In order to reduce costs and increase the operating temperatures in aero-turboengines and space propulsion systems, net-shape or near net-shape production processes have been developed for static parts through HIPing (Hot Isostatic Pressing) of nickel base superalloys prealloyed powders. The presented results hereafter are related to the manufacturing processes and the mechanical properties (tensile, creep and LCF) characterisation. The effects of net shape surfaces and of surface conditioning have been investigated too. Examples of actual parts (CFM56 turbine casing and Vulcain rocket engine gas generator) illustrate the presentation. This study has confirmed the interest of this production route and future potential for development.

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Production of net-shape static parts by direct HIPing of nickel base superalloy prealloyed powders

https://www.researchgate.net/profile/C_Verdy/publication/268482069_Vacuum_Plasma_Spray_Process_Applied_to_High_Thickness_Components_for_LRE/links/567414bb08ae502c99c7763f.pdf

Vacuum Plasma Spray Process Applied to High Thickness Components for LRE

The work described in this paper is part of a general study concerning new methods for the manufacturing of turbo-engine and turbo-pump parts. The presented results concern a VPS formed nickel-based alloy, the Astroloy (AFNOR NK17CDAT). In a first time are presented the metallographic microstructures of the as-sprayed and heat-treated deposits and secondly spray formed test pieces developed in order to characterize the mechanical properties of such materials. Then, the mechanical properties, including the tensile properties, the Low Cycle Fatigue life-time, the creep life-time and the adherence are presented. The results have been compared with those of sintered parts and the measured performances of such plasma formed free-standing shapes were found to be equivalent or superior. Such good results are attributed to the very fine grained, recrystallized microstructures and to the very low level of macroporosities in the deposit.

The plasma spray forming of Astroloy

ISOPREC® est un procede de metallurgie des poudres dans lequel un moule particulierement elabore est rempli de poudre puis densifie en Compression Isostatique a Chaud (C.I.C.). Apres compaction, le moule est elimine mecaniquement ou chimiquement, et une piece aux cotes finales est obtenue. Les deformations importantes et complexes qui interviennent au cours de la densification ne peuvent etre predites manuellement et un outil de modelisation numerique est developpe, de facon a minimiser les cycles et les couts de developpement des pieces. Des exemples d'application de cette technologie dans les domaines aeronautiques et spatiaux sont presentes. Les proprietes mecaniques elevees obtenues sur les pieces associees a la grande precision dimensionnelle du procede font d'ISOPREC® une reponse au difficile challenge de la recherche de l'amelioration des performances au moindre cout.

F. Pellerin

Papers

The plasma spray forming of Astroloy

Le procédé de mise en forme ISOPREC