Characterisation of defects following MicroCT sampling inspection of specimens produced by electron beam powder bed fusion

With the maturation of metal additive manufacturing (AM) technologies, and the evolution of the machine capabilities, the discussions in literature are pivoting towards reliability and quality of the components produced. There is still much concern amongst stakeholders in the medical, aerospace and automotive industries about whether metal AM parts will meet many of the strict quality requirements. Following a Systems-V approach to quality assurance verification, this work focused on the characterisation of defects detected by µCT sampling scans of Ti-6Al-4V specimens produced via electron beam powder bed fusion (EB-PBF). Pore characteristics were classified by volume, surface area, diameter, compactness, sphericity, spatial distribution and orientation. From a statistical analysis of these attributes, a covariance matrix was established that revealed defect dependencies important to consider for manufacturing quality components in EB-PBF. Due to the sampling method employed, the results were combined with machine process parameters to predict the expected levels of porosity for the entire specimens with good agreement. Thus, this work provides evidence in support of quality verification by µCT sampling methods.