Hydrogen susceptibility linked to the mechanical properties and microstructural aspects of common steel for future decarbonated mobility

Clemang Sylvain - ABS Centre Métallurgique (France)

Mid of 2023, the European Union Council announced an agreement to ban the sale of new thermal cars from 2035 in its member countries [1]. Following recent debates during the campaign for the European elections in June 2024 [2], clarifications have been provided. The president of the commission, Ursula Von der Leyen, has assured that this ambition will be maintained. She will not change the objective of 100% zero-emission new cars by 2035, even if synthetic fuels will apparently be authorized.

In this context of energy transition, the future of fossil fuels is almost definitively sealed in Europe. This is why for several years now, car manufacturers, encouraged by states, have developed alternative solutions, including electric vehicles. However, in the current state of technology, electric solutions have drawbacks, particularly in terms of autonomy, charging time and power. These current technical limitations mean that this technology can’t positively meet all of our mobility needs, particularly for buses, trucks, construction machinery, tractors, trains, etc… A possible alternative could be hydrogen, whether used in HFC (Hydrogen Fuel Cells) or in H-ICE (Hydrogen Combustion Engines).

Present work will be focus on standard construction steel grade that could be used in future hydrogen solutions, for example for hydrogen storage tanks or for parts of the hydrogen combustion engine. The potential will be evaluated at different levels of mechanical characteristics according to their sensitivity to hydrogen after electrolytic charging. Links between the behaviour face to the Hydrogen Embrittlement and different microstructural parameters, like dislocation density, apparent diffusion coefficient and trapping energy will be in particular presented and discussed. Understanding the role of these parameters should allow us to better design future steel grades to have low HE.