How wide is the range past "optimal" annealing?

[Pareto]

I've been thinking of getting a garden variety annealer (like Annealeez, EP or Ugly) to help with the Lapua 6br brass I've managed to acquire. I don't compete but I'd like to keep things reasonably uniform without going to full competition lengths.

When I googled the problem, I didn't get consistent info. Lot of statements about over annealing, but the only serious study I saw seemed to suggest that once you got to the "right" temperature in the area, over annealing (within reason and far from melting the brass) didn't make a lot of difference. This was partly inspired by Erik Cortina's over annealing video but mostly based on this article.

The Science of Cartridge Brass Annealing

Want to know how annealing brass works? We examine the science here.

bisonballistics.com

This pic was especially relevant. Seems to show that there is a wide nearly flat range past the mid 700 degree point where it is said we want to heat the brass to. This would suggest (for example) that if the optimal heating time for a given annealer and gas flame were say, 5 seconds, that anything up to 10 secs or more would still work.

The reason this is important is that this suggests, the important variable is getting to the minimal heating for the small area of the neck and shoulder first and then going a little bit over is not too critical.

Has anyone personally done such tests systematically for themselves? Such as taking some brass and then heating various examples at 5, 8, 12, 15 seconds and then seeing if they shoot differently (while keeping the temps mostly in the 800-900 range and below?)

Thanks.

 

[MikeRu]

I use anneal-rite from cartridgeanneal.com, it's almost "free" and just follow the instructions, uses 2 propane torches. I heat about 8-10 sec till i just start to see a dull red glow in a darkened room. This is a little past 750F based on temiplaq. I often aim the flame at the body shoulder junction or just above, so as to gradually heat the neck, which has less brass (less mass). For safety you should paint a few case bodies with tempilaq 400 and make sure the case head/lower body is not overheated, per the instructions. It's certainly cheaper than other methods and have a suspicion it's just as consistent or better than "automated". Faint red glow = nice simple endpoint, and hard to mess up. Gets a little tedious for 200 cases, so take a break.

 

[Pareto]

I don't plan to anneal more than 50-100 cases at a time, as I only handload rounds for precision. I buy plinking factory ammo.
I'm also terrible with putting stuff together and making them work, so I want to buy a finished product with warranties. In fact, given the number of times I've had to use the warranty for a variety of rifles and pistols and reloading products in the last three months, I have to assume I'm cursed.

 

[Pareto]

Also, this published article is interesting as it shows no different effects on cracking of different temperatures used in annealing at the factory.

Defense Technical Information Center

apps.dtic.mil

 

[Ned Ludd]

I have read many posts where it has been stated that if a case has been "over-annealed", it has been "ruined". I have yet to see where anyone described exactly how and why the case was ruined, or exactly what constituted "over-annealing". Erik's video clearly demonstrated that a case could pretty much be nuked during the annealing process and not suffer any apparent isues. Does that mean we should all start annealing cases to bright cherry red in a fully lighted room for 30 seconds to one minute? Of course not. But it casts some doubt on the accuracy of statements suggesting that even cases that have been slightly over-annealed have been ruined.

Consistent with that notion, if you're willing to search online long enough, you can find some very good scholarly articles about exactly what is happening when we anneal cases. The conditions generally described for the annealing process would not be considered complete annealing; i.e. we are not taking the brass fully back to the ground state. A typical annealing process will detectably reduce brass hardness, but is usually not sufficient to completely alter the grain structure of the brass. Only higher temperatures and/or longer annealing times are sufficient to accomplish that. So the typical annealing process as used by reloaders seems to be a sort of early to middle ground along the path to fully annealed brass.

So the question is what happens if the brass is pushed much farther toward a fully annealed state; i.e. "over-annealed"? I can imagine the hardness might be reduced a bit further, and the grain structure would likely be more completely altered than might ordinalrily be observed when using a typical annealing process. Could that mean the brass might become so soft as to lose structural integrity and fail when fired? I seriously doubt that as the case is surrounded/supported by the chamber. In support of that notion, Erik's fully nuked case did not fail when fired. Unless the case-head/webbing region was actually annealed via induction, I doubt we would notice a major effect at all. Could it mean totally inconsistent neck tension/interference fit within a set of cases? Could it mean the case necks became so soft that the desired neck tension/interference fit could no longer be achieved? I really don't have the answers to these questions. But I suspect that slight to moderate over-annealing of cases is not the major problem some might have you believe. I have been annealing cases to dull cherry red in a [somewhat] darkened room since I first started annealing. As best I can tell, these cases are achieving a temperature of at least as high as the 850 to 900 degree F range, which is well in excess of the ~750 degrees F commonly advertised as the goal of the annealing process. It's never been a problem for me.

At the end of the day, I don't think you are likely to find definitive data on exactly how far you can take the annealing process without potentially damaging the brass, if that can even realistically be done. If you haven't already, take a look at some of the annealing studies the folks at AMP have done:

https://www.ampannealing.com/articles/

I think they do about as good a job as anyone with respect to studying this topic. It might even be worth giving them a call if your questions remain unanswered.

 

[3Sigma]

There is a reason cartridge brass has conditions known as "Soft", "1/4 Hard", "1/2 Hard", etc. Brass is one of those magical metals that can be easily "reset" with time and temperature.

This has been known a long time and generated a qualitative nomenclature with metallurgical a long time ago. We've been doing this dance in cartridge manufacturing for over 100 years.

My assumption is we are taking the brass from a full Hard or >80% Hard condition and moving it back to a 1/4 hard condition. But, I'd need a micro hardness tester to prove it.

 

[RegionRat]

You will probably not find much that is in public domain. All of the serious texts are copyright protected as are the proceedings from conferences. What little I can share that is in the public domain, includes enough to have the discussion.

Below I will show the values for the M855 cartridge brass, but the values would be very close regardless of the bottleneck cartridge design.



In the diagram, you will notice there is a MAX-MIN style specification. If our heat treat process goes below 90, we reject the brass.

That isn't arbitrary, it is because it is important to keep the neck material strong enough to withstand all the downstream events. If we "over do" the heat treat, it will go lower than the 90 level and fail the specifications.

However, this value isn't like a physical wall or physics barrier that would show you an instant failure. You may or may not notice if you over soften the brass. You can make workable ammo out of necks below 90 HV. I would not advise it, but you would be able to "get away with it" to some level.

There is a point at which I would say, "don't come crying" if that doesn't work out well since you are aware that the above specs are known to work well across many calibers and requirements from military to sporting, bolt to full auto. etc..

The same it true for not annealing, meaning you could allow brass to harden and exceed the 115 level while not noticing any catastrophic consequences. However, from the load tuning view you would certainly be able to "shoot the difference" if your tune was sensitive to neck tension.

Keep in mind, we only use HV as a proxy for many other important material properties like the Yield Strength and the Modulus, both of which are affected and coupled to the HV which is why we use that as a proxy.

For the long term best performance from your reloads, try to stay as close to that chart as you can manage. You can make ammo that performs just fine with brass that fails that chart, but the reasons to stay within those boundaries have been worked out over a great many different tests and requirements that you may never encounter. As always, YMMV

 

[Pareto]

I have read many posts where it has been stated that if a case has been "over-annealed", it has been "ruined". I have yet to see where anyone described exactly how and why the case was ruined, or exactly what constituted "over-annealing". Erik's video clearly demonstrated that a case could pretty much be nuked during the annealing process and not suffer any apparent isues. Does that mean we should all start annealing cases to bright cherry red in a fully lighted room for 30 seconds to one minute? Of course not. But it casts some doubt on the accuracy of statements suggesting that even cases that have been slightly over-annealed have been ruined.

Consistent with that notion, if you're willing to search online long enough, you can find some very good scholarly articles about exactly what is happening when we anneal cases. The conditions generally described for the annealing process would not be considered complete annealing; i.e. we are not taking the brass fully back to the ground state. A typical annealing process will detectably reduce brass hardness, but is usually not sufficient to completely alter the grain structure of the brass. Only higher temperatures and/or longer annealing times are sufficient to accomplish that. So the typical annealing process as used by reloaders seems to be a sort of early to middle ground along the path to fully annealed brass.

So the question is what happens if the brass is pushed much farther toward a fully annealed state; i.e. "over-annealed"? I can imagine the hardness might be reduced a bit further, and the grain structure would likely be more completely altered than might ordinalrily be observed when using a typical annealing process. Could that mean the brass might become so soft as to lose structural integrity and fail when fired? I seriously doubt that as the case is surrounded/supported by the chamber. In support of that notion, Erik's fully nuked case did not fail when fired. Unless the case-head/webbing region was actually annealed via induction, I doubt we would notice a major effect at all. Could it mean totally inconsistent neck tension/interference fit within a set of cases? Could it mean the case necks became so soft that the desired neck tension/interference fit could no longer be achieved? I really don't have the answers to these questions. But I suspect that slight to moderate over-annealing of cases is not the major problem some might have you believe. I have been annealing cases to dull cherry red in a [somewhat] darkened room since I first started annealing. As best I can tell, these cases are achieving a temperature of at least as high as the 850 to 900 degree F range, which is well in excess of the ~750 degrees F commonly advertised as the goal of the annealing process. It's never been a problem for me.

At the end of the day, I don't think you are likely to find definitive data on exactly how far you can take the annealing process without potentially damaging the brass, if that can even realistically be done. If you haven't already, take a look at some of the annealing studies the folks at AMP have done:

https://www.ampannealing.com/articles/

I think they do about as good a job as anyone with respect to studying this topic. It might even be worth giving them a call if your questions remain unanswered.

Thank you. I did read the majority of their articles but they mostly show it with respect to their own annealer and not to making small over annealing tests. They show us what they think is optimal, but not how big the effects are of slight to moderate non-optimality. Hence my citing the scientific paper on under annealing (lower temperature) effects (or lack thereof). I don't doubt the quality of their work on the optimal point, but not on any claims about deviations. Many annealer producers often (in videos and online) refer to the problems of over annealing by as little as half a second in the second

You will probably not find much that is in public domain. All of the serious texts are copyright protected as are the proceedings from conferences. What little I can share that is in the public domain, includes enough to have the discussion.

Below I will show the values for the M855 cartridge brass, but the values would be very close regardless of the bottleneck cartridge design.

View attachment 1416012

In the diagram, you will notice there is a MAX-MIN style specification. If our heat treat process goes below 90, we reject the brass.

That isn't arbitrary, it is because it is important to keep the neck material strong enough to withstand all the downstream events. If we "over do" the heat treat, it will go lower than the 90 level and fail the specifications.

However, this value isn't like a physical wall or physics barrier that would show you an instant failure. You may or may not notice if you over soften the brass. You can make workable ammo out of necks below 90 HV. I would not advise it, but you would be able to "get away with it" to some level.

There is a point at which I would say, "don't come crying" if that doesn't work out well since you are aware that the above specs are known to work well across many calibers and requirements from military to sporting, bolt to full auto. etc..

The same it true for not annealing, meaning you could allow brass to harden and exceed the 115 level while not noticing any catastrophic consequences. However, from the load tuning view you would certainly be able to "shoot the difference" if your tune was sensitive to neck tension.

Keep in mind, we only use HV as a proxy for many other important material properties like the Yield Strength and the Modulus, both of which are affected and coupled to the HV which is why we use that as a proxy.

For the long term best performance from your reloads, try to stay as close to that chart as you can manage. You can make ammo that performs just fine with brass that fails that chart, but the reasons to stay within those boundaries have been worked out over a great many different tests and requirements that you may never encounter. As always, YMMV

Thank you. What then do you have to say about the E Cortina video, where neck tension didn't change a lot for drastic increases in over annealing essentially doubling or quadrupling his normal time of treatment?

 

[RegionRat]

Thank you. What then do you have to say about the E Cortina video, where neck tension didn't change a lot for drastic increases in over annealing essentially doubling or quadrupling his normal time of treatment?

I'm not a great writer, but I'm thinking I would say the same again....

 

[Phys86]

You will probably not find much that is in public domain. All of the serious texts are copyright protected as are the proceedings from conferences. What little I can share that is in the public domain, includes enough to have the discussion.

Below I will show the values for the M855 cartridge brass, but the values would be very close regardless of the bottleneck cartridge design.

View attachment 1416012

In the diagram, you will notice there is a MAX-MIN style specification. If our heat treat process goes below 90, we reject the brass.

That isn't arbitrary, it is because it is important to keep the neck material strong enough to withstand all the downstream events. If we "over do" the heat treat, it will go lower than the 90 level and fail the specifications.

However, this value isn't like a physical wall or physics barrier that would show you an instant failure. You may or may not notice if you over soften the brass. You can make workable ammo out of necks below 90 HV. I would not advise it, but you would be able to "get away with it" to some level.

There is a point at which I would say, "don't come crying" if that doesn't work out well since you are aware that the above specs are known to work well across many calibers and requirements from military to sporting, bolt to full auto. etc..

The same it true for not annealing, meaning you could allow brass to harden and exceed the 115 level while not noticing any catastrophic consequences. However, from the load tuning view you would certainly be able to "shoot the difference" if your tune was sensitive to neck tension.

Keep in mind, we only use HV as a proxy for many other important material properties like the Yield Strength and the Modulus, both of which are affected and coupled to the HV which is why we use that as a proxy.

For the long term best performance from your reloads, try to stay as close to that chart as you can manage. You can make ammo that performs just fine with brass that fails that chart, but the reasons to stay within those boundaries have been worked out over a great many different tests and requirements that you may never encounter. As always, YMMV

Thanks. Would you say that the commonly used method of heating in a dark room until a dull red glow appears gets the brass neck into the 90-115 hardness range?

 

[Ned Ludd]

...In the diagram, you will notice there is a MAX-MIN style specification. If our heat treat process goes below 90, we reject the brass.

That isn't arbitrary, it is because it is important to keep the neck material strong enough to withstand all the downstream events. If we "over do" the heat treat, it will go lower than the 90 level and fail the specifications...

There could be reasons a company might reject the brass beyond a likelihood for catastrophic failure. In the litigious society in which we exist, companies often go to ridiculous lengths to protect themselves from potential lawsuits, even if there is little chance of such an event happening. The existence of a lower hardness "fail" limit (i.e. 90 HV) is not proof that a catastrophic event is necessarily likely for brass with a lower hardness value in the neck/shoulder regoin. So the real question here is whether you know with any certainty that brass [over]-annealed to hardness values of less 90 constitute a serious safety risk, and that this is in fact has been demonstrated by rigorous testing? I find it hard to believe that such a failure would be likely in the event that someone accidentally [over]-annealed their brass a little bit, especially in light of the fact that the brass is likely going to be surrounded/supported by a half inch thick steel action. However, this is conjecture on my part. For obvious reasons I have not personally done any testing in this arena and therefore do not know with certainty that what I surmise is correct. Can you enlighten us with actual test results that demonstrate a brass hardness value of less than 90 actually constitutes a major safety risk?

 

[RegionRat]

So the real question here is whether you know with any certainty that brass [over]-annealed to hardness values of less 90 constitute a serious safety risk, and that that this is in fact demonstrated by rigorous testing?

Those failure modes have more to do with a basic lowering of the tensile strength, yield strength, and modulus. I have already stated that you can make working ammo with "failed HVs" in my post, above or below the specs. However...

What very low HVs do is reduce the MOS (margin of safety), some of which pertain to the requirements for full automatic needs, not just pressure rupture. In so many words, the brass has more than one type of job to do, and some of it has to do with the violence of case feed, and not causing us to adjust the rest of the processes over and over due to weaker necks.

The limits were set by my predecessors, and as the years rolled on many of us had chances to challenge them and yet ended up agreeing with them. In reality is isn't hard to meet them.

Would you say that the commonly used method of heating in a dark room until a dull red glow appears gets the brass neck into the 90-115 hardness range?

It worked when I started, and it worked when I retired. It is a happy coincidence that the Draper Point coincides with the heat treat temp for cartridge brass.