INFLUENCE OF HYDROGEN CONTENT IN BIOMETHANE ON THE FRACTURE TOUGHNESS AND FATIGUE CRACK GROWTH RESISTANCE OF A PRESSURE VESSEL LOW-ALLOY STEEL
Résumé
This presentation reports on an experimental study initiated in the framework of the HORIZON EUROPE BioStar2C project to review the applicability of Compressed Natural Gaz (CNG) tank to gas blends containing biomethane and a small percentage of hydrogen. Indeed, up to now, standards recommend a maximum percentage of 2% hydrogen in volume in the gas. However, the effect of an hydrogen concentration around 2% on the susceptibility to hydrogen embrittlement of the steel used has not been extensively documented so far. Within this framework, the present study is concerned with the fracture toughness and fatigue crack growth resistance of a low-alloy 34CrNiMo6 steel in methane blended with different hydrogen concentrations of 2%, 4% and 6%. A special attention was paid to the impact of hydrogen on fracture toughness properties, namely KQ, CTOD and Jm, and to the fatigue crack growth rate enhancement under cyclic loading. The results indicate a limited effect of the hydrogen percentage, in the range considered, on the fracture toughness properties KQ, CTOD and Jm , while the fatigue crack growth rates are in any case typically one order of magnitude higher than in air. These data are analysed on the basis of fracture surface observations. Finally, a comparison with data obtained in hydrogen gas with a pressure corresponding to the 4% blend suggests an effect of the total pressure, particularly pronounced around the transition between the moderately accelerated and the highly-accelerated fatigue crack growth regimes. Differences in the mechanisms at play are discussed.
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|---|
| Licence |