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Karl:<br>
It has a ball<br>
Understand your standpoint on the technical stuff.<br>
You are quite correct in your statements. BTW: I used to use a 600
deg. steam cabinet for normalizing <br>
and a passivationg bath. (Neither of which belonged to me.)<br>
Bill Glaze<br>
<br>
<br>
Bob Kane wrote:
<blockquote
cite="mid20050909034259.68750.qmail@web30206.mail.mud.yahoo.com"
type="cite">
<pre wrap="">Does that one use the point or the ball, I can't
remember . . . .
--- "Karl G. Mueller" <a class="moz-txt-link-rfc2396E" href="mailto:kgamueller@rogers.com"><kgamueller@rogers.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Bill,
You're correct that aluminum has to be quenched,
usually in some type of salt bath,
to be annealed. In the case of a header you are
looking at a finished item with
various material thicknesses (flange). If you quench
an item like this you will
induce stresses because part of the item (thin wall
tubing) will cool of faster than the
heavier flange. I have used this method (electric
oven) a lot to take the T6 hardness
out of 6061 aluminum.
I don't think that the heat from the exhaust is high
enough to put the header in a
continued annealed condition, but high enough to
cause some artificial aging ???
Vibration and more so continuous flexing of the
header with too much weight
(tuned pipe) on the end of it will cause it to break
eventually.
I did not want to get to technical in my first post,
just something the average modeler
should be able to do. Not everybody has a Brinnell
Hardness Scale at home :-).
Karl G. Mueller
<a class="moz-txt-link-abbreviated" href="mailto:kgamueller@rogers.com">kgamueller@rogers.com</a>
----- Original Message -----
From: Bill Glaze
To: <a class="moz-txt-link-abbreviated" href="mailto:discussion@nsrca.org">discussion@nsrca.org</a>
Sent: Thursday, September 08, 2005 9:50 AM
Subject: [Bulk] Re: [Bulk] Heat treating aluminum
header?
This is getting to be a rather absorbing thread;
at least for me. I had always been taught that
aluminum anneals like brass and copper; that is,
opposite to steel. I had been taught that to anneal
aluminum, (or brass, as in cartridge cases, or
copper, as in cold worked bullet jackets) that one
heats the material, then chills it rapidly. In
fact, even with lead, which most people would think
is, well, just lead, that lead in its pure state, or
alloyed with the common metals, (tin, antimony,
others) can be hardened. In fact, by heating lead
bullets in an oven to just below deformation
temperatures, (just below where the bullets would
begin to "slump") for an hour, then rapidly
immersing them in cold water, I have been able to
raise the Brinnell of the bullets from 9-10 to over
20.
What I am wondering is if the aluminum headers are
being hardened to brittleness by "work hardening"
caused by minute vibrations, repeated thousands of
times.
Because the applied exhaust heat would, it seems,
tend to put the aluminum in a continual annealing
condition.
I was in the aluminum window manufacturing
business for many years. We used several hardnesses
of aluminum, and several different hardening
processes; heat treating, artificial aging,
artificial hardening, etc.
Of course, when flying for United Airlines, in
severe turbulence, I found myself hoping that the
wing spars hadn't been work hardened to the
brittleness stage!
Sorry for the long posting, but, as I said, it is
an extremely interesting thread.
Bill Glaze
Karl G. Mueller wrote:
Jon,
The problem with the aluminum being heated and
cooled every time
you run the engine acts like an artificial aging
(hardening). In time the
material will get very brittle and therefore
break very easy. Here is a little
trick you can try that I know works: If you have
a self cleaning electric oven
at home, put the header in the oven run the
cleaning cycle. Do that at night
before you go to bed and the next morning you
header will be annealed.
It has to cool of slowly.This is the opposite
process of hardening. This makes
the aluminum more flexible and less prone to
breakage.
Karl G. Mueller
<a class="moz-txt-link-abbreviated" href="mailto:kgamueller@rogers.com">kgamueller@rogers.com</a>
----- Original Message -----
From: <a class="moz-txt-link-abbreviated" href="mailto:JonLowe@aol.com">JonLowe@aol.com</a>
To: <a class="moz-txt-link-abbreviated" href="mailto:discussion@nsrca.org">discussion@nsrca.org</a>
Sent: Wednesday, September 07, 2005 8:39 PM
Subject: [Bulk] Heat treating aluminum header?
After many many flights, I had an aluminum
header break for my OS 1.60. I had it welded up by
a very good welder, but the header broke again after
one flight in an area removed from the weld, but
close enough that it would have gotten pretty hot.
I suspect that the heat treat of the header got
changed. Any ideas on how to try to heat treat a
second pipe that has benn welded to try to at least
get more than one flight? I've odered a new header,
but it is not here yet.
Thanks
Jon Lowe
</pre>
</blockquote>
<pre wrap=""><!---->
Bob Kane
<a class="moz-txt-link-abbreviated" href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</a>
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