Alloy 718: Laser Powder Bed Additive Manufacturing for Turbine Applications

Kelkar, Rajandra; Andreaco, A.; Ott, Eric; Groh, Jon

doi:10.1007/978-3-319-89480-5_3

Cited by 12 publications

(4 citation statements)

References 6 publications

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“…The powder PSD is between 22-50 µm, and particles are mostly spherical with occasional satellites, see supplier specification in [33]. Alloy 718 was chosen for this study as it is commonly processed with PBF-LB/M in industry [34,35] and its behavior in PBF-LB/M is well documented [36]. A validated parameter set could be provided by EOS, which reduced the risk of error from build defects.…”

Section: Methodsmentioning

confidence: 99%

Validation of powder layering simulation via packing density measurement for laser-based powder bed fusion

Haapa,

Gopaluni,

Piili

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Powder bed fusion using a laser beam (PBF-LB/M) is considered one of the most versatile additive manufacturing methods as the parts printed have high resolution thanks to the low layer thickness used. The powder packing density (PD) of the powder layer has a significant impact on the density, surface roughness and other mechanical properties of the built parts. Due to the difficulty of characterizing the powder bed in situ, simulation has often been used to study the powder behavior on the powder bed. However, in order for the simulation to have practical value, there must be some way of confirming the results via experimental methods, also called validation. The aim of this study was to develop a powder packing density-based validation method for a powder bed simulation. The developed method featured a simplistic “open cup” style sample which traps powder inside for PD measurement. The samples were built with an EOS M 290 PBF-LB/M system using Alloy 718 (also known as “IN718” or “Inconel”) powder. Average PD over the five built samples was 52.4 %, with a standard deviation of 0.2 %. The method was used to successfully validate a powder bed simulation with four recoated powder layers, modelled using FLOW-3D DEM simulation software from Flow Science Inc. Similar methods for PD characterization were found in literature, but in many cases the method does not fully correspond to the conditions of a simulated powder bed, the scale is very small, or the reliability of the PD measurement is not confirmed. The method presented in this study corresponds to typical powder bed simulation conditions, while retaining high reliability and repeatability of results.

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Section: Methodsmentioning

confidence: 99%

Validation of powder layering simulation via packing density measurement for laser-based powder bed fusion

Haapa,

Gopaluni,

Piili

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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“…After the parts were removed from the build plate, the material blanks went through a hot isostatic pressing (HIP) operation at 1162 • C and 100 MPa for 4 h. Following the HIP process, the specimens were solution-annealed and precipitation heat-treated. The times and temperatures for both the solution-anneal and precipitation heat-treat process were determined from [19][20][21]. The material was solution-annealed at 980 • C for 1 h and then followed by a two-stage precipitation heat-treatment.…”

Section: Methodsmentioning

confidence: 99%

Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance

Johnson,

Kujawski

2023

Materials

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This study was completed in effort to characterize the notch sensitivity of additively manufactured (AM) Inconel 718 produced by laser powder bed fusion (L-PBF). Three different root radii on V-notched test specimens and smooth specimens were evaluated under tensile conditions for specimens built in vertical and horizontal orientations. Both the total axial strain and localized notch diametral strain were measured. Finite element analysis (FEA) was completed on each specimen geometry to confirm the actual strain measurements near the notch. Test results showed the tensile strength of the notched specimens were larger than the tensile strength values of the smooth specimens. These tensile results equate to a notch-sensitivity ratio (NSR) greater than one, indicating that the L-PBF Inconel 718 material is a notch-strengthened material. It is suspected that the notch strengthening is a result of increased triaxial stress produced near the notch tip causing added material constraints, resulting in higher strength values for the notched specimens. Fractography analysis was completed on the various fracture surfaces and identified a dominate ductile failure mode within all of the specimens; however, the amount of ductility reduced with smaller notch root radii. While this study provides the initial notch responses of the L-PBF Inconel 718, further research must be completed in regard to the impact of notches on more complex loading behaviors, such as fatigue and stress-rupture conditions.

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“…As a meta-stable phase, the c 00 phase is susceptible to transformation into d. The d phase will often form from meta-stable c 00 when IN718 spends extended periods of time at elevated temperatures between * 650 and * 1000 °C [104,175]. When d forms, it often has a needle or platelet like morphology [51,94,102,158,[176][177][178].…”

Section: Matrix Phasementioning

confidence: 99%

Powder bed fusion additive manufacturing of Ni-based superalloys: a review of the main microstructural constituents and characterization techniques

et al. 2022

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Metal additive manufacturing (AM) has unlocked unique opportunities for making complex Ni-based superalloy parts with reduced material waste, development costs, and production lead times. Considering the available AM methods, powder bed fusion (PBF) processes, using either laser or electron beams as high energy sources, have the potential to print complex geometries with a high level of microstructural control. PBF is highly suited for the development of next generation components for the defense, aerospace, and automotive industries. A better understanding of the as-built microstructure evolution during PBF of Ni-based superalloys is important to both industry and academia because of its impacts on mechanical, corrosion, and other technological properties, and, because it determines post-processing heat treatment requirements. The primary focus of this review is to outline the individual phase formations and morphologies in Ni-based superalloys, and their correlation to PBF printing parameters. Given the hierarchal nature of the microstructures formed during PBF, detailed descriptions of the evolution of each microstructural constituent are required to enable microstructure control. Ni-based superalloys microstructures commonly include γ, γ′, γ′′, $$\delta$$ δ , TCP, carbides, nitrides, oxides, and borides, dependent on their composition. A thorough characterization of these phases remains challenging due to the multi-scale microstructural hierarchy alongside with experimental challenges related to imaging secondary phases that are often nanoscale and (semi)-coherent. Hence, a detailed discussion of advanced characterization techniques is the second focus of this review, to enable a more complete understanding of the microstructural evolution in Ni-based superalloys printed using PBF. This is with an expressed goal of directing the research community toward the tools necessary for a thorough investigation of the processing-microstructure-property relationships in PBF Ni-based superalloy parts to enable microstructural engineering.

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Alloy 718: Laser Powder Bed Additive Manufacturing for Turbine Applications

Cited by 12 publications

References 6 publications

Validation of powder layering simulation via packing density measurement for laser-based powder bed fusion

Validation of powder layering simulation via packing density measurement for laser-based powder bed fusion

Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance

Powder bed fusion additive manufacturing of Ni-based superalloys: a review of the main microstructural constituents and characterization techniques

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