Accessible Requires Authentication Published by De Gruyter May 26, 2013

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

Erhöhung der Auffindwahrscheinlichkeit POD von Fehlern im Inneren von strukturellen Materialien mit hoher Schallschwächung durch die Verwendung von SAFT-prozessierten Ultraschall-Prüfdaten
Martin Spies and Hans Rieder
From the journal Materials Testing


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.


Dieser Beitrag befasst sich mit der Größenbestimmung von Fehlern im Innern von Duplexstählen und der Bestimmung der Fehlerauffindwahrscheinlichkeit (Probability of Detection, POD) anhand von Ultraschalldaten. Das ferritisch-austenitische Mischgefüge dieser Stähle bedingt eine starke Schwächung der Ultraschallwellen. Daher wurde die Synthetische Apertur Fokus Technik SAFT eingesetzt, die zur Reduzierung der Gefügerauschsignale und damit zur Verbesserung der Fehlerdetektion führt. Unter Verwendung von HF-Daten, die an einem Testblock mit Modellfehlern aufgezeichnet wurden, haben wir eine â-versus-a-Analyse durchgeführt, um die POD für den untersuchten Duplex-Testkörper gemäß dem Standard MIL-HDBK-1823 zu bestimmen. Es wird gezeigt, dass die SAFT-Verarbeitung der Ultraschalldaten zu einer erheblichen Verbesserung der Fehlerdetektion führt.

Privatdozent Dr. habil. Martin Spies, born in 1963, studied Physics at the University of Kaiserslautern and at the University of Saarland in Saarbrücken as well as Materials Science at the University of Houston, Texas. He obtained his academic degrees including the Venia Legendi in ‚Nondestructive Testing Techniques' at the Technical Faculty of the University of Saarland. In October 2007 he left Fraunhofer IZFP, Saarbrücken, and joined the Fraunhofer-Institute for Industrial Mathematics ITWM in Kaiserslautern. His specific scientific interests are in the field of modeling and simulation of nondestructive testing.

Dipl.-Ing. Hans Rieder, born in 1954, studied Electrical Engineering at the University of Saarland in Saarbrücken. With his main focus on software development, embedded systems and signal processing he held the position of a department leader at the Fraunhofer-Institute for Nondestructive Testing IZFP for long years. In October 2007 he joined the Fraunhofer ITWM, his scientific interest is on imaging techniques; in particular he is dealing with problems of data acquisition and signal processing.

Both authors perform research in the field of imaging techniques for defect testing and materials' characterization with the Ultrasonic Imaging group. They have been awarded the Berthold-Price 2009 of the Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. (DGZfP).


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Published Online: 2013-05-26
Published in Print: 2010-03-01

© 2010, Carl Hanser Verlag, München