Defect detection in L-PBF Metal Additive Manufacturing using on-line and off-line inspection processes

Laser powder bed fusion (L-PBF) additive manufacturing enables new industrial possibilities for high precision manufacturing and design optimization while reduces material loses. Manufactured parts complex geometries represent a major challenge for non-destructive testing and quality control. The aim of this study is to assess defect detection precision by means of in-line and off-line inspection techniques. For that, a set of samples of Inconel718 have been manufactured in a RenAM500Q Renishaw machine. The samples include intentionally induced defects in the mid-plane considering a width varying from 0.11 to 0.35mm. Samples have been monitored on-line, trough on-axis optical monitoring system, and off-line, trough ultrasonic testing (UT). Samples have been inspected by UT in an immersion tank and by laser ultrasounds. Defects geometry has been determined through destructive characterization. All inspection methods are able to detect induced defects with resolutions in the range of 0.3 mm.