Hydrogen Energy Test and Research Center eC

Fukuoka-shi, Japan

Hydrogen Energy Test and Research Center eC

Fukuoka-shi, Japan

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Awane T.,Japan National Institute of Advanced Industrial Science and Technology | Awane T.,Kobe Material Testing Laboratory Co. | Awane T.,Kyushu University | Fukushima Y.,Japan National Institute of Advanced Industrial Science and Technology | And 5 more authors.
International Journal of Hydrogen Energy | Year: 2014

Hydrogen contained in austenitic stainless steel is classified as diffusible or nondiffusible. The hydrogen distribution in austenitic stainless steel changes with time owing to hydrogen diffusion at room temperature, and such changes in hydrogen distribution cause the mechanical properties of the steel to change as well. It is therefore important to analyze the time variation of the hydrogen distribution in austenitic stainless steel at room temperature to elucidate the effects of hydrogen on the steel's mechanical properties. In this study, we used secondary ion mass spectrometry (SIMS), a highly sensitive detection method, to analyze the time variation of the distribution of hydrogen charged into 316L austenitic stainless steel. SIMS depth profiles of hydrogen that were acquired at the three measurement times were analyzed, and the results were compared among the measurement times. 1H- intensities and distribution of the intensities changed with time due to diffusion of hydrogen in the hydrogen-charged 316L steel sample at room temperature. Moreover, the time variation of the hydrogen concentration distribution of the hydrogen-charged 316L sample was calculated using a one-dimensional model based on Fick's second law. The time variations of the measured hydrogen intensities and of the calculated values are compared. Copyright © 2013, Hydrogen Energy Publications, LLC.


Matsuo T.,Hydrogen Energy Test and Research Center eC | Yamabe J.,Kyushu University | Furukawa H.,Tokyo Electron | Seki K.,Tokyo Electron | And 3 more authors.
Experimental Mechanics | Year: 2014

The output changes of two conventional strain gages (Cu-Ni and Ni-Cr) and a newly-selected strain gage for high-pressure hydrogen gas use (Fe-Cr-Al) in 90 MPa hydrogen and nitrogen gases were measured under unloading conditions to find a high-performance strain gage for high-pressure hydrogen gas use. The changes in the outputs of the Cu-Ni and Ni-Cr gages in hydrogen gas were much larger than those in nitrogen gas, and the Fe-Cr-Al gage showed almost the same output changes in both gases. These results imply that the Fe-Cr-Al gage is superior to the others as a strain gage for high-pressure hydrogen gas use. A large amount of hydrogen entered the Cu-Ni and Ni-Cr foils, and the electrical resistances of these foils were significantly changed by hydrogen exposure, whereas almost no hydrogen entered the Fe-Cr-Al foil, and its electrical resistance was not changed. These resistance changes of the foils as a result of hydrogen entry were consistent with the gage output changes in hydrogen gas. © 2013 Society for Experimental Mechanics.


Matsuo T.,Hydrogen Energy Test and Research Center eC | Yamabe J.,Kyushu University | Matsuoka S.,Kyushu University
International Journal of Hydrogen Energy | Year: 2014

The effects of hydrogen on the tensile properties and fracture surface morphologies of Type 316L stainless steel were investigated using virgin and prestrained specimens. Hydrogen gas exposure at 10 MPa and 250 C for 192 h resulted in its uniform distribution in the specimens. Such internal hydrogen degraded the tensile ductility of the specimens. Cup-cone fracture occurred in the non-, Ar-, and H-exposed specimens. The fracture surfaces were covered with large and small dimples. The H-exposed specimens exhibited larger small-dimple areas than the non- and Ar-exposed ones. The diameter of the large dimples decreased with increasing small-dimple area. Three-dimensional analysis of the dimples showed that the small-dimple regions were void sheets produced by local shear strain. Hydrogen accelerated nucleation of voids and formation of the void sheets by enhancing localization of shear deformation, thereby reducing the average size of the dimples. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserver.

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