How much stronger is anodized aluminum?

[hurricaneracing]

One of the projects I am working on the customer has bent the unfinished product a couple of times. I have read that the ano process will make the aluminum stronger. Anybody know how much stronger or is there a process that is out there?

[acidrain]

The ano layer is very strong... it has a scratch resistance slightly lower than stainless steel, and I've heard of it being comparable to diamond in ductile strength.
A thin piece of aluminum anodized on both sides is extremely resistant to bending... kind of like a sandwich of liberglass laminate with a lightweight core.
BUT... if the aluminum was damaged from bending (work hardened, stress cracked), the ano may behave differently at the site, or even attack the tiny fractures.

[engineerscott]

The surface is much harder than "plain" aluminum and hence imparts a good deal of scratch/wear resistance to the part, but I don't think anodizing will have any measureable impact on the bulk material properties of any decent sized part. The anodized layer is just too thin compared with the thickness of most "normal" sized parts. So, the bulk properties (compressive strength, tensile strength, shear strength, modulus of elasticity, etc. ) will remain the same as unanodized Aluminum but the surface will be much more wear resistant. Remember, anodizing is a surface treatment so we really only expect to modify the characteristics of a fairly thin layer at the surface.

[kebo]

For what it's worth.....

MIL Spec A-8625F section 6.1.3 states... "Hard coating may reduce fatigue strength..."
kevin