EFFECTS OF LASER POWER, SCAN SPEED AND HEAT TREATMENT ON MICROSTRUCTURE AND HARDNESS OF PBF-LB INCONEL 718

Ahmed Abdelghany; Matias Jaskari; Sami Westman; Ilkka Poutiainen; Antti Järvenpää

doi:10.17222/mit.2025.1581

Ahmed Abdelghany Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland https://orcid.org/0000-0003-4226-2378
Matias Jaskari Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland https://orcid.org/0000-0001-8955-105X
Sami Westman Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland https://orcid.org/0000-0002-3869-8331
Ilkka Poutiainen Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland https://orcid.org/0000-0001-5118-0310
Antti Järvenpää Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland https://orcid.org/0000-0002-4309-4786

DOI: https://doi.org/10.17222/mit.2025.1581

Keywords: additive manufacturing, PBF-LB, Inconel 718, laser power, scan speed, line energy, heat treatment

Abstract

This study quantifies the effects of laser power and scan speed on the aged microstructure and hardness of PBF-LB Inconel 718 processed under the EOS-standard heat-treatment schedule. Cylindrical specimens were fabricated on an EOS M290 using six power–speed combinations spanning a line energy (E_line = P/v) range of 0.167–0.583 J·mm^–1, followed by solution annealing and double ageing according to the EOS recommendation. Microstructure was assessed by EBSD, and hardness was measured in both the as-built and aged conditions. EBSD revealed build-direction-aligned columnar  grains under all conditions, while increasing line energy was associated with a progressively coarser boundary/subgrain network. The lowest line-energy (highest scan-speed) condition (200 W/1200 mm·s^–1; 0.167 J·mm^–1) achieved the highest post-age hardness (459 HV5), whereas the highest line-energy condition (350 W/600 mm·s^–1; 0.583 J·mm^–1) exhibited the lowest hardness (438 HV5) together with void-like, non-indexed features consistent with porosity. Overall, the results provide a compact process–structure–property map and energy-aware guidance for selecting PBF-LB Inconel 718 parameter windows, highlighting that while lower line-energy conditions maximise performance, higher-speed regimes may still deliver sufficient quality for short-life or productivity-driven components.

Author Biographies

Ahmed Abdelghany, Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland

¹ Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland

² Design and Production Engineering Dept., Faculty of Engineering, Ain Shams University, Cairo 11535, Egypt

Matias Jaskari, Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland

¹ Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland

Sami Westman, Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

³ Laser processing and additive manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

Ilkka Poutiainen, Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

³ Laser processing and additive manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

Antti Järvenpää, Laser Processing and Additive Manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology, LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

¹ Future Manufacturing Technologies (FMT), Kerttu Saalasti Institute, University of Oulu, Nivala 85500, Finland

³ Laser processing and additive manufacturing, Mechanical Engineering Department, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, P.O. Box 20, FI-53851, Lappeenranta, Finland

References

[1] G. Kasperovich, J. Gussone, G. Requena, N. Schell, A. Stark, J. Haubrich, Tailoring the strength of Inconel 718: Insights into LPBF parameters and heat-treatment synergy, Mater. Des., 250 (2025) 113627, doi:10.1016/j.matdes.2025.113627.
[2] C. Smith, G. Hommer, M. Keeler, J. Gockel, K. Findley, C. Brice, A. Clarke, J. Klemm-Toole, Assessing volumetric energy density as a predictor of defects in laser powder bed fusion 316L stainless steel, JOM, 77 (2025) 737–748, doi:10.1007/s11837-024-06946-z.
[3] EOS NickelAlloy IN718 Material Data Sheet, online: https://www.eos.info/var/assets/05-datasheet- images/Assets_MDS_Metal/EOS_NickelAlloy_IN718/Material_DataSheet_EOS_ NickelAllo y_IN718_en.pdf.
[4] S. Ghaemifar, H. Mirzadeh, Precipitation kinetics of gamma double prime phase during direct aging treatment of Inconel 718 superalloy additively manufactured by selective laser melting, J. Mater. Res. Technol., 27 (2023) 4248–4255, doi:10.1016/j.jmrt.2023.10.267.
[5] N. Ghanadi, K. Son, M. Alvarado, S. Yang, H.M. Kao, C.H. Chang, B.K. Paul, S. Pasebani, Effect of LPBF processing parameters on Inconel 718 lattice structures: Geometrical characteristics, surface morphology, and mechanical properties, Mater. Des., 253 (2025) 113864, doi:10.1016/j.matdes.2025.113864.
[6] H. Liu, W. Cheng, Y. Sun, R. Ma, Y. Wang, J. Bai, L. Xue, X. Song, C. Tan, Effects of process parameters and heat treatment on microstructure and mechanical characteristics of laser powder bed fusion alloy Inconel 718, Coatings, 13 (2023) 189, doi:10.3390/coatings13010189.
[7] G.V. de Leon Nope, L.I. Perez-Andrade, J. Corona-Castuera, D.G. Espinosa-Arbelaez, J. Muñoz-Saldaña, J.M. Alvarado-Orozco, Study of volumetric energy density limitations on the IN718 microstructure in laser powder bed fusion process, J. Manuf. Process., 64 (2021) 1261–1272, doi:10.1016/j.jmapro.2021.02.043.
[8] S. Zhang, X. Lin, L. Wang, X. Yu, Y. Hu, H. Yang, L. Lei, W. Huang, Strengthening mechanisms in selective laser-melted Inconel 718 superalloy, Mater. Sci. Eng. A, 812 (2021) 141145, doi:10.1016/j.msea.2021.141145.
[9] H. Pan, T. Dahmen, M. Bayat, K. Lin, X. Zhang, Independent effects of laser power and scanning speed on IN718’s precipitation and mechanical properties produced by LBPF plus heat treatment, Mater. Sci. Eng. A, 849 (2022) 143530, doi:10.1016/j.msea.2022.143530.
[10] M. Khedr, K. Elkhouly, M. Jaskari, M.A.J. Finnilä, A. Järvenpää, A.W. Abdelghany, Role of printing density in internal defect evolution and hydrogen embrittlement of PBF-LB 316L stainless steel fabricated from recycled powder, Mater. Des., 257 (2025) 114506, doi:10.1016/j.matdes.2025.114506.

EFFECTS OF LASER POWER, SCAN SPEED AND HEAT TREATMENT ON MICROSTRUCTURE AND HARDNESS OF PBF-LB INCONEL 718

Abstract

Author Biographies

References

Most read articles by the same author(s)