Of hydrogen and steels

North part of the globe

The most abundant substance in the visible universe. Multiple times higher energy density per kg than in other commonly used fuels. And known to embrittle steels and many other metals with first reports dating back to late nineteenth century. Still today, hydrogen poses great challenges, but also great opportunities.

With the global green transition including e.g., the European Green Deal, hydrogen attracts more interests than ever. And for a good reason – steel industry is still today a major CO2 emitter with a ~7 % share. Emissions from transport are more than twice as high with a ~16 % share. A shift to hydrogen-fuelled future calls for major development of both industrial processes and transport, including storage and transport of hydrogen. For overall effectiveness, utilisation of higher-performance high-strength steel structures can help in e.g., minimising material consumption and maximising the load-bearing capacity – when embrittlement is kept under control.

Material candidates for hydrogen transport are and could be ferritic pressure-vessel steels and structural steels for arctic conditions, 34CrMo4 and similar for transport tubes, austenitic stainless steel like 316NG (= ’316HG hydrogen grade’), but especially traditional low-strength pipeline steels like API 5L X52 and X60 due to already existing pipeline networks. Transforming these natural gas pipelines for hydrogen transport is one of the key aspects in changing to hydrogen powered solutions. There are also several pilot projects around the world exploring hydrogen blending into natural gas stream – 15-20% blends have been already reported successful.

However, these steel grades may not be the optimal solutions, and suitable strength levels are still unclear on top of lacking standardisation. Whereas European Industrial Gases Association (EIGA) has recommended earlier ultimate strength of a steel to be no higher than 950 MPa, for example an US collaboration lead by Sandia National Laboratories works to develop new hydrogen-specific bainitic Ni-Cr-Mo steels with a target tensile strength of 1000 MPa. Higher strength steels are needed especially in mobile transport, where the carrying capacity is limited by the weight of the steel tubes. Other novel materials like medium-Manganese steels have shown great potential also.

In PerforMat, the work carried out in WP2 case 2 is concentrating on hydrogen embrittlement in ultrahigh-strength steels (UHSS). Methods include in-situ mechanical testing both at macro and micro scale, quantification of local and global hydrogen, and state-of-art HE modelling using peridynamics. Target is to accelerate development of H-tolerant UHSS. Within this framework, a Black Metal for the Green Planet – Performance of advanced high-strength steels concerning fatigue, fracture, and hydrogen -webinar was arranged recently by The Centre for Advanced Steels Research (CASR).

Now, the excellent presentations are available for a rewind through: https://www.oulu.fi/en/events/black-metal-green-planet

More information related to the presentations of the Black Metal for the Green Planet -webinar:

Dong Wang, Xu Lu, Meichao Lin, Di Wan, Zhiming Li, Jianying He, Roy Johnsen. (2022) Understanding the hydrogen effect on pop-in behavior of an equiatomic high-entropy alloy during in-situ nanoindentation. Journal of Materials Science & Technology. vol. 98.

Margot Pinson, Saurubh M Das, Hauke Springer, Tom Depover, Kim Verbeken. (2022) The addition of aluminum to brittle martensitic steels in order to increase ductility by forming a grain boundary ferritic microfilm. Scripta Materialia, vol. 213, pp. 114606

Moritz Braun, Jonas Hensel, Shi Song, Sören Ehlers. (2021) Fatigue strength of normal and high strength steel joints improved by weld profiling. Engineering Structures, vol. 246, pp.113030

Bernd Schönbauer, Sumit Ghosh, Jukka Kömi, Tero Frondelius, Herwig Mayer. (2021) Influence of small defects and nonmetallic inclusions on the high and very high cycle fatigue strength of an ultrahigh‐strength steel. Fatigue & Fracture of Engineering Materials & Structures, vol. 44 (11), pp. 2990-3007

Renata Latypova, Tun Tun Nyo, Timo Kauppi, Sakari Pallaspuro, Saara Mehtonen, Hannu Hänninen, Jukka Kömi. (2020) Hydrogen-induced stress corrosion cracking studied by the novel tuning-fork test method. Materials and Corrosion, vol. 71 (10), pp. 1629-1636



Sakari Pallaspuro

  • Postdoctoral researcher
  • Materials science, Fracture mechanics
  • Materials and Mechanical engineering
  • University of Oulu
  • +358294487481
  • Sakari.Pallaspuro@oulu.fi
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