Corrosion of the Magnesium Alloy AZ91 and its Influence on Fatigue Properties
- Prof. Dr.-Ing. K. U. Kainer
Published Online: 15 MAY 2006
Copyright © 2000 Wiley-VCH Verlag GmbH
Magnesium Alloys and their Applications
How to Cite
Müller, C., Koch, R. and Deinzer, G. H. (2000) Corrosion of the Magnesium Alloy AZ91 and its Influence on Fatigue Properties, in Magnesium Alloys and their Applications (ed K. U. Kainer), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, FRG. doi: 10.1002/3527607552.ch73
GKSS-Forschungszentrum Geesthacht GmbH, Institut für Werkstofforschung, Max-Planck- Straße, D-21502 Geesthacht, Germany
- Published Online: 15 MAY 2006
- Published Print: 20 SEP 2000
Print ISBN: 9783527302826
Online ISBN: 9783527607556
- magnesium alloys;
- influence on fatigue behavior
The influence of corrosion on fatigue behaviour and vice versa of the magnesium die cast alloy AZ91 was investigated by rotating beam testing. The samples were corroded by salt spray testing. Specimens taken from bulk material show poor fatigue properties. No influence of corrosion on fatigue strength behaviour was observed although the surface is strongly corroded. Fracture surface analysis indicates that pores (binding defects) act as crack nucleation sites, leading to poor fatigue properties independent of the surface state. In order to reduce the size of pores, fatigue specimens were directly cast showing considerably improved fatigue properties. Fatigue lifetime is deteriorated by about 40 % for heavily precorroded specimens.
The corrosion behaviour of AZ91 was measured by electrochemical polarisation curves in a 5% NaCl solution. In order to investigate the influence of fatigue loading on corrosion, a servohydraulic testing machine was equipped with a potentiostat and a container filled with an aqueous NaCl solution, allowing to record electrochemical polarisation curves during fatigue testing. A significant influence of mechanical loading on rest potential and anodic current was observed.