Defect Detection in Additively Manufactured Components: Laser Ultrasound and Laser Thermography Comparison

Despite continuous technological advances in additive manufacturing, the lack of non-destructive inspection techniques during the manufacturing process is a limit for the industrial breakthroughs. Additive manufacturing is mainly used in industrial sectors where the zero defect target is crucial. The inclusion of the integrity assessment into the additive manufacturing process would allow corrective actions to be performed before the component is completed. To this end, the development of in-process monitoring and processing techniques is of great interest. This work proposes and compares two remote non-destructive inspection techniques: laser ultrasound and laser thermography. The two techniques are evaluated on Inconel samples with laser drilling holes to establish their sensitivity. Experimental results show that those discontinuities are efficiently detected with both techniques. The remote inspection by optical methods would allow the integration of the evaluation system into the additive manufacturing equipment, thus allowing continuous monitoring throughout the entire production process. Potential benefits and limitations of the two techniques are discussed. Copyright (C) 2018 The Authors. Published by Elsevier B.V.