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hornluv
02-13-2004, 12:06 AM
Hey Everyone,

Some friends of mine and I have been discussing stress relieving brass tubing after bending using a low temperature soak. We can't seem to come to a general consensus though on how long or what temperature. Temp ranges discussed are from 250 to 400*F at anywhere from 4 to twelve hours. Does anyone have any thoughts and/or experience with this? What are some good resources? How much is too much with regards to temp and time?

Thanks,
Stuart

Buckshot
02-13-2004, 09:08 AM
........I have nothing technical to offer, re: temps and time. I routinely anneal brass cartridge cases commonly made of 70/30 alloy. Heated to dull red in dim light, and tipped into cool water. This probably isn't what you're looking for as the result is softer and not just stress relieved. But, fwiw.

Rick

decoy91288
02-13-2004, 10:26 AM
The claims for cryogenic treatment of instruments all smell suspiciously of snake oil. I have been a musician working with some of the very best performers over the years. Not one of them gave the process any credit for improvement of sound or playability. We first ran into individuals promoting the process at conventions about 30 years ago and as a high school band director I had several conversations with such promotors -- it sounded like a hocus pocus sales pitch to me. But - read it for yourself.

http://www.percryo.com/music.htm

What causes me the most suspician is the claim (esp as regards brass instruments) that the process is most effective on new instruments. That is handy, the guy that has played a horn for ten years will be best able to detect any performance differences in a particular instrument. The BS snake oil and crygenics salesman has handily managed to cut off the most competent group of musicians who might reveal the scam. That said -- there just might be a difference between treated and untreated instruments at the molecular level, but it is not enough of a difference to have meaning to the performer. Hours of practice every day is a more effective investment.

hornluv
02-13-2004, 11:18 AM
One of the guys in my group has a metallurgist for an uncle and we asked him about cryo. He said from tests he has done, when the metal is in sub zero the grain size changes, but once it warms back up to room temp it just goes back to what it was.

I don't think this low temperature heat treatment is really annealing, though it might be. It apparently is possible to make a piece dead soft, which is why we would like to know more exact temps and times. We would like the operation to even out the parts and make them consistent (This is for musical instruments, btw). Unlike Cryo, we can do this in our home ovens. The only risk being if our wives catch us doing it (Why's the oven been on for twelve hours?!?!?!).

Stuart

hornluv
02-13-2004, 09:29 PM
Hey everyone,

I found this nifty little piece of info regarding my query and thought I'd pass it along.

http://www.brass.org/Publicat/pub117/sec52.htm

Thrud
02-14-2004, 05:00 AM
The best stress relief is six months diving in cayman brac...

hornluv
02-16-2004, 01:10 AM
So I've been doing some more research and haven't found much more, but I'd like to ask a question of all the people out there who do heat treating. I've been looking through Bill Bryson's "Heat Treatment, Selection, and Application of Tool Steels" and I would imagine that many of the same principles for stress relieving steel would apply to nonferrous metals as well, just with different time/temp figures. Am I right or sadly mistaken? The object to be stress relieved is thin wall tubing, so I think the soak time should be quite short. Should I warm it slowly, hold it at temperature, then cool slowly or would a faster heat and cool be called for? The real question is, how do I test to see if it worked? I've run across a couple of metallurgy class experiments and they describe the process for the experiment, but no results and no testing methods. What do you esteemed gentlemen think?

Stuart