Mechanical Properties of Zr-2.5Nb Pressure Tubes Made from Electrolytic Powder
Notice bibliographique
Résumé
Abstract Pressure tubes in CANDUCANada Deuterium Uranium (CANDU) is a registered trademark of Atomic Energy of Canada Limited and RBMK reactors are fabricated from Zr-2.5Nb alloy. This paper describes the mechanical properties of tubes used in power reactors made by four routes using electrolytic powder as the base material. The microstructures developed by each route are distinct: CW: cold-worked material consists of flattened α-Zr grains surrounded by a skin of β-Zr phase; used in CANDU 6 reactors. CW-A: material that was cold-worked and annealed at 540°C contains elongated α-Zr grains mixed with equiaxed α-Zr grains and particles of β-Nb phase; used in all RBMK 1000 reactors. TMT-1: material quenched from the (α+β)-Zr phase into water follow by cold-working consists of α′-phase and between 10 and 20 % of untransformed α-phase; used in RBMK 1500, Ignalina 1. TMT-2: material quenched from the (α+β)-phase into argon-helium gas mixture followed by cold-working consists of Widmanstätten α-phase and untransformed α-phase. This material is used in RBMK 1500, Ignalina 2. The CW and TMT-2 tubes have a higher proportion of grains with basal plane normals in the transverse direction, FT of 0.52 to 0.57, than in the radial direction, FR of 0.38, while quenched and annealed materials (TMT-1 and CW-A) have similar values of FT and FR, about 0.38 in quenched materials and 0.41 in annealed materials. Transverse tensile strength, crack growth resistance, dJ/da, and axial crack velocity, VH, of delayed hydride cracking (DHC) were evaluated, using standard techniques, between 250 and 300°C on as-fabricated materials. In-reactor creep deformation was evaluated from measurements of tube diameter in RBMK 1000s, RBMK 1500s and two CANDU 6 power reactors. Strength and crack growth resistance were measured on TMT-1 and TMT-2 tubes removed from Ignalina NPP Units 1 and 2 after 12–17 years of in-reactor service. As-received cold-worked material had the highest strength; the annealed material had the lowest strength while the quenched materials had intermediate strength. Irradiation increased the strength by about 200 MPa in all four materials. Although DHC is sensitive to texture and the distribution of the β-Zr phase, the dominating factor controlling crack velocity appears to be material strength: with an increase of strength by a factor of about two, VH increased by a factor of 30. Since harmful trace elements were well controlled during manufacturing, other factors affecting crack growth resistance could be assessed. Again, strength appeared important; dJ/da declined approximately linearly with increase in strength induced by irradiation, decreasing from about 350 to 100 MPa as the strength increased from about 250 to 850 MPa. The exception was TMT-2 material where crack growth resistance was maintained after irradiation. TMT-2 material also had good diametral creep resistance in-reactor, attributed to both its texture and grain structure. The other three materials had similar creep resistance controlled mostly by their texture.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,004 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».