Littérature scientifique sur le sujet « ABD-900AM »

Abstract Nickel-base superalloys containing 30 to 50% gamma prime (γ') volume fraction are typically used in hot section components (e.g. guide vanes or blades) for power generating gas turbines, and suitable time dependent properties are required for longterm elevated temperature operation. Additive manufacturing (AM) has recently been used to develop complex hot-section parts utilizing innovative designs with enhanced cooling features which improve efficiencies by reducing cooling air consumption. To further explore the opportunity to improve timedependent AM superalloys, this paper focuses on a fundamental creep study and characterization of a novel nickel-base superalloy (ABD®-900AM) that was manufactured using a laser-based powder bed fusion AM process. The material was subjected to a sub-solvus solution anneal and multi-step aging heat-treatment to produce a bi-modal distribution with ~35% volume fraction of gamma prime without post-processing hot isostatic pressing (HIP). Microstructural characterization was carried out for the as-built and fully heat-treated structures, and a creep-rupture test program was conducted to study the resultant creep properties. Activation energies and stress exponents in addition to rupture strength and deformation resistance, were compared to traditionally cast IN939 and IN738 materials. After testing, specimens were evaluated using a variety of microscopy tools to determine location and features associated with creep damage.

Ce projet de recherche est une étude prospective des liens entre des microstructures types et ses comportements tribologiques associés. Il s'agit de comprendre l'impact de l'anisotropie morphologique et cristalline sur le comportement tribologique de surfaces, tout en conservant la même chimie. Pour cela, le procédé fusion laser sur lit de poudre (L-PBF) est utilisé pour sa capacité à générer des microstructures types multi-échelles. Le matériau d'étude est l'ABD-900AM, un superalliage base nickel spécialement développé pour la fabrication additive qui est imprimable sans défaut sur une large gamme de paramètres procédé. Les différentes caractéristiques microstructurales étudiées sont la structure granulaire (taille, morphologie, texture cristallographique) et la structure cellulaire. Afin de générer ces microstructures types, différentes stratégies de lasage sont employées. Le choix de paramètre procédé consiste en une modification du parcours du laser et de l'orientation des pièces dans la chambre de fabrication, sans modifier les paramètres de lasage (puissance, vitesse). Les microstructures sont essentiellement caractérisées par les techniques DRX, MEB et EBSD. En termes de structures granulaires, différentes tailles de structure allant de quelques centaines à quelques milliers de µm² et de textures cristallographiques ((200), (220), (111) combinaison de plusieurs textures et non texturées) sont obtenues. La structure cellulaire est aussi modifiée selon la stratégie de lasage, et permet d'accéder à différentes épaisseurs (de 0,61 ± 0,13 µm à 0,85 ± 0,31 µm) et morphologies (colonnaire ou équiaxe) et de générer des différences d'homogénéités. Les essais tribologiques sont menés à température ambiante en configuration bille/plan en mouvement alterné avec une charge normale de 30 N, une fréquence de 1 Hz, et une distance de glissement de 10 mm. Différentes durées d'essais (120 s, 600 s, 1800 s et 3600 s) pour suivre l'évolution des mécanismes d'usure au cours du temps sont étudiées. Dans ces conditions de chargements, seuls les essais de 3600 s permettent de discriminer les microstructures. Ainsi, la tenue à l'usure des microstructures est associée au développement des couches interfaciales sur les traces d'usure, et à la capacité des microstructures à maintenir ces couches interfaciales à la surface. La taille et l'homogénéité de la structure cellulaire sont les éléments microstructuraux prépondérants qui permettent de maintenir ces couches interfaciales par le renforcement qu'elles apportent à la matrice. Un modèle d'usure phénoménologique basé sur l'analyse des traces d'usure pour différentes durées d'essais conclut ce projet
This research project is a prospective study examining the relationships between specific microstructures and their associated tribological behaviors. The aim is to understand the impact of morphological and crystallographic anisotropy on the tribological behavior of surfaces, while maintaining a consistent chemical composition. To achieve this, the Laser Powder Bed Fusion (L-PBF) process is employed for its ability to generate multi-scale characteristic microstructures. The material under investigation is ABD-900AM, a nickel-based superalloy specifically developed for additive manufacturing, known for its defect-free printability across a wide range of process parameters. The microstructural features studied include the grain structure (size, morphology, crystallographic texture) and the cellular structure. To generate these characteristic microstructures, various laser scanning strategies are employed. The process parameters are selected by modifying the laser path and the orientation of the parts within the build chamber, while keeping key laser settings (power, speed) constant. The microstructures are primarily characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). For the grain structures, a range of sizes, from a few hundred to several thousand µm², and crystallographic textures ((200), (220), (111), combinations of multiple textures, and non-textured) were achieved. The cellular structure was also modified according to the laser scanning strategy, resulting in variations in thickness (from 0.61 ± 0.13 µm to 0.85 ± 0.31 µm), morphologies (columnar or equiaxed), and degrees of homogeneity. Tribological tests were conducted at room temperature using a ball-on-flat reciprocating sliding configuration with a normal load of 30 N, a frequency of 1 Hz, and a sliding distance of 10 mm. Various test durations (120 s, 600 s, 1800 s, and 3600 s) were examined to track the evolution of wear mechanisms over time. Under these loading conditions, only the 3600 s tests were able to effectively distinguish between different microstructures. The wear resistance of the microstructures was linked to the development of interfacial layers on the wear tracks and the ability of the microstructures to maintain these layers at the surface. The size and homogeneity of the cellular structure were identified as the key microstructural factors that enabled the retention of these interfacial layers by reinforcing the matrix. A phenomenological wear model based on the analysis of wear tracks for different test durations concludes this project

Abstract The power industry has been faced with continued challenges around decarbonization and additive manufacturing (AM) has recently seen increased use over the last decade. The use of AM has led to significant design changes in components to improve the overall efficiency of gas turbines and more recently, hot-section components have been fabricated using AM nickel-base superalloys, which have shown substantial benefits. This paper will discuss and summarize extensive studies led by EPRI in a novel AM nickel-base superalloy (ABD·900-AM). A comprehensive high temperature creep testing study including >67,000 hours of creep data concluded that ABD-900AM shows improved properties compared to similar ~35% volume fraction gamma prime strengthened nickel-base superalloys fabricated using additive methods. Several different creep mechanisms were identified and various factors influencing high temperature behavior, such as grain size, orientation, processing method, heat treatment, carbide structure, chemistry and porosity were explored. Additional studies on the printability, recyclability of powder, wide range of process parameters and several other factors have also been studied and results are summarized. A summary on the alloy -by-design approach and accelerated material acceptance of ABD-900AM through extensive testing and characterization is further discussed. Numerous field studies and examples of field use cases in ABD-900AM are also evaluated to showcase industry adoption of ABD-900AM.

Abstract Nickel-base superalloys containing 30 to 50% gamma prime (γ′) volume fraction are typically used in hot section components (e.g. guide vanes or blades) for power generating gas turbines, and suitable time dependent properties are required for long-term elevated temperature operation. Additive manufacturing (AM) has recently been used to develop complex hot-section parts utilizing innovative designs with enhanced cooling features which improve efficiencies by reducing cooling air consumption. To further explore the opportunity to improve time-dependent AM superalloys, this paper focuses on a fundamental creep study and characterization of a novel nickel-base superalloy (ABD®-900AM) that was manufactured using a laser-based powder bed fusion AM process. The material was subjected to a sub-solvus solution anneal and multi-step aging heat-treatment to produce a bi-modal distribution with ∼35% volume fraction of gamma prime without post-processing hot isostatic pressing (HIP). Microstructural characterization was carried out for the as-built and fully heat-treated structures, and a creep-rupture test program was conducted to study the resultant creep properties. Activation energies and stress exponents in addition to rupture strength and deformation resistance, were compared to traditionally cast IN939 and IN738 materials. After testing, specimens were evaluated using a variety of microscopy tools to determine location and features associated with creep damage. The optimized chemistry for ABD®-900AM was printed crack free and fully dense in contrast to studies on similar alloys where significant process development and post-build heat-treatments were required. High-temperature mechanical properties in the heat-treated material showed some decrease in creep strength when compared to traditional casting. This strength and rupture life debit was dependent on build orientation, but a considerable increase in creep ductility was observed due to differences in the microstructure when compared with similar AM alloys. Analysis of creep data showed differences in creep mechanisms compared to traditional cast alloys. The relationship between microstructure and creep mechanisms is discussed, and ongoing work to further improve rupture strength through heat-treatment optimization will be highlighted.