Abstract
Steel lightweight construction in hydrogen technologies is one of the key challenges in mobility and aerospace. Nowadays, austenitic stainless steels of the 3xx series used for high-pressure hydrogen applications are limited in strength and austenite stability. For further increasing the gravimetric energy density of storage systems, austenitic stainless steels with ultimate tensile strengths well above 1 GPa are needed. For that purpose, three different high-strength austenitic and one martensitic stainless steel are presented in the present work. The austenitic stainless steels differ by the nickel and chromium contents between 11% to 26% and 15% to 20%, respectively, and the hardening mechanism. The risk of hydrogen embrittlement (HE) was evaluated by slow strain rate testing (SSRT) using the hollow sample technique and subsequent fracture surface analyses. The samples were drilled and reamed, reaching high geometry accuracy and homogenous inner surface roughness. Different strain rates were applied to study the role of diffusion time and hydrogen uptake on the HE risk. The results of the hollow sample technique were compared to electrochemical and autoclave testing. The main differences arise from the hydrogen uptake and the stress states due to the gas pressures.