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The results of the Round-Robin trials conducted under the PISC I exercise (1976-1980) showed large discrepancies in the defect detection and sizing capability among different flaws. To identify the causes of such dispersions a number of steel specimens containing various artificial defects was made available for measurement. The defects were ultrasonically scanned by standard methods and by some advanced techniques, the high performance of which had been established in the PISC Round Robin Tests. This report deals with the beam focussing technique: 2 MHz 45 shear wave transducers have been used in immersion to collect the signals generated by the reference reflectors. The results show that the depth and the size of a defect do not affect significantly its detection and sizing, provided that the natural variation of sensitivity and of beam diameter along the propagation axis is taken into account. On the other hand, parameters such as the orientation and the roughness modify the conditions of impact and interference of the acoustic beam with the defect surface, and therefore strongly influence the energy partition in diffracted and specularly reflected rays. As an example, sharp smooth defects insonified under an angle of 45 return to the transducer signals approximately 10 times smaller than the ASME code calibration level.

Additional information

Authors: DOMBRET P, VinÇotte, Bruxelles (BE)
Bibliographic Reference: EUR 12433 EN (1989) 22 pp., FS, ECU 5
Availability: (2)
Record Number: 199010290 / Last updated on: 1994-12-01
Original language: en
Available languages: en
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