Influence of the focus offset on the defects, microstructure, and mechanical properties of an Inconel 718 superalloy fabricated by electron beam additive manufacturing

Lee, Hae-Jin; Kim, Hankyu; Hocheng, H.; Lee, Byoung-Soo

doi:10.1016/j.jallcom.2018.12.070

Cited by 38 publications

(14 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ti) to Nb ratio [142] and thermo-mechanical processing routes [143,144]. In PBF materials, similar phenomena correlated to the aforementioned mechanisms of c 00 strengthening and coarsening [145], and c 0 -c 00 co-precipitation have also been reported in heat-treated materials [37,102,146].…”

Section: Matrix Phasesupporting

confidence: 60%

“…While the formation of defects can be a common occurrence within PBF, to keep the review focused on phase formation and morphology, the reader is directed toward the following works [35][36][37][38]. Further, we do not discuss mechanical properties as there have been several reviews on this subject [7,10,31,33].…”

Section: Scope Of This Reviewmentioning

confidence: 99%

“…Similarly, as discussed in ''c 0 phase'' section, the potential impact of cooling rate in PBF on the partitioning of elements and the potential impact on the formation of c 00 remains unexplored. Looking at E-PBF studies more broadly, sizes of c 00 precipitates vary from 2 nm to hundreds of nanometers depending on the build height and processing conditions [37,94,107,158].…”

Section: Matrix Phasementioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2022

View full text Add to dashboard Cite

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.

show abstract

Section: Matrix Phasesupporting

confidence: 60%

Section: Scope Of This Reviewmentioning

confidence: 99%

Section: Matrix Phasementioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2022

View full text Add to dashboard Cite

show abstract

“…10e and f. In the case of AC and WC, the corresponding durations in the precipitation range of the strengthening phase was * 3 min and \ 1 min, respectively, which are insufficient for c 00 phase precipitation [56] due to its reported sluggish precipitation [56,57]. Such effect of the employed cooling rates has also been previously observed in LPBF-built [25] and wrought [47,54] Alloy 718.…”

Section: Potential To Design Shorter Tailored Posttreatment For Ebm Amentioning

confidence: 57%

Microstructure evolution-based design of thermal post-treatments for EBM-built Alloy 718

et al. 2020

View full text Add to dashboard Cite

Alloy 718 samples were fabricated by electron beam melting (EBM) additive manufacturing process. The work focused on systematic investigation of response of the material to various thermal post-treatments, involving hot isostatic pressing (HIPing), solution treatment (ST) and two-step aging, to tailor post-treatment procedure for EBM-built Alloy 718. Results showed that HIPing at lowered temperature can be used for attaining desired defect closure while preserving grain size. Subjecting the material to ST, with or without prior HIPing, mainly caused precipitation of δ phase at the grain boundaries with prior HIPing decreasing the extent of δ phase precipitation. Moreover, results suggest that the utility of ST, with prior HIPing, could be dictated by the need to achieve a certain δ phase content, as the typically targeted homogenization after ST had already been achieved through HIPing. Detailed investigation of microstructural evolution during subsequent aging with and without prior HIPing showed that a significantly shortened aging treatment (‘4 + 1’ h), compared to the ‘standard’ long treatment (‘8 + 8’ h) traditionally developed for conventionally produced Alloy 718, might be realizable. These results can have significant techno-economic implications in designing tailored post-treatments for EBM-built Alloy 718. Graphical abstract

show abstract

“…In a word, a systematic increase in line offset (processing speed) from 75 to 325 µm resulted in an increased defect content ranging from 0.1% to 17% in the investigated samples. It is worth mentioning that large defects such as those observed in samples AB#5 (LS = 275 µm) and AB#6 (LS = 325 µm) are not typical of an EBM built even with not fully optimized processing conditions [23]. However, these samples were produced for the present 'proof of concept' investigation regarding the extent of defect closure enabled through HIPing.…”

Section: Resultsmentioning

confidence: 99%

Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?

et al. 2020

View full text Add to dashboard Cite

Electron beam melting (EBM) is gaining rapid popularity for production of complex customized parts. For strategic applications involving materials like superalloys (e.g., Alloy 718), post-treatments including hot isostatic pressing (HIPing) to eliminate defects, and solutionizing and aging to achieve the desired phase constitution are often practiced. The present study specifically explores the ability of the combination of the above post-treatments to render the as-built defect content in EBM Alloy 718 irrelevant. Results show that HIPing can reduce defect content from as high as 17% in as-built samples (intentionally generated employing increased processing speeds in this illustrative proof-of-concept study) to <0.3%, with the small amount of remnant defects being mainly associated with oxide inclusions. The subsequent solution and aging treatments are also found to yield virtually identical phase distribution and hardness values in samples with vastly varying as-built defect contents. This can have considerable implications in contributing to minimizing elaborate process optimization efforts as well as slightly enhancing production speeds to promote industrialization of EBM for applications that demand the above post-treatments.

show abstract

Influence of the focus offset on the defects, microstructure, and mechanical properties of an Inconel 718 superalloy fabricated by electron beam additive manufacturing

Cited by 38 publications

References 49 publications

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

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

Microstructure evolution-based design of thermal post-treatments for EBM-built Alloy 718

Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?

Contact Info

Product

Resources

About