PSI - Issue 81

Vitalii Mocharskyi et al. / Procedia Structural Integrity 81 (2026) 31–34

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a b Fig. 5. SEM images of the surface of unprocessed nitinol samples after tensile testing: a - magnification x20, b - magnification x500

a b Fig. 6. SEM images of nitinol samples before (a) and after (b) laser processing after tensile testing. The red lines show the direction of crack propagation. Magnification x20

4. Conclusions Nanosecond laser processing changes the structure of the surface layer of nitinol, increasing the amount of martensite. The predominant direction of crack growth from the surface to the depth of the material is observed, both in the treated and untreated material. The surface after laser processing and static tensile testing also differs significantly from the nitinol in the virgin state. A large number of cracks are observed, which are caused by different elongations of the martensite and austenite phases in the material. Due to the increase in the amount of martensite, cracks formed faster on the surface, and the material failed more rapidly, leading to a decrease in σ u (ultimate tensile strength) by more than 8% and a relative elongation of the samples by more than 10%. The next step will be to study cyclic loading of nanosecond-laser-treated nitinol samples. References Swen Grossmann, Eric Bohne, Volkmar Senz, Niels Grabow, Klaus-Peter Schmitz, and Stefan Siewert. Water-supported femtosecond laser ablation of Nitinol for cardiovascular stents. Current Directions in Biomedical Engineering, vol. 8, no. 2, 2022, 455-458. H. Huang, H.Y. Zheng, G.C. Lim. Femtosecond laser machining characteristics of Nitinol, Applied Surface Science, Volume 228, Issues 1 – 4, 2004, 201-206. Muhammad, N., Whitehead, D., Boor, A. et al. Picosecond laser micromachining of nitinol and platinum – iridium alloy for coronary stent applications. Appl. Phys. A 106, 2012, 607 – 617. Ming Chu Kong, Jie Wang. Surface Quality Analysis of Titanium and Nickel-based Alloys Using Picosecond Laser, Procedia CIRP, Volume 13, 2014, 417-422. Biffi, C.A.; Fiocchi, J.; Rancan, M.; Gambaro, S.; Cirisano, F.; Armelao, L.; Tuissi, A. Ultrashort Laser Texturing of Superelastic NiTi: Effect of Laser Power and Scanning Speed on Surface Morphology, Composition and Wettability. Metals 2023, 13, 381. Changyoung Ryu, S.S. Mani Prabu, I.A. Palani, Anh Phan Nguyen, Jung Bin In. Improving the actuation behavior of nitinol shape memory alloys by nanosecond laser surface texturing, Optics & Laser Technology, Volume 176, 2024, 110957. Choi, H., Na, M., Jun, I. et al. Repetitive Nanosecond Laser-Induced Oxidation and Phase Transformation in NiTi Alloy. Met. Mater. Int. 30, 2024, 1200 – 1208. Shang Li, Zeqin Cui, Wei Zhang, Yuancheng Li, Lin Li, Dianqing Gong. Biocompatibility of micro/nanostructures nitinol surface via nanosecond laser circularly scanning, Materials Letters, Volume 255, 2019, 126591. Cadena C. Mariana, Elisa Vázquez-Lepe, J. Israel Martínez-López, Ciro A. Rodríguez, Erika García-López. Influence of process parameters on surface topography of nitinol manufactured by fiber laser cutting for medical applications., Procedia CIRP, Volume 110, 2022, 82-86. Neha Agarwal, Mehran Bahramyan, Paul Healy, Muhannad Ahmed Obeidi, Dermot Brabazon. Control of surface finish and mechanical properties of nitinol stents fabricated via laser powder bed fusion, Journal of Materials Research and Technology, Volume 37, 2025, 1808-1821 ASTM F2516-14. Standard Test Method for Tension Testing of Nickel-Titanium Superelastic Materials. Book of Standards Volume: 13.02.