Evaluation of defects in laser powder bed fusion metal parts via in-process optical measurements and post-process X-ray computed tomography

Laser powder bed fusion (LPBF) enables the fabrication of metal parts characterized by high geometrical complexity, unique possibilities of customization and increasingly good mechanical properties. However, parts produced by LPBF are often characterized by poor geometrical and dimensional accuracy as well as by a number of internal defects, which undermine a wider application of LPBF in industry. Several in-process measurement methods have been proposed to identify out-of-control process conditions and take immediate action, as well as to improve the understanding of the LPBF process. However, the correlation between in-process measurement results and actual defects in the fabricated parts is not always clear yet. This work presents an experimental study aimed at defining a reproducible methodology for comparing optical in-process evaluations to X-ray computed tomography post-process measurements of actual defects.