The BF-MASCOT and SRC-JustH2Transit projects enabled me to explore and experience the ways of working in a state-of-the-art hydrogen materials testing laboratory at the Sandia National Laboratories, located in Livermore, CA, USA. The lessons learned during my 3-month technical exchange are of outstanding importance for the method development at VTT and provide improved scientific understanding for the materials which enable the success for the rapidly expanding H2 economy.
Figure 1. Handsome fellows at the Hydrogen Effects on Materials Laboratory entrance: Joseph Ronevich (left), Janne Pakarinen, and Chris San Marchi.
The hydrogen economy has the potential to speed up the green transition by integrating renewables into power generation and by decarbonizing various energy-intensive hard-to-abate industrial sectors, such as steel manufacturing and heavy transport.
The ambition of the EU is to produce 10 million tons and import another 10 million tons of renewable H by 2030. Nationally, the Finnish government has adopted a resolution with the aim to produce at least 10% of the zero-emission hydrogen of the EU by 2030, and to become the European leader in the entire hydrogen value chain.
However, with the high potential, there are also several materials challenges associated with large-scale, high-pressure hydrogen storage, distribution and usage which need to be resolved. Being a very small atom, hydrogen has the tendency to penetrate steels and cause deterioration of their mechanical properties. The resulting hydrogen embrittlement, although documented already over 100 years ago, has not been fully resolved yet. Most notably, this causes headaches for applications where steel would be the preferred materials solution. Pipelines of low-carbon steels for transporting gaseous hydrogen and compressor components of austenitic stainless steels serve as two good examples.
A research team leader’s dream: hands-on experience at a world-class lab
My technical visit to Sandia National Laboratories focused on materials testing under high pressure hydrogen. Dr Chris San Marchi and Dr Joe Ronevich warmly welcomed me to their lab. After working several years mainly with my laptop, I had the opportunity to get involved into the hands-on materials testing – what else could a research team leader wish for? Well – sunshine and escape from the Finnish winter. Got that one too.
Figure 2. Janne setting up a pre-cracking for a specimen that will be later tested under high pressure hydrogen.
Hydrogen Effects on Materials Laboratory (HEML) at Sandia can be considered as a reference laboratory for materials testing under hydrogen. Especially, they have been pioneering the fracture and fatigue crack-growth experiments during the last twenty years.
The methods strongly rely on standard testing of standard specimens, but a huge effort has been devoted to developing the testing environments which enable materials testing under realistic and/or accelerated conditions. Most notably, for hydrogen research, this means that the testing can be carried out at pressures over 1000 bar. In addition, specimens can also be H-charged at elevated temperature. As a reference, the materials testing at VTT is currently limited to a maximum pressure of 100 bar at room temperature.
Pushing the limits: high-pressure hydrogen testing in action
After rigorous transport efforts, I finally received two sets of samples from Finland for testing at HEML. One of the batches consisted of typical pipeline steels and the other set consisted of austenitic 316L steels.
For the testing, two different approaches were applied. As the hydrogen diffusion into the austenitic 316L steels is slow, these specimens were pre-charged under gaseous H2 at about 1400 bar and 300 °C for two weeks and subsequently tested in air. In contrast, the pipeline steels where H diffusion is fast, were not pre-charged but were tested under high pressure H2 environment.
While the materials testing results are currently being further analyzed and specimens characterized at VTT, there are several important takeaways from the visit.
First, systematic ways of working allow for the generation of a reliable database for hydrogen materials, which is the key for setting up guides and codes for safe design and operation. This cannot be stressed too much, especially when most of the testing is performed under extreme conditions. It was enlightening to notice that even with well-documented operation procedures, there is always the need for experienced and highly skilled operators. As the testing under gaseous high-pressure H2 is demanding, the data in the open literature may contain results which might overlook the role of the hydrogen gas purity. Oxygen contamination, for example, is something to pay special attention to when further developing the materials testing infra at VTT.
What’s next? Future collaborations and knowledge exchange
The results from the work have been accepted to be presented at the PVP 2025 conference in July, and there are several journal articles under preparation. A couple of Research Council of Finland research proposals were recently submitted which include further collaboration with Sandia and the nearby Lawrence Livermore National Laboratory.
Whenever a suitable candidate is found for changing the Californian sun to the Finnish slush, we are happy to host guests at VTT.
