CT vs conventional NDT for additive manufacturing: what can each actually detect?

Short answer: X-ray computed tomography is uniquely useful for three-dimensional internal inspection of complex AM geometry, but it is not universally superior. Detectability depends on voxel size, material density, part thickness, defect morphology, orientation, reconstruction quality and acceptance criteria.

Where CT is strongest

• Internal porosity and lack-of-fusion populations that are inaccessible from the surface.
• Complex internal channels and hidden geometry.
• Three-dimensional defect location, morphology and distribution.
• Correlative process-development and failure-analysis work.

What CT cannot be assumed to do

Recent research shows that XCT performance can degrade for irregular defects and that detection probability is not determined by voxel size alone. A 2024 Ti-6Al-4V study found that achieving high detection rates required flaw sizes substantially larger than the nominal voxel size. Therefore “CT resolution = defect detection limit” is an unsafe simplification.

Why conventional NDT still matters

Ultrasonic, penetrant, eddy-current and radiographic techniques can remain appropriate depending on defect type, surface access, section thickness, material and production economics. The inspection plan should be built around the critical defect population and validated probability of detection, not around a preferred instrument.

Scientific references

• Sun et al. (2024), Thin-Walled Structures, “X-ray computed tomography in metal additive manufacturing: A review on prevention, diagnostic, and prediction of failure.”
• Baig et al. (2025), Scientific Reports, “Non-destructive detection of critical defects in additive manufacturing.”
• ISO/ASTM 52908:2023 — post-processing, inspection and testing of metal PBF parts.

Related Addithive: CT Inspection Bottleneck · NDT for Additive Manufacturing