[Hallicrafters] Blooming meters

[Rich Oliver]

Lloyd et al,

My metallurgist friend came up with essentially the same explanation. 
 As he explained it the brass goes through a phase change from one 
crystalline form to another.  The final form is slightly more dense and 
the effect is that the brass shrinks.  If the piece is prevented from 
shrinking it will fail at its weak points, in this case the axial 
striations from the extrusion process.  Annealing forces the phase 
change to take place all at once rather than over a period of years and 
so prevents future shrinkage and "blooming".

73, Rich, KC9GQ

Lloyd wrote:

>Well, close. As I understand it the meter case was formed from a "billet" or
>"slug" of brass. This was placed hot in a hydraulic press and the case was
>formed in one punching operation. The cracks that form much later in the
>case are the thinner spots caused by scratches on the punch and/or
>impurities in the brass plus the phenomenon called "work hardening" The
>metal gets harder as it is worked. If the cases had been annealed i.e.
>heated to approx 1350 degrees F, the metal would have relaxed and the
>problem would have never occurred. They could have then been retempered to
>harden the case. Each of these steps is time and time is money.Besides
>nobody ever thought we would be trying to revive these things in 50 years.
>Lloyd Godsey  KK7IZ
>1315 N. Udall Circle
>Mesa, Az  85203
>
>1-480-620-7145 (cell)
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>Please visit my web page
>http://members.cox.net/kk7iz/kk7iz/index.htm
>
>kk7iz at cox.net
>
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