For the purpose of the application for an on-tank valve (OTV), various Al alloy series were tested, to which different contents of up to 0.3 % Sc and Zr were added. The hardening curves were plotted for different temperatures and correlated with the corresponding mechanical tests. The alloys were characterized by hardness measurements, tensile tests and corrosion tests. By characterizing the materials, transferring them to simulation models and developing design guidelines, the foundations are laid for technology transfer to other applications of these materials.

Current On-Tank-Valves are used in hydrogen applications for pressure ranges up to 700/900 bar. In the automotive industry, the materials currently used for such valves are aluminium 6061 T6 or stainless steel (1.4435, 1.4475). The OTV is a complex component that requires long machining times and a large number of special tools. To achieve the required tolerances for hydrogen tightness, complex machining cuts are required, which currently make the valve a relatively expensive component.

Lightweight materials such as aluminium alloys have been developed, optimized and applied for a long time. Therefore, the potential for improvement is generally small. One way to improve the properties of aluminium alloys is to add very small quantities of the element scandium. In particular, the high price of scandium and the monopoly position of individual countries in the supply of scandium have so far prevented the widespread use of aluminium-scandium alloys. New sources and process routes for scandium extraction are now being identified and developed. In addition to new suppliers for the raw material, a significant reduction in costs can also be expected. This will make the material interesting for a variety of new applications with larger quantities.

Various Al-alloy series were tested with different contents of up to 0.3 % Sc and Zr.characterized with optical microscopy, hardness measurements, tensile tests and corrosion tests. We observed minimal changes for the 6xxx and 7xxx alloys. Here the Sc could not develop its full effect with the traditional heat treatments. A significant increase of in hardness values was found for the 3xxx and 5xxx alloys. A possible increase of 50% was shown for a 3003 alloy and 34% for 5083. Previously, no heat treatment was necessary for these alloys and could therefore be optimized for the addition of Sc. The hardness curves for these two alloys for different temperatures were plotted. The 5083 alloy was selected for a more detailed study. The evolution of the materials over the whole production steps, i.e. as casted, after rolling or extrusion were compared. The amount of Sc and Zr additions were optimized as well as the temperature profiles. The results were compared with the state of the art 6082 alloy.