[TowerTalk] Grading of Aluminum

[K0FF]

6061 and 6063 refer to the alloys that the metal is made from, Very small
amounts of other metals antimony, magnesium) are added to dead soft pure
aluminum, and their crystal structure embrittles and strengthens the base
metal. The T# refers to the heat treating that the alloyed material receives
at the mill. The heat treating causes physical characteristics to change
drastically, and is only good until the sample is subjected to further heat
cycles, or mechanical stress.
The 6061-T6 is strong, but not very flexible. Good for booms and mounting
plates. since it is so hard, it can't be easily drawn,to size, but rather is
extruded, so that the final dimensions are somewhat intolerant. Therefore
the sizes don't telescope well or at all. Neither can the piece be curved,
bent or the ends be swedged (reduced to accept another size inside).
6061-T6 is always simply cut off square on the end.  The plates are very
strong and well suited for boom-to-mast brackets. Hit a slab of it and it
tinks like a bell.

The 6063-T832 is much more ductile and can be drawn over a mandrel during
manufacturing, and holds precise dimensions. To me it's much softer (what is
yield strength anyway), and can be bent, curved and the ends squeezed down
without cracking. Great for elements for these reasons. Hit this and it
thuds.

Airplanes are made of a sandwich of 6061-T6 inside of very thin sheets of
pure aluminum. The 6061 gives it it's great strength, and the pure aluminum
coating keeps the corrosion away. The sandwich is squeezed together
mechanically to for a single piece of metal, and is what they refer to as
Dur-Al.
See the ARRL Handbook and the ARRL publication :"Physical Design of Yagi
Antennas".  Somewhere I've got copies of my articles about Aluminum alloys,
and Stainless Steel varieties. If I can locate them, I'll post them here
some day.

Have fun, Antenna Construction is one of the last avenues open far Ham
homebrewing.

Geo>K0FF
-----Original Message-----
From: Tom Hellem <redpines@cybrzn.com>
To: Towertalk Submit <towertalk@contesting.com>
Date: Thursday, May 11, 2000 6:02 PM
Subject: [TowerTalk] Grading of Aluminum


>
>Gentlemen:
>Can someone tell me what is the difference between 6061-T6 and 6063-T832
>grades of aluminum? Texas Towers advertises both grades and says they have
>equal yield strengths of 40,000 psi. We are considering the construction of
>a beam antenna.
>
>Can anyone recommend a handbook or manual which explains all the different
>grades of aluminum and maybe also tells what the manufacturers produce and
>all the various sizes of tubing, channel, angle, etc. It seems to me there
>must be some sort of reference manual out there.
>
>Thanks to all.
>Tom K0SN
>Porterfield, WI
>
>
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