Microstructure of IN738LC Fabricated Using Laser Powder Bed Fusion Additive Manufacturing

Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al γ' phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small-scale businesses in fabricating high-γ′ nickel-base superalloys on a desktop laser powder bed fusion AM equipment.

Menon, N., Mahdi, T. H., and Basak, A. "Microstructure of IN738LC Fabricated Using Laser Powder Bed Fusion Additive Manufacturing." Journal of Turbomachinery 144, no. 3 (2022). https://doi.org/10.1115/1.4052404. Published by the American Society of Mechanical Engineers

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Work Title Microstructure of IN738LC Fabricated Using Laser Powder Bed Fusion Additive Manufacturing
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Open Access
Creators
  1. Nandana Menon
  2. Tanjheel Hasan Mahdi
  3. Amrita Basak
Keyword
  1. Additive manufacturing
  2. Laser powder bed fusion
  3. Nickel-base superalloys
  4. IN738LC
  5. Microstructures
License CC BY 4.0 (Attribution)
Work Type Article
Publisher
  1. Journal of Turbomachinery
Publication Date October 18, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1115/1.4052404
Deposited August 03, 2022

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Version 1
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  • Created
  • Added TURBO-21-1177.pdf
  • Added Creator Nandana Menon
  • Added Creator Tanjheel Hasan Mahdi
  • Added Creator Amrita Basak
  • Published
  • Updated Keyword, Description, Publication Date Show Changes
    Keyword
    • Additive manufacturing , Laser powder bed fusion, Nickel-base superalloys, IN738LC, Microstructures
    Description
    • <p>Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni<sub>3</sub>Ti or Ni<sub>3</sub>Al (γ<sup>′</sup> phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small-scale businesses in fabricating high-γ<sup>′</sup> nickel-base superalloys on a desktop laser powder bed fusion AM equipment.</p>
    • <p>Nickel-base superalloys are extensively used in the production of gas turbine hot-section components as they offer exceptional creep strength and superior fatigue resistance at high temperatures. Such improved properties are due to the presence of precipitate-strengthening phases such as Ni<sub>3</sub>Ti or Ni<sub>3</sub>Al γ' phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, the presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, specimens of IN738LC are fabricated on a Coherent Creator laser powder bed fusion (L-PBF) additive manufacturing (AM) equipment. Optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) are carried out to characterize the deposit region. Metallurgical continuity is achieved in the entire deposit region and the specimens do not show any warpage. However, the specimens show voids (e.g., pores and cracks) in the deposit region. The results show that the percentage void area decreases along the build height direction. The deposited IN738LC shows polycrystalline grains in the entire deposit region as confirmed by XRD and EBSD. The grain size also shows variations along the build direction. In summary, the results open opportunities for academic researchers and small-scale businesses in fabricating high-γ<sup>′</sup> nickel-base superalloys on a desktop laser powder bed fusion AM equipment.</p>
    Publication Date
    • 2022-03-01
    • 2021-10-18
  • Updated