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Cher(e)s collègues, (english below)
Guillaume Hachet, nouveau chargé de recherche CNRS au laboratoire à partir de février 2025, nous rendra visite le lundi 25 novembre et fera une présentation à 10h30 en salle de séminaire, intitulée "Boron segregation in martensitic steels to improve the resistance against hydrogen embrittlement".
Vous trouverez un résumé de cette présentation à la fin de ce message,
cordialement,
Xavier
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Dear colleagues,
Guillaume Hachet, new CNRS research scientist who wil start in February 2025 in the lab, will visit us the 25th of November and will deliver a presentation at 10:30 in the seminar room, on the following topic: "Boron segregation in martensitic steels to improve the resistance against hydrogen embrittlement".
An abstract is provided below.
best regards,
Xavier
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Boron segregation in martensitic steels to improve the resistance against hydrogen embrittlement
Guillaume Hachet*, Ali Tehranchi, Manoj Prabhakar, Shaolou Wei, Katja Angenendt, Stefan Zaefferer, Binhan Sun, Baptiste Gault, Dirk Ponge, Dierk Raabe
Max-Planck-Institut für Eisenforschung, Max-Planck-Straße, 1, 40237, Düsseldorf
*g.hachet@mpie.de
Hydrogen is nowadays viewed as a key element for developing low-carbon energies, but it diffuses in metals and alloys and segregates in crystalline defects, reducing the ductility of the material. This phenomenon is well-known and called hydrogen embrittlement (HE). In this work, we aim to reduce the negative impact of hydrogen by adding boron at interfaces to improve the resistance against HE. Boron mostly segregates to prior austenite grain boundaries (PAGBs) before the martensitic transformation in steels. This segregation naturally improves resistance to HE compared to boron-free steel by avoiding the intergranular fracture at PAGBs. The competition between boron and hydrogen at PAGBs has been investigated further using thermal desorption spectroscopy (TDS) experiments and ab initio calculations. The TDS measurements on boron-free steel indicate an additional peak not observed for the boron-doped steel (CB = 40 wppm). It presumably corresponds to hydrogen segregated in PAGBs and the segregation energies between hydrogen and the different microstructure features of the steel have been estimated using the Kissinger approach. These energies have been compared to ab initio calculations, confirming the attraction between hydrogen and boron-free GBs and the repulsion between boron-doped GBs [1]. This approach has also been extended to other solutes for designing doped grain boundary resistance to HE.
[1] Segregation at prior austenite grain boundaries: the competition between boron and hydrogen, G. Hachet, A. Tehranchi, H. Shi, M. Prabhakar, S. Wei, K. Angenendt, S. Zaefferer, B. Gault, B. Sun, D. Ponge, D. Raabe, 2025, doi: 10.48550/arXiv.2407.03763
