Analysis of metal powder geometrical characteristics influencing the quality of additively manufactured parts

Laser powder bed fusion (LPBF) is increasingly used to produce metal industrial components for high value-added sectors, such as aerospace, automotive and biomedical. However, mechanical and structural properties of LPBF parts are often hindered by the large quality variability, poor geometrical and dimensional accuracy, complex surface texture and low density. The quality of the feedstock material is an important aspect to be taken into account, as it significantly influences such possible issues. In particular, metal powder used in LPBF should have shape and size distribution designed to facilitate good flowability and packing behaviour, so that the final fabricated parts have acceptable density, surface finish and mechanical properties. The powder size and shape can be simultaneously measured from three-dimensional reconstructions obtained by X-ray computed tomography (CT). This work investigates the accuracy of these CT measurements of powder characteristics. X-ray CT is compared with other methods such as laser diffraction and scanning electron microscopy. The influence of powder characteristics evaluated by X-ray CT on the surface texture and density of LPBF parts is also discussed.