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Surface inspection and remanence imaging with magnetic field distortion measurement

: Youssef, Sargon; Szielasko, Klaus; Sourkov, Alexander; Gupta, Bhaawan; Youssef, Amir

Fulltext urn:nbn:de:0011-n-3995665 (508 KByte PDF)
MD5 Fingerprint: efe22f2fcd78efb6eaa0ce8185e10b14
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Created on: 28.6.2016

International Committee for Non-Destructive Testing -ICNDT-; Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin:
19th World Conference on Non-Destructive Testing, WCNDT 2016 : Munich, Gemany, 13-17 June 2016; Proceedings; USB-Stick
Berlin: DGZfP, 2016
ISBN: 978-3-940283-78-8
Paper Th.2.F.3, 8 pp.
World Conference on Non-Destructive Testing (WCNDT) <19, 2016, Munich>
Conference Paper, Electronic Publication
Fraunhofer IZFP ()

Measurement of magnetic field distortion (MFD) allows for a high-resolution detection of magnetic and geometrical anomalies in ferromagnetic surfaces. This method is based upon the distortion of a magnetic field at surface irregularities. The setup for MFD measurement requires a magnetic field source such as a permanent magnet, and a magnetic field strength sensor like a Hall probe or GMR sensor. As opposed to conventional magnetic flux leakage (MFL) measurement, the flux density inside the material is very small, and only the surface facing the sensor is evaluated. Local damage of the surface, e.g. corrosion-related pitting can be located and imaged accurately, independent on its overall lateral direction. Sensor synergies between MFD and MFL setups allow combining both methods with further benefits. MFL measurements can be designed to be sensitive for both sides of ferromagnetic pipe material, i.e. the side facing the sensor as well as the far side. This way, combining the information of both methods allows separating inner from outer defects and additionally determining the lateral outline of outer defects. Besides the application for defect detection, MFD sensors can be used for imaging and documentation of remnant magnetic fields.