Effect of the reuse of powder on material properties of Ti6Al4V processed by SLM

The repeated reuse of excess powder is an essential part of the economics of powder-bed additive manufacturing processes. Although many studies on selective laser melting cover the topics of material properties at the micro- and macroscale, little is known about the influence of the multiple reuse cycles of powder. Titanium alloys, in particular, are sensitive to chemical contamination, especially in the presence of oxygen and hydrogen which can lead to inferior material properties. Furthermore, grain size distribution and form change over time which can have an influence on build quality. In this study, the influence of the chosen powder on the quality and material properties of the widely used titanium alloy Ti6Al4V is investigated with focus on porosity, surface quality, microstructure and tensile strength.