著者

村上 敬宜 金崎 俊彦 福島 良博 田中 裕之 戸室 仁一 久保山 孝治 松栄 雅樹 伊藤 義雄 安藤 晴彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 A編 (ISSN:03875008)

巻号頁・発行日

vol.75, no.749, pp.93-102, 2009-01-25 (Released:2017-06-09)

参考文献数

6

被引用文献数

4 7

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The fatigue failure analysis of SUS316L flexible hose of the hydrogen station which was demonstrated during EXPO 2005 in Nagoya was carried out. The fatigue fracture surface where hydrogen leakage was detected showed clear striations which revealed a unique evidence of hydrogen effect on the ratio of striation height and spacing. The number of striations observed on the leakage fracture surface was 270. Considering that the number of hydrogen supply to the fuel cell buses was 280, it can be concluded that the fatigue fracture process during the demonstration is completely controlled by microplasticity resulting ductile fracture contrary to the conventional concept expressed with a term of decohesion or hydrogen embrittlement. The striation data were used to make the fatigue crack growth rate equation which was applied to the life prediction and structural integrity assessment for a new hydrogen station. The fatigue crack growth data showed the evidence of a strong frequency effect of fatigue crack growth rate of SUS316L used in the hydrogen environment with 8 minutes hydrogen supply time at the hydrogen station.

著者

金崎 俊彦 楢崎 千尋 峯 洋二 松岡 三郎 村上 敬宜

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.72, no.723, pp.1717-1724, 2006-11-25

被引用文献数

11 17

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The effect of hydrogen on fatigue crack growth behavior of four stainless steels has been investigated from the viewpoint of martensitic transformation. The crack growth rates in hydrogen-charged SUS304 and SUS316 were accelerated. The crack growth rate in hydrogen-charged SUS316L was slightly higher than uncharged SUS316L. However, the crack growth rate in SUS405 hardly changed in comparison with uncharged specimens. The matensitic transformation on fatigue fracture surface was detected by X-ray diffraction both in hydrogen-charged and uncharged specimens of SUS304, SUS316 and even in SUS316L. However, the fracture surface of SUS316L, in which the crack growth rate was increased slightly by hydrogen, showed less martensitic transformation than that of SUS304 or SUS316. It is presumed that martensitic transformation in the vicinty of fatigue crack tip contributed to the effect of hydrogen on crack growth rate. Fatigue tests of SUS304 and SUS316L, which were pre-strained at -70℃ to enhance a martensitic transformation, were carried out to study the influence of hydrogen and martensite on crack growth. Crack growth rate was remakably increased by hydroggen in not only pre-strained SUS304 but also in pre-strained SUS316L. The hydrogen content of pre-strained hydrogen-charged specimen was much higher than unstrained hydrogen-charged specimens due to the increase in martensite through which hydrogen diffuses much easier and faster than through austenite. The slip bands around crack tip in the hydrogen-charged specimens were less and more discrete than that in the uncharged specimens.