39079 Investigation of acoustic pressure fields in advanced water squirters, application to ultrasonic inspection of composite materials : Violette, D.; Blanc-Benon, P.; Juve, D. Proceedings of the 4th European Conference on Non-Destructive Testing, London (United Kingdom), 13–17 Sep. 1987. Vol. 1, pp. 752–760. Pergamon Press, 3173 pp. (1988)

Abstract

A study has been made into the causes of the false indications sometimes observed upon ultrasonic inspection of austenitic stainless steel welds. The path taken by transverse ultrasonic waves through an austenitic stainless steel specimen embodying a butt-weld was traced by repeatedly shaving the surface of the specimen and scanning at each stage the newly uncovered surface with a dynamic sensor to obtain a C-scan of the through-transmission pattern of the beam penetrating through the surface. This showed that the false indications are back reflections, from the metal surface, of waves that have propagated along dendritic crystal formations developed in the weld metal. The present work provides evidence that certain indications obtained on austenitic stainless steel welds are in fact spurious, and should not be ascribed to defects in the weld.