Metal finishing Q&As since 1989

Shot Peening & Anodization to Maximize Fatigue & Corrosion Resistance of 6082-T6

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Q. Hi There,

I'm looking to replace a 316 stainless part in a marine application with aluminum for weight savings. The parts are currently CNC machined from a round bag and passivated.

The two main factors where the SS is helpful is in fatigue strength and corrosion resistance. Our part is subject to fairly high/irregular cyclic torsional loading. It is also threaded for stainless steel hardware, these areas are not strength critical but I mention due to the corrosion factor.

I want to give our replacement aluminum solution the best possible chance of surviving field trials, we are a small and rather new company so many rounds of testing are not practical and there is not much data I have found on torsional fatigue behavior of various alloys.

My plan is to try 6082-T6, CNC to shape, shot peen the area under highest load, hard anodize (Class III?), and finally seal the surface...

Would love to hear if I'm on the right track and any specifics on the treatments I should be requesting to optimize fatigue and corrosion resistance. Probably more importantly would be recommendations on experienced suppliers that would be willing to work with orders of ~100 parts at a time.

I've got a great machinist in Indiana (Abell Tool & Die) but don't know where to start with shot peening and getting the very best anodization.

Also all ears if anyone have any alternative methods I should consider!