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Influence of Humid Environment on Fatigue Behaviour of Cast AM60B Magnesium

Biallas, Gerhard und Maier, Hans Jürgen und Gall, Ken (2006) Influence of Humid Environment on Fatigue Behaviour of Cast AM60B Magnesium. In: Proc. 9th Int. Fatigue Congress. Elsevier (UK). Fatigue 2006, 2006-05-14 - 2006-05-19, Atlanta, GA (USA).

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Kurzfassung

Low-cycle fatigue (LCF) tests were performed on cast AM60B Mg at room temperature in a high vacuum, at ambient conditions, and in 20 Torr pure water vapor (100 % relative humidity at room temperature). Surprisingly, fatigue life increased in the case of cycling in a humid atmosphere as compared to loading in vacuum. This behavior is attributed to the surface film formed on magnesium by water vapor, which suppresses slip band formation, but favors crack initiation in interdendritic regions. Consequently, only few fatigue cracks are formed early in fatigue life in water vapor, and link-up of these cracks is retarded. The number of cycles to crack initiation is much larger in vacuum environment. However, a high number of slip bands is formed early in fatigue life throughout the specimen surface. Many small cracks nucleate at these slip bands and then rapidly link-up to form the fatal crack that causes premature failure. To rationalize the effect of a humid environment, a plasticity-enhanced hydration mechanism is proposed. Hydration of the surface film on magnesium is intensified for aluminum contents below 4 wt%, which is the case for the primary α-Mg within the dendrite cells of AM60B. Plasticity-induced enhancement of the hydration prevents crack initiation at slip bands within dendrite cells in the LCF range.

Dokumentart:Konferenzbeitrag (Paper)
Titel:Influence of Humid Environment on Fatigue Behaviour of Cast AM60B Magnesium
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Biallas, GerhardNICHT SPEZIFIZIERT
Maier, Hans JürgenUniversität Paderborn
Gall, KenGeorgia Institute of Technology
Datum:2006
Erschienen in:Proc. 9th Int. Fatigue Congress
Referierte Publikation:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Verlag:Elsevier (UK)
Name der Reihe:pdf-file
Status:veröffentlicht
Stichwörter:cast AM60B magnesium, in-situ fatigue, slip bands, small cracks, environmental degradation, surface film, hydrogen embrittlement, damage mechanisms
Veranstaltungstitel:Fatigue 2006
Veranstaltungsort:Atlanta, GA (USA)
Veranstaltungsart:internationale Konferenz
Veranstaltungsdatum:2006-05-14 - 2006-05-19
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Luftfahrt
HGF - Programmthema:Starrflügler
DLR - Schwerpunkt:Luftfahrt
DLR - Forschungsgebiet:L AR - Starrflüglerforschung
DLR - Teilgebiet (Projekt, Vorhaben):L - Strukturen & Werkstoffe
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Werkstoff-Forschung > Werkstoffmechanische Prüfung
Hinterlegt von: Dr.-Ing. Gerhard Biallas
Hinterlegt am:23 Nov 2006
Letzte Änderung:27 Apr 2009 04:55

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