Enhancement of the POD of Flaws in the Bulk of Highly Attenuating Structural Materials by Using SAFT Processed Ultrasonic Inspection Data

Abstract The determination of the size of flaws in the bulk of duplex stainless steels and the determination of the Probability of Detection (POD) from ultrasonic data is addressed. The ferritic-austenitic mixed microstructure of these steels causes a strong attenuation of the ultrasonic waves. Therefore, the Synthetic Aperture Focusing Technique SAFT has been applied which leads to a reduction of the microstructural noise signals and thus to an improvement of defect detection. Based on the ultrasonic rf-data acquired on a test block with model defects an â-versus-a-approach has been performed to determine the POD for the inspected duplex specimen according to MIL-HDBK-1823. It is shown that SAFT-processing of the ultrasonic data leads to a remarkable improvement of defect detectability.