Ask A Scientist© Engineering Archive

Index Key:   ENG046
Author:      wayne y tanabe
Subject:     Residual stress release through cryogenics in metals.
I am looking for information on the effects of cryogenically freezing non-
ferrous metals (brass, copper, silver, and gold) down to temperatures as low
as -375 F.  Would like to know if it is possible to stress relieve these
metals by freezing.  Trying to remove residual stress left in these metals
in the forming or shaping process.  Can it be done?  How much stress can be
released?  Where or who can I talk to in regards to this subject?

Response #:  1 of 2
Author:      david r munoz
I always thought that the annealing temperatures were pretty high (approxi-
mately  500 C).  Even though I am not a metallurgist, it would seem that the
cryogenic temperature would "freeze" the state disallowing stress relax-
ation.



Response #:  2 of 2
Author:      edward p barth
Periodically I have heard bits and pieces about this idea of stress relief
or other effects of taking brass to low temperatures, although never with
any supporting data or information.  Certainly conventional stress relief is
done at high temp and would only slow down below rom temperature.  It is
conceivable that there are phase changes at low temperature, but off the top
of my head, I doubt it.