Acoustic Parameters in Reference Standards for Calibration of the Industrial Ultrasound Test System (#418)

Authors

Vera Alvarado, Jorge Wilfredo

Caballero García, Luis Fernando

Taboada Neira, Martin

Abstract

The non-destructive method of industrial ultrasound uses reference standards for calibration of the test system, a key factor to characterize a defect dimensionally. In welded steel structures, the AWS D 1.1 code suggests, depending on availability, various types of reference standards for calibration. It is important for the repeatability of the inspection results, regardless of whether one or another reference standard is used, to be certain of the measurement of its acoustic properties. The objective of the research was to obtain the speed and ultrasonic attenuation in the DSC, K1 and K2 type reference standards, with longitudinal and transversal beam, by varying the frequency of the beam. The acoustic parameters in each reference were obtained by the direct contact method, pulse-echo technique, 16 experimental runs were carried out with three repetitions to produce acoustic waves with a straight and transversal beam with refraction angles of 45o, 60o and 70º and frequencies of the 2.25, 5.0, 10.0 and 15 MHz transducer. The results reported that the comparable acoustic parameters differ in each reference standard, the speed of the ultrasonic beam decreased and the attenuation increased, as the frequency of the transducer increased, due to generating greater dispersion of the ultrasonic beam. It was not possible to obtain reliable results with transverse beam for sweep frequencies of 10 and 15 MHz. The type of reference standard and the frequency of the transducer have a significant effect on the measurements of the acoustic parameters.