Effect of Loading History on Hydrogen Content in Pipeline Steels
Notice bibliographique
Résumé
The application of high strength pipeline steels for oil and gas transmission is believed to provide greater gas flow capacity due to increased design pressure, and reduced line pipe cost due to material tonnage savings. However, the use of high strength pipeline steels is concerned with high risk of brittle failures such as hydrogen induced cracking, fractures due to low ductility. In this study, three grades of modern pipeline steel (X65, X80, X100) were examined to determine their susceptibility to hydrogen permeation and hydrogen trapping under the influence of various mechanical loading conditions. The steel samples were placed in a solution of sulfuric acid poisoned with arsenic trioxide to create an environment where hydrogen can enter the steel. Initially, round bar samples were charged for various times at a low current density to establish that 24 hours was a sufficient charging time for the three steels. Tensile samples were loaded and held at stress levels corresponding to the respective yield strength and the amount of hydrogen entering the steel was then measured. The stress, normalized to the yield strength, and hydrogen contents, normalized to as received contents, were used to rank the three steel grades and to find the steel that was the most susceptible to hydrogen entry. For the samples charged prior to loading, two times as much diffusible hydrogen was found in the X100 as compared to the other steels, but the trapped hydrogen content was equivalent. Four loading conditions were used for each grade of steel: 1) 2% strain; 2) 2% strain and hold at load for 24 hours; 3) 2% strain then 100 cycles at R = 0.1; and 4) 2% strain, 100 cycles at R = 0.1 then hold at load for 24 hours. For the loaded samples, the amount of hydrogen, both diffusible and trapped increased with load severity, with the highest amounts found in the highest grades of steel. The most pronounced increase was not found in the X100, but in the X-80 steel. Micro structural features, such as banded structure, seemed to have a more prominent role on the hydrogen content of the X100 than in the other steels as it seemed less affected by the loading condition than by charging time.
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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) | 0,008 | 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 ».