The ramp-up of infrastructure for green hydrogen gas generation, distribution and use is now in full swing. In many critical components, 316L steel and other fcc materials are used as they have good compatibility with hydrogen. However, due to their high cost, a replacement with lower cost materials would be highly desirable. At FAU Erlangen, we are therefore developing a new type of Ni and Mo free C based austenites as an alternative. Unlike the currently used 316L type steels, these steels are not corrosion resistant, but this is not strictly a requirement in pressure gas hydrogen systems. In these steels, the fcc phase is stabilised by C, which is arguably the lowest-cost alloying element. We have previously shown this possibility by heat treating a cold-work tool steel (X210CrW13) to fully a austenitic microstructure and showing that this produces a high resilience to hydrogen induced failure. This steel, with a commercially available composition, does however have a large volume fraction of primary carbides, which drastically reduce fracture elongation.

In this talk, we will present a first generation of C austenites with a tailor made compositions and their properties after high pressure (1000 bar) hydrogen gas exposure. These prototype materials are generated using laser powder deposition, allowing for the rapid screening of a large composition space. We will show results on the thermal stability of these materials down to temperatures of 4K. Additionally we will present results on laser welding of C steels and the resulting microstructure and properties.