A Review of Diagnostics Methodologies for Metal Additive Manufacturing Processes and Products

Abstract

Additive manufacturing technologies based on metal are evolving into an essential advanced manufacturing tool for constructing prototypes and parts that can lead to complex structures, dissimilar metal-based structures that cannot be constructed using conventional metallurgical techniques. Unlike traditional manufacturing processes, the metal AM processes are unreliable due to variable process parameters and a lack of conventionally acceptable evaluation methods. A thorough understanding of various diagnostic techniques is essential to improve the quality of additively manufactured products and provide reliable feedback on the manufacturing processes for improving the quality of the products. This review summarizes and discusses various ex-situ inspections and in-situ monitoring methods, including electron-based methods, thermal methods, acoustic methods, laser breakdown, and mechanical methods, for metal additive manufacturing.

On the current research progress of metallic materials fabricated by laser powder bed fusion process: a review

“…Consequently, a large temperature gradient is generated in the LPBF part, leading to large residual thermal stresses. The high thermal gradient, along with the residual stress, causes the initiation and propagation of cracks in a fabricated part [60,138,139]. Two main types of cracks occur during LPBF: hot and cold cracks.…”

Stress Interference in Multilayer Additive Friction Stir Deposition of AA6061 Aluminum

“…In such AM techniques, laser power, laser translation speed, and path con gurations can strongly affect the width, depth, and overlapping area of melting pool [6], which further changes the microstructure [7] and residual stress evaluations [8,9] within certain layers. These subjects have been extensively studied in the laser fusion-based AM community with various processes parameters and materials [10]. In addition, the interference between the multilayers also signi cantly affects the overall mechanical properties distributions within the printed products [9].…”

Measuring the Cooling Behavior of Melt Pools in L-PBF by Pyrometry

“…McCann et al [ 2 ], Everton et al [ 6 ], Hou et al [ 7 ] as well as Yang et al [ 8 ] provide an overview of L-PBF process monitoring technologies and their challenges. Here, McCann et al [ 2 ] point out the main problem of pyrometry: Without knowledge about the emissivity of the regarded material, only qualitative statements can be made.…”