Test Method to Establish Hydrogen Compatibility of Materials in High Pressure Hydrogen Gas Environments for Fuel Cell Vehicles

Components for hydrogen vessels and accessories in fuel cell vehicles (FCVs) are exposed to high pressure hydrogen gas environments. A limited range of materials that do not exhibit hydrogen embrittlement in such environments have been permitted for use as component materials. However, expansion of the range of usable materials is required for the widespread commercialization of FCVs. National projects have thus been promoted in the automobile field to expand the usable materials for high-pressure hydrogen environments. In these projects, the establishment of test methods to accurately evaluate the hydrogen compatibility of materials was one of the primary aims. The second aim was to standardize materials selection methods for high pressure hydrogen gas services. Two different test methods are proposed to evaluate the hydrogen compatibility of materials for FCVs. One is a methodology based on the notched specimen fatigue life test and the other is based on the slow strain rate technique (SSRT) and smooth specimen fatigue life test. These test methods are now under deliberation to be included in the Global Technical Regulation (HFCV-gtr) phase 2.