Abstract: An ultrasonic test apparatus for testing tubes or rods by rotating transducers to provide a helical scan, the test transducer, or each of a plurality of transducers, is mounted for adjustable motion along an axis which is inclined by an angle .omega. with respect to a perpendicular axis intersecting the workpiece surface. The angle .omega. is selected to provide a desired incident angle .alpha. of the ultrasonic energy upon the workpiece surface, whereby to cause a refracted angle .beta. of the ultrasonic energy. Within the range of measuring accuracy for small angles it can be assumed that angle .omega. approximates angle .alpha..

Abstract: In a pulse-echo ultrasonic test arrangement the back reflected echo acoustic wave signal as well as the scattered longitudinal wave and scattered shear wave signals are utilized in an evaluation circuit for determining more accurately the characteristics of a defect in a workpiece. The evaluation circuit, most suitably, includes a digital computer which in a typical embodiment of the invention is programmed to provide by Fourier transforms the frequency amplitude spectrum and the frequency phase spectrum of the supplied three signals, hence producing six characteristic outputs for a particular defect.