Speaker
Dr
Kenichi Oikawa
(Japan Atomic Energy Agency)
Description
The Japanese swords are very attractive not only as a work of art but also a metallurgical point of view. There are various kinds of the structure combining the Japanese swords materials, i.e., the steel combining method of making Japanese sword blade (Tsukurikomi). Among them, Honsanmai was popular in Edo period (1603–1867) and is also popular in modern Japanese swords. However, at rather early stage of the Japanese sword history, Mukukitae (formula without combining different steels) was adopted. Various kinds of Tsukurikomi swords were already studied by using destructive methods, such as microscope, chemical analysis, X-ray diffraction, etc. This observation style was possible in the past, but at the present time when Japanese vintage swords became valuable, it is indispensable to establish non-destructive analysis method to identify the type of Tsukurikomi.
Non-destructive experiments such as pulsed neutron imaging and diffraction are powerful tools to study metallic cultural heritages due to their high penetrating power and capability to give crystallographic information. For example, the strained and the no strained samples show different shape of the Bragg edge spectra as well as the Bragg peak patterns, which indicates difference in treatment methods of steel. For the first trial of our study, three kinds of Japanese swords were made by a swordsmith. Two of them are Mukukitae and one is Honsanmai. Pulsed neutron imaging and diffraction experiments were performed at RADEN and NOBORU at J-PARC, respectively. Each sword samples were cut in three parts to be measured simultaneously by using the 100 × 100 mm2 area detector, nGEM. Neutron diffraction experiments were focused on specific parts of the swords to see the difference in combination of the steels. We are now analyzing the measured 2D-transmission spectra using RITS code to obtain spatial distribution of the crystallite size, the texture variation and the edge shift and broadening (hardness) mapping for each sample. Complementary diffraction data analysis is also on going. Detailed analysis results will be presented.
Acknowledgments:
The authors would like to thank Naohiko Sasaki from the Japan Steel Works, Ltd. for forging sword samples and valuable comments on them.
Primary author
Dr
Kenichi Oikawa
(Japan Atomic Energy Agency)
Co-authors
Prof.
Akira Uritani
(Nagoya University)
Mr
Genki Hori
(Nagoya University)
Dr
Kenichi Watanabe
(Nagoya University)
Dr
Takenao Shinohara
(Japan Atomic Energy Agency)
Dr
Tetsuya Kai
(Japan Atomic Energy Agency)
Prof.
Yoshiaki Kiyanagi
(Nagoya University)
Mr
Yuho Hirata
(Nagoya University)
