Chickering brass flanges

[Yardarm103669107@AOL.COM]

In a message dated 4/6/2001 9:41:07 PM Central Daylight Time, JIMRPT@AOL.COM 
writes:

<< 
 <<"Generally, heating brass does little more than make it hot;">> 
 
 Paul yes this is true unless you get the brass hot enough to rearrange the 
 molecular structure. This process is called "annealing" and is a well 
 accepted technique for metals and glass. You can't just get it "hot"....... 
 you have to bring it almost to the point of melting before this change 
 happens.  An old 'brittle' piece of metal will become mallable and lose most 
 of the britlleness that comes from work hardening and or age(?). There is 
 quite a bit on this subject in the archives if you can ever find it! :-)
  >>

Jim:
Thanks for the response. My experience with metallurgists, glass-blowers 
(exwife), ceramics makers and iron forgers, plus the testing labs we have 
accessed here in Chicago gave me a great deal of information about annealing 
and particularly heating brass. This is what I learned (and paid for!) for 
what it's worth:

1) Alpha brass (less than 34% zinc) doesn't decombine and recombine 
molecularly when heated up to its melting point. It remains a stable alloy 
although, as in all materials when heated, the molecules move around faster. 
When the testing labs here heated and cooled (not by annealing unless you 
call air cooling annealing) and  then tested alpha brass for hardness 
(Rockwell, Vin, Brinnell), they found absolutely no change in the character 
of the material from the prior state. Annealing, or gradient cooling by a 
stepping-down process (annealing ovens are really expensive bits of equipment 
and circuitry), also has no bearing on the nature of the brass. Now on the 
other hand, non-alpha brasses which we did not test (although I suspect that 
the brass flanges are beta brasses and agraffes are alpha, which is what we 
did test) may be more prone to surface brittleness and perhaps heating and 
rapid cooling, or heating and annealing (controlled cooling) may have more 
impact on them. I do go back to the issue of the creation of fracture lines 
and points in impacted metals as the most significant reason for the original 
failure of these flanges. But this is not a proved point and I only posit it 
speculatively.
PR-J