Selective laser melting of NiTi stents with open-cell and variable diameter

This work investigates the processing of NiTi open-cell peripheral stents with variable diameter by SLM and consecutive heat treatments. The production of open-cell designs via SLM requires dedicated processing strategies to avoid the use of support structures with comparable dimensions to the stent struts. Process parameters were studied using an SLM system operating with pulsed wave emission to assess the geometrical fidelity and the density of thin struts. The novel stent mesh was designed and produced employing gaps with unmelted powder between the consecutive cells along the build direction. Solution annealing and stress relieving treatments were assessed after SLM. The results show that regular struts with high density (>99.5%) with an austenitic transformation finish below the room temperature can be achieved with SLM and dedicated heat treatment.