Application of the total focusing method for quantitative nondestructive testing of anisotropic welds with ultrasound

Abstract

Abstract In this paper, we report on the application of the ultrasonic Total Focusing Method for quantitative imaging of cracks in austenitic welds. Imaging inspection procedures provide more information than punctual measurements. In addition, an image provides more easy access for most human viewers. In ultrasonic testing, array transducers have played an important role in imaging for many years. The Full Matrix Capture technique in combination with Total Focusing is one of the newer methods with decisive advantages. In combination with fast electronics, computer technology and image processing, it now enables tomographic imaging in real time. The functionality of the method and the technical requirements are explained here. Austenitic weld seams are considered as examples for anisotropic materials, which can be examined with this method. An important requirement for quantitative measurement of defect size in anisotropic materials is the knowledge of the ultrasonic phase and group velocities of the inspected volume. The Gradient Elastic Constant Descent Method can deliver unknown parameters, which are needed to calculate these velocities.