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Metal magnetic memory technique - prospects and restrictions

  • Magnetic testing methods are frequently applied in non-destructive evaluation of ferromagnetic materials. In the past decade, metal magnetic memory (MMM) technique according to ISO 24497 is gaining considerable interest in the magnetic NDT community. In contrast to traditional Magnetic Flux Leakage (MFL) testing, the inspection objects are not intentionally magnetized by an external magnetic field. Due to physical coupling between mechanical stress and magnetization in ferromagnetic materials, it is assumed that the distribution of the “natural” MFL (self-magnetic-leakage field, SMLF) indicate zones of different remanent magnetization, which in turn, correspond to the internal stress of specimen or in the most general sense to material degradation. Usually, MMM measurements are performed by relatively bulky magnetic inspection sensors providing a spatial resolution in millimetre range. High precision GMR (Giant Magneto Resistance) measurements in the micrometer regime along with imageMagnetic testing methods are frequently applied in non-destructive evaluation of ferromagnetic materials. In the past decade, metal magnetic memory (MMM) technique according to ISO 24497 is gaining considerable interest in the magnetic NDT community. In contrast to traditional Magnetic Flux Leakage (MFL) testing, the inspection objects are not intentionally magnetized by an external magnetic field. Due to physical coupling between mechanical stress and magnetization in ferromagnetic materials, it is assumed that the distribution of the “natural” MFL (self-magnetic-leakage field, SMLF) indicate zones of different remanent magnetization, which in turn, correspond to the internal stress of specimen or in the most general sense to material degradation. Usually, MMM measurements are performed by relatively bulky magnetic inspection sensors providing a spatial resolution in millimetre range. High precision GMR (Giant Magneto Resistance) measurements in the micrometer regime along with image based representation and evaluation can provide a higher degree of information. We present a concise summary of a broader research project aimed at studying the correlation of magnetic structure and microstructure of steels. Particularly, we compare residual stress measurements in S235JR steel by means of neutron diffraction with high resolution magnetic field measurements. In addition, we discuss the influence of deformation-induced magnetization in plastically deformed specimens with and without notches due to various quasi-static and cyclic load levels. Furthermore, comparative measurements with common non-destructive testing methods are presented. Despite of a quantitative evaluation of material degradation, the in the field inspection by MMM remains problematic due to substantial influences on such as external magnetization, anisotropy of internal magnetization and material degradation, as well as geometry and surface effects of the inspection objects on SMFL signals. The prospects and restrictions of the MMM technique are discussed in this contribution.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Robert Stegemann
Koautoren/innen:Sandra Cabeza, Nadja Sonntag, Sharatchandra Waikom Singh, Giovanni Bruno, Birgit Skortzki, Marc Kreutzbruck
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2016
Organisationseinheit der BAM:5 Werkstofftechnik
5 Werkstofftechnik / 5.1 Materialographie, Fraktographie und Alterung technischer Werkstoffe
5 Werkstofftechnik / 5.2 Experimentelle und modellbasierte Werkstoffmechanik
6 Materialschutz und Oberflächentechnik
7 Bauwerkssicherheit
8 Zerstörungsfreie Prüfung
8 Zerstörungsfreie Prüfung / 8.4 Akustische und elektromagnetische Verfahren
8 Zerstörungsfreie Prüfung / 8.5 Mikro-ZfP
9 Komponentensicherheit
9 Komponentensicherheit / 9.3 Schweißtechnische Fertigungsverfahren
6 Materialschutz und Oberflächentechnik / 6.0 Abteilungsleitung und andere
7 Bauwerkssicherheit / 7.0 Abteilungsleitung und andere
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurbau
Freie Schlagwörter:GMR sensor (Giant Magneto Resistance); Magnetic testing; Materials characterisation; Neutron diffraction; Residual stress; Standards and training (certification, qualification)
Themenfelder/Aktivitätsfelder der BAM:Infrastruktur
Material
Veranstaltung:19th World Conference on Non-Destructive Testing (WCNDT 2016)
Veranstaltungsort:Munich, Germany
Beginndatum der Veranstaltung:13.06.2016
Enddatum der Veranstaltung:17.06.2016
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:21.11.2016
Referierte Publikation:Nein