Исследование выявляемости поверхностных объемных дефектов при ультразвуковом контроле с применением волн Рэлея, генерируемых электромагнитно-акустическим преобразователем

Abstract

The paper presents the study of the "pitting corrosion" surface operational flaws detectability by the ultrasonic method of non-destructive testing. The possibility of using Rayleigh surface waves excited by an electromagnetic acoustic transducer (EMAT) for these purposes is considered. Blind vertical drills of various diameters and depths were used as artificial defects to simulate these flaws in low-carbon steel specimens. Based on the measurement results, the dependences of the amplitude of the received signals on the drilling parameters were plotted. During the statistical processing of the results, the signal-to-noise ratio was taken into account upon excitation of the Rayleigh wave using EMAT on defect-free areas of the samples. To construct curves of probability of detection (PoD), optimal models of the amplitudes distribution are determined. Under the conditions of the experiments carried out using the constructed PoD curves, conclusions were made about the minimum dimensions of a "pitting corrosion" type defect, detected with a probability of 90 %, taking into account the confidence interval of 95%, and about the possibility of adjusting the ultrasonic testing parameters using signals reflected from vertical drills.