Ultrasonic Imaging of welded metals using simplified ultrasonic computerized tomography

In this paper, as a new measurement method to estimate the infinitesimal change of material condition, the simplified ultrasonic computerized tomography (CT) system, which uses the information of three directions. i.e., the 90, +45degrees and -45degrees-directions about the inspection plane, is proposed. The use of the simplified ultrasonic CT system has two merits: First, the measurement time is very short compared with that of the conventional CT method. Second, it can detect sensitively infinitesimal defects in vertical or oblique directions about the inspection plane because the obtained image is not a C scan image but a CT image calculated froth the three directions. Due to these merits. this method can be considered to be a very effective method for the evaluation of material condition. In order to determine the applicability of actual NDT, several kinds of welded specimens are investigated. The results showed that the CT images obtained were very similar to actual defects of specimens. Also, the same CT images were obtained by computer simulation and the obtained CT images by computer simulation were almost the same as the experimental images.