Strengthening and embrittlement mechanisms in laser-welded additively manufactured Inconel 718 superalloy
Hamada, Atef; Ghosh, Sumit; Rautio, Timo; Jaskari, Matias; Abd-Elaziem, Walaa; Järvenpää, Antti (2024-11-30)
Springer
30.11.2024
Hamada, A., Ghosh, S., Rautio, T. et al. Strengthening and embrittlement mechanisms in laser-welded additively manufactured Inconel 718 superalloy. Weld World 69, 81–98 (2025). https://doi.org/10.1007/s40194-024-01897-0.
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© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
https://creativecommons.org/licenses/by/4.0/
© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202412097110
https://urn.fi/URN:NBN:fi:oulu-202412097110
Tiivistelmä
Abstract
Although laser-welded additively manufactured Inconel 718 joints find numerous high-temperature industrial applications, their strengthening and embrittlement mechanisms remain underexplored. To bridge this gap, we herein prepared such joints by the laser welding of the as-built material (built-LW), laser welding of double-aging heat-treated as-built material (DAT-LW), and double-aging heat treatment of laser-welded as-built material (LW-DAT). The microstructures of the joint fusion zones (FZs) were examined using scanning electron microscopy (electron backscatter diffraction and secondary electron imaging), while nanoscale features were probed by transmission electron microscopy, and mechanical properties were evaluated using microindentation hardness (HIT) measurements and tensile tests. The FZs of the built-LW and DAT-LW joints contained no strengthening precipitates, such as the Laves phase and γ′ and γ″ nanoparticles. In stark contrast, the FZ of the LW-DAT joint contained spherical nanoparticles of the γ′ and γ″ phases responsible for precipitation hardening. The DAT-LW joint displayed base metal (BM) strengthening and FZ softening (HIT = 6.47 and 3.6 GPa, respectively), whereas the LW-DAT joint demonstrated BM and FZ strengthening (HIT = 6.2 and 6.5 GPa, respectively). The built-LW joint exhibited the lowest ultimate tensile strength (UTS) of 833 MPa, primarily because of the absence of strengthening precipitates. The DAT-LW joint, despite experiencing FZ softening, exhibited a higher UTS of 1086 MPa and a limited elongation of 2%, while the LW-DAT joint featured the highest UTS of 1440 MPa, primarily because of the enhancement of nanosized γ′ and γ″ strengthening phases facilitated by postwelding double-aging heat treatment.
Although laser-welded additively manufactured Inconel 718 joints find numerous high-temperature industrial applications, their strengthening and embrittlement mechanisms remain underexplored. To bridge this gap, we herein prepared such joints by the laser welding of the as-built material (built-LW), laser welding of double-aging heat-treated as-built material (DAT-LW), and double-aging heat treatment of laser-welded as-built material (LW-DAT). The microstructures of the joint fusion zones (FZs) were examined using scanning electron microscopy (electron backscatter diffraction and secondary electron imaging), while nanoscale features were probed by transmission electron microscopy, and mechanical properties were evaluated using microindentation hardness (HIT) measurements and tensile tests. The FZs of the built-LW and DAT-LW joints contained no strengthening precipitates, such as the Laves phase and γ′ and γ″ nanoparticles. In stark contrast, the FZ of the LW-DAT joint contained spherical nanoparticles of the γ′ and γ″ phases responsible for precipitation hardening. The DAT-LW joint displayed base metal (BM) strengthening and FZ softening (HIT = 6.47 and 3.6 GPa, respectively), whereas the LW-DAT joint demonstrated BM and FZ strengthening (HIT = 6.2 and 6.5 GPa, respectively). The built-LW joint exhibited the lowest ultimate tensile strength (UTS) of 833 MPa, primarily because of the absence of strengthening precipitates. The DAT-LW joint, despite experiencing FZ softening, exhibited a higher UTS of 1086 MPa and a limited elongation of 2%, while the LW-DAT joint featured the highest UTS of 1440 MPa, primarily because of the enhancement of nanosized γ′ and γ″ strengthening phases facilitated by postwelding double-aging heat treatment.
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- Avoin saatavuus [38840]
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