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Journal ArticleDOI

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

01 Jul 2011-Advanced Materials Research (Trans Tech Publications, Ltd.)-Vol. 278, pp 277-282
TL;DR: In this article, the effects of net shape surfaces and surface conditioning have been investigated for static parts of aero-turboengines and space propulsion systems using HIPing of nickel base superalloys prealloyed powders.
Abstract: 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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Citations
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Journal ArticleDOI
TL;DR: In this paper, a high strength high γ ′ fraction of nickel-based superalloy powder RR 1000 has been hot isotatically pressed (HIPed) at different temperatures.
Abstract: A high strength high γ ′ fraction nickel-based superalloy powder RR 1000 has been hot isotatically pressed (HIPed) at different temperatures. Microstructural analysis and assessment of the tensile properties were performed on these samples. It was found that HIP led to the formation of (Hf,Zr)O 2 particles on prior particle boundaries (PPBs) which were not present in the as-received powder. It is suggested that the oxides are formed by the diffusion of Hf and Zr from the interior of powder particles to the particle surfaces where oxygen level is usually high. When different HIP temperatures were used, no obvious effect on oxide size and distribution was observed but there was an effect on the microstructure and tensile properties. Thus, HIPing at super-solvus temperatures reduced the density of PPBs over the density observed in samples HIPed at sub-solvus temperatures by making grains within the original powder particles grow beyond the precipitates on PPBs, resulting in larger grains with serrated boundaries. Slow cooling from HIPing temperatures also led to the formation of irregular-shaped γ ′. The 0.2% yield strengths at room temperature and at 700 °C were found to decrease with increase of HIP temperature but the high temperature ultimate tensile strengths and elongation increased considerably. Increasing HIPing temperature from sub-solvus to super-solvus temperatures also led to the transition of fracture mode from interparticle debonding to transgranular fracture mode.

98 citations

Journal ArticleDOI
TL;DR: In this article, a nickel-based superalloy powder RR1000 has been hot isostatically pressed (HIPed) and heat treated to produce different microstructures using a scanning electron microscope (SEM).

65 citations


Cites background from "Production of net-shape static part..."

  • ...Net-shape HIPing [1-5] offers a possible solution to this high cost of producing components from powder since this would lead to the reduction in forging and machining operations and thus to considerable cost reduction....

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  • ...It is suggested that the optimum treatment of the powder superalloy is to solution-treat and age after HIPing; this results in properties which are comparable with those of thermomechanically processed samples....

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  • ...However, the mechanical properties (especially tensile strengths) of as-HIPed RR1000 samples could not meet actual requirements due to the development of irregular and coarse γ´ during slow cooling from HIPing temperature [15]....

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  • ...Previously, a HIPing condition which minimized the harmful PPBs has been developed for RR1000 alloy powder [15]....

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  • ...Therefore, it is very important to find out proper processing conditions for net-shape HIPing of nickel-based superalloy powder....

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Journal ArticleDOI
TL;DR: Inconel 718 powders have been hot-isostatic-pressed (HIPed) at representative temperatures to investigate the variations in microstructure, tensile properties and tensile fracture mode of the powder compact as discussed by the authors.
Abstract: Inconel 718 powders have been hot-isostatic-pressed (HIPed) at representative temperatures to investigate the variations in microstructure, tensile properties and tensile fracture mode of the powder compact. Microstructure of the powder compacts were characterized by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and so on. The results showed that the interdendritic precipitates inherited from the powders were partially retained in the powder compacts when the powders were HIPed at or below 1210 °C but were eliminated when HIPed at and above 1260 °C. The grain size uniformity of the powder compacts first increases and then decreases with increasing HIPing temperature. Prior particle boundaries (PPBs) were observed in the powder compacts HIPed at and below 1260 °C but was eliminated when HIPed at 1275 °C. The PPBs were decorated with carbide particles, the amount of the carbide particles at the PPBs decreases with increasing HIPing temperature. Most of the PPBs were pinned by the carbide particles in the compacts HIPed at 1140 °C. When the HIPing temperature was increased to 1210 °C and 1260 °C, a large number of PPBs de-pinned and moved beyond the pinning carbide particles, leading to grain growth and leaving carbide particles at the site of the original PPBs within the new grains. With increasing HIPing temperature, the 0.2% yield strength of the powder compacts at 650 °C decreases, the tensile elongation increases, and the tensile fracture mode changed from inter-particle dominant fracture to fully dimple ductile fracture.

62 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of strain distribution in a simple forging geometry on the propensity for recrystallization, and its impact on mechanical properties has been investigated in a newly developed experimental nickel-based superalloy.
Abstract: In the current study, the effect of strain distribution in a simple forging geometry on the propensity for recrystallization, and its impact on mechanical properties has been investigated in a newly developed experimental nickel-based superalloy. The new alloy was produced via a Powder Metallurgy (PM) route and was subsequently Hot Isostatic Processed (HIP), isothermally forged, and heat treated to produce a coarse grain microstructure with average grain size of 23–32 μm. The alloy was examined by means of Electron Back-Scatter Diffraction (EBSD) to characterise the microstructural features such as grain orientation and morphology, grain boundary characteristics and the identification of potential Prior Particle Boundaries (PPBs) throughout each stage of the processing route. Results at the central region of the cross-section plane parallel to the loading direction showed significant microstructural differences across the forging depth. This microstructural variation was found to be highly dependent on the value of local strain imparted during forging such that areas of low effective strain showed partial recrystallisation and a necklace grain structure was observed following heat treatment. Meanwhile, a fully recrystallised microstructure with no PPBs was observed in the areas of high strain values, in the central region of the forging.

52 citations

Journal ArticleDOI
TL;DR: A hot-isostatic-pressing (HIPing) scheme, which consists of a short time holding above the solidus and a long time annealing below the incipient temperature of Laves phase, has been proposed for Inconel 718 powder as mentioned in this paper.
Abstract: A new hot-isostatic-pressing (HIPing) scheme, which consists of a short time holding above the solidus and a long time annealing below the incipient temperature of Laves phase, has been proposed for Inconel 718 powder to avoid the formation of prior particle boundaries (PPBs). The powder metallurgy Inconel 718 compacted with the above HIPing scheme is free of PPBs, features transgranular ductile fracture mode during tensile tests, and possesses a stress rupture life that is much longer than that of the wrought alloy.

40 citations

References
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Journal ArticleDOI
R Baccino, F. Moret, F Pellerin1, D. Guichard2, G. Raisson 
TL;DR: The ISOPREC process as discussed by the authors is a powder metallurgy process in which a highly sophisticated mold is filled with powder and further densified through a HIP cycle, and a net shape part is obtained.

72 citations

Journal ArticleDOI
TL;DR: In this paper, the evolution of design principles and better evaluation of the impact of cleanliness has led to an evolution of metallurgy (grades and microstructure) and processes.
Abstract: Industrial production of critical parts in aero engine by PM is now more than 30 years old. During this period, evolution of design principles and better evaluation of the impact of cleanliness has led to an evolution of metallurgy (grades and microstructure) and processes. The basis of this evolution will be presented and illustrated by examples taken from companies worldwide.

37 citations


"Production of net-shape static part..." refers background in this paper

  • ...Mechanical properties can be similar to those of extruded + forged products [1,2]....

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  • ...In as-HIPed conditions, mechanical properties of superalloys are very similar to those obtained on extruded + forged products [1, 2]....

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Journal ArticleDOI
TL;DR: ISOPREC® as discussed by the authors is a 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.).
Abstract: 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.

1 citations


"Production of net-shape static part..." refers methods in this paper

  • ...• Vulcain gas generator for Ariane rocket engine Isoprec@ process has been first used for titanium alloy components in rocket engine parts (impellers in pumps) [4] and later for hotter parts....

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