Comparison of Porosity Analysis Based on X-Ray Computed Tomography on Metal Parts Produced by Additive Manufacturing

The determination of uncertainty in porosity analysis based on X-ray computed tomography (XCT) images is currently the focus of research. This study aims to contribute to that by investigating the variation in porosity analysis resulting only from the segmentation and data analysis and by focusing on metal parts produced by different additive manufacturing processes, partially fabricated with intended porosity. Samples manufactured from aluminum, titanium alloy and nickel-chromium-based feedstock by liquid metal jetting (LMJ), laser-based powder bed fusion (PBF-LB) and directed energy deposition (DED) were scanned by XCT. The reconstructed volumes were distributed to four operators with different experience levels using Avizo, Dragonfly, Image J/Fiji, IPSDK Explorer, and VG Studio Max for porosity analysis. It was found that for all parts, the majority of operators chose a global manual threshold for image segmentation. Depending on the characteristics of the pores in the investigated samples, relative standard uncertainties up to 12% and 38% were observed for the LMJ and PBF-LB parts. For the part produced by DED, which showed the lowest overall porosity, relative standard uncertainties between 70% and 89% were observed for different image qualities; all were affected by the presence of artefacts investigated on purpose.