Use total focusing method to image the near-surface planar defect in welded joint

Total focusing method (TFM) is used to synthetically focus at every image point in a target region. Half-Skip TFM (HSTFM), as a post-processing imaging algorithm of ultrasonic array data, is developed based on TFM. TFM and HSTFM are to image and characterize near-surface planar defects (vertical to the surface of welded joint) in the welded joint, respectively. The result showed that only the indication of the defect tip without root can be seen in the TFM image; in the image formed using HSTFM, the indication of the whole face of the planar defect can be clear observed. Meanwhile, using the HSTFM image of the defect, the near-surface defect with great reliability is sized.