Report [1] published by the IEA in 2023 predicts that hydrogen production must reach over 150 Mt by 2030 to achieve net zero emissions by 2050. This is a huge amount compared to the global demand of 95 Mt in 2022.

Hydrogen production, with such a rapid development of the hydrogen economy, requires safe and efficient storage and transmission systems. Such systems are currently made used polymers/composites or steels, depending on the parameters characterizing the given system. Steel systems must possess sufficient strength and resistance to hydrogen embrittlement, especially in the case of storage tanks. In particular, the degradation during hydrogen exposure is manifested by hydrogen-enhanced decohesion, hydrogen-induced phase transformation, hydrogen-enhanced local plasticity, adsorption-induced dislocation emission and hydrogen-enhanced strain-induced vacancy.

Among the various grades of austenitic stainless steel dedicated to hydrogen economy, AISI 904L is used, which shows less susceptibility to hydrogen embrittlement compared to other steels, but is not resistant to it. Studies have shown that hydrogen can affect the stability of the passive layer of AISI 904L, potentially reducing its corrosion resistance and ductility under certain conditions [2]. Furthermore, the plasticity of the material decreases significantly when it is subjected to high cathodic current density. This indicates a risk of hydrogen-enhanced cracking.

We tested AISI 904L steel protected by two types of coatings based on: 1) organically modified SiO2, and 2) Al2O3. The mechanical properties under monotonic and very high cycle fatigue loading conditions after hydrogen loading at ambient pressure/elevated temperature, and room temperature/elevated pressure were tested and discussed. Moreover, electrochemical tests were performed on hydrogen-exposed specimens to evaluate their passivity and corrosion resistance.

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[1] World Energy Outlook, International Energy Agency /IEA/, 2023, https://www.iea.org/reports/world-energy-outlook-2023

[2] J. Michalska, B. Chmiela, J. Łabanowski, W. Simka, Hydrogen Damage in Superaustenitic 904L Stainless Steels, JMEPEG (2014) 23:2760–2765, https://doi.org/10.1007/s11665-014-1044-2