Correlative Laser Confocal Microscopy Study and Multimodal 2D/3D Registration as Ground Truth for X-ray Inspection of Internal Defects in LPBF Manufacturing

In a time when engineers working in the additive manufacturing field are interested in the standardized x-ray computed tomography (XCT) image analysis workflow, an insight into a higher resolution imaging and ground truth validation become invaluable. In this work, we propose a repeatable and automated 2D/3D registration protocol between an XCT volume and a laser confocal microscopy image, thus allowing a correlative multiscale validation and comparison study of the flaw detection capabilities and uncertainties of an XCT analysis of additivelymanufactured parts. Once the spatial correlation achieved, a comparison study evaluating the level of confidence of the flaw detection and measurement computed from the XCT volume is presented. To this end, a pore-to-pore comparison between the XCT volume and the laser confocal image, which offers a 4 times higher resolution as well as a better signal to noise ratio, is carried out and various pore morphology metric distributions are compared. The generality of the proposed approach is ensured by the use of printed Ti64 LPBF samples with different levels of the intentionally seeded and controlled porosity.