A novel heat treatment procedure combining the shot-peening with a two-step aging operation was proposed to improve both the strength and the stress corrosion cracking (SCC) resistance of the high-strength 7075 aluminium alloy. The heat treatment included one shot-peening stage before or between the two stages of aging at 120°C for 24 h and at 160°C for 1 h, respectively. The mechanical properties obtained during the aforementioned operations were extremely similar to those of the T6 sample owing to the unaffected bulk microstructure over such a low over-aging period. The SCC resistance of these samples was considerably improved, compared to that of the T6 sample and of the conventional shot-peened T6 sample due to the over-aging of the surface like the T7 treatment leading from the diffusion acceleration by the dislocations generated in the surface layer during shot-peening. In spite of the further depth of deformation caused by shot-peening prior to the first step of aging, the sample shot-peened after the first step of aging showed no significant decrease in the SCC resistance because of its higher generated dislocation by shot-peening.

Volume Subject Area:
Advances in Aerospace Technology
Keywords:
Aluminum, Aerospace, corrosion testing, heat treating, Surface engineering
Topics:
Aluminum alloys, Shot peening, Dislocations, Heat treating (Metalworking), Aerospace industry, Aluminum, Corrosion, Deformation, Diffusion (Physics), Heat, Mechanical properties, Stress corrosion cracking, Surface engineering, Testing
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Copyright © 2009
 by ASME
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