Effect of Nd-YAG laser welding on the functional properties of the Ni–49.6at.%Ti

Welding and Joining of NiTi Shape Memory Alloys: A Review

“…It was also observed that the critical stress, for the stress-induced transformation, in the welded joint decreased, when compared to the base material. Similar findings, regarding the decrease of the critical stress for the occurrence of the superelastic plateau, were also reported in [137,140]. It is suggested that this stress reduction occurs due to the microstructural modifications introduced in both HAZ and FZ, which allows for these regions to reach the constant stress plateau, after the initial elastic deformation, at lower stress values than those of the original base materials.…”

“…This dependence was studied by Tuissi et al [137], where two heat treatments were performed on the NiTi base material prior to welding. One of the heat treatments consisted of a full solution at 900°C for 60 min and the other one was ageing at 400°C during 20 min.…”

“…In the former the functional properties of the material suffer a degradation during cyclic solicitation, while the latter the material fails, during high cyclic loads like any other engineering material. Several studies report the cycling behaviour of NiTi welds [31,125,126,132,137,140,144,166]. However, a significant disparity in the reported experiments is observed.…”

Effect of laser welding parameters on the austenite and martensite phase fractions of NiTi

“…Among the different joining techniques available, fusion-based ones, such as tungsten inert gas (TIG) [2] and laser welding [3][4][5][6], have presented the best results in terms of the mechanical properties of the joints. Laser welding is by far the most used process for welding NiTi due to the reduced extension of the thermally affected regions, which is especially important for NiTi due to the deterioration of its functional properties (shape memory effect and superelasticity) at high temperatures.…”

Martensite stabilization during superelastic cycling of laser welded NiTi plates

“…Laser welding has proven to be a suitable joining technique for NiTi shape memory alloys [1][2][3][4][5]. The functional behavior, either by superelasticity or shape memory effect, of the laser welded NiTi joints is dependent on the laser welding procedure.…”