Subject: Re: Welding tempered aluminum.

From: [email-masked] (Harry Phinney)
Date: Wed, 12 Oct 1994 21:53:22 GMT

Jeff Case ([email-masked]) wrote:
: Some mast manufacturers cut to taper, then weild, then temper.
: Others buy a pretempered tube, cut to taper, then weild.
: The masts are 6061 and I think about T4.
: I was under the impression that weilding causes loss of temper and this
: would make the mast more likely to fail under load.

Some strength properties for 6061:

Alloy and     |  Tensile Str    |  Yield Str    |
Temper        |    psi          |   psi         |  % elongation
--------------+-----------------+---------------+---------------
6061 Al alloy |                 |               |
-T4 As Fab    |   35,000        |  21,000       |  22
--------------+-----------------+---------------+---------------
6061 Al alloy |                 |               |
-T6 As Fab    |   45,000        |  40,000       |  12
--------------+-----------------+---------------+---------------
6061 Al alloy |                 |               |
As Welded     |   30,000        |  19,000       |  11
--------------+-----------------+---------------+---------------
6061 Al alloy |                 |               |
Post Weld     |   35,000        |    ???        |  8
Aged Only     |                 |               |
--------------+-----------------+---------------+---------------
6061 Al alloy |                 |               |
Post Weld T6  |   44,000        |  40,000       |  5
--------------+-----------------+---------------+---------------

This is a bit simplified, because the as-welded properties depend on the
filler, which may be different depending on whether or not a
post-welding heat treatment will be done.

: Which is the acceptable way to do this?

Either can be acceptable as long as the builder takes the resulting
material properties into account when designing the part.

Harry Phinney   [email-masked]