604 湿潤大気環境下における7075アルミニウム合金中の水素の挙動解析(材料と組織)

概要

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Aluminum alloys are proposed as a liner material of a high-pressure hydrogen tank for the fuel cell vehicles (FCV). However, it is known that some aluminum alloys cause hydrogen embrittlement, when they are stretched in the moist air. Especially in 7075 aluminum alloys, it is said that hydrogen embrittlement occurs conspicuously. Thus, in this study, the behavior of hydrogen in a 7075 aluminum alloy was investigated by means of the hydrogen microprint (HMP) technique. Sheet tensile specimens of 7075 alloy with T6 temper were subjected to a moist air with relative humidity of 95% on one surface and to a dry nitrogen gas with a photographic emulsion layer on the other surface, and then tensile-deformed by 3.5% both at an usual and a slow strain rates. By this plastic deformation, the surface oxide layer is fractured, resulting in the hydrogen evolution and intrusion into the specimen after the reaction between fresh metallic surface and water vapor. It was found that the hydrogen evolved on the moist air side intrudes into the specimen and moves with gliding dislocations when specimen is deformed at the slow strain rate. In contrast, when deformed at the usual strain rate, it was presumed that the hydrogen is unable to move with dislocations and is trapped by stationary dislocations even if the specimen is kept under the moist air for prolonged period.
社団法人日本機械学会の論文
2006-09-14