Characteristic and recognition of ultrasonic TOFD signal and image for planar defect

Considering several typical planar defects that were common flaws in thick aluminum weld, the characteristics of Ultrasonic TOFD (time of flight diffraction) was studied. Ultrasonic TOFD A-scan signal and B, D-scan image were analyzed and interpreted. Linearization was introduced in processing B and D-scan image. The results show that planar defect can be effectively recognized, located and sized by the characteristics of the received signal and image. Linearization effectively improves time resolution of the received images, which makes the characteristics of the defect more markedly and leads to more accurate quantitative measurement.