Inspection of Laser Powder Deposited Layers

Laser powder deposition is a process where a powder is sprayed on to a substrate at the same time as a laser is used to melt it. In this way layers of the powder material are built up into structures that can be very fine and complex. For critical requirements it is useful to inspect the structure as the layers are deposited as the final component may have considerable added value. The main challenge for the NDT methods are the small sizes involved, which in turn lead to detection of small flaws being required. Laser ultrasonics, laser thermography and eddy currents were identified as methods that might be deployed for the inspection. This paper describes the results obtained from these methods on a specially developed set of reference samples and on specific deposition samples with induced flaws.