Nondestructive evaluation of additively manufactured metallic parts: In situ and post deposition

Additive manufacturing (AM) is a technique for prototype and component production that produces parts by joining a material layer upon layer, as opposed to a subtractive process with the removal of material. The adequate inspection and qualification of AM components is vital for increasing use of the technology, particularly in critical or fatigue sensitive applications. Post-production inspection can be difficult due to complex internal and external features, surface condition, and microstructural complexity, so attention is turning to in process metrology to bypass these issues encountered when inspecting completed components. This article reviews the state of the art in nondestructive evaluation and standardization techniques with a focus on metals produced from powder feedstock. In situ inspection and characterization methods are reviewed in depth due to the potential transformational impact of successful application of such inspection methods.