Void closure behavior during hot forming of an Fe-Al alloy
Aliakbar EMDADI, Felix JENSCH, Joanna SZYNDLER, Hsuan-Po HUANG, Sebastian HÄRTEL, Sabine WEIß
Abstract. Hot forging is a forming process that can be used as a post-processing treatment to close residual porosity and refine the microstructure of additively manufactured materials, resulting in improved mechanical properties. During hot forging, void closure occurs through plastic deformation resulting from a predominantly compressive stress state at elevated temperatures. In the present work, Fe-25Al-1.5Ta (at. %) samples have been produced by laser powder bed fusion (LPBF) using a larger layer thickness and scan speed than commonly used to achieve a target porosity fraction of approximately 10%. Full densification is attempted in the subsequent hot compression step at various height reduction ratios. The as-built LPBF samples contained 8-10% voids. After deformation to true strains of 0.2, 0.4, and 0.6, the void fraction decreased significantly to approximately 4%, 2.3%, and 1.1%, respectively. Hot compression resulted in the complete closure of large pores with a size range of 200-300 µm and a significant reduction in the size of small to medium pores. These results show potential for improving the productivity of the LPBF by speeding up the process by increasing layer thickness and scanning speed while maintaining a reasonable density. Full densification should be achieved by subsequent hot forging.
Keywords
Laser Powder Bed Fusion (LPBF), Post-Processing, Hot Metal Forming, Void Closure, X-Ray Micro-Computed Tomography
Published online 5/7/2025, 9 pages
Copyright © 2025 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Aliakbar EMDADI, Felix JENSCH, Joanna SZYNDLER, Hsuan-Po HUANG, Sebastian HÄRTEL, Sabine WEIß, Void closure behavior during hot forming of an Fe-Al alloy, Materials Research Proceedings, Vol. 54, pp 927-935, 2025
DOI: https://doi.org/10.21741/9781644903599-99
The article was published as article 99 of the book Material Forming
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
References
[1] M. Yi, W. Tang, Y. Zhu, C. Liang, Z. Tang, Y. Yin, W. He, S. Sun, S. Su, A holistic review on fatigue properties of additively manufactured metals, Journal of Materials Processing Technology 329 (2024) 118425. https://doi.org/10.1016/j.jmatprotec.2024.118425
[2] C. Du, Y. Zhao, J. Jiang, Q. Wang, H. Wang, N. Li, J. Sun, Pore defects in Laser Powder Bed Fusion: Formation mechanism, control method, and perspectives, Journal of Alloys and Compounds 944 (2023) 169215. https://doi.org/10.1016/j.jallcom.2023.169215
[3] S. Tammas-Williams, P.J. Withers, I. Todd, P.B. Prangnell, Porosity regrowth during heat treatment of hot isostatically pressed additively manufactured titanium components, Scripta Materialia 122 (2016) 72–76. https://doi.org/10.1016/j.scriptamat.2016.05.002
[4] Q. Tan, G. Zhu, W. Zhou, Y. Tian, L. Zhang, A. Dong, D. Shu, B. Sun, Precipitation, transformation, and coarsening of carbides in a high-carbon Ni-based superalloy during selective laser melting and hot isostatic pressing processes, Journal of Alloys and Compounds 913 (2022) 165196. https://doi.org/10.1016/j.jallcom.2022.165196
[5] I. Sizova, A. Sviridov, M. Bambach, M. Eisentraut, S. Hemes, U. Hecht, A. Marquardt, C. Leyens, A study on hot-working as alternative post-processing method for titanium aluminides built by laser powder bed fusion and electron beam melting, Journal of Materials Processing Technology 291 (2021) 117024. https://doi.org/10.1016/j.jmatprotec.2020.117024
[6] C.I. Pruncu, C. Hopper, P.A. Hooper, Z. Tan, H. Zhu, J. Lin, J. Jiang, Study of the Effects of Hot Forging on the Additively Manufactured Stainless Steel Preforms, Journal of Manufacturing Processes 57 (2020) 668–676. https://doi.org/10.1016/j.jmapro.2020.07.028
[7] J. Hafenecker, D. Bartels, C.-M. Kuball, M. Kreß, R. Rothfelder, M. Schmidt, M. Merklein, Hybrid process chains combining metal additive manufacturing and forming – A review, CIRP Journal of Manufacturing Science and Technology 46 (2023) 98–115. https://doi.org/10.1016/j.cirpj.2023.08.002
[8] Y.S. Lee, S.U. Lee, C.J. Van Tyne, B.D. Joo, Y.H. Moon, Internal void closure during the forging of large cast ingots using a simulation approach, Journal of Materials Processing Technology 211 (2011) 1136–1145. https://doi.org/10.1016/j.jmatprotec.2011.01.017
[9] H. Kakimoto, T. Arikawa, Y. Takahashi, T. Tanaka, Y. Imaida, Development of forging process design to close internal voids, Journal of Materials Processing Technology 210 (2010) 415–422. https://doi.org/10.1016/j.jmatprotec.2009.09.022
[10] M. Saby, P.-O. Bouchard, M. Bernacki, Void closure criteria for hot metal forming: A review, Journal of Manufacturing Processes 19 (2015) 239–250. https://doi.org/10.1016/j.jmapro.2014.05.006
[11] M. Saby, M. Bernacki, E. Roux, P.-O. Bouchard, Three-dimensional analysis of real void closure at the meso-scale during hot metal forming processes, Computational Materials Science 77 (2013) 194–201. https://doi.org/10.1016/j.commatsci.2013.05.002
[12] M. Bambach, I. Sizova, A. Emdadi, Development of a processing route for Ti-6Al-4V forgings based on preforms made by selective laser melting, Journal of Manufacturing Processes 37 (2019) 150–158. https://doi.org/10.1016/j.jmapro.2018.11.011
[13] A. Emdadi, S. Bolz, F. Jensch, M. Tovar, S. Weiß, On the Hot Deformation of a Fe-Al-Ta Iron Aluminide Prepared via Laser Powder Bed Fusion, Crystals 13 (2023) 627. https://doi.org/10.3390/cryst13040627
[14] A. Emdadi, S. Bolz, S. Weiß, Hot Working of an Fe-25Al-1.5Ta Alloy Produced by Laser Powder Bed Fusion, Crystals 13 (2023) 1335. https://doi.org/10.3390/cryst13091335
[15] M. Palm, F. Stein, G. Dehm, Iron Aluminides, Annu. Rev. Mater. Res. 49 (2019) 297–326. https://doi.org/10.1146/annurev-matsci-070218-125911
[16] D.D. Risanti, G. Sauthoff, Microstructures and mechanical properties of Fe–Al–Ta alloys with strengthening Laves phase, Intermetallics 19 (2011) 1727–1736. https://doi.org/10.1016/j.intermet.2011.07.008
[17] A. Emdadi, I. Sizova, M. Bambach, U. Hecht, Hot deformation behavior of a spark plasma sintered Fe-25Al-1.5Ta alloy with strengthening Laves phase, Intermetallics 109 (2019) 123–134. https://doi.org/10.1016/j.intermet.2019.03.017
[18] A. Emdadi, S. Bolz, S. Weiß, Hot Working of an Fe-25Al-1.5Ta Alloy Produced by Laser Powder Bed Fusion, Crystals 13 (2023) 1335. https://doi.org/10.3390/cryst13091335
[19] A. Emdadi, Y. Yang, S. Bolz, O. Stryzhyboroda, M. Tovar, S. Gein, U. Hecht, S. Weiß, Mechanisms of necklace recrystallization in a BCC Fe-Al-Ta alloy with strengthening Laves phase precipitates, Scripta Materialia 237 (2023) 115705. https://doi.org/10.1016/j.scriptamat.2023.115705
[20] A. Emdadi, S. Bolz, J. Buhl, S. Weiß, M. Bambach, Laser Powder Bed Fusion Additive Manufacturing of Fe3Al-1.5Ta Iron Aluminide with Strengthening Laves Phase, Metals 12 (2022) 997. https://doi.org/10.3390/met12060997
[21] B.V. Reddy, S.C. Deevi, Thermophysical properties of FeAl (Fe-40 at.%Al), Intermetallics 8 (2000) 1369–1376. https://doi.org/10.1016/S0966-9795(00)00084-4
[22] Z. Snow, A.R. Nassar, E.W. Reutzel, Invited Review Article: Review of the formation and impact of flaws in powder bed fusion additive manufacturing, Additive Manufacturing 36 (2020) 101457. https://doi.org/10.1016/j.addma.2020.101457
