INFLUENCE OF ACOUSTIC TRANSPARENCY OF SURFACE-CONTACT LAYER ON FLAW DETECTABILITY IN ULTRASONIC TESTING

On the basis of extensive experiments, conducted on a representative s ample of specimens with different kinds of autocorrelated function of surface profile, the following dependencies were obtained: correlative links between parameters of regular and stochastic unevenness and abs orption coefficient in the coupling layer for several ultrasonic trans ducers produced by firms such as Krautkramer; Sonatest, Tokimek, Volna and others; correlative links between height parameters of unevenness and the amplitude of an auxiliary signal from the SRC-probe; correlat ive links between absorption coefficient in coupling layer for ultraso nic transducers (normal transducers and angle transducers) and the amp litude of an auxiliary signal from the SRC-probe. On this scientific b asis, the following nomograms were plotted and generalised: mathematic al dependence of absorption coefficient in the coupling layer of an ul trasonic transducer on the geometrical size of its working surface, an gle of ultrasound incidence, frequency, surface unevenness expressed i n parameter Rz and amplitude of special signal from SRC-probe. This al lowed us to develop a fundamentally new method (technology) of ultraso nic testing named the SRC-technique (Surface-Roughness-Correction tech nique).