Investigation of WAAM-PAW Fabricated 316L Steel/Invar 36 Nb Alloys for the Development of Functionally Graded Materials

Abstract:

Functionally graded materials represent a promising strategy for locally optimizing component properties while reducing both economic and environmental costs. To date, no study has addressed the development of a compositional gradient between 316L stainless steel and Invar 36 using the Wire Arc Additive Manufacturing (WAAM) process, despite the strong potential of this material combination. Indeed, such a gradient would combine the very low coefficient of thermal expansion (CTE) of Invar 36 with the low cost and excellent chemical resistance of 316L stainless steel. A particularly relevant application for this type of gradient is the storage of hydrogen or liquefied natural gas, where tanks are subjected to severe thermal stresses due to cryogenic operating temperatures. In addition, these structures must withstand aggressive environments and hydrogen exposure, which can induce material embrittlement, while maintaining sufficient mechanical properties to ensure structural integrity during service. Designing an optimal gradient therefore requires a detailed understanding of how mechanical, thermal, and chemical properties evolve with chemical composition. This study provides a preliminary assessment of these evolutions. The results show that the addition of 15–25 wt.% Invar 36 to 316L leads to a reduction in microhardness and ultimate tensile strength (UTS), associated with the disappearance of ferritic and σ phases, while significantly enhancing ductility. At higher Invar 36 contents, microhardness increases and ductility decreases due to carbide formation. From a thermal standpoint, the CTE does not follow a linear trend: it remains high up to approximately 75 wt.% Invar 36 Nb, then decreases sharply as the ferromagnetic behavior characteristic of Invar becomes dominant. Corrosion resistance remains satisfactory for Invar 36 contents below 15 wt.%, whereas higher contents lead to reduced chemical performance due to chromium dilution. Overall, these findings establish clear criteria for selecting optimal compositions in the design of a 316L–Invar 36 compositional gradient. They provide an essential foundation for the development, via WAAM, of robust and high-performance functionally graded materials suitable for applications requiring high dimensional stability, good chemical resistance, and controlled costs.

• Periodical: Key Engineering Materials (Volume 1047)
• Pages: 83-93
• Online since: April 2026
• Authors: Lucas Weber*, Anis Hor, Leon Ratsifandrihana, Mathilde Alcaraz
• Keywords: 316L Stainless Steel, Corrosion Resistance, Functionally Graded Materials (FGM), Invar 36 Nb, Mechanical Properties, Microhardness, Plasma Arc Welding (PAW), Thermal Expansion Coefficient (CTE), Wire Arc Additive Manufacturing (WAAM)

References

[1] J. N. DuPont, « Microstructural evolution and high temperature failure of ferritic to austenitic dissimilar welds », International Materials Reviews, vol. 57, no 4, p.208‑234, juill. 2012.

DOI: 10.1179/1743280412Y.0000000006

[2] A. Nazir et al., « Multi-material additive manufacturing: A systematic review of design, properties, applications, challenges, and 3D printing of materials and cellular metamaterials », Materials & Design, vol. 226, p.111661, févr. 2023.

DOI: 10.1016/j.matdes.2023.111661

[3] A. Shah, R. Aliyev, H. Zeidler, et S. Krinke, « A Review of the Recent Developments and Challenges in Wire Arc Additive Manufacturing (WAAM) Process », JMMP, vol. 7, no 3, p.97, mai 2023.

DOI: 10.3390/jmmp7030097

[4] T. A. Rodrigues et al., « Wire and arc additive manufacturing of 316L stainless steel/Inconel 625 functionally graded material: development and characterization », Journal of Materials Research and Technology, vol. 21, p.237‑251, nov. 2022.

DOI: 10.1016/j.jmrt.2022.08.169

[5] X. Chen et al., « A functionally graded material from TC4 to 316L stainless steel fabricated by double-wire + arc additive manufacturing », Materials Letters, vol. 300, p.130141, oct. 2021.

DOI: 10.1016/j.matlet.2021.130141

[6] W. S. Park, M. S. Chun, M. S. Han, M. H. Kim, et J. M. Lee, « Comparative study on mechanical behavior of low temperature application materials for ships and offshore structures: Part I—Experimental investigations », Materials Science and Engineering: A, vol. 528, no 18, p.5790‑5803, juill. 2011.

DOI: 10.1016/j.msea.2011.04.032

[7] M. Teshigawara, M. Harada, M. Ooi, T. Kai, F. Maekawa, et M. Futakawa, « Development of invar joint for hydrogen transfer line in JSNS », Journal of Nuclear Materials, vol. 431, no 1‑3, p.212‑217, déc. 2012.

DOI: 10.1016/j.jnucmat.2011.11.031

[8] A. Cornelius, L. Jacobs, M. Lamsey, L. McNeil, W. Hamel, et T. Schmitz, « Hybrid manufacturing of Invar mold for carbon fiber layup using structured light scanning », Manufacturing Letters, vol. 33, p.133‑142, sept. 2022.

DOI: 10.1016/j.mfglet.2022.07.019

[9] D. C. Hofmann et al., « Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing », Sci Rep, vol. 4, no 1, p.5357, juin 2014.

DOI: 10.1038/srep05357

[10] A. Arbogast, S. Roy, A. Nycz, M. W. Noakes, C. Masuo, et S. S. Babu, « Investigating the Linear Thermal Expansion of Additively Manufactured Multi-Material Joining between Invar and Steel », Materials, vol. 13, no 24, p.5683, déc. 2020.

DOI: 10.3390/ma13245683

[11] H. Guo, D. Liu, M. Xu, Z. Dong, et L. Zhang, « Preparation, characterization and composition optimization design of laser powder bed fusion continuously graded Invar36/316L stainless steel alloys », Materials Characterization, vol. 209, p.113709, mars 2024.

DOI: 10.1016/j.matchar.2024.113709

[12] T. Osuki, K. Ogawa, et H. Hirata, « Analysis of the solidification process in Fe–36%Ni weld metal with NbC crystallization », Welding International, vol. 20, no 2, p.116‑126, févr. 2006.

DOI: 10.1533/wint.2006.3544

[13] D. Jafari, T. H. J. Vaneker, et I. Gibson, « Wire and arc additive manufacturing: Opportunities and challenges to control the quality and accuracy of manufactured parts », Materials & Design, vol. 202, p.109471, avr. 2021.

DOI: 10.1016/j.matdes.2021.109471

[14] X. Yu et al., « Effect of composition gradient design on microstructure and mechanical properties of dual-wire plasma arc additively manufactured 316L/IN625 functionally graded materials », Materials Chemistry and Physics, vol. 307, p.128121, oct. 2023.

DOI: 10.1016/j.matchemphys.2023.128121

[15] U. Gürol, E. Kocaman, S. Dilibal, et M. Koçak, « A comparative study on the microstructure, mechanical properties, wear and corrosion behaviors of SS 316 austenitic stainless steels manufactured by casting and WAAM technologies », CIRP Journal of Manufacturing Science and Technology, vol. 47, p.215‑227, déc. 2023.

DOI: 10.1016/j.cirpj.2023.10.005

[16] A. Iturrioz, E. Ukar, et J. C. Pereira, « Influence of the manufacturing strategy on the microstructure and mechanical properties of Invar 36 alloy parts manufactured by CMT-WAAM », Int J Adv Manuf Technol, déc. 2024.

DOI: 10.1007/s00170-024-14853-5

[17] F. Veiga, A. Suárez, T. Artaza, et E. Aldalur, « Effect of the Heat Input on Wire-Arc Additive Manufacturing of Invar 36 Alloy: Microstructure and Mechanical Properties », Weld World, vol. 66, no 6, p.1081‑1091, juin 2022.

DOI: 10.1007/s40194-022-01295-4

[18] C. Wang, T. G. Liu, P. Zhu, Y. H. Lu, et T. Shoji, « Study on microstructure and tensile properties of 316L stainless steel fabricated by CMT wire and arc additive manufacturing », Materials Science and Engineering: A, vol. 796, p.140006, oct. 2020.

DOI: 10.1016/j.msea.2020.140006

[19] A. Saboori, A. Aversa, G. Marchese, S. Biamino, M. Lombardi, et P. Fino, « Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review », Applied Sciences, vol. 10, no 9, p.3310, mai 2020.

DOI: 10.3390/app10093310

[20] G. Jiao et al., « High performance ultrasonic vibration assisted Wire-arc directed energy deposition of Invar alloy », Journal of Materials Processing Technology, vol. 332, p.118534, nov. 2024.

DOI: 10.1016/j.jmatprotec.2024.118534

[21] T. Wegener et al., « On the structural integrity of Fe-36Ni Invar alloy processed by selective laser melting », Additive Manufacturing, vol. 37, p.101603, janv. 2021.

DOI: 10.1016/j.addma.2020.101603

[22] E. Aldalur, A. Suárez, et F. Veiga, « Thermal expansion behaviour of Invar 36 alloy parts fabricated by wire-arc additive manufacturing », Journal of Materials Research and Technology, vol. 19, p.3634‑3645, juill. 2022.

DOI: 10.1016/j.jmrt.2022.06.114

[23] G. Huang, G. He, Y. Liu, et K. Huang, « Anisotropy of microstructure, mechanical properties and thermal expansion in Invar 36 alloy fabricated via laser powder bed fusion », Additive Manufacturing, vol. 82, p.104025, févr. 2024.

DOI: 10.1016/j.addma.2024.104025

[24] X. Chen, J. Li, X. Cheng, H. Wang, et Z. Huang, « Effect of heat treatment on microstructure, mechanical and corrosion properties of austenitic stainless steel 316L using arc additive manufacturing », Materials Science and Engineering: A, vol. 715, p.307‑314, févr. 2018.

DOI: 10.1016/j.msea.2017.10.002

[25] C. Penot, « Corrosion performance of an austenitic stainless steel fabricated by wire arc additive manufacturing ».

[26] C. Wang, P. Zhu, F. Wang, Y. H. Lu, et T. Shoji, « Anisotropy of microstructure and corrosion resistance of 316L stainless steel fabricated by wire and arc additive manufacturing », Corrosion Science, vol. 206, p.110549, sept. 2022.

DOI: 10.1016/j.corsci.2022.110549