Laser welding of a NiTi alloy: Mechanical and shape memory behaviour

Welding and Joining of NiTi Shape Memory Alloys: A Review

“…Although the irrecoverable strain of the welded joints was small (bellow 0.1 and 0.3% for strains of 4 and 6%, respectively), these were less performant than the base material. The effect of imposed strain on the shape memory recovery for Ti-rich laser welded NiTi was also evidenced by Falvo et al [138]. Fig.…”

“…In the former, the hardness in the FZ increased compared to the base material, while in the latter, the opposite behaviour was registered: lower hardness of the FZ. Nevertheless, [31,138] did not observe a significant change when measuring the hardness across the different regions of the weld.…”

“…Falvo et al [138] reported a decrease in the martensitic plateau after welding, as shown in Fig. 17.…”

“…For Ti-rich NiTi a significant decrease of the UTS (more than 30% that of the base material [127,138]) in the joints is justified by the grain boundary precipitation of Ti ?2 Ni in the HAZ and the presence of micro-cracks in the FZ [127]. An embrittlement of the welded material, when compared to the base material, justified the lower ductility and tensile strength.…”

Fracture analysis of Ag nanobrazing of NiTi to Ti alloy

“…Laser welding has been performed over a range of parameters in pulsed and continuous mode with a Nd/YAG laser in overlap welds of 1 mm thick samples of equiatomic NiTi and Ti6Al4V with good results [5]. This is particularly relevant in NiTi since the superelastic behavior of the alloy was not affected [6,7].…”