"Gene Kearns" wrote in message
...
On Fri, 21 Apr 2006 03:27:30 GMT, "Calif Bill"
wrote:




And you want 5000 series aluminum. 5086 probably the best for most jobs
where salt water is contacted. 6061 is a tougher alloy. The 5000 is very
low copper content.


More like no copper... the major alloying element in the 5000 series
being magnesium. 6061 is a tougher alloy because it can be heat
treated... the 5000 series cannot.

Heat treatables are 2000, 6000, and 7000 series.... Major alloy in
2000 is copper, 6000 is magnesium and silicon, and 7000 is zinc.

6000 series is acceptable in salt water service, but as you suggest,
5000 is probably a better choice if you don't need a hardened
alloy....

Problem with the 6000 is not very formable. You can not bend it to make a
radius bottom, without danger of it wanting to crack or crack in the future.
For flat plates, is good. All Aluminum will have some copper, just part of
the beast, but the alloys mentioned have very minute amounts.