On the scalability of strength and presumed size effects in SLM-produced 316L stainless steel

On the scalability of strength and presumed size effects in SLM-produced 316L stainless steel

VYSOCHINSKIY Dmitry, MOE Ole-Bjørn

Abstract. As additive manufacturing (AM) technology advances toward the production of structurally utilized metallic components, an accurate evaluation of mechanical properties becomes crucial. Understanding the effect of the printed cross-section size on material strength is exceptionally important since AM technology, especially laser powder bed fusion (L-PBF), enables topology optimization and favors the production of thin struts, lattice structures, and other small cross-sections, as well as thin-walled profiles. Structural designers need to know to what degree the size of the printed cross-section might affect material strength. This study focuses on the effect of printed cross-section size on the mechanical properties of L-PBF-produced 316L stainless steel. The findings reported in existing literature so far are conflicting, indicating a need for further investigation. In the presented paper, the mechanical properties of net-shape printed samples with cross-section diameters ranging from 2.5 mm to 6.0 mm are compared. Tensile tests reveal that smaller diameter net-shape samples exhibit lower strength compared to larger diameters. Machined samples display higher strength than net-shape samples. The observed size-dependent strength variations in L-PBF-produced 316L stainless steel can be explained by the surface layer being weaker than the core of the sample. Whether the effect is due to differences in microstructure between the surface and core of the sample or is simply caused by a reduction of the effective cross-sectional area due to surface roughness could be debated, but both factors are likely to contribute to the phenomenon.

Keywords
Powder Bed Fusion, Selective Laser Melting, 316L, Metal Additive Manufacturing, Mechanical Properties, L-PBF

Published online 4/24/2024, 10 pages
Copyright © 2024 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: VYSOCHINSKIY Dmitry, MOE Ole-Bjørn, On the scalability of strength and presumed size effects in SLM-produced 316L stainless steel, Materials Research Proceedings, Vol. 41, pp 60-69, 2024

DOI: https://doi.org/10.21741/9781644903131-7

The article was published as article 7 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] N.-E. I. 52900, Additiv produksjon. Generelle prinsipper. Terminologi = Additive manufacturing. General principles. Terminology, vol. NS-EN ISO/. in Norsk Standard, vol. NS-EN ISO/. Lysaker: Norsk Standard, 2017.
[2] I. Jeon, L. Yang, K. Ryu, and H. Sohn, “Online melt pool depth estimation during directed energy deposition using coaxial infrared camera, laser line scanner, and artificial neural network,” Addit Manuf, vol. 47, p. 102295, Nov. 2021. https://doi.org/10.1016/J.ADDMA.2021.102295
[3] B. Cheng, J. Lydon, K. Cooper, V. Cole, P. Northrop, and K. Chou, “Melt pool sensing and size analysis in laser powder-bed metal additive manufacturing,” J Manuf Process, vol. 32, pp. 744–753, Apr. 2018. https://doi.org/10.1016/j.jmapro.2018.04.002
[4] J. Yu, D. Kim, K. Ha, J. B. Jeon, and W. Lee, “Strong feature size dependence of tensile properties and its microstructural origin in selectively laser melted 316L stainless steel,” Mater Lett, vol. 275, p. 128161, Sep. 2020. https://doi.org/10.1016/J.MATLET.2020.128161
[5] J. Yu, D. Kim, K. Ha, J. B. Jeon, D. J. Kim, and W. Lee, “Size effect due to contour laser scanning in 316L stainless steel produced by laser powder bed fusion,” Journal of Materials Research and Technology, vol. 15, pp. 5554–5568, Nov. 2021. https://doi.org/10.1016/J.JMRT.2021.11.034
[6] J. Bültmann, S. Merkt, C. Hammer, C. Hinke, and U. Prahl, “Scalability of the mechanical properties of selective laser melting produced micro-struts,” J Laser Appl, vol. 27, p. null, 2015. https://doi.org/10.2351/1.4906392
[7] X. Wang, J. A. Muñiz-Lerma, O. Sanchez-Mata, M. A. Shandiz, and M. Brochu, “Microstructure and mechanical properties of stainless steel 316L vertical struts manufactured by laser powder bed fusion process,” Materials Science and Engineering: A, vol. null, p. null, 2018. https://doi.org/10.1016/J.MSEA.2018.08.069
[8] A. M. Roach, B. C. White, A. Garland, B. H. Jared, J. D. Carroll, and B. L. Boyce, “Size-dependent stochastic tensile properties in additively manufactured 316L stainless steel,” Addit Manuf, vol. 32, p. 101090, Mar. 2020. https://doi.org/10.1016/J.ADDMA.2020.101090
[9] L. Hitzler, J. Hirsch, B. Heine, M. Merkel, W. Hall, and A. Öchsner, “On the anisotropic mechanical properties of selective laser-melted stainless steel,” Materials, vol. 10, no. 10, 2017. https://doi.org/10.3390/ma10101136
[10] ISO 6892-1:2019(en) Metallic materials — Tensile testing — Part 1: Method of test at room temperature. 2019. Accessed: Nov. 19, 2021. [Online]. Available: https://www.iso.org/standard/61856.html
[11] B. C. Salzbrenner et al., “High-throughput stochastic tensile performance of additively manufactured stainless steel,” J Mater Process Technol, vol. 241, pp. 1–12, Mar. 2017. https://doi.org/10.1016/j.jmatprotec.2016.10.023
[12] D. Barba, C. Alabort, Y. T. Tang, M. J. Viscasillas, R. C. Reed, and E. Alabort, “On the size and orientation effect in additive manufactured Ti-6Al-4V,” Mater Des, vol. 186, p. 108235, Jan. 2020. https://doi.org/10.1016/J.MATDES.2019.108235
[13] J. Dzugan et al., “Effects of thickness and orientation on the small scale fracture behaviour of additively manufactured Ti-6Al-4V,” Mater Charact, vol. 143, pp. 94–109, Sep. 2018. https://doi.org/10.1016/J.MATCHAR.2018.04.003
[14] Z. Dong, X. Zhang, W. Shi, H. Zhou, H. Lei, and J. Liang, “Study of Size Effect on Microstructure and Mechanical Properties of AlSi10Mg Samples Made by Selective Laser Melting,” Materials 2018, Vol. 11, Page 2463, vol. 11, no. 12, p. 2463, Dec. 2018. https://doi.org/10.3390/MA11122463
[15] D. Vysochinskiy and N. Akhtar, “On the Influence of Cross-Section Size on Measured Strength of SLM-Produced AlSi10Mg-Alloy,” Key Eng Mater, vol. 926, pp. 132–140, Jul. 2022. https://doi.org/10.4028/P-G078SC
[16] N. Takata, H. Kodaira, A. Suzuki, and M. Kobashi, “Size dependence of microstructure of AlSi10Mg alloy fabricated by selective laser melting,” Mater Charact, vol. 143, pp. 18–26, Sep. 2018. https://doi.org/10.1016/J.MATCHAR.2017.11.052
[17] A. Röttger et al., “Microstructure and mechanical properties of 316L austenitic stainless steel processed by different SLM devices,” The International Journal of Advanced Manufacturing Technology 2020 108:3, vol. 108, no. 3, pp. 769–783, Jul. 2020. https://doi.org/10.1007/S00170-020-05371-1