elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Impressum | Kontakt | English
Schriftgröße: [-] Text [+]

Environmentally Influenced Microstructurally Small Fatigue Crack Growth in Cast Magnesium

Gall, Ken und Biallas, Gerhard und Maier, Hans Jürgen und Horstemeyer, Mark F. und McDowell, David L. (2005) Environmentally Influenced Microstructurally Small Fatigue Crack Growth in Cast Magnesium. Materials Science and Engineering A, 396, Seiten 143-154.

Dieses Archiv kann nicht den gesamten Text zur Verfügung stellen.

Kurzfassung

We examine the growth of microstructurally small fatigue cracks in cast AM60B magnesium (Mg) cycled in a water vapor environment. The behavior and growth rates of the small cracks were measured in situ during cycling using a fatigue loading stage contained within an environmental scanning electron microscope (ESEM). We provide quantitative data describing the interaction of representative small fatigue cracks with microstructural features, along with the average growth rate data for approximately 20 different cracks. Small surface and corner cracks, with sizes ranging from 20 to 200 µm, are observed to interact strongly with the surface microstructure during growth. The small cracks preferentially propagate through the dendrite cells, and the particle laden interdendritic regions typically act as barriers to fatigue crack propagation. As the small cracks approach the interdendritic boundaries, measured growth rates decrease and the cracks sometimes becomes temporarily pinned at the boundary. Cracks smaller than 100 µm experience more significant disruptions in crack growth rates at interdendritic boundaries compared to the larger cracks that interact with the boundaries, but with less change in crack growth rates. Under nominally identical loading conditions, isolated microstructurally small cracks grow, on average, two orders of magnitude faster in a sample containing a higher fraction of porosity. The significantly higher crack growth rates in the more porous sample were attributed to local amplification of the nominal stress field in the vicinity of the microstructurally small cracks rather than explicit interactions between growing cracks and pores. Analogous to the wrought materials, the growth rate of microstructurally small cracks is observed to be significantly higher compared to long fatigue cracks at equivalent maximum cyclic stress intensity values.

Dokumentart:Zeitschriftenbeitrag
Titel:Environmentally Influenced Microstructurally Small Fatigue Crack Growth in Cast Magnesium
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Gall, KenUniversity of Colorado
Biallas, GerhardNICHT SPEZIFIZIERT
Maier, Hans JürgenUniversität Paderborn
Horstemeyer, Mark F.Mississippi State University
McDowell, David L.Georgia Institute of Technology
Datum:2005
Erschienen in:Materials Science and Engineering A
Referierte Publikation:Ja
In ISI Web of Science:Ja
Band:396
Seitenbereich:Seiten 143-154
Status:veröffentlicht
Stichwörter:cast magnesium, fatigue, small cracks, environmental scanning electron microscopy, in situ fatigue
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:27 Jan 2006
Letzte Änderung:27 Apr 2009 04:55

Nur für Mitarbeiter des Archivs: Kontrollseite des Eintrags

Blättern
Suchen
Hilfe & Kontakt
Informationen
electronic library verwendet EPrints 3.3.12
Copyright © 2008-2013 Deutsches Zentrum für Luft- und Raumfahrt (DLR). Alle Rechte vorbehalten.