Fatigue Testing of AA7050-T7451 with Various Corrosion Prevention Surface Treatments
DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
Pagination or Media Count:
The aluminium components of combat aircraft are usually manufactured with corrosion preventative surface treatments. This report presents the results of a fatigue coupon testing program carried out on AA7050-T7451 that was used to aid in the understanding of the fatigue life effect that anodising and an etching surface treatment can have in comparison to as-machined surfaces. The testing program included both high and low stress concentration geometry coupons that were subjected to a combat wing root bending moment spectrum. The results of the fatigue testing showed a reduction in the fatigue lives of anodised and etched coupons, especially in the low stress concentration geometry coupons. An investigation into the anodising process indicated the cause of the pitting found was likely chemical attack during a chemical cleaning process prior to the anodic layer being applied. These pits, which were numerous, acted as relatively large crack initiation discontinuities.
- Properties of Metals and Alloys