<DIV>Been a long time since I had a metallurgy class so a google search finds:</DIV>
<DIV> </DIV>
<DIV><A href="http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-42,GGLD:en&q=annealing+aluminum">http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-42,GGLD:en&q=annealing+aluminum</A></DIV>
<DIV> </DIV>
<DIV><A href="http://www.evergreengardenworks.com/copperwi2.htm">http://www.evergreengardenworks.com/copperwi2.htm</A></DIV>
<DIV> </DIV>
<DIV><A href="http://www.tinmantech.com/html/aluminum_alloys_continued.html">http://www.tinmantech.com/html/aluminum_alloys_continued.html</A><BR><BR><B><I>Bill Glaze <billglaze@triad.rr.com></I></B> wrote:</DIV>
<BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">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.<BR>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.<BR>Because the applied exhaust heat would, it seems, tend to put the aluminum in a continual annealing condition.<BR>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.<BR>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!<BR>Sorry for the long posting, but, as I said, it is an extremely interesting thread.<BR><BR>Bill Glaze<BR><BR>Karl G. Mueller wrote:<BR>
<BLOCKQUOTE cite=mid004701c5b471$5b084560$04000005@cr398119a type="cite">
<META content="MSHTML 6.00.2800.1515" name=GENERATOR>
<STYLE></STYLE>
<DIV>Jon,</DIV>
<DIV> </DIV>
<DIV>The problem with the aluminum being heated and cooled every time</DIV>
<DIV>you run the engine acts like an artificial aging (hardening). In time the </DIV>
<DIV>material will get very brittle and therefore break very easy. Here is a little</DIV>
<DIV>trick you can try that I know works: If you have a self cleaning electric oven</DIV>
<DIV>at home, put the header in the oven run the cleaning cycle. Do that at night</DIV>
<DIV>before you go to bed and the next morning you header will be annealed.</DIV>
<DIV>It has to cool of slowly.This is the opposite process of hardening. This makes</DIV>
<DIV>the aluminum more flexible and less prone to breakage.</DIV>
<DIV> </DIV>
<DIV>Karl G. Mueller<BR><A href="mailto:kgamueller@rogers.com">kgamueller@rogers.com</A><BR></DIV>
<BLOCKQUOTE dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: rgb(0,0,0) 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal">----- Original Message ----- </DIV>
<DIV style="BACKGROUND: rgb(228,228,228) 0% 50%; FONT: 10pt arial; font-size-adjust: none; font-stretch: normal; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial"><B>From:</B> <A title=JonLowe@aol.com href="mailto:JonLowe@aol.com">JonLowe@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>To:</B> <A title=discussion@nsrca.org href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>Sent:</B> Wednesday, September 07, 2005 8:39 PM</DIV>
<DIV style="FONT: 10pt arial; font-size-adjust: none; font-stretch: normal"><B>Subject:</B> [Bulk] Heat treating aluminum header?</DIV>
<DIV><BR></DIV>
<DIV>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.</DIV>
<DIV> </DIV>
<DIV>Thanks</DIV>
<DIV> </DIV>
<DIV><FONT size=2 ptsize="10">Jon Lowe<BR></FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE><p>__________________________________________________<br>Do You Yahoo!?<br>Tired of spam? Yahoo! Mail has the best spam protection around <br>http://mail.yahoo.com