ON THE ACCURACY IMPROVEMENT IN ULTRASONIC INSPECTION BY USING COMPUTER GRAPHICS AND WAVEFORM ANALYSIS

The C-scan images of defects made by drilled holes with different types are obtained and the effect of length and inclination of drilled holes on the images are discussed in this paper. The artificial cylindrical defect of diameter 1mm and 2mm were made in a steel plate specimen of 9mm thick and 3D images of these defects are obtained by using a graphic software on a workstation from the maximum amplitude data and path length data of received waves. In the detail waveform analysis of boundary and bottom echo the method to get more accurate size of defect are shown. And in order to apply C-scan ultrasonic test to a field inspection the effect of surface roughness and thickness of specimen on their images are analyzed and the modified immersion method to use a small water bag between a probe and a specimen are proposed.