Advancements in the accuracy investigation of X-ray computed tomography characterization of additively manufactured metal surfaces

X-ray computed tomography (CT) has recently started to be used for evaluating the surface topography of metal parts produced by additive manufacturing (AM). Differently from conventional contact and optical measuring techniques, CT enables non-destructive measurements of both internal and difficult-to-access AM surfaces, including typical complex micro-scale re-entrant features. This work aims at improving the understanding of the accuracy of CT-based surface topography characterization using a newly proposed reference sample design. The sample geometry allows evaluating the CT measurement accuracy on external and internal, planar and curved surfaces oriented along two orthogonal directions within the CT volume. An actual sample was produced by laser-powder bed fusion of Ti6Al4V and cut by micro electrical discharge machining to enable optical calibration of reference surface profiles.