Improving the Efficiency of Ultrasonic Testing Based on Additional Information on Defect Scattering Indicatrices

Abstract

An ultrasonic testing (UST) method is proposed that allows one to classify internal defects in welded joints into planar and bulk ones by using defect scattering indicatrices. Dedicated angle twin-crystal transducers of the Duet type with probe angles of 29° and 61°, exciting a head wave in the test object, are employed as a transmitter and receiver for ultrasonic testing. Informative signs of defects based on using their scattering indicatrices are considered. These signs make it possible to improve the reliability of ultrasonic testing results. It is shown that due to the peculiarities of propagation of head waves, defect scattering indicatrices are most informative for the probe angle of 29° (a wedge angle close to the first critical value for the PMMA–aluminum-magnesium-alloy pair of materials) and the probe angle of 61° (the angle close to the value complementing the angle of 29° to 90°). The statistical significance of the results of calculating correlation and concordance coefficients were estimated for given significance levels \(\alpha = \) 0.05 and \(\beta = \) 0.05, where α and β are the probabilities of the errors of the first and second kind, respectively. Correlation matrices were compiled for the obtained defect scattering indicatrices. Additionally, the reliability of the results was verified by comparing the obtained data with a database of previously performed measurements and their results.