Functional Behaviour of Cold-Worked and Straight-Annealed NiTi Elements Processed with Ultrashort Laser Cutting

Among functional materials, quasiequiatomic NiTi alloys are one of the most promising and diffused for some sectors, from biomedical to aerospace ones. Their peculiar performance, namely, shape memory effect pseudoelasticity, is induced via a thermomechanical treatment called setting or with heat annealing. This carried out in cold-worked conditions. The present work studies material conditions straight annealing cold working on performance diamond-shaped microdevices realised through ultrashort laser cutting. In detail, experiments were aimed at studying power, scanning speed, number passes kerf width focus defining suitable process condition both straight-annealed sheets 100 µm thickness. After parameters had been defined, transformation temperatures superelastic behaviour analysed though differential calorimetry force–displacement testing. femtosecond cutting did not change characteristic base material, while same soft martensitic respect due accumulation effect.