Aluminium tubing

[xtramad]

Does anyone know if aluminium can become harder during storage?
We recieved some tubing 6062 T3 and 7075 T3 which have been stored at our
airforce base for a unknown time, maybe as long as 20 years.
They where to be used in a F-16 fighter but when we atempted to bend these
to the correct shape, they snapped after only a couple degrees of bending,
something which they are NOT supposed to do.
This has never been a problem before and of coarse this has caused a bit of
concern.
The tubes where covered in a thin coat of aluminium oxide and have been
stored indoors at temperatures ranging -25 deg. to +25 deg. celcius.
Of coarse these tubes will be analized at our lab but any thoughts on the
subject would be great.

[material guy]

It is my understanding that the T3 condition will undergo room
temperature aging gaining strength for several years. It probably loses
ductility in the process.

There is data on this in some of the ASM metals handbooks.

Years ago, I worked with a design group that would spec materials such
as AL 2024-t3/4 which meant to them that they didn't care if it was
either T3 (rapid cooled) or T4 ( quenched and thermally aged).

They were interested in being able to do things with stock on hand,
cheaply, and this was their solution.

Later, they were able to crow that after a long period of time, parts
made from the T3 alloy would get stronger as they got older.

They even generated data to prove it.

So, you seem to be in the same boat, so to speak. Natually aged T3
(years) can be stronger and harder and more brittle than the analogous
T4 alloy.

[craigmcc36]

Not familiar with 6062 or 7075 Al, the T3 denotes the condition treated to,
however yes aluminum can age at room temp., example is 2024, after solution
treating it will age harden at 70 deg. in 72 hours. If post forming
operations must be delayed, the aluminum must be stored in a freezer until
they can be done. This is an interesting question and I will get back with a
more accurate answer after I find out for sure, but it does seem possible
after that many years.
xtramad <hel...@c2i.net> wrote in message
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[xtramad]

craigmcc36 <craig...@home.com> wrote in message
news:B4MW3.450$n5.6...@news1.rdc2.pa.home.com...

> Not familiar with 6062 or 7075 Al, the T3 denotes the condition treated
to,
> however yes aluminum can age at room temp., example is 2024, after
solution
> treating it will age harden at 70 deg. in 72 hours. If post forming
> operations must be delayed, the aluminum must be stored in a freezer until
> they can be done. This is an interesting question and I will get back with
a
> more accurate answer after I find out for sure, but it does seem possible
> after that many years.

A typing error snuck in, it is 6061 T3, not 6062 T3