Concept and evaluation method of hydrogen compatible steels for high pressure hydrogen tank in vehicles

Abstract

It is regarded as an important issue for achievement of hydrogen society to use safety and economical steels in the high pressure hydrogen gaseous environment. Materials used for high pressure hydrogen tank in FCV (Fuel Cell Vehicles) are high Ni balance austenitic stainless steels because of those high hydrogen embrittlement resistance. However, for spread of FCV the usage of economical and commonly used material like SUS304 is expected. Therefore, an applicable test method and criteria to evaluate the hydrogen embrittlement susceptibility of materials is being studied in high pressure gaseous hydrogen environments. The material compatibility is measure by SSRT (Slow Strain ate Technique) test and fatigue life test under the most severe environment. Materials which meet criteria in the high pressure hydrogen environment by SSRT test will be compared a fatigue limit in high pressure hydrogen environment and that in the atmospheric environment. The test results will be discussed from the standpoint of stability of microstructure and hydrogen embrittlement mechanism.