MIL-A-8625 Ty III Hard Anodize and Fatigue

[SkyPunk]

Have read that Ty III hard anodize may reduce the fatigue life of some materials up to 50%. Would the fact that something (7050 T7) is shot peened, subseqently hard anodized, and then damaged through both the anodize, and compressive pre-stress shot peen be more succeptable to local area cracking? Or would the shot peen be for lack of better words canceled out by the hard anodize, and now you have a for all intents and purposes regular piece of 7050 T7 that happens to be very resistant to abrasion, and corrosion without any need for organic finish?

 

[rb1957]

i don't know about the hard anodize aspect of your post, but "damaged through both the anodize, and compressive pre-stress shot peen" would have me worried. shot peening sets up a surface compressive stress, and a sub-surface tension stress field (to balance out the compression), so i think your damage has exposed this tension field, which wouldn't be good.