Single-crystal laser deposition of superalloys: processing–microstructure maps

Gäumann, M.; Bezençon, Cyrille; Canalís, Paula; Kurz, W.

doi:10.1016/s1359-6454(00)00367-0

Cited by 816 publications

(365 citation statements)

References 24 publications

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“…It should be noted that in Equation (8) the undercooling is defined relative to the average solute concentration in the undercooled extradendritic liquid, C l . In the [2], [8] and [11] is used instead the initial alloy composition, C 0 , to determine the undercooling for dendrite growth. In the [13] adopted C l for equiaxed growth, but C 0 for columnar growth.…”

Section: Results Of Coupling Between the Multiphase/multiscale Model mentioning

confidence: 99%

“…The previous works [11] [12] used instead the initial composition ( ) 0 C to determine the undercooling for dendrite growth. Others works [8] and [13] adopted l C for equiaxed growth, but 0 C for columnar growth.…”

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confidence: 99%

“…The main new feature of the model proposed in [3] is that both the equiaxed and columnar dendrite growth velocities are controlled by a solutal undercooling proportional to the difference between the local liquidus concentration and the local average solute concentration in the extradendritic liquid (Equation (8)). At least for columnar growth, all other models [7] [8] [11]- [13] [24] used the initial alloy composition C 0 instead of C l in the dimensionless undercooling. Governing equations of phase-field model are presented in the following section.…”

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confidence: 99%

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Numerical Simulation of Microstructural Evolution via Phase-Field Model Coupled to the Solutal Interaction Mechanism

Ferreira¹,

Tomaskewski²,

Paradela³

et al. 2015

MSA

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Section: Results Of Coupling Between the Multiphase/multiscale Model mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Numerical Simulation of Microstructural Evolution via Phase-Field Model Coupled to the Solutal Interaction Mechanism

Ferreira¹,

Tomaskewski²,

Paradela³

et al. 2015

MSA

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“…Un traitement monocristallin peutêtre obtenu lors de rechargement et de plaquage par laser, principalement en raison des gradients thermiquesélevés relatifs aux procédés [20][21][22]. Ainsi, la réparation monocristalline d'aubes défectueuses et le dépôt de couche de protection monocristalline sont envisageables.…”

Section: Application Au Traitement Par Laser Des Superalliagesunclassified

Fissuration à chaud : des alliages organiques aux superalliages

Drezet

Grasso

Rappaz

2004

Mécanique & Industries

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Résumé -L'apparition de fissures ou criquesà chaud pendant la coulée des matériaux métalliques représente un défaut sérieux. L'EPF-Lausanne a développé un critère d'initiation de fissures qui est basé sur l'équation de conservation de la masse appliquéeà la zone solide-liquide (zone pâteuse) et qui prend en compteà la fois une déformation subie par le squelette solide perpendiculairement aux dendrites et l'appel de liquide induit par le retrait de solidification. Le modèle introduit une chute de pression dans les films liquides au-delà de laquelle la cavitation, i.e. la germination d'un premier pore, a lieu. Des observations in situ sur des alliages organiques transparents permettent de mettre enévidence l'importance de la coalescence entre les dendrites ; en effet, la prise de rigidité mécanique de la zone pâteuse se fait par l'établissement de ponts solides entre les dendrites. Enfin, le critère est appliqué successivementà la coulée semi-continue d'alliages d'aluminium,à la coulée continue des aciers et au traitement par laser des superalliages.Mots clés : Solidification / fissurationà chaud / coalescence / alliages organiques / coulée continue / alliages d'aluminium / aciers / superalliages Abstract -Hot tearing: from organic alloys to superalloys. The appearance of solidification cracks or hot tears during casting is a serious defect. EPF-Lausanne has developed a criterion for the appearance of hot tears which is based upon a mass balance performed over the liquid and solid phases and which takes into accounts for the tensile deformation of the solid skeleton perpendicular to the growing dendrites and for the induced interdendritic liquid feeding. This model introduces a critical pressure drop beyond which cavitation, i.e., nucleation of a first void, occurs. In situ observations on transparent organic alloys point our the importance of coalescence between dendrites; indeed the mechanical rigidity of the mushy zone is completed by the appearance of solid bridges between the dendrites. Eventually, the criterion is applied successively to the semi-continuous casting of aluminium alloys, to the continuous casting of steel and to the laser treatment of superalloys.

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“…Epitaxial welding can be achieved on single-crystal (SX) components if adequate control of welding process is maintained, Norman et al [10], Liu and Dupont [14], Park et al [15], Richards et al, [16], Vitek, [17], Mokadem et al, [18] and Gaümann et al, [19]. It requires solidification theory for a close control of macroscopic heat input (epitaxy) and microstructure development to control the columnar to equiaxed transition (CET).…”

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Simulaciones Multiescala en Soldaduras

Bonifaz

2012

Av. Cienc. Ing. (Quito)

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Welding processes involve complex couplings between fluid dynamics, heat transfer and the metallurgical changes experienced by the base metal. Distortion, residual stresses, grain structure, cooling rates, high temperatures and consequently the reduced strength of a structure in and around a weld joint are produced by the localized thermal cycling caused by the intense heat input of fusion welding. With the virtual prediction of weld profiles (shape and size), solidification structures, distribution of impurities, formation of dislocations, distortions and residual stresses of a welded part, processes can be optimized in the early stages of prototyping. The technological properties of fusion welds are formed due to the simultaneous effects of different physical phenomena which occur on different length scales. Correspondingly the simulation of technological properties of fusion welds requires the multiscale approach.Keywords. Residual Stresses, Voronoi Cell Finite Element Modeling (VCFEM), Welding, Solidification; Dislocations. ResumenLos procesos de soldadura involucran acoplamientos complejos entre dinámica de fluídos, transferencia de calor y los cambios metalúrgicos que experimenta el metal base. Distorsión, tensiones residuales, estructura granular, tasas de enfriamiento, altas temperaturas y consecuentemente la resistencia reducida de una estructura en y alrededor de una junta soldada, son producidos por el ciclo térmico localizado causado por la intensa entrada de calor en soldadura de fusión. Con la predicción virtual de perfiles de suelda (forma y tamaño), estructuras de solidificación, distribución de impurezas, formación de dislocaciones, distorsiones y tensiones residuales de una parte soldada, los procesos pueden ser optimizados en la etapa temprana del diseño (prototipo). Las propiedades tecnológicas de las sueldas de fusión son formadas debido a los efectos simultáneos de diferentes fenómenos físi-cos los cuales ocurren a diferentes escalas. Correspondientemente, la simulación de las propiedades tecnológicas requiere la aproximación multiescala.Palabras Clave. Tensiones residuales, Modelación Voronoi-Elementos Finitos, Soldadura, Solidificación, Dislocaciones.Fusion welding processes are widely used for general repair applications. Successful repair requires the transient heat and fluid flow phenomena of the weld pool be addressed adequately to prevent the formation of new grains, equiaxed or columnar, ahead of the epitaxial columnar dendrites. It is well known that the dynamic behaviour of weld pools, due to heat and fluid flow in the weld pool, has significant influence on the temperature distribution, shape and size of the weld pool, final solidification microstructures, and consequently the resultant mechanical properties of the welded joints [1]. It is of great significance to understand the process quantitatively, focused on modelling the transient dynamics of the weld pool, especially the transient heating period after the arc ignites and the transient cooling period after the arc e...

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Single-crystal laser deposition of superalloys: processing–microstructure maps

Cited by 816 publications

References 24 publications

Numerical Simulation of Microstructural Evolution via Phase-Field Model Coupled to the Solutal Interaction Mechanism

Numerical Simulation of Microstructural Evolution via Phase-Field Model Coupled to the Solutal Interaction Mechanism

Fissuration à chaud : des alliages organiques aux superalliages

Simulaciones Multiescala en Soldaduras

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