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Kusumoto, Toshiyuki*; Saruta, Koichi; Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Hasegawa, Kazuo*; Tsuboi, Akihiko
Jikken Rikigaku, 23(4), p.310 - 315, 2023/12
Reducing spatter, i.e., melt droplets flown out of the melt pool, is one of the critical issues when laser cutting is employed as a machining tool for radioactive wastes because the ejected droplets can lead to radioactive contamination with potential human exposure. The spattering phenomena are complicated processes that involve multiple physical phenomena, causing difficulty in the determination of laser parameters to minimize the amount of spatter. Here we observe the spatter ejected from 316L stainless steel plates using a high-speed camera and apply a machine learning technique to these captured images on the basis of three distinctive behaviors appeared at specific time intervals of the process of spattering phenomena: (I) a vapor, (II) a liquid film and breakup into droplets, and (III) a liquid capillary. The numerical model established through the machine learning technique predicts the spattering phenomena with an accuracy of 89% and can be used to determine the laser power and beam diameter that reduce the spatter eruption during laser irradiation.
Kitagawa, Yoshihiro; Shirahama, Takuma*; Kisohara, Naoyuki; Tsuboi, Akihiko
Dai-96-Kai Reza Kako Gakkai Koen Rombunshu (Internet), p.91 - 96, 2022/01
Laser scanning quenching is a locally and rapidly heat-treated process and has an advantage of no coolant required. Compared with conventional technique such as induction quenching, the region of laser quenching is about 0.5
0.7mm in depth and it needs to be expanded for more applications or durability. For this purpose, the temperature distributions and transitions in materials during laser irradiation have been revealed by using a 3D heat transfer computer code, micro-structural observation and hardness transitions in depth direction. The results indicate the laser irradiation with low power and low scan speed condition allows deeper quenching area, but it also suggests the hardness of the deepest quenching area is degraded due to slow temperature decreasing rate after laser heat scanning. Multiple times continuous irradiation have been proposed and studied to resolve this hardness degradation, and maximum quenching depth of 1.4mm is obtained under three times irradiation and controlling its power and scan speed properly.
Kobayashi, Kojiro*; Ida, Toshio*; Yamaguchi, Takeshi*; Daido, Hiroyuki; Muramatsu, Toshiharu; Sano, Kazuya; Tsuboi, Akihiko*; Shamoto, Hideyasu*; Ikeda, Takeshi*
Reza Kako Gakkai-Shi, 19(1), p.63 - 67, 2012/03
Laser cutting method, is that the metal melted by laser power is removed by assist gas, has some advantages which are high speed cutting and narrow line-width cutting for the thin metal. We has conducted the joint research with the relevant organizations on the R&D of the laser cutting technology for cutting stainless and carbon steel of over the 150 mm thickness which is maximum thickness of core structure in Fugen. We report the R&D plan and the current status of the laser cutting test.
Kobayashi, Kojiro*; Ida, Toshio*; Yamaguchi, Takeshi*; Daido, Hiroyuki; Muramatsu, Toshiharu; Sano, Kazuya; Tsuboi, Akihiko*; Shamoto, Hideyasu*; Ikeda, Takeshi*
Yosetsu Gijutsu, 59(7), p.64 - 69, 2011/07
no abstracts in English
Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.
JAEA-Technology 2009-030, 165 Pages, 2009/07
JAEA-Technology-2009-030.pdf:69.18MB
The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.
Tsuboi, Akihiko
no journal, ,
no abstracts in English
Shobu, Takahisa; Tominaga, Aki; Kisohara, Naoyuki; Maeda, Hideo*; Yamagishi, Ryuichiro*; Okihara, Shinichiro*; Tsuboi, Akihiko
no journal, ,
In this study, the internal defects and strain distribution in metal additive manufacturing and their changes by laser peening were evaluated. These studies using X-ray computed tomography and diffraction technique were carried out at BL22XU in synchrotron radiation facility SPring-8. As a result, it was confirmed that a large number of voids existed inside the additive manufacturing. However, almost no difference due to laser peening was confirmed. On the other hand, it was confirmed that the strain inside the additive manufacturing was almost
Shobu, Takahisa; Tominaga, Aki; Kisohara, Naoyuki; Maeda, Hideo*; Yamagishi, Ryuichiro*; Okihara, Shinichiro*; Tsuboi, Akihiko
no journal, ,
In this study, the internal defects and strain distribution in metal additive manufacturing and their changes by laser peening were evaluated. These studies using X-ray computed tomography and diffraction technique were carried out at BL22XU in synchrotron radiation facility SPring-8. As a result, it was confirmed that a large number of voids existed inside the additive manufacturing. However, almost no difference due to laser peening was confirmed. On the other hand, it was confirmed that the strain inside the additive manufacturing was almost uniformly tensile strain, and that it changed to compressive strain near the surface due to laser peening.
Hashimoto, Takashi; kisohara, Naoyuki; Tsuboi, Akihiko; Takijiri, Akihide*
no journal, ,
no abstracts in English
