Stability of fatigue cracks at 350 °C in air and in liquid metal in T91 martensitic steel
Résumé
The low cycle fatigue behaviour of a 9Cr1MoNbV martensitic steel has been investigated at 350 °C in air and inlead–bismuth eutectic (LBE) with low and high oxygen content. Total strain controlled tests were performed from Δεt=0.40% to 1.2%. The material exhibited a pronounced cyclic softening in both environments. LBE reduced the fatigue resistance. LBE accelerated the formation of the long crack by promoting the growth of the first short cracks. A clear change in propagation mode was observed. In air, ductile fatigue striations were observed while in LBE a brittle fracture decorated by voluminous and largely spaced striations were visible. From EBSD analysis, it was concluded that in LBE, the long crack advanced quickly by repeated and discontinuous cleavage.
Domaines
MatériauxOrigine | Fichiers produits par l'(les) auteur(s) |
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