Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Effect of Different Post-treatments on the Microstructure of EBM-Built Alloy 718
Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). (PTW)ORCID-id: 0000-0001-5676-7903
Quintus Technologies AB, Västerås, Sweden.
ARCAM AB, Mölndal, Sweden.
Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).ORCID-id: 0000-0001-5521-6894
2019 (Engelska)Ingår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 28, nr 2, s. 673-680Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Electron beam melting (EBM) of Alloy 718 is of rapidly growing interest as it allows cost-effective production of complex components. However, the inherent flaws in the component in as-built state are of concern in view of the severe working conditions in which Alloy 718 components typically operate. The present work entails an investigation of changes in microstructure that accompany some post-treatments that are being widely considered to address defects in EBM processed Alloy 718. The effect of two different post-treatments, namely hot isostatic pressing (HIP) and a combined HIP + heat treatment (HT) carried out inside the HIP vessel, have been studied and results from as-built and post-treated specimens were compared in terms of porosity/lack-of-fusion, microstructure, phase constitution (NbC content, ÎŽ-phase) and micro-hardness. Post-treatment resulted in reduction in defect content by more than an order of magnitude. HIPing led to complete dissolution of ÎŽ phase. In comparison to as-built material, HIPed specimens exhibited significant drop in hardness. However, a sharp ‘recovery’ of hardness to yield values higher than in as-built condition was observed after HIP + HT and can be attributed to precipitation of γ′′ phase. © 2018, The Author(s).

Ort, förlag, år, upplaga, sidor
2019. Vol. 28, nr 2, s. 673-680
Nyckelord [en]
3D printers, Cost effectiveness, Defects, Electron beam melting, Electron beams, Hardness, Heat treatment, Hot isostatic pressing, Microhardness, Microstructure, Alloy 718, Complete dissolution, Complex components, Cost-effective production, Defect contents, Phase constitution, Post treatment, Yield value, Niobium compounds
Nationell ämneskategori
Bearbetnings-, yt- och fogningsteknik
Forskningsämne
TEKNIK, Produktions- och materialteknik
Identifikatorer
URN: urn:nbn:se:hv:diva-13133DOI: 10.1007/s11665-018-3712-0ISI: 000458782100012Scopus ID: 2-s2.0-85055983075OAI: oai:DiVA.org:hv-13133DiVA, id: diva2:1263961
Forskningsfinansiär
KK-stiftelsen, 20160281
Anmärkning

First Online: 29 October 2018

Tillgänglig från: 2018-11-19 Skapad: 2018-11-19 Senast uppdaterad: 2020-11-04Bibliografiskt granskad
Ingår i avhandling
1. Post-treatment of Alloy 718 produced by electron beam melting
Öppna denna publikation i ny flik eller fönster >>Post-treatment of Alloy 718 produced by electron beam melting
2019 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Electron beam melting (EBM), a metal additive manufacturing (AM) process, has received considerable industrial attention for near net shape manufacture of complex geometries with traditionally difficult-to-machine materials. This has fuelled considerable academic interest in investigating EBM of Alloy 718, a nickel ironbased superalloy possessing an exciting combination of good mechanical behaviour and cost effectiveness. EBM production of Alloy 718 is particularly promising for aerospace and other sectors which value rapid production of components with large scope for design flexibility. The EBM builds are characterized by presence of inevitable defects and, anisotropy within a build is also a concern. Consequently, as-built Alloy 718 has to be subjected to post-build thermal-treatments (post-treatments) to ensure that the parts eventually meet the critical service requirements. Not withstanding the above, limited knowledge is available about optimal post-treatments for EBM-built Alloy 718. Therefore, the main focus of the work presented in this thesis was to systematically investigate the response of EBM-built material to post-treatments, which include hotisostatic pressing (HIPing), solution treatment (ST), and aging.

HIPing of EBM-built Alloy 718 led to more than an order of magnitude reduction in defect content, which was reduced from as high as 17% to < 0.2% in samples built with intentionally introduced porosity to investigate limits of defect closure achievable through HIPing. In addition, HIPing also caused complete dissolution of δ and γ" phases present in the as-built condition, with the latter causing dropin hardness of the material. HIPing had no effect on the carbides and inclusions such as TiN, Al2O3 present in the built material. The evolution of microstructure during ST and aging was systematically investigated. Growth of potentially beneficial grain boundary δ phase precipitates was found to cease after a certain duration of ST, with samples subjected to prior-HIPing exhibiting lesser precipitation of the δ phase during ST. While the specimen hardness increased onaging, it was observed to plateau after a duration significantly shorted than the specified ASTM 'standard' aging cycle. Therefore, prima facie there are promising prospects for shortening the overall heat treatment duration. A combination of HIPing, ST, and aging treatments in a single uninterrupted cycle was also explored. Future work involving incorporation of a shortened heat treatment schedule in a combined cycle can have significant industrial implications.

Ort, förlag, år, upplaga, sidor
Trollhättan: University West, 2019. s. 73
Serie
Licentiate Thesis: University West ; 25
Nyckelord
Additive Manufacturing, Electron Beam Melting; Alloy 718; HIP; Heat Treatment; Solutionizing; Aging; HIP+HT; Microstructure; γ"; δ
Nationell ämneskategori
Bearbetnings-, yt- och fogningsteknik
Forskningsämne
Produktionsteknik; TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-13547 (URN)978-91-88847-25-6 (ISBN)978-91-88847-24-9 (ISBN)
Presentation
2019-02-18, F206, University West, Trollhättan, 10:00 (Engelska)
Handledare
Anmärkning

Articles submitted to journals and unpublished manuscripts are not included in this registration

Tillgänglig från: 2019-02-18 Skapad: 2019-02-18 Senast uppdaterad: 2022-09-19Bibliografiskt granskad
2. Thermal post-treatment of Alloy 718 produced by electron beam melting
Öppna denna publikation i ny flik eller fönster >>Thermal post-treatment of Alloy 718 produced by electron beam melting
2020 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Additive manufacturing (AM) has emerged as a disruptive technology and it is a vital part in the present era of fourth industrial revolution, Industry 4.0.Electron beam melting (EBM), a metal AM process, has received considerable industrial attention for near net shape manufacture of complex geometries with traditionally difficult-to-machine materials. EBM production of Alloy 718, a nickel-iron based superalloy possessing good mechanical and corrosion properties at elevated temperatures, is particularly promising for aerospace and energy sectors. However, EBM Alloy 718 builds are typically characterized by presence of inevitable defects and anisotropy, warranting post-processing thermal-treatments (post-treatments) to ensure that the components eventually meet the critical servicerequirements. The existing post-treatment standards include hot isostatic pressing (HIPing) over the temperature range of 1120°C-1185°C, followed by solution treatment (ST) and a two-step (‘8+8’ hours) aging under conditions conventionally adopted for cast and wrought Alloy 718, and no effort has yet been invested in optimizing post-treatment schedules specifically for EBM Alloy 718. Consequently, the objective of this work was to systematically investigate the response of EBM-built material to eachof the post-treatment steps to develop an improved understanding of howthe microstructure evolves with time during each step, since such knowledge can lay the foundation for optimizing the post-treatment protocol.Through study of microstructure and mechanical property assessment it was found that the temperature during HIPing can be reduced to 1120°C compared to the common practice employing higher temperatures. In addition, HIPing also caused complete dissolution of δ and γ"/γ' phases, promoted homogenization and resulted in drop in hardness but had no evident effect on the carbides and inclusions such as TiN and Al2O3 present in the as-built material. Subjecting EBM Alloy 718 to ST and two-step agingled to precipitation of δ phase and γ"/γ' phases, respectively.

The evolution of microstructure during ST and two-step aging was also systematically investigated. Progressive precipitation and growth of grain boundary δ phase precipitates was observed during the entire 1 hour duration of ST, with samples not subjected to prior-HIPing exhibiting higher amount of the δ phase precipitation during ST. During the two-stepaging, detailed investigation of microstructure evolution and hardness changes showed that, particularly the conventional ‘8+8’ hour long two-stepaging treatment can be shortened to a ‘4+1’ hours treatment. Such shortened treatment was observed to be robust when applied to various kinds of EBM builds. Another approach for shortening post-treatment by integrating HIPing and HT inside the HIP vessel was also successfully implemented. These approaches with shortened post-treatment were also found to not compromise the mechanical response of EBM Alloy 718. Further shortening of the typical long thermal post-treatment cycle, through reduction in HIPing time from 4 hours to 1 hour and possible elimination of ST, also appears promising.

Ort, förlag, år, upplaga, sidor
Trollhättan: University West, 2020. s. 95
Serie
PhD Thesis: University West ; 41
Nyckelord
Additive Manufacturing, Electron Beam Melting; Alloy 718; Hot Isostatic Pressing; Heat Treatment; Microstructure Evolution; Mechanical Properties
Nationell ämneskategori
Metallurgi och metalliska material
Forskningsämne
Produktionsteknik
Identifikatorer
urn:nbn:se:hv:diva-16003 (URN)978-91-88847-77-5 (ISBN)978-91-88847-76-8 (ISBN)
Disputation
2020-11-26, F104 Albertsalen, Högskolan Väst, Trollhättan, 13:15 (Engelska)
Opponent
Handledare
Forskningsfinansiär
KK-stiftelsen
Tillgänglig från: 2020-11-05 Skapad: 2020-11-04 Senast uppdaterad: 2021-02-03

Open Access i DiVA

fulltext(2120 kB)261 nedladdningar
Filinformation
Filnamn FULLTEXT01.pdfFilstorlek 2120 kBChecksumma SHA-512
55b139b50eda3935e46a4d4fa295edf34c13edbe7a8ee570972dd4e428f49bcac423609e28b73db9f085c20e668e288b11fd00ef6bbc8a57599153995d89a61f
Typ fulltextMimetyp application/pdf

Övriga länkar

Förlagets fulltextScopus

Person

Goel, SnehaJoshi, Shrikant V.

Sök vidare i DiVA

Av författaren/redaktören
Goel, SnehaJoshi, Shrikant V.
Av organisationen
Avdelningen för avverkande och additativa tillverkningsprocesser (AAT)Forskningsmiljön produktionsteknik(PTW)
I samma tidskrift
Journal of materials engineering and performance (Print)
Bearbetnings-, yt- och fogningsteknik

Sök vidare utanför DiVA

GoogleGoogle Scholar
Totalt: 262 nedladdningar
Antalet nedladdningar är summan av nedladdningar för alla fulltexter. Det kan inkludera t.ex tidigare versioner som nu inte längre är tillgängliga.

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 426 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf