Fatigue and hydrogen embrittlement assessment of stainless steel and aluminium liners for hydrogen storage tanks

Abstract

This thesis presents an experimental study on the fatigue and hydrogen embrittlement behaviour of EN AW-5083 aluminium alloy and austenitic stainless steels (304L and 316L), commonly used as liner materials in hydrogen storage tanks. With hydrogen gaining prominence as a clean energy vector, ensuring mechanical reliability of these materials under cyclic loading and hydrogen exposure is essential for safe and durable storage solution.

The aluminium alloy specimens, joined using MIG welding, were examined through fatigue crack growth rate testing in both ambient air and hydrogen-rich environments. Advanced characterization techniques such as EBSD, TEM, and SKPFM were employed to assess microstructural evolution and hydrogen accumulation across different weld zones. For stainless steels, hydrogen was introduced via electrochemical charging, followed by slow strain rate tensile testing (SSRT) and thermal desorption spectroscopy (TDS) to evaluate hydrogen-assisted degradation. Fractographic and microstructural analyses highlighted the role of hydrogen in altering fracture modes, promoting phase transformation, and accelerating failure.

The results reveal significant differences in hydrogen embrittlement mechanisms across materials. Aluminium exhibited localized hydrogen accumulation influenced by weld-induced phase morphology, whereas stainless steels showed composition-dependent susceptibility, with 316L displaying better resistance compared to 304L.