Discovering New Aspects in a Japanese Sword

Takahashi, Tsuneo; Murakami, Takeshi; Okada, Senri; Fujii, Norihisa

doi:10.2355/tetsutohagane1955.71.15_1818

Cited by 5 publications

(9 citation statements)

References 6 publications

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“…It shows a relatively good agreement with the value reported in Ref. 3. In contrast, the value of C, estimated from the tetragonality of the martensite from formula (2), and denoted by MS in the lower section of Fig.…”

Section: Lattice Constant Mass Fraction and Carbon Contentsupporting

confidence: 89%

Microstructure Distribution of Japanese Sword Cross Sections Analyzed by the Diffractometer TAKUMI at J-PARC

Oikawa

Harjo

Pham

et al. 2021

Proceedings of the 3rd J-Parc Symposium (J-Parc2019)

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Four cross sections of Japanese swords produced in different ages and regions were measured with neutron diffraction to obtain information about the manufacturing process. Time-of-flight engineering diffractometer TAKUMI at J-PARC was used to elucidate position-dependent crystallographic characteristics, such as quenching depth, degree of texture, crystallite size, and microstrain in an mm scale by using the Rietveld refinement program and sample broadening analysis implemented in MAUD. The position-dependent carbon content estimated from the phase fraction of the secondary phase showed qualitatively good agreement with those obtained by the spark-OES and EPMA analysis conducted in the mid-1980s in Japan. On the other hand, carbon contents estimated by the tetragonality (c/a ratio) in the martensite phase are obviously low. Crystallite size and microstrain are very similar in the four samples, regardless of any differences in the age and area of production.

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Section: Lattice Constant Mass Fraction and Carbon Contentsupporting

confidence: 89%

Microstructure Distribution of Japanese Sword Cross Sections Analyzed by the Diffractometer TAKUMI at J-PARC

Oikawa

Harjo

Pham

et al. 2021

Proceedings of the 3rd J-Parc Symposium (J-Parc2019)

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“…A lot of non-metallic inclusions were reported to be distributed in Japanese sword [14,16], but those details had not been studied enough up to now. The size distribution and the area percentage of non-metallic inclusions above three specific zones were Microsoft co.…”

Section: Methodsmentioning

confidence: 99%

“…This hardness level almost corresponds to the hardness of martensite which contains 0.78 mass% carbon. Several researchers [14,18] had investigated hardness of Japanese swords on surface plane and cross section up to now. They had reported the maximum hardness level in sharp edge was about 700-820 HV.…”

Section: Micro Hardness Distributionmentioning

confidence: 99%

“…He pointed out that Hamon martensite structure and troostite (fine pearlite) structure with optical microscopy. Takahashi et al [14] had investigated the fundamental properties such as microstructure, micro hardness, chemical composition and nonmetallic inclusion about old sword and 2nd generation sword. Kitada [15] had reported the microstructure and non-metallic inclusion on some old sword.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of Microstructures on Cross Section of JAPANESE SWORD

Yaso¹,

Takaiwa²,

Minagi³

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. An old, famous Japanese sword has been studied metallurigically to observe its microstructure by optical microscopy and scanning electron microscopy. The microstructure in the sharp edge of cross-sectional part is fine martensite and the morphology is lath type martensite. The other parts of sword, side and central part, of cross section show the structure of fine pearlite or coarse pearlite dominantly. The hardness of the sharp edge is high enough to possess the sharp cutting property. SEM-EDX observations indicated that several kinds of non-metallic inclusions exist in the sword which are considered to be originated from the slag smelting reaction in Tatara process. The amount of non-metallic inclusions in the sword is 50-100 times more than that of the ordinary steel. In the sharp edge the amount of inclusions is fewer and the sizes are finer in comparison with side and central part of the sword. It is considered that repeatedly forging and folding operations in making sword process are responsible for that.

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“…Detailed manufacturing techniques, such as methods of obtaining raw materials [1], an iterative hammering process and the method for combining different steels [2] in the Koto age, are not clear, since they were handed down secretly within each school and have been lost over time. Various kinds of Japanese swords were sliced thickly and the cut surface were studied by conventional methods, such as microscopy and chemical analysis, EPMA, and so on [3]. This analytical approach was possible in the past, but at the present time when Japanese vintage swords have become valuable, it is indispensable to Neutron Radiography -WCNR-11…”

Section: Introductionmentioning

confidence: 99%

Pulsed Neutron Imaging Based Crystallographic Structure Study of a Japanese Sword made by Sukemasa in the Muromachi Period

Oikawa

Kiyanagi

Sato

et al. 2020

Materials Research Proceedings

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Energy-resolved neutron imaging using a pulsed neutron source is capable of visualizing crystallographic information over a large area of a sample by analyzing positiondependent Bragg-edge transmission spectra. We applied this method to a Japanese sword, signed by Sukemasa, to elucidate position dependent crystallographic characteristics, including but not limited to: degree of hardening, crystallite size, degree of preferred orientation. By comparing the degree of hardening to that of a contemporary short Japanese sword (dagger), the Sukemasa showed relatively small changes in the position of Bragg-edge (110) and its broadening. No coarse grain was found within the detector resolution (ca. 1 mm), and the crystallite size of the blade area was analyzed to be almost uniform and less than 1 µm. We thus recognize in a comprehensive manner that the Sukemasa sword was manufactured with great care.

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Discovering New Aspects in a Japanese Sword

Cited by 5 publications

References 6 publications

Microstructure Distribution of Japanese Sword Cross Sections Analyzed by the Diffractometer TAKUMI at J-PARC

Microstructure Distribution of Japanese Sword Cross Sections Analyzed by the Diffractometer TAKUMI at J-PARC

Study of Microstructures on Cross Section of JAPANESE SWORD

Pulsed Neutron Imaging Based Crystallographic Structure Study of a Japanese Sword made by Sukemasa in the Muromachi Period

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