Annealing: Specific Heat Question

[Lenny Foffa]

I can see that I am UNDER annealing my brass, as I merely get a slight straw color at the neck and shoulder. I set mt Burst Fire machine at 50 or 51, with the blue flame just touching the neck of the case. That straw color completely goes away after a few hours in the Lyman vibrating case cleaner.

 

[nksmfamjp]

This is completely opposite of the established science on the subject. Is this your personal opinion or do you have something based in science that supports your conjecture?

Are you sure?

I read this to say the if you use something that is 850F to heat something to ~750F that it will rise to ~500F pretty quick, but really slows as you approach 850F, thus making 4s wait vs 10s wait less important.

Seems like you are thinking that annealing takes more time at lower temps so it takes a timer to make sure it was held in for long enough.

Propane has a flame temp around 2000F so you need to anneal at higher temps like 750F, but for less time because it is still rapidly increasing in temperature which shortens the anneal time. Thus you do need pretty decent flame and entry/exit into flame controls to keep from over doing it.

Did I misunderstand?

 

[VenatusDominus]

Are you sure?

I read this to say the if you use something that is 850F to heat something to ~750F that it will rise to ~500F pretty quick, but really slows as you approach 850F, thus making 4s wait vs 10s wait less important.

Seems like you are thinking that annealing takes more time at lower temps so it takes a timer to make sure it was held in for long enough.

Propane has a flame temp around 2000F so you need to anneal at higher temps like 750F, but for less time because it is still rapidly increasing in temperature which shortens the anneal time. Thus you do need pretty decent flame and entry/exit into flame controls to keep from over doing it.

Did I misunderstand?

There are multiple studies demonstrating no measurable changes in cartridge brass held at 750F for 30 min. In order to return the neck/shoulder of a cartridge to its factory state, you need to apply enough heat for enough time to stress relieve the neck /shoulder. If the heat is to low, then the time required allows the heat to propagate down the brass and soften the body and base (bad). This means the anneal time needs to be kept to seconds. In order to return the brass to its virgin, factory state your neck/ shoulder needs to get north of 1050F for several seconds. Coincidentally, this is the temp at which brass begins to glow. This is very achievable with commonly used flame and induction annealers. This is impossible with a salt bath at 850F. At least that is what the scientific studies demonstrate.

 

[Mikecr]

Maybe you can point us to a 'scientific study' showing that dip annealing does nothing?
That our brass sees no grain recovery at 850degF?

 

[VenatusDominus]

Maybe you can point us to a 'scientific study' showing that dip annealing does nothing?
That our brass sees no grain recovery at 850degF?

Here are two. I have asked before, but I will ask again. Do you have any science based evidence that annealing at 850F for less than 4 minutes produces any measurable changes in the brass?

Salt Bath Annealing - Does It Work? | Learn More | AMP

View the latest articles from AMP Annealing. Get tips and tricks from our R&D. Here we upload articles to provide your the best possible information on innovations in the annealing process.

www.ampannealing.com

Deformation and Annealing of Cartridge Brass

Copper and its alloys are among the most malleable metals and alloys in existence. Cartridge brass, Cu – 30% Zn, has been used for many years to produce cartridge cases for ammunition due to its superior cold forming characteristics. This article shows the microstructure and hardness of...

vacaero.com

 

[Iketurner]

Good info in this thread. Answered alot of questions I had about the process

 

[smokey3]

Well if we "Trust The Science" like they tell us to do, then this debate is likely settled. Very informative articles although the Vacaero article is highly technical and harder to follow than the article by AMP.

 

[BrentM]

The induction annealer sounds good. Where did you get the instructions for the one you built?

YouTube. I was looking into it again and found a much easier solution.

 

[Maol]

Wonder why if high temps for brief periods of time are inconsequential or ineffective, why then historic caution to keep the brass below the shoulder from ever going above 450 F?

Curious also that since brass is an alloy made of roughly Copper (70%) and Zinc (30%), are the effects of raising a brass case's temperature above Zinc's melt temp of 420°C (787°F) the reason for the traditional 750 F max neck temperature?

Interestingly the outer core of a candle's flame (light blue) is roughly1400 °C, and the inner red portion is around 1070 K (800 °C). Both are more than hot enough to anneal according to a old school method of using a candle to anneal. It's done while holding the case in your fingers above the head while rotating it until it is to hot to hold and dropping it on a wet towel and wiping the carbon black off. Slow and unscientific yet anecdotal evidence says it works, and gives consistent results which is my purpose for annealing. Brass life is a bonus.

I don't use a candle, I use a Gen 2 Burstfire with a grill propane tank and a regulator. It check it with a laser temperature gun and Tempilaq 750.

 

[VenatusDominus]

Wonder why if high temps for brief periods of time are inconsequential or ineffective, why then historic caution to keep the brass below the shoulder from ever going above 450 F?

Curious also that since brass is an alloy made of roughly Copper (70%) and Zinc (30%), are the effects of raising a brass case's temperature above Zinc's melt temp of 420°C (787°F) the reason for the traditional 750 F max neck temperature?

Interestingly the outer core of a candle's flame (light blue) is roughly1400 °C, and the inner red portion is around 1070 K (800 °C). Both are more than hot enough to anneal according to a old school method of using a candle to anneal. It's done while holding the case in your fingers above the head while rotating it until it is to hot to hold and dropping it on a wet towel and wiping the carbon black off. Slow and unscientific yet anecdotal evidence says it works, and gives consistent results which is my purpose for annealing. Brass life is a bonus.

I don't use a candle, I use a Gen 2 Burstfire with a grill propane tank and a regulator. It check it with a laser temperature gun and Tempilaq 750.

From AMP's web site:

"

1. Cartridge brass melts at 915°C (1679°F). Up to that temperature it remains homogeneous (Appendix 1 - 1.1).
2. Dezincification of brass can occur because of chemical attack, but heating brass, even to high annealing temperatures cannot cause dezincification unless chemicals are present. The zinc content of the alloy cannot burn or melt out up until boiling point (Appendix 1 - 1.6)."

I cannot opine as to the "historic caution" of never going above 450F or the erroneously propagated "750F max neck temp" to anneal brass. If I had to guess, someone saw a chart indicating brass would anneal at 750F but failed to also see that it required 1 hour at that temperature.

I know when I started in my own profession in the mid 1990's, there were many things done, especially in the OR, because "it has always been done that way" or "it just made sense". In the last 15 years we have moved away from this methodology and now practice "evidence based medicine". With proper scientific studies it was discovered that many of the "traditional" things we did provided no benefit to the outcomes, and in some cases were detrimental. This, and for many other reasons, is how I know Dr. Fauci is a QUACK. He went on national television and said "It just makes sense that two masks are better than one." We don't practice this kind of medicine anymore. Where is the double blind, placebo controlled study to show that two masks are better than one?

I think long range shooting has entered a similar period, where we are applying science to see what actually affects the outcome versus what "traditional methods" have no effect or are, in fact, detrimental.

 

[Maol]

While the AMP appears to be the cat's meow, and I admit I would be happy to have one, flame 'annealing' seems be giving the results I am looking for.

Seems folks have been doing it for at least 70 years.

"[C]ases are polished and then placed on a small block of wood or metal. The case is placed on the platform and a flame from a suitable torch is played over the neck as the block is turned. This continues until the brass has a slight color change, and then the flame is removed. The flame must be hot enough so that the neck is heated sufficiently fast enough to prevent the base from heating to a critical point." - Earl Naramore "Principles and Practices of Loading Ammunition": (1954)

 

[LRNut]

I ordered the Mark 2 amp anneal er a few days ago and it's really awesome! It will anneal a case is seconds. Wasn't cheap but worth the money I spent on it

The AMP and A&D scales are money well spent. I have two of each - one in each reloading room. The AMP is so far ahead of flame stuff it isn't even close.

 

[Hugnot]

Various infra-red thermometers measure up to 750 F. Annealing temps are within that range. I can buy an infra-red thermometer for about $65 - worth a try.

 

[Maol]

Yep I have a infrared now. Tempilaq is a mess in a bottle. I will not get more. It is helpful for training your eye though.