Advanced X-ray CT porosity analysis for metal laser powder bed fusion: comparing results using a process-specific reference object

While laser-based powder bed fusion of metals (PBF-LB/M) enables the production of complex, high-performance components, it can introduce internal defects, especially irregular pores that can compromise part integrity. Accurate porosity measurement in PBF-LB/M parts is crucial for improving the process and part performance. X-ray computed tomography (CT) allows nondestructive inspection of internal defects, yet metrologically traceable porosity analysis remains challenging, particularly for lack-of-fusion pores with complex shapes and entrapped powder. In this work, a process-specific reference object developed for PBF-LB/M is exploited to enable traceable CT-based porosity measurements. Artificial defects calibrated through a three-dimensional data-fusion approach combining multi-view optical profilometry and high-resolution CT are used to evaluate different CT porosity analysis algorithms and to support the development of enhanced approaches. In addition, the feasibility of using silicon-based polymeric replicas as surrogate defect models is investigated to support calibration scenarios involving materials that are particularly challenging for an adequate CT inspection. The results demonstrate how calibrated reference objects can be effectively exploited to compare different algorithms for porosity analysis, quantify measurement errors, assess repeatability, and support traceable porosity measurements, contributing to improved reliability of CT-based quality assurance and process optimisation in PBF-LB/M.