PSI - Issue 69

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ScienceDirect

Procedia Structural Integrity 69 (2025) 47–52

13th European Symposium on Martensitic Transformation 2024 (ESOMAT 2024) Effect of beam shaping in laser welding on the microstructure and transformation temperatures of NiTiHf high-temperature shape memory alloy C.A. Biffi 1, *, A.G. Demir 2 , L. Caprio 2 , J. Fiocchi 1 , B. Previtali 2 , A. Tuissi 1 1 CNR-ICMATE, Unit of Lecco, Italy 2 Politecnico di Milano, Department of Mechanical Engineering, Milan, Italy Abstract Beam shaping in laser welding of NiTiHf high temperature shape memory alloy (HTSMA) is explored for the first time with promising perspectives. Such alloys are typically characterized by high brittleness, therefore advanced thermal processing may limit their cracking susceptibility. In details, novel prospective in laser welding regards the possibility of tuning the laser power distribution, namely beam shaping, which can module significantly the thermal cycle induced into the material. In this work, the effect of the beam shape and welding speed are explored on the cross section of the welded beads, highlighting the focus on the defects promoted. Moreover, the transformation temperatures of the martensitic transformation were checked from the base material to the welded one. It was demonstrated that beam shaping in laser welding can be a promising solution for adjusting the weldability of brittle materials. © 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

Keywords: laser beam welding; high-temperature shape memory alloy; NiTiHf, beam shaping

* Corresponding author. Tel.: -39 0341 2350111 E-mail address: carloalberto.biffi@cnr.it

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.2025.07.007