Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 02, 2019 - November 04, 2019
The objective of is to clarify the effect of high-temperature hydrogen on material strength in order to consider safety issue of advanced hydrogen energy technologies working in high-temperature hydrogen environment such as SOFC, SOEC, RFC and hydrogen gas turbine. SSRT and creep tests were carried out in Ar and H2 under a gas pressure of 0.12 MPa in absolute pressure. The test materials were SUS304 and Ti-6Al-4V. The temperature of the environment was 25 - 600 ℃ for the SSRT and 600 ℃ for the creep test. In the SSRT of the SUS304, hydrogen embrittlement (HE) occurred at 25 ℃ and no HE occurred at 100 ℃ and higher temperature. The reason of the no HE was hydrogen does not have interaction with dislocations according to the literatures. However, it was observed that the work hardening rate in H2 decreased. In the creep test of the SUS304 in H2, the initial creep strain increased, and creep rate also increased. As a result, the creep life significantly reduced in H2. The morphology of the fracture surfaces was changed depending on the environment and creep life. Dimple fracture was observed in H2 particularly short life region. When the creep life was relatively short, the fracture surface in Ae was consisted of dimple and intergranular cracking. On the other hand, the fracture surface in H2 was covered by dimple. When the creep life was relatively long, the fracture surface was covered by intergranular cracking in Ar and consistent of dimple and intergranular in H2. In the SSRT of Ti-6Al-4V, no ductility loss in H2 occurred at 25 and 100 ℃.
