Transformaciones de fase en aceros de bajo contenido en C microaleados con Nb y V
Notice bibliographique
Résumé
The phase transformations occurring during continuous cooling in Nb-V microalloyed steels have been analyzed in depth on this thesis. In particular, three compositions of niobium microalloyed steels and three steels microalloyed with vanadium have been characterized. \nThe work is divided into six chapters and begins with a brief introduction which aims to value the importance of the steel in the modern world. Then, on the second chapter, the most important metallurgical concepts related especially to low carbon steels in the literature have been reviewed and summarized. \nChemical compositions and experimental techniques carried out are detailed on the third chapter. Experimental techniques have consisted mainly in two types of tests (dilatometry and multipass torsion tests). The data obtained from the continuous cooling tests have been used to develop two mathematical models. These models aim to summarize the behavior of the analyzed steels according to three leading variables: the austenite grain size, accumulated deformation and cooling rate. \nAt the fourth chapter, the results obtained and the principles governing the two developed models have been described. This chapter is divided into four blocks, the first one consists on a summary of the microstructural characterization performed and continuous cooling diagrams (CCT diagrams) obtained by dilatometry tests. These tests were carried out with the three Nb microalloyed steels and C-Mn-V1. \nIn the second block of results, a predictive model of the austenite transformation kinetics is developed. The microstructures obtained are composed of one or more phases (ferrite, pearlite and bainite) upon cooling from different austenite microstructures (recrystallized and deformed). \nOn the third block the study has been focused on the austenite-ferrite transformation (low cooling rates). Besides the improvement in predicting the mean ferrite size, a model that takes into account the heterogeneity of the austenite grain size distributions before the phase transformation has been developed. The effect of heterogeneity in the austenite-ferrite transformation has been studied in terms of different variables (Effective Austenite grain size and cooling rate). The objective of the model is to predict the grain size distribution of transformed ferrite from different austenite conditions. \nFinally, a study of the hot rolling process on different industrial profiles is described with two steels similar to C-Mn-V1 composition. The effect of varying temperatures and strain distribution has been studied by hot torsion multi-pass testing. Then, after quantifying the microstructural changes associated to these changes in the rolling process, the austenite-ferrite transformation model has been validated again. These microstructures correspond to a similar range of cooling rates compared to the microstructures obtained by dilatometry trials, which have been adjusted the model parameters. \nIn the fifth chapter of this work the conclusions and future lines of work have been presented. Finally, the three publications developed during the course of this thesis have been attached. Specifically, an international journal publication (ISIJ International, Vol 55, n.9, 2015), an international conference proceeding contribution (British Columbia, Canada, June 2015) and a contribution to the XIII National Materials Congress (Barcelona, June 2014).
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 ».