Abstract
Hydrogen, as a prominent green energy carrier, facilitates the transition from fossil fuels to renewable energy. However, conventional steels used in hydrogen applications are susceptibility to hydrogen embrittlement, which causes deterioration of mechanical properties. Therefore, there is a critical need to develop material solutions, such as physical barriers, to ensure safe and reliable hydrogen storage and transport systems.
In this study, the behavior of two commercially available barrier candidates, 316L stainless steel and 6082 aluminum alloy, was investigated under pressurized air and hydrogen gas. The mechanical response was assessed using slow strain rate tensile testing of hollow specimens internally charged with hydrogen gas. Tensile testing results revealed no significant hydrogen-induced degradation in ultimate tensile strength and elongation at maximum load for either material. Minor variations in elongation at fracture were observed, remaining within the expected scatter range for both alloys.
Fractographic analysis revealed a mixed-mode fracture in 316L SS, characterized by dimples and quasi-cleavage facets. In addition, secondary cracking in the δ-ferrite phase indicated a potential contribution of a HEDE mechanism, manifested in the microstructural images as longitudinal cracks aligned with the loading direction. In contrast, AA-6082 exhibited predominantly ductile fracture features under both conditions. Furthermore, electron back scattered diffraction analysis was performed before and after hydrogen-tensile testing. The results are then correlated with the tensile response and microstructural features obtained through post-mortem analysis to evaluate the effectiveness of the investigated materials against hydrogen-induced degradation.