CT-based method to measure metal powder characteristics and to study their influence on the quality of additively manufactured parts

Abstract

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 characteristics, 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, spreading and packing behaviour, so that the final fabricated parts have acceptable density, surface finish and mechanical properties. This work focuses on the accuracy of simultaneous measurement of powder size and shape from three-dimensional reconstructions obtained by X-ray computed tomography (CT). Results of CT measurements are compared with results from other methods based on laser diffraction and scanning electron microscopy. Different materials and powder morphologies were investigated. In addition, the CT-measured powder characteristics can be used to improve other CT analyses of LPBF parts.