Intergranular Stress Corrosion Cracking Growth Behavior of Ni-Cr-Fe Alloys in Pressurized Water Reactor Primary Water
Notice bibliographique
Résumé
The purpose of this research was to compare the stress corrosion cracking (SCC) resistance of materials used at the present time for steam generator (SG) tubing in pressurized water reactor (PWR) primary water. Our results in PWR primary water for 20% cold-worked (CW) Alloy 800 (UNS N08800) are compared with already published data for SCC growth from 20%CW Alloy thermally treated (TT)690 (UNS N06690), 20%CW Alloy mill-annealed (MA)600 (UNS N06600), and 20%CW austenitic stainless steels. The second purpose was to examine the dependence of SCC growth on nickel and chromium in PWR primary water; the objective was to obtain the basic knowledge to understand SCC behavior of SG tubing materials. The third objective was to understand whether accelerated testing at higher temperatures is appropriate for predicting SCC initiation and growth at lower temperatures. For these objectives, SCC growth was measured in PWR primary water at 290, 320, 330, 340, and 360°C under static load conditions. Tests were performed using 0.5T compact tension-type specimens using laboratory-melted 20%CW Alloy 800 (UNS N08800, CW800NG) and 20%CW X%Ni-16%CW-Fe alloys in the range of nickel concentration between 16% to 60%. Four important patterns were observed. First, excellent SCC growth resistance was observed for 20%CW 800NG at 320°C and 340°C; second, significant effect of nickel on IGSCC resistance was observed at 340°C and 360°C. The rate of IGSCC growth decreases with increasing nickel concentration in the range of nickel concentration between 10% to 25% nickel; then, the rate of IGSCC increases with increasing nickel concentration in the range of nickel content between 50% to 76%. This trend is quite similar to the results reported by Coriou and Staehle tested in dearated pure water at 350°C. No significant dependence of IGSCC in pure water at 320°C and 290°C was observed. The change in SCC growth dependence on nickel concentration suggested that the main rate-limiting processes on IGSCC growth seems to change between 320°C to 340°C. Third, significant beneficial effects of chromium in alloys were observed at 320°C. However, no beneficial effect of chromium addition in alloys was observed at 360°C. Finally, peak temperatures in growth rate of IGSCC were observed in almost all test materials except for 20%CW Alloy 600. The most important engineering meaning of the complicated temperature dependence with peak is that the mechanism of IGSCC growth at higher temperature is different from that at operating temperature. Furthermore, the order of SCC resistance at higher temperature is not the same at operating temperature. This means that we should pay careful attention to assess SCC from accelerated testing at higher temperatures.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 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) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».