Inspection of 3D-printed parts by laser ultrasonics

3D-printing or additive manufacturing is a novel manufacturing technology, which is presently expanding quasi-exponentially. For the manufacturing of metallic parts, laser or electron beam is the main heat source for the... [ view full abstract ]

3D-printing or additive manufacturing is a novel manufacturing technology, which is presently expanding quasi-exponentially. For the manufacturing of metallic parts, laser or electron beam is the main heat source for the fusion of powders or wires. Metal powders can be injected either as a jet (powder deposition setup) or spread into layers, which are replenished after each fusion pass (power bed configuration). The power bed approach, in which the laser or electron beam is scanned along a path predetermined according to the part design, is presently the most widely used technology for additive manufacturing of components in industry. In contrast, the direct laser or electron beam deposition can use powder and/or wire feed and thus is particularly flexible for manufacturing or remanufacturing (refurbishing) of value-added components.

Besides the dimensional accuracy of the part in accordance with the design, metallic structural parts, such as those used in aero engines, must be free of major defects, such as cracks, lack of bonding between layers, and porosity. In addition, the microstructure characteristics should enable the desired mechanical performance. To detect the defects appearing in the additive manufacturing and acquire some information on the microstructure (e.g. grain size and orientation), ultrasonics is a most promising technique. Laser-ultrasonics is attractive due to its non-contact nature and thus is especially suited for the analysis of parts with complex geometries. In addition, the technique is well adapted to online implementation and real-time measurement during the manufacturing process. The inspection can be performed from either the top deposited layer or the underside of the substrate using bulk waves or surface waves.

In this presentation, a variety of results obtained off-line on INCONEL® 718 and Ti-6Al-4V coupons that were manufactured using laser powder or electron beam wire deposition, respectively, will be reported and discussed.