Four-Point Bending Cyclic Behavior of NiTi Superelastic Wires Micro-Welded by GTAW Double Pulses

In this paper, the bending cyclic behavior of welded joints obtained by micro–Gas Tungsten Arc Welding (GTAW) with double pulses in NiTi SMA superelastic wires was evaluated. Four-point bending tests were carried out on the welded wires for different amplitudes of cyclic strain. The fracture mechanism in the welded joint was investigated and discussed based on its microstructure. In the evaluated range of strain amplitude (0.90–1.31%), as-received and welded NiTi wires showed cyclic life between 10³ and 10⁵ cycles. The micro-welding process using GTAW double-pulse shows promising potential cyclic conditions in NiTi wires. This technique can facilitate the development of structures with complex geometries for various applications across different fields and substitute the use of laser welding, which is a welding process with higher costs compared to GTAW.