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Ebihara, Kenichi; Sekine, Daiki*; Sakiyama, Yuji*; Takahashi, Jun*; Takai, Kenichi*; Omura, Tomohiko*
International Journal of Hydrogen Energy, 48(79), p.30949 - 30962, 2023/09
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)To understand hydrogen embrittlement (HE), which is one of the stress corrosion cracking of steel materials, it is necessary to know the H distribution in steel, which can be effectively interpreted by numerical simulation of thermal desorption spectra. In weld metals and TRIP steels, residual austenite significantly influences the spectra, but a clear H distribution is not well known. In this study, an originally coded two-dimensional model was used to numerically simulate the previously reported spectra of high-carbon ferritic-austenitic duplex stainless steels, and it was found that H is mainly trapped at the carbide surface when the amount of H in the steel is low and at the duplex interface when the amount of H is high. It was also found that the thickness dependence of the H desorption peak for the interface trap site is caused by a different reason than the conventional one.
Ebihara, Kenichi; Iwamoto, Takashi*; Matsubara, Yukio*; Yamada, Hiroki*; Okamura, Tsukasa*; Urushihara, Wataru*; Omura, Tomohiko*
ISIJ International, 54(1), p.153 - 159, 2014/01
Times Cited Count：13 Percentile：53.08(Metallurgy & Metallurgical Engineering)For understanding the mechanism of hydrogen embrittlement that is one cause of stress corrosion cracking, it is necessary to identify the location of hydrogen segregation (hydrogen existing state) in steels. The thermal desorption spectrum of hydrogen that is obtained by measuring hydrogen desorbing from specimens heated at a constant rate is a useful data for identifying the hydrogen existing state. In the paper, using the numerical simulation, we examined the difference of the thermal desorption spectra between two specimens of pre-strained high-strength steel, one was charged with hydrogen by the method used widely in laboratories, the other was by the method simulating hydrogen penetration in real environment. As a result, it was found that the difference results from the difference of the initial hydrogen distribution caused by the amount of charged hydrogen. If the amount of charged hydrogen is small, the thermal desorption spectrum is more sensitive to the initial distribution.
Ebihara, Kenichi; Iwamoto, Takashi*; Miwa, Noriaki*; Yamada, Hiroki*; Okamura, Tsukasa*; Urushihara, Wataru*; Omura, Tomohiko*
"Suiso Zeika Kenkyu No Kiban Kochiku" Kenkyukai Hokokusho, p.21 - 26, 2013/10
In order to explore the properly hydrogen-charging method for the estimation of hydrogen embrittlement of steels, in the workshop of Fundamental construction for hydrogen embrittlement supported by the Iron and Steel Institute of Japan of which I took part for understanding the mechanism of hydrogen embrittlement which is one cause of stress corrosion cracking, the thermal desorption spectrum of hydrogen and the amount of charged hydrogen were estimated among various kinds of steels charged with hydrogen by various methods. The presentation is a part of a series of the final report about the results obtained in the workshop. In the presentation, I talk about the numerical estimation of the desorption spectrum of low alloy steel mainly on the basis of the paper which is going to be published in the ISIJ International. Particularly, the kind of defects in the steel that capture hydrogen forming the spectrum and the experimental method for identifying the defects are explained in details.
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dual phase steelEbihara, Kenichi; Sekine, Daiki*; Sakiyama, Yuji*; Takahashi, Jun*; Takai, Kenichi*; Omura, Tomohiko*
no journal, ,
Hydrogen embrittlement (HE) in high-strength steels and advanced high-strength steels is a phenomenon that must be understood for its prediction and prevention. Since the austenite phase ( phase) in these steels traps more H than the matrix phase, its effect on HE is of concern. In this study, we numerically reproduced the previously reported H thermal desorption spectra of a high-carbon - duplex stainless steel specimen to clarify the H-trapping defects in the specimen. The results show that H is trapped at the carbide surface when the amount of H inside the sample is low, but that the amount of H trapped at the phase surface increases as the H content increases, and that H trapped inside the phase is desorbed at relatively low temperatures. It was also found that the H entry simulation may not yield an appropriate pre-temperature initial H distribution. The conference will address this point.
