Nagata, Kazahiro*; Furunushi, Yasuko*; Matsubara, Akihiro*; Kokubu, Yoko; Nakamura, Toshio*
Tetsu To Hagane, 105(4), p.488 - 491, 2019/04
The Japanese nails had been produced by the traditional ironmaking way of Tatara until the Edo period since the late of 6 Century. The quality of the Japanese nails is affected from steel produced by Tatara in each age. The C ages of 3 Japanese nails collected at shrines and temples at their repair were measured with accelerator mass spectrometry and calibrated to calendar years. Each C age provided plural calendar year periods with definite probabilities, and one of the periods determined in comparison with the history of temples and their repair records. The production ages of nails used in the Daibutuden of the Todaiji temple, the living quarters of the Manjuin temple and the Zaoudo of the Yoshino-Kongoji temple are before 1692, the 12 Century and before 1592, respectively, when they were repaired or reconstructed.
Toda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujiwara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.
Tetsu To Hagane, 105(2), p.240 - 253, 2019/02
no abstracts in English
Amemiya, Yutaro*; Nakada, Nobuo*; Morooka, Satoshi; Kosaka, Makoto*; Kato, Masaharu*
Tetsu To Hagane, 105(2), p.314 - 323, 2019/02
For deeper understanding of a dynamic accommodation mechanism of internal stress in pearlite originated from the lattice misfit between ferrite and cementite phases, the lattice parameter ratios of cementite were locally analyzed in detail by using the electron backscatter diffraction (EBSD) technique. The EBSD analysis has revealed that lattice parameter ratios of cementite lamellae obviously differ from those of spheroidized cementite particles, which demonstrates that pearlite has a certain amount of internal stress as long as it maintains lamellar structure. The internal stress in pearlite gradually decreased during isothermal holding at 923 K after pearlitic transformation due to interfacial atomic diffusion of iron atoms. However, comparing with theoretical values under Pitsch-Petch orientation relationship, it was understood that large amount of internal stress had been already accommodated upon pearlitic transformation by introduction of misfit dislocations and structural ledges on ferrite/cementite lamellar interfaces. That is, the internal stress of pearlite is dynamically reduced by two different processes; built-in accommodation upon pearlitic transformation and additional time-dependent relaxation after pearlitic transformation. On the other hand, EBSD analysis and neutron diffraction technique gave remarkably different lattice parameters of cementite. From this result, it is concluded that various crystallographic orientation relationships between ferrite and cementite coexist in pearlite. Furthermore, elastic strain energy analysis suggests that the invariant-line criterion on ferrite/cementite interface plays an important role for the selection of orientation relationships in pearlite.
Yamashita, Takuya; Yamashita, Hayato; Nagae, Yuji
Tetsu To Hagane, 105(1), p.96 - 104, 2019/01
no abstracts in English
Ikeda, Yoshimasa*; Takamura, Masato*; Hakoyama, Tomoyuki*; Otake, Yoshie*; Kumagai, Masayoshi*; Suzuki, Hiroshi
Tetsu To Hagane, 104(3), p.138 - 144, 2018/03
Neutron engineering diffraction is a powerful technique which provides the information of the micro structure of steels in bulk-average, while X-ray diffraction or Electron backscatter diffraction can provide information only from the surface layer. However, such measurement using neutron diffraction is typically performed in a large facility such as a reactor and a synchrotron, while a compact neutron source has never been used for this purpose. Authors have recently developed a neutron diffractometer installed in Riken Accelerator driven compact Neutron Source (RANS) and succeeded in the measurement of texture evolution of a steel sheet. In this study, we made an attempt to measure the volume fraction of retained austenite by RANS. Background noise was carefully eliminated in order to detect as many diffraction peaks as possible with low flux neutrons. The volume fraction was estimated by Rietveld analysis. The accuracy of the measurement result was discussed by comparing with those obtained by a large neutron facility (J-PARC TAKUMI). The volume fraction obtained by RANS with reasonable measurement time, i.e. 30 to 300 min, showed only 1 to 2 % discrepancies with those obtained in J-PARC. These comparisons suggest that neutron diffraction by RANS is capable of quantitative analysis of the volume fraction of crystal phases, showing the possibility of practical use of an in-house compact neutron source in the industry.
Sato, Shigeo*; Kuroda, Asumi*; Sato, Kozue*; Kumagai, Masayoshi*; Harjo, S.; Tomota, Yo*; Saito, Yoichi*; Todoroki, Hidekazu*; Onuki, Yusuke*; Suzuki, Shigeru*
Tetsu To Hagane, 104(4), p.201 - 207, 2018/00
Tsuchida, Yutaka*; Ebihara, Kenichi
Tetsu To Hagane, 103(11), p.653 - 659, 2017/11
A single peak in thermal desorption profiles of hydrogen, which are measured in low-temperature thermal desorption spectrometry (L-TDS) for a very thin plate specimen of tempered martensitic steel, was reproduced successfully by the superposition of two Gaussian distributions. Then, the parameters concerning the detrapping rate constants for both peaks, which are trap energy and pre-exponential factor, were calculated using the Choo-Lee plot. We confirmed that Kissinger model incorporating the obtained parameters could simulate the two peaks. In addition, we reproduced the single peak well using the reaction-diffusion equation incorporating the obtained parameters and the appropriate trap site concentration. From the results, we interpreted that the one peak corresponds to dislocation and the other to grain-boundary.
Tomota, Yo*; Sekido, Nobuaki*; Xu, P. G.; Kawasaki, Takuro; Harjo, S.; Tanaka, Masahiko*; Shinohara, Takenao; Su, Y.; Taniyama, Akira*
Tetsu To Hagane, 103(10), p.570 - 578, 2017/10
Tomota, Yo*; Sato, Shigeo*; Harjo, S.
Tetsu To Hagane, 103(2), p.73 - 85, 2017/01
Nagata, Kazahiro*; Matsubara, Akihiro*; Kokubu, Yoko; Nakamura, Toshio*
Tetsu To Hagane, 102(12), p.736 - 741, 2016/12
Steel of Japanese swords has been produced with Tatara process from iron sand and charcoal. Carbon dissolved in steel was absorbed from wooden charcoal fuel at the production of the steel. From the decay of C activity in the steel, the C age of Japanese sword can be determined. The C ages of 4 Japanese swords were calibrated to a few calendar years. There are several generations of the same names of sword masters. The year of production of each sword was determined from the calendar year and the sword master's name cut in the grip of his sword after taking the age of charcoal into account. The oldest calendar year with high probability agreed with the age of sword master.
Onizawa, Takashi; Nagae, Yuji; Kikuchi, Kenji*
Tetsu To Hagane, 100(8), p.999 - 1005, 2014/08
The applicability of high chromium (Cr) steel as the main structural material in fast breeder reactors (FBR) has been explored to enhance the safety, the credibility and the economic competitiveness of FBR power plants. Tungsten (W) is believed to improve the high temperature strength of high Cr steels by solid-solution strengthening mechanism, although the long-term effectiveness and stability of such a strengthening mechanism has not fully been understood yet. High Cr steels controlling W content are produced and tensile tests, creep tests, aging tests and charpy impact tests were conducted to investigate the long-term material properties. It was observed that the short-term creep strength could be improved by W. However, there is almost no influence of W on the long-term creep strength. And it was observed that the impact properties after aging could be improved by decreasing of W. It was found that the optimal W content for excellent high Cr steel of FBR grade are 0.1 wt.%, under FBR operating conditions.
Suzuki, Tetsuya*; Yamanaka, Keisuke*; Ishino, Mayuko*; Shinohara, Yasuhiro*; Nagai, Kensuke*; Tsuru, Eiji*; Xu, P. G.
Tetsu To Hagane, 98(6), p.262 - 266, 2012/06
Yamashita, Takako*; Katsuyama, Jinya; Sato, Kaoru*; Mizuno, Masataka*; Araki, Hideki*; Shirai, Yasuharu*
Tetsu To Hagane, 97(11), p.558 - 565, 2011/11
The hardness of Fe-Cu alloys is known to increase by the precipitation of Cu clusters during thermal aging. However, the mechanism of Cu precipitation has not been clarified yet. In this study, the positron lifetime and coincidence Doppler broadening techniques have been used to investigate the recovery behavior of lattice defects such as vacancies, vacancy clusters and dislocations as well as the diffusion behavior of Cu atoms of cold rolled and thermally-aged Fe-Cu alloys. Both vacancies and dislocations caused by cold rolling were reduced through the thermally aging process. Some dislocations remained even after aging at 550C, although the vacancies almost disappeared after aging at 300C. Cu clusters precipitate mainly on the dislocations, where is the sinks of the vacancies, caused by the diffusion of Cu atom and vacancies.
Obara, Satoshi; Wakai, Takashi; Asayama, Tai; Yamada, Yoshiyuki*; Nakazawa, Takanori*; Yamazaki, Masayoshi*; Hongo, Hiromichi*
Tetsu To Hagane, 96(4), p.172 - 181, 2010/04
This paper describes the effect of heat treatment on mechanical properties of 9Cr-W-Mo-V-Nb steel as a part of development of high Cr steel for fast breeder reactor (FBR). The effects of normalizing temperature and tempering temperature and time on creep properties were investigated from the viewpoint of microstructures. Creep strength increased with increase in normalizing temperature from 950C to 1200C. The microstructural factors that improve creep strength are increased amount of MX which precipitated during tempering process and increased dislocation density. In addition, coarsening of prior austenite grain size also contribute to increasing creep strength. Although creep rupture time of 780C-1h tempering specimen was greater than that of 700C-1h and 750C-1h tempering specimen in a long-term region exceeding 20000h at 650C, creep ductility and reduction of area of the former remarkably degraded compared to those of the latter.
Obara, Satoshi; Wakai, Takashi; Asayama, Tai; Yamada, Yoshiyuki*; Nakazawa, Takanori*
Tetsu To Hagane, 95(5), p.417 - 425, 2009/05
This paper describes the effect of heat treatment on mechanical properties of high chromium (Cr) ferritic steel 9Cr-W-Mo-V-Nb steel as a part of development of high Cr steel for fast breeder reactor (FBR). The effects of normalizing temperature and tempering temperature and time on high temperature tensile properties and Charpy impact properties were investigated from the viewpoint of microstructures.
Ebihara, Kenichi; Suzudo, Tomoaki; Kaburaki, Hideo; Takai, Kenichi*; Takebayashi, Shigeto*
Tetsu To Hagane, 94(11), p.62 - 71, 2008/11
We have developed a numerical model to simulate the hydrogen desorption profiles for pure iron and eutectoid steel, which is obtained in thermal desorption analysis (TDA). Our model incorporates the equation of McNabb and Foster without the hydrogen diffusion term combined with the Oriani's local equilibrium theory. It is found that the present numerical model successfully simulates the hydrogen desorption profile using the concentration of hydrogen trapping sites which is inferred from experiments both for pure iron and for eutectoid steel. We further verify the model by discussing the trapping site concentration and the effect of hydrogen diffusion. (Although this paper is similar to [ISIJ International 47(2007)1131], the process of numerical calculation is described in more detail.)
Inoshita, Shinya*; Suzuki, Shogo*; Okada, Yukiko*; Kato, Masahiko*; Hirai, Shoji*; Kimura, Atsushi; Hatsukawa, Yuichi; Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi
Tetsu To Hagane, 94(9), p.345 - 350, 2008/09
"Tatara" is Japanese original steel making method. Steel made by "Tatara" is famous as low alloy and suited to "Kaji" process. By authors' study, it turned out that we could estimate the source region of raw material of Tatara by As and Sb concentration ratio in Tatara sample. But the concentration of these element in Tatara sample is very low (ppm or sub-ppm order), therefore, quantitative analysis is very difficult. In this study, we adopted Neutron Activation Analysis combined with Multiple -ray detection (NAAMG) to analyze As and Sb in "Tatara" sample (iron lump and sand iron, slag). NAAMG is high sensitive and non-destructive analysis method which combined NAA (Neutron Activation Analysis) and multiple -ray detectors. Each "Tatara" sample (iron lump, sand iron, slag) were irradiated for 1-2 h (for As measurement), 8-17 h (for Sb measurement) in JRR-3M HR irradiation field (thermal neutron flux was about 9.010 n/m s). And cooling time was 4-5 days (As), and 19-36 days (Sb). Coincidence -rays were measured by -ray detector array, GEMINI-II. Counting time was 1-8 hours (As), and 2-41 hours (Sb). Quantification was made by comparison method. As a result of measurement, the concentration of As and Sb in all "Tatara" samples were determined by NAAMG and these were sub-ppm order. Lower Limit of Determination (LLD) of As was 0.1 ppm order and Sb is 0.01ppm order. From the above-mentioned point, the effectiveness of NAAMG to analyze trace element in "Tatara" sample was confirmed.
Onizawa, Takashi; Ando, Masanori; Wakai, Takashi; Asayama, Tai; Kato, Shoichi
Tetsu To Hagane, 94(3), p.91 - 98, 2008/03
Employment of high Cr steel as a main structural material is considered as a way to achieve economical competitiveness of fast breeder reactors. A series of trial products controlling V and Nb contents is produced and aging tests are conducted to investigate the long term stability of the MX strengthening mechanism. Before and after a long term aging process, metallurgical examinations and quantitative analyses are conducted to investigate the stability of MX particles. After aging, Z-phase was observed in high Cr steel content Nb. With precipitation and rapid coarsening of Z-phase, decrease in number of density of MX particles. Therefore, it is supposed that the long term efficiency of MX precipitation strengthening mechanisms is decrease in high Cr steel content Nb. In contrast, it is expected that VX precipitation strengthening mechanisms is stable in high Cr steel content only V, because Z-phase isn't precipitate and VX is stable after aging.
Ishio, Kotaro*; Nakajima, Hideo
Tetsu To Hagane, 92(2), p.90 - 96, 2006/02
no abstracts in English
Ishio, Kotaro*; Hamada, Kazuya; Nakajima, Hideo
Tetsu To Hagane, 92(1), p.30 - 35, 2006/01
no abstracts in English