The weldability of Shape Memory Alloy

In this work a Nd: YAG laser was used for welding 2mm thick tapes of Ti-50.9at.%Ni shape memory alloy (SMA). Both reference and laser welded samples were chosen to investigate mechanical and shape memory behaviour. Their mechanical properties were tested by stress-strain measurements respectively. Comparative microstructures of the reference and the welded materials were studied with SEM and XRD analysis. Moreover, hardness measurements allowed further clarification that the modification was induced by the welding procedure. The results obtained on the weld joint material indicate that the stress-induced martensite and the recovery mechanisms are weakly modified by the presence of the welding zone, while the microstructure of the weld joint is strongly affected.