Computed Tomography for the Nondestructive Testing of Additive Manufactured Components: Opportunities and Limitations

Abstract

The additive manufacturing (AM) process has grown from university research laboratories into a production process for complex-shaped components. Due to the uniqueness of the manufacturing process, new challenges have arisen regarding process control, quality assurance, and surface finishing. This paper will show how the nondestructive radiographic testing (RT) technique computed tomography (CT) can make a valuable contribution to quality assurance at each step of the AM process. The use of CT is demonstrated using an example of chrome-nickel steel nozzles manufactured using the laser powder bed fusion (LPBF) process. The surface of the nozzles is then reworked with the Hirtisation process, a trademarked part finishing technology that is based on a combination of electrochemical pulse methods, hydrodynamic flow and particle assisted chemical removal, and surface treatment. In addition to the already known use of CT for detecting internal discontinuities, CT can be used to ensure sufficient wall thickness, measure internal channel surface roughness, and gauge the geometrical correctness of parts. In this paper, it is demonstrated how to use this RT technique to optimize the design and production process during the component development phase.