Just thinking off the top of the head - no expert opinion -
The rack stuff likely went through a number of thermal cycles. Since Al is softer
than the typical steel we work with - it might have had an internal migration of alloy
rather flowing in a sense. Something like glass.

Martin

Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder


RoyJ wrote:
At most places if you say "6061" you will get some T6 or T651, better
places will ask if you want som "T0"

The hardness differences you see is more likely T6 that has been sitting
around for a while. We did a bending job with customer supplied 6061-T6.
Operators complained LOUDLY that they could not hold the tolerances.
After we sorted the stock into "the stuff with the green label" and "the
stuff with the blue label" and did two setups, things went much better.
We strongly suspected that the stiffer batch had been sitting on the
racks for a couple of years, the other was mill fresh.

Tim Wescott wrote:

RoyJ wrote:

"6061-T6" or "6061-T6 Aluminum" will do just fine. If you just say
6061 they will know it is aluminum but will ask you for what temper
you want.

pogo wrote:

Thanks for all of the GREAT info!
How would I refer to the number if I were ordering some 6061
aluminum ? Call
it "alloy number" ? "alloy mixture" ?



Or they'll just hand you whatever 6061 they have in stock, and it'll
range from really hard* to really soft.

* I'm not sure of what the range of hardness there is available in
6061, because I've only got experience with 6061-T6. T6 is the most
common, and if you just ask for 6061 and get it that's most likely
what you'll get -- but you can't be sure.


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