so, i know, and do anneal my rifle case necks regularly. and it does seem to make the brass live longer. but my question is this. does the molecular structure change at all because of the flame heating the brass? i know it leaves a carbon ring on the brass, no big deal, but is some of the copper or zinc burning out of the brass when i am doing this?
Annealing question
- Thread starter Xwrench3
- Start date
Cases can last 10 X longer if properly annealed. If you do it wrong you can ruin them. If you ever see the flame turn orange you've gone too far as thats the zinc buring off.
More than you want to know http://www.6mmbr.com/annealing.html
In order to get consistent results I built this machine.
Video's and more photos of it are here.
http://s121.photobucket.com/albums/o213/jmorrismetal/annealer/
More than you want to know http://www.6mmbr.com/annealing.html
In order to get consistent results I built this machine.
Video's and more photos of it are here.
http://s121.photobucket.com/albums/o213/jmorrismetal/annealer/
The brass in the case neck starts out soft (large crystalline structure), and as it is worked, the large brass crystals are broken in to smaller ones (harder brass). When you anneal the brass the heat allows the small crystals to grow into larger ones again (softer). Crystalline structure of the brass how the molecules of the brass is arraigned. The copper and zinc atoms remain relatively constant during the annealing process...not burned out.
It the case necks are heated to hot during the annealing, they will soften too much and cause problems in the reloading process.
The only way brass can be hardened is by physically working it...hammering, bending, etc. The only way brass can be softened is by heating it.
There is no carbon ring on the brass after annealing...it is an "oxide". A small amount of brass on the surface is converted to an oxide. But, not a significant amount to be concerned about. The oxide from annealing is usually polished off in the commercial process when new cases are annealed at the factory after forming.
wncchester
New member
If you heat case brass to a point that you can see a red glow, you've gone too far and zinc is burned out. That leaves a copper neck that's dead soft and has little bullet grip.
It is true that too much heat will leave a neck that is too soft to grip the bullet correctly. However, the "...zinc is be burned out..." is not true. The brass would melt long before the zinc would reach its vaporization temperature.
Unfortunately, the advice you get on this forum and elsewhere, is often only worth what you pay for it. Enthusiasm to be part of the solution may be greater that the knowledge to do so. Be careful who's advice you follow, and if in doubt, ask for credentials. (As part of my degree in Machine Tool Technology, I have studied metallurgy in college.)
wncchester
New member
" However, the "...zinc is be burned out..." is not true. The brass would melt long before the zinc would reach its vaporization temperature."
Okay, I was quoting what I've read in what presumed to be authoritative articles.
But if it's not a loss of zinc, what IS happening to make the case necks dead soft, with no hope of restoration?
Okay, I was quoting what I've read in what presumed to be authoritative articles.
But if it's not a loss of zinc, what IS happening to make the case necks dead soft, with no hope of restoration?
I agree with the basic point that making the brass too hot leaves it too soft. I think that is mainly due to growth in the grain size of the alloy. Grains grow larger when heated, and too large is too soft.
With respect to the zinc component of the alloy, I am no expert. But, I know that "burning out" and "vaporizing" are not the same thing. It seems that it MIGHT be possible to OXIDIZE the zinc near the surface of the case if the metal got too hot. Zinc is much more easily oxidized than copper. I don't think that could affect the alloy deep enough below the surface to make any real difference in its strength. But, I am interested in whether the appearance of "orange" in the flame is due to zinc oxidizing from the alloy and what that might indicate about the metal reaching a certain temperature.
SL1
With respect to the zinc component of the alloy, I am no expert. But, I know that "burning out" and "vaporizing" are not the same thing. It seems that it MIGHT be possible to OXIDIZE the zinc near the surface of the case if the metal got too hot. Zinc is much more easily oxidized than copper. I don't think that could affect the alloy deep enough below the surface to make any real difference in its strength. But, I am interested in whether the appearance of "orange" in the flame is due to zinc oxidizing from the alloy and what that might indicate about the metal reaching a certain temperature.
SL1
See my first post, growth of large crystals. Do you read any posts but your own?
"Dead soft" is not a metallurgical term. Even lead has a Brinnell hardness scale reading. The terms: too soft to be usable is a better description.
"no hope of restoration"...The brass could be hardened again by working it. However, it is unlikely to be successful.
The "orange glow" from the flame used to be considered the correct temperature. Nowadays, to be more precise, there are temperature indicating "crayons" that are used to show proper temperature( they melt at the correct temperature).
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wncchester
New member
1. "Dead soft" is not a metallurgical term. Even lead has a Brinnell hardness scale reading. The terms: too soft to be usable is a better description."
Too soft to be properly usable is a what reloaders call dead soft. Meaning, when it's too soft to have much "spring" or elasticity, it's "dead soft."
2. "no hope of restoration"...The brass could be hardened again by working it. However, it is unlikely to be successful."
You counter my comment strangly. First saying it could be hardened again by working it but then that we are unlikely to be successful in work hardening it! So, in a circular way, you have come back to agree that it can't be restored once it's damaged with excess heat. ??
My "Burning out the zinc" comment was only meant to be a relitive observation that too much zinc is lost if a neck is over heated, it's not an absolute. But, surely no rational person reading my comment would think the zinc is suddenly going to be totally absent? It sure seems to get too low to make any difference if the necks have been over heated to any marked degree and, you are right, it can't be worked back hard enough to matter.
And you haven't answered my question; What changes in the brass alloy to make it "too soft to be usable" or even to be work hardened afterwards if it is not a loss of zinc?
Too soft to be properly usable is a what reloaders call dead soft. Meaning, when it's too soft to have much "spring" or elasticity, it's "dead soft."
2. "no hope of restoration"...The brass could be hardened again by working it. However, it is unlikely to be successful."
You counter my comment strangly. First saying it could be hardened again by working it but then that we are unlikely to be successful in work hardening it! So, in a circular way, you have come back to agree that it can't be restored once it's damaged with excess heat. ??
My "Burning out the zinc" comment was only meant to be a relitive observation that too much zinc is lost if a neck is over heated, it's not an absolute. But, surely no rational person reading my comment would think the zinc is suddenly going to be totally absent? It sure seems to get too low to make any difference if the necks have been over heated to any marked degree and, you are right, it can't be worked back hard enough to matter.
And you haven't answered my question; What changes in the brass alloy to make it "too soft to be usable" or even to be work hardened afterwards if it is not a loss of zinc?
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Well, ok, i have a raytek thermometer (non- contact) . How hot should i be getting the case necks? From the sounds of it, i have been getting them to hot. As for bullet grip, i crimp everything i load with a lee factory crimp die, so i am not sure how important this is. My main objective is long case life.
Just off the top of my head, I cannot remember the correct temperature. Someone here may have it, or Googling on "anneal temperature brass" may provide the results you seek.
But, crimping will not solve your problem if they are softened too much. The "spring back" of the brass in the neck area may be too loose to provide the proper tension on the bullet. Crimping the bullets would keep them in place, but those cases would not likely provide consistent accuracy, or proper powder ignition for that matter.
http://www.gun-tests.com/performance/jun96cases.html
According to them, 650-660 F.
Non-contact thermometers can easily be fooled by the emissivity of the surface.
Shiny surfaces tend to have a lower emissivity (that is why heat sinks are made black) and the temperature read will be lower than the actual temperature.
More expensive non-contact thermometers have adjustments for emissivity and can be calibrated for the surface the measurement is being taken from.
You place a thermocouple on the item and use te thermometer to measure right beside the thermocouple.
Heat the article to near the desired temperature and adjust the thermometer to match the thermocouple.
For quick work you can create a black spot on the target to aim the thermometer at.
Shiny surfaces tend to have a lower emissivity (that is why heat sinks are made black) and the temperature read will be lower than the actual temperature.
More expensive non-contact thermometers have adjustments for emissivity and can be calibrated for the surface the measurement is being taken from.
You place a thermocouple on the item and use te thermometer to measure right beside the thermocouple.
Heat the article to near the desired temperature and adjust the thermometer to match the thermocouple.
For quick work you can create a black spot on the target to aim the thermometer at.
There is also a method that uses the heat setting on a casting pot full of lead. The temp is set at desired, the neck of the case dipped into the lead, when too hot to hold, the case is dropped into water. The neck could not get too hot, the head could not get too hot because you would have to drop it.
No problem, glad to share
A few members sent me pm’s about getting one of the “blades” for the machine above and the scale drawing of the top plate, arms and drive wheel. $60 shipped is the cost until I run out.
The infrared temperature sensors don’t work well on small objects, what you need is Tempilac temperature sensitive paint.
Again http://www.6mmbr.com/annealing.html is the best source I’ve found to answer your annealing questions.
A few members sent me pm’s about getting one of the “blades” for the machine above and the scale drawing of the top plate, arms and drive wheel. $60 shipped is the cost until I run out.
The infrared temperature sensors don’t work well on small objects, what you need is Tempilac temperature sensitive paint.
Again http://www.6mmbr.com/annealing.html is the best source I’ve found to answer your annealing questions.