Simulation and experiment of ultrasonic phased array for additive manufacturing titanium alloy with columnar crystal structure

The influence of the grain structure of titanium alloys, used for additive manufacturing (AM), on the propagation of ultrasonic beams is of great significance for the non-destructive testing of components manufactured from this material. In order to explore the issues related to ultrasonic testing, such as low signal-to-noise ratio (SNR) and large imaging error of internal defects, an ultrasonic phased array C-scan image was obtained and the measurements of ultrasonic noise level and defect distortion caused by columnar crystals were analysed. Ultrasonic wave theory was combined with the Voronoi algorithm to establish a finite element (FE) model of the AM titanium alloy with a columnar crystal structure. The focusing and scattering of ultrasonic beams in different grain structures was studied and the defect echo signals from the FE model and the experimental results were extracted and compared. Comparisons of the signal-to-noise ratio and the background noise of three typical sections were in good agreement, which shows that the proposed simulation model can be used to analyse the propagation and scattering of beams for the inspection of AM titanium alloys. Finally, suggestions to improve the ultrasonic detection results of AM titanium alloy components and the applicability of the wave simulation model for other polycrystalline materials are discussed.