The potential of scattered or diffracted ultrasound in the determination of crack depth

Abstract This article reports an investigation which was a part of a wider study of defect sizing techniques. The authors have examined the method of crack depth determination using scattered ultrasound developed by Bottcher et al with special reference to contract probe studies with normal grade structural steels. They conclude that the use of amplitude of the scattered signal as a measure of crack depth, as proposed, suffers from a number of serious drawbacks in these contexts. However, the alternative of using the change of time delay between the transmitted and the first received signal has been investigated here and appears to provide a very attractive alternative.