.. .. Calcul,

, Propriétés des inclusions potentielles après un ajout de ferroalliage de cérium, p.41

. .. , Propriétés des inclusions utilisées pour les essais d'inoculation exogène, p.41

, Résumé des observations MEB pour les échantillons inoculés

, Efficacité des différents ajouts d'inoculants

, Propriétés des sulfures de manganèse avant et après inoculation

, Intensités de microségrégation estimées avec Thermo-Calc

.. .. Mesures,

, Caractéristiques géométriques des inclusions après ajouts de cérium

, Paramètres utiles pour les calculs sur les effets solutaux de l'inoculation cérium, p.105

, Température du socle en fer avant la coulée et maximum atteint en cours de coulée, p.116

. .. , Teneurs en cérium réelles en pied, milieu et tête des lingots inoculés, p.124

, Propriétés morphologiques des inclusions dans les lingots 8 kg

B. Ce and S. .. , 1 Paramètres d'interaction du premier ordre pour O, p.160

, Enthalpies libres standards de formation à 1600 ? C

, Caractéristiques inclusionnaires des 100Cr6 inoculés Ce

, Propriétés matériaux utilisées pour le calcul de l'énergie élastique

, Différents symboles et valeurs utilisées dans le calcul de la vitesse du liquide, p.196

, Propriétés matériaux utilisées pour la simulation COMSOL

, Prédiction des paramètres procédés au passage du liquidus sur l'axe du lingot

. .. , Propriétés matériaux utilisées pour le calcul de température de pointe

, Coefficients n pour la ferrite et l'austénite en fonction de l'intensité de la convection, p.201

F. Acier-en and . .. Dans-le-monde, Évolution de la production d

, Exemples de pièces produites à partir d'aciers Ascométal

.. .. Structure,

, Exemple d'indice de macroségrégation normalisé sur l'axe d'un lingot 6,2 t 100Cr6

, Nombre d'occurrence du terme "Macroségrégation" dans les articles scientifiques

. .. Énergie-libre-d'un-germe-sphérique-d'austénite-dans-un-liquide-surfondu, , p.11

, Germination d'un solide hémisphérique à une interface particule étrangère/liquide, p.12

, Influence du temps de maintien sur la taille de grains équiaxes

. .. Inoculation, , p.25

. Dendrites and . .. Rx,

.. .. Coupes-sériées-d'une-dendrite-d'acier-Équiaxe,

. .. , Chemins de solidification des nuances 100Cr6, 42CrMo4, 34Cr4, p.39

, Consigne en puissance et réponse en température lors d'un essai en sole froide, p.44

, Dispositif expérimental du four de coulée à induction sous vide

, Lingotière modifiée pour les essais VIM

V. .. Température-mesurées-lors-d'une-expérience,

, Exemple d'une acquisition thermique pour la coulée inoculée 6

, Macroattaque HCl d'une plaque de 100Cr6 d'un lingot de 6,2 t

, Mesure de taille de grains de la zone équiaxe par détourage manuel

, Exemples de diamètres de Feret pour des grains expérimentaux

, Exemples de fractions intragranulaires pour des grains expérimentaux, p.58

. .. , Influence du nombre de lignes sur la longueur moyenne interceptée, p.60

, Géométries et microstructures numériques pour l'étude de sensibilité des intercepts, p.61

, Influence de la géométrie sur les fonctions de répartition des longueurs interceptées, p.62

. .. , Influence des défauts recouvrement/polydispersité sur les intercepts, p.63

, Exemple de défaut de recouvrement pour deux croix

. .. , Géométries des enveloppes numériques pour la simulation de coupes, p.64

, Propriétés des coupes Monte-Carlo en fonction de l'angle au sommet, p.65

. .. , Évolution des faciès de coupe pour différentes géométries d'enveloppes, p.66

, Dendrite isotrope issue d'un calcul mésoscopique

, Grains expérimentaux similaires aux coupes de structures numériques, p.68

, Motif hexagonal utilisé pour la création d'une structure colonnaire numérique, p.68

, Définition des angles utilisés pour repérer l'orientation de la structure colonnaire, p.69

, Faciès de coupe pour un motif colonnaire

, Position de l'échantillon prélevé pour les coupes sériées

, Mesure 3D de grains de solidification après découpe sériée

, Principe du calcul des diamètres de Feret

, Évolution du Feret 2D moyen en fonction de la plaquette de mesure, p.76

. .. , Histogrammes des Feret mesurés en 2D (à droite) et 3D (à gauche), p.76

, Enveloppes des grains 3D reconstruits sur l'ensemble du volume analysé, p.77

, Cartographie des facteurs d'allongement 3D

3. .. Ferets, 79 4.33 Compositions et masses des inclusions des lingots 8 kg inoculés cérium, Cartographie des densités de l'orientation des

.. .. , 139 4.42 Influence de l'ajout de cérium sur la taille de grains équiaxes pour les lingots 6,2 t, vol.132

, 2 Microstructure MEB d'un grain de poudre de ferroalliage de cérium, A.1 Fonction de répartition des tailles du ferroalliage de cérium, p.153

A. , Fonctions de répartition des tailles inoculants exogènes

, Densités volumiques de classe calculées des inoculants exogènes

B. , Diagrammes ln(a Ce ) -ln(a O ) -ln(a S ) à 1600 ? C issus de la littérature, p.162

?. C. , 163 B.3 État inclusionnaire final en fonction du cérium ajouté dans une nuance 42CrMo4, Diagrammes calculés log(a Ce ) -log(a O ) -log(a S ) à 1600, p.164

. .. , État final d'un acier 42CrMo4 en fonction de la composition en O et en S, p.165

, État inclusionnaire final d'un acier 42CrMo4 prédit par Thermo-Calc

D. , Macrographies des lingots 100Cr6 inoculés en sole froide au cérium

, Évolution de la taille de grains de la nuance 100Cr6 avec la teneur en cérium, p.175

, Formes et morphologies des grains de 100Cr6 inoculé Ce en sole froide, p.175

, Macrographies des lingots 100Cr6 inoculés au cérium prélevés en creuset VIM, p.177

, Synthèse des mesures effectuées sur les prélèvements 100Cr6 inoculés Ce, p.177

, Macrographies des lingots 100Cr6 VIM de 20 kg inoculés cérium

, Micrographies des lingots 100Cr6 inoculés au cérium coulés

D. , Synthèse des mesures effectuées sur les lingots de 20 kg 100Cr6 inoculés Ce, p.179

, 10 Mesures effectuées sur les lingots 100Cr6 coulés en sole froide avec ajouts de poudre, p.181

E. , Macrographies des lingots sole froide 42CrMo4 inoculés poudres

, 3 Macrographies sole froide 42CrMo4 inoculés cérium après mesure de taille de grains, Macrographies des lingots sole froide 100Cr6 inoculés poudres, p.186

. .. E.4-;, Micrographies sole froide 42CrMo4 inoculés poudres après mesures, p.187

E. , Micrographies sole froide 100Cr6 inoculés poudres après mesures

E. , Macrographies des lingots 8 kg après découpe de la masselotte

E. , Micrographies des lingots 6,2 t après mesure de taille de grains

, Effet d'un ajout de Si 3 N 4 sur la variation d'énergie libre associée la germination, p.193

, Exemples de morceaux d'oxydes flottant à la surface de la goutte liquide, p.196

, Comparaison des profils de température expérimentaux et simulés par COMSOL, p.197

F. , Détermination des conditions (G,V) sur l'axe d'un bouton de sole froide, 0198.

, Carte de sélection de phase à différentes intensités de convection

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, Une première série de lingotins (50 g) a montré l'effet affinant de poudres à bonne cohérence cristallographique avec la ferrite et l'effet grossissant d'un ferroalliage de cérium. Après une étude à plus grande échelle (8 kg) pour les meilleurs candidats (poudres de TiN, CeO 2 , Si 3 N 4 et ferroalliage de cérium), un ajout de cérium a été fait dans un lingot industriel de 6,2 t. Le cérium est responsable de la croissance des grains équiaxes pour l'ensemble des lingots caractérisés. Il agit probablement sur les tensions interfaciales solide/liquide et moule/liquide tout en remplaçant les sites de germination, Résumé L'amélioration de la solidification de lingots d'acier industriels de plusieurs tonnes demeure un défi scientifique. Lors de cette étape cruciale, des hétérogénéités chimiques -à l'échelle du mètre -peuvent se développer

, Mots-clés: Solidification des lingots d'acier, Caractérisation 2D/3D, Inoculation