PSI - Issue 69

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ScienceDirect

Procedia Structural Integrity 69 (2025) 76–79

13th European Symposium on Martensitic Transformation 2024 (ESOMAT 2024) Deformation Behavior of NiTi Shape Memory Alloy Subjected to Severe Torsion Deformation Victor Komarov a, b, c *, Roman Karelin a, b , Vladimir Cherkasov b , Ivan Postnikov c , Grzegorz Korpala c , Irina Khmelevskaya a, b , Vladimir Yusupov a , Rudolf Kawalla c , Ulrich Prahl c , Sergey Prokoshkin b Abstract In the present work, the possibility of application severe torsion deformation (STD) to a bulk near-equiatomic NiTi shape memory alloy in order to accumulate high strain was studied. STD was performed using the multidirectional test system “BÄHR MDS 830” in a temperature range of 300-600 °C (the dynamic polygonization range) in 10 turns with accumulated true strain of e =3. The results obtained show the prospects of application STD to bulk NiTi samples in terms of large strains accumulation. The STD at 350-600 °C leads to the formation of steady state flow stress stage. The polygonized dislocation substructure can be formed in this temperature range at e = 0.6 to 3. The obtained flow curves can be used for mathematical modeling and optimization of deformation processes of NiTi alloys. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Guest Editors a Baikov Institute of Merallurgy and Materials Science RAS, Leninskiy pr. 49, 119334 Moscow, Russia b National University of Science and Technology MISIS, Leninskiy pr. 4, 119049 Moscow, Russia c TU Bergakademie Freiberg, Bernhard-von-Cotta-Straße 4, 09599 Freiberg, Germany

Keywords: shape memory alloys; NiTi; severe plastic deformation; torsional deformation; deformation behavior

1. Introduction NiTi shape memory alloys (SMA) are attractive functional materials that are widely used in various fields of engineering and medicine for production of shape-memory devices [1-5]. The severe plastic deformation (SPD) is one

* Corresponding author. E-mail address: vickomarov@gmail.com

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of Guest Editors 10.1016/j.prostr.2025.07.011