A review of ultrasonic testing applications in additive manufacturing: Defect evaluation, material characterization, and process control

•Reviews the ultrasonic testing techniques applied to additive manufacturing (AM)•Considers both in-situ and offline ultrasonic testing techniques applied to AM.•All accessible work done on this topic is included in this paper.•Makes suggestions for future work. Ultrasonic testing (UT) techniques are highly capable of detecting defects in engineering components. The present manuscript intends to review the ultrasonic testing techniques applied to additive manufacturing products; either in-situ or offline. While the in-situ applications of ultrasonic testing to additive manufacturing are more favorable, literature holds a few research works on this topic. On the other hand, most of the works reported on ultrasonic testing of additive manufacturing products deal with offline applications. In many of these works, samples with artificial defects are prepared and tested through ultrasonic testing techniques including laser ultrasonics, phased arrays, guided waves and immersion ultrasonic testing. These UT methods and their applications in damage detection of additive manufacturing products are discussed in detail. Moreover, the codes and standards which are currently being developed for ultrasonic testing of additive manufacturing products are introduced. The choice of UT methods in detecting defects and material characterization in additive manufacturing is found to be highly dependent on the manufacturing process and capabilities of UT techniques.