The influence of surface treatments on the fatigue properties of an Al-Li-Cu-Mg-Zr (8090) alloy
The influence of surface treatments on the fatigue properties of an Al-Li-Cu-Mg-Zr (8090) alloy
The requirement for improved materials for aerospace applications has led to the development of aluminium-lithium alloys with reduced density and higher stiffness when compared to conventional aluminium alloys. Due to the operating conditions encountered, the fatigue properties of any alloy are of paramount importance, such that control of the microstructure and surface finish to maximise fatigue resistance is required. In the present work the properties of the 8090 (Al-Li-Cu-Mg-Zr) alloy are studied, with particular emphasis on the fatigue properties after chromic acid anodising. For comparative purposes the conventional alloys 2014 (Al-Cu-Mg-Si) and 7010 (Al-Zn-Mg-Cu-Zr) are included. The microstructures of the alloys are characterised by means of optical and transmission electron microscopy. The fatigue performance is evaluated by means of rotating bend (R= -1) and tension - tension (R= 0.1) testing; the latter being carried out in conjunction with an acetate replication technique to monitor the initiation and early crack growth in the 8090 alloy. The anodic oxide films are examined by means of optical and scanning electron microscopy, together with chemical analysis by X-ray photo-electron spectroscopy and X-ray diffraction. The mechanical properties of the oxides are assessed using scratch adhesion tests and tensile fracture experiments. The fatigue results are discussed in terms of the microstructure of the alloys and the physical properties of the oxide films and their effect on the underlying substrate.
University of Southampton
1991
Bolam, Vivienne Jane
(1991)
The influence of surface treatments on the fatigue properties of an Al-Li-Cu-Mg-Zr (8090) alloy.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The requirement for improved materials for aerospace applications has led to the development of aluminium-lithium alloys with reduced density and higher stiffness when compared to conventional aluminium alloys. Due to the operating conditions encountered, the fatigue properties of any alloy are of paramount importance, such that control of the microstructure and surface finish to maximise fatigue resistance is required. In the present work the properties of the 8090 (Al-Li-Cu-Mg-Zr) alloy are studied, with particular emphasis on the fatigue properties after chromic acid anodising. For comparative purposes the conventional alloys 2014 (Al-Cu-Mg-Si) and 7010 (Al-Zn-Mg-Cu-Zr) are included. The microstructures of the alloys are characterised by means of optical and transmission electron microscopy. The fatigue performance is evaluated by means of rotating bend (R= -1) and tension - tension (R= 0.1) testing; the latter being carried out in conjunction with an acetate replication technique to monitor the initiation and early crack growth in the 8090 alloy. The anodic oxide films are examined by means of optical and scanning electron microscopy, together with chemical analysis by X-ray photo-electron spectroscopy and X-ray diffraction. The mechanical properties of the oxides are assessed using scratch adhesion tests and tensile fracture experiments. The fatigue results are discussed in terms of the microstructure of the alloys and the physical properties of the oxide films and their effect on the underlying substrate.
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Published date: 1991
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Local EPrints ID: 461005
URI: http://eprints.soton.ac.uk/id/eprint/461005
PURE UUID: c57b95c7-9833-4970-959d-4e382eeee1e6
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Date deposited: 04 Jul 2022 18:33
Last modified: 04 Jul 2022 18:33
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Author:
Vivienne Jane Bolam
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