Microstructure and shape memory effect of laser welded Nitinol wires

•The effects of laser welding on NiTi SME were evaluated using change of indentations.•Heating induces the size shrinkage of indentations in width, depth and volume.•The HAZ and FZ show the perfect SME from the volume change of indentations.•HAZ and FZ lost about 5% and 20% recovery rate in depth, respectively. In this study, crossed Nitinol wires were joined by laser welding, and the microstructures of the joint in various zones were revealed by transmission electron microscopy. A series of nanoindentation experiments were performed across the joint, and the size changes of indentations after heating were used to evaluate the shape memory effects. Compared to BM, HAZ retained about the 95% shape recovery, higher than FZ, which retained about the 75% recovery rate.