Research Progress on Ultrasonic Nondestructive Testing Technology for Metallic Additive Manufacturing Components: A Review

Additive manufacturing (AM) is a new manufacturing technology for building complex 3D components by progressively adding material in a layer-by-layer fashion. Despite the many apparent advantages of AM, the instable heat transfer during the melting of metallic material and the stacking manufacturing processing increases the probability of generating internal defects that may cause the AM components to deform or fail. To ensure the quality and safety of additively manufactured metallic components, nondestructive testing technologies that are fast, accurate and low-cost are needed. In this paper we review the defect formation mechanism and the nondestructive testing methods for metallic AM components, and focus on the development of ultrasonic testing in AM. We analyze the influence of the manufacturing process, material microstructure and detection parameters on ultrasonic testing and summarize the application of ultrasonic testing for offline and online detection of defects in metallic AM components. On this basis, the application and advantages of phased array ultrasonic testing, laser-generated ultrasonic testing and hybrid nondestructive testing detection are discussed. The development trends of ultrasonic testing for metallic AM are discussed and some suggestions are made.