Enhanced tomographic porosity measurements in laser powder bed fusion metal parts using a novel reference object

Laser powder bed fusion of metals (PBF-LB/M) enables the fabrication of intricate parts with good mechanical properties. Nevertheless, challenges such as porosity formation compromise component integrity and require advanced solutions for part quality control and qualification. Accurate measurement and characterisation of internal defects are essential for quality assurance and process optimisation. X-ray computed tomography (CT) emerges as a powerful tool for comprehensive evaluation of internal features. However, establishing metrological traceability in CT porosity measurements is crucial for aiding decision-making in part quality control as well as in product and process development. This study presents a novel reference object designed to enhance porosity measurements in components fabricated by PBF-LB/M. A data fusion calibration strategy combining multi-view optical profilometry and X-ray CT has been developed and applied to defects specifically designed to resemble the geometry of typical process-induced porosities. An experimental campaign was conducted to compare different CT porosity analysis algorithms, evaluating measurement errors in internal defects, both without and with entrapped powder particles. A new porosity analysis approach, the local-adaptive method, is proposed and benchmarked against existing industrial practices. The results demonstrate its advantages in improving tomographic porosity measurements and highlight its feasibility for application to industrial PBF-LB/M components.