Vari-aperture Focusing Inspection Technique Based on Ultrasonic Annular Phased Array

Ultrasonic annular phased array has the potential to replace multi-zone focusing ultrasonic technique (UT) for the inspection of powder metallurgical (PM) turbine disks due to the advantage of efficiency and high sensitivity. The present work investigated the ultrasonic phased array inspection technique for PM turbine disks by simulation and experimental verification,in order to solve the problems of focal size control,sensitivity consistence and near-surface resolution. Vari-aperture focusing inspection technique was put forward on the basis of annular phased array ultrasonic focus theory. With the technique in the present work,the sensitivity consistence was optimized from 5 dB to 3 dB,and near-surface resolution reduced to 3.2 mm. Compared to conventional multi-zone focusing UT,the present technique has similar defects detection capability,while the time consumption reduces by 3/4.