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Your search keyword '"Horikawa, Keitaro"' showing total 304 results
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304 results on '"Horikawa, Keitaro"'

5. Hydrogen-induced pore formation in Ni–P-plated Al–Zn–Mg alloys revealed by synchrotron X-ray computed tomography and hydrogen detection.

Author

Horikawa, Keitaro, Hino, Makoto, Shimizu, Kazuyuki, Toda, Hiroyuki, Hoshino, Masato, and Uesugi, Kentaro

Subjects
*COMPUTED tomography, *HYDROGEN analysis, *ALLOY plating, *ALLOY analysis, *TENSILE strength
Abstract

The internal microstructures of Ni–P-plated Al–Zn–Mg-based alloys were investigated using synchrotron X-ray computed tomography, together with various analytical methods for hydrogen detection. We clarified that hydrogen-induced pores were generated and segregated near the top and bottom surfaces of a rolled sheet of a commercial-purity Al–Zn–Mg-based alloy with Ni–P plating. In contrast, such segregation of hydrogen micropores was not observed in the high-purity-grade Al–Zn–Mg alloys with Ni–P plating. This result suggests that hydrogen enters the Ni–P plating layer during the plating operation and generates pores in the surface region owing to surface inclusions. Additionally, the hydrogen-induced defects deteriorated the tensile properties such as tensile strength and elongation of the commercial-purity Al–Zn–Mg-based alloys containing higher levels of impurities such as Fe and Si with Ni–P plating. [Display omitted] • Internal microstructures of Ni–P-plated Al–Zn–Mg-based alloys investigated. • Synchrotron X-ray computed tomography and hydrogen detection methods were employed. • H enters plating layer and generates surface micropores due to surface inclusions. • H-induced defects deteriorate the tensile properties of the plated pure alloy. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Origin of Ductile Fracture in Aluminum Alloys

Author

Toda, Hiroyuki, Oogo, Hideyuki, Tsuruta, Hideki, Horikawa, Keitaro, Uesugi, Kentaro, Takeuchi, Akihisa, Suzuki, Yoshio, Kobayashi, Masakazu, Weiland, Hasso, editor, Rollett, Anthony D., editor, and Cassada, William A., editor

Published
2016
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30. Numerical Analysis and Experiment for Stress Wave Propagation in Two Connected Cylindrical Bodies with Different Cross-Sectional Area and Same Mechanical Impedance

Author

Kobayashi Hidetoshi, Seo Yuya, Ogawa Kinya, Horikawa Keitaro, and Tanigaki Ken-ichi

Subjects
Physics, QC1-999
Abstract

In this study, the behaviour of elastic stress wave propagating two connected cylindrical bodies was examined using dynamic finite element method (FEM). They consist of two bodies with different cross-sectional area, different Young’s modulus and identical mechanical impedance. It was found that when an incident wave passes through the boundary step between two different cross-sectional areas, a pair of reflected waves which has the same amplitude and opposite sign was observed, despite the same mechanical impedance. This phenomenon appears to be caused by the loading and unloading the boundary section due to the arrival and the passage of incident wave. It was also found that a connection manner to insert the smaller diameter cylinder into the other cylinder with a little length is quite effective for the reduction of the reflected wave, because of the superposition of waves from two edges and control of local deformation. This phenomenon was verified by a series of impact experiments using two cylindrical bodies connected by interference fit.

Published
2018
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39. Origin of Ductile Fracture in Aluminum Alloys

Author

Toda, Hiroyuki, primary, Oogo, Hideyuki, additional, Tsuruta, Hideki, additional, Horikawa, Keitaro, additional, Uesugi, Kentaro, additional, Takeuchi, Akihisa, additional, Suzuki, Yoshio, additional, and Kobayashi, Masakazu, additional

Published
2012
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