sizes of specimens are evaluated by means of both experiments and finite element analysis. Elastic finite element analysis shows that the strain fields in the instrumented striker in contact with different materials and sizes of specimens are not exactly the same as those for the standard specimen. As a result of experiment and analysis, the decrease in stiffness or size of specimens results in a decrease in the calibration factor. Those are attributable to strain localization near the region in which the strain gage is attached. Therefore, the measured load for low-stiffness materials or miniaturized specimens is overestimated when the decrease of calibration factor is disregarded. Those results strongly suggest that the system must be calibrated for the different materials and sizes of specimens to obtain accurate toughness data.. |
| 253. | T. Hashizume, T. Kobayashi, 戸田 裕之, Strengh and fracture toughness of shape memory alloy actuated titanium matrix composites, the 3th Oxford Kobe Materilals Seminer, 1999.09. |
| 254. | S. Takahashi, T. Kobayashi, 戸田 裕之, Al-X (X=Nb, Cr, Fe) ultra-high strength in-situ composite wire, the 3th Oxford Kobe Materilals Seminer, 1999.09. |
| 255. | L. Qian, T. Goda, 戸田 裕之, T. Kobayashi, Particle size effect on the dynamic fracture behavior of the 6061 Al composite, the 3th Oxford Kobe Materilals Seminer, 1999.09. |
| 256. | F. Zeismann, L. Zellmer, P. Pitz, Y. Motoyashiki-Besel, Hiroyuki Toda, A. Brückner-Foit, Observation of three-dimensional crack path in a dual phase steel, 3rd International Conference on Heterogeneous Materials Mechanics, ICHMM 2011, Fatigue cracks were initiated in a dual-phase ferritic-martensitic steel using smooth specimens. Tiny sub-specimens containing typical crack configurations were then cut out by spark erosion which could be put in a synchrotron beam-line (spring8 in Japan). This allowed determining the three-dimensional shape of the cracks. Afterwards, the local microstructure in the vicinity of the crack front was investigated in the SEM including the crystallographic orientations via EBSD. This was done on the specimen surface as well as in depth direction by polishing in well defined steps. Consequently, the local microstructure along the crack front was known and its influence on three-dimensional crack could be analyzed.. |
| 257. | 戸田 裕之, 3D/4D strain mapping using in-Situ X-ray microtomography, SEM XII International Congress & Exposition on Experimental & Applied Mechanics: Measurement Challenges for New Structures and Materials (SEM XII), June 11-14, 2012, Hilton Orange County/Costa Mesa, Costa Mesa, CA, USA. |
| 258. | 戸田 裕之, 3D/4D strain mapping using in-Situ X-ray microtomography, SEM XII International Congress & Exposition on Experimental & Applied Mechanics: Measurement Challenges for New Structures and Materials (SEM XII), June 11-14, 2012, Hilton Orange County/Costa Mesa, Costa Mesa, CA, USA. |
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