Anodized aluminum sheet - cut edges

[SolarWeenie]

Hi,

We are considering the use of 0.1" thick anodized aluminum sheet for a non-structural application. Specifically, 6061 T6 with Type II, Class 2 anodizing. However, the anodization will obviously be destroyed in shearing (possibly also in bending?).

The application environment potentially includes severe marine atmospheric exposure. Desired life is 30 year without it falling apart, 20 years without major aesthetic issues.

Is this an appropriate materials choice?

Thanks,

Carl

 

[kenvlach]

No way. Edges like this can corrode over a weekend in municipal water containing a trace of chlorine disinfectant.

Anodize in good condition on a more-corrosion resistant alloy* could last if well-maintained: Kept clean by fresh water washing, annual application of a high quality wax, total avoidance of galvanic problems. * anodize is purer alumina and hence more resistant on purer alloys.

Best choice for architectural sheeting is Al 5005. Best coating would be Kynar® powder-coated over either anodize or chromate pretreatment. Good chance at 30 years with occasional washing. Other Al alloys for marine applications are 5052-H34 and 5083. Also, 6063-T6 is considerably better than 6061-T6, but not as good as the 5000 series alloys.