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Miyagi, Masanori*; Hongze, W.*; Yoshida, Ryohei*; Kawahito, Yosuke*; Kawakami, Hiroshi*; Shobu, Takahisa
Scientific Reports (Internet), 8(1), p.12944_1 - 12944_10, 2018/08
Times Cited Count：42 Percentile：81.64(Multidisciplinary Sciences)The behavior inside the metal during laser welding is very important because it greatly affects the material strength, defect generation, and so on. In this study, weld pool dynamics in laser welding of various series of aluminum alloys were investigated by the 
synchrotron radiation X-ray phase contrast imaging system. The experimental results showed that metal irradiated by laser was evaporated immediately, which generated the keyhole. Then metal surrounding the keyhole was melted gradually with the heat from keyhole. The growth rate of keyhole depth had a positive linear correlation with the total content of low boiling temperature elements (TCE), so did the keyhole depth and diameter at the stable stage. Then, by repeating the experiment, we succeeded in quantifying the effect of alloying elements on the dynamics of the weld pool in laser welding of aluminum alloys.
Komatsu, Kazumi*; Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi*; Nishimura, Akihiko
Hozengaku, 16(3), p.89 - 95, 2017/10
no abstracts in English
Yamada, Hirokazu*; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, G.*; Nagao, Yoshiharu; Takada, Fumiki; Nishikawa, Masahiro*
Journal of Nuclear Materials, 340(1), p.57 - 63, 2005/04
Times Cited Count：5 Percentile：35.66(Materials Science, Multidisciplinary)This study was performed to clear the effect of neutron re-irradiation on mechanical properties to welding material un-irradiated and irradiated stainless steel. The effect of re-irradiation to these weldaments were evaluated by tensile tests, metallographical observation and hardness test. The result of tensile tests shows that ultimate tensile strength of all joints specimen were almost similar, 0.2% yield strength and total elongation were depend on the irradiation damage and weldaments or not. Therefore, fracture mechanism was not change by re-irradiation. However, brittlement of material was depend on irradiation damage and the property of deformation was sensitive by the effect of irradiation damage or the effect of welding heat.
Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*; Yamada, Tomonori; Muramatsu, Toshiharu; Kono, Fumiaki; Ozawa, Takayuki
no journal, ,
The laser welding method is expected to be applied to the joint between inner and outer ducts for the fast reactor fuel assemblies with inner duct structure. In this study, an anneal effect of the residual stresses in the laser welded steel was investigated using the in-situ strain measurement technique with high energy synchrotron X-rays. We have succeeded in observation of the phenomenon that elastic strain is relaxed before annealing process and the dislocation density gradually decreases thereafter. In addition it was found that the FWHM is a useful parameter for in-situ evaluation of the heat treatment process to effectively optimize the heat treatment condition.
Furusawa, Akinori
no journal, ,
In this work, it is reported that pipe work repairing system and evaluation method of the repairing quality. The repairing system, which is composed of the insertion laser-torch, rotating mechanism, hybrid optical fiber and CW laser source, enable us to repair and reprocess inner surface of the pipework. Operators are able to manipulate the system while monitoring the laser irradiation point through the hybrid optical fiber. On the other hand, the repairing quality is confirmed by visual images, it is natural of developing remote evaluation method for the repairing quality to enhance the value of the repairing system. One of the most promising techniques for remote repairing quality evaluation is ultrasonic guided wave. In this work, we focus on the evaluating butt-welding quality with guided wave, investigating its applicability experimentally. Guided wave is generated and measured on butt-welded pipes that are butt-welded in different conditions. Through the experiments and investigation of the wave profiles, it is found that welding condition effects on the strength of the guided wave detecting signal, revealing its applicability and obtaining some knowledge to establish remote repairing quality evaluation method.
Sato, Yuji; Kamei, Naomitsu; Shobu, Takahisa; Aoyagi, Yuji*; Muramatsu, Toshiharu
no journal, ,
no abstracts in English
