Found: The proper term for the kind of annealing we are trying to do

[BoydAllen]

If you do a little searching, I think that you will agree that the proper term for what we are trying to accomplish when we "anneal" cases, is process or intermediate annealing. Take a look, and I think that you will see what I am referring to. In the past, in online discussions I have tried to find an accurate term for what is being done, when we change, but do not fully anneal brass cases in the neck and shoulder area. These are the correct terms.

 

[jlow]

+1 Good find!

Found the following two description in Wiki. I think "Intermediate annealing" is what we want and "Full annealing" is what we try to avoid.

Process annealing
Process annealing, also called "intermediate annealing", "subcritical annealing", or "in-process annealing", is a heat treatment cycle that restores some of the ductility to a work piece allowing it to be worked further without breaking. Ductility is important in shaping and creating a more refined piece of work through processes such as rolling, drawing, forging, spinning, extruding and heading. The piece is heated to a temperature typically below the austenizing temperature, and held there long enough to relieve stresses in the metal. The piece is then furnace cooled. It is then ready again for additional cold working. This can also be used to ensure there is reduced risk of distortion of the work piece during machining, welding, or further heat treatment cycles.

The temperature range for process annealing ranges from 260 °C(500 °F) to 760 °C(1400 °F), depending on the alloy in question.

Full anneal
Full annealing temperature rangesA full anneal typically results in the second most ductile state a metal can assume for metal alloy. It creates an entirely new homogeneous and uniform structure with good dynamic properties. To perform a full anneal on steel for example, steel is heated to its annealing point (about 50°C above the austenic temperature as graph shows) and held for sufficient time to allow the material to fully austenitize, to form austenite or austenite-cementite grain structure. The material is then allowed to cool slowly so that the equilibrium microstructure is obtained. In some cases this means the material is allowed to air cool. In other cases the material is allowed to furnace cool. The details of the process depend on the type of metal and the precise alloy involved. In any case the result is a more ductile material that has greater stretch ratio and reduction of area properties but a lower yield strength and a lower tensile strength. This process is also called LP annealing for lamellar pearlite in the steel industry as opposed to a process anneal which does not specify a microstructure and only has the goal of softening the material. Often material that is to be machined, will be annealed, then be followed by further heat treatment to obtain the final desired properties.

 

[amamnn]

One takes note of the term "furnace cooled" put forth as a part of this process, which is something we do not do when annealing rifle brass, most especially if the cases are immediately dumped in a container of water after heating................which all makes for another argument in favor of air cooling our cases as opposed to "quenching."

 

[jlow]

Noticed that too… Yea, used to worry about where to drop that hot brass but found that you can just drop it into an open cardboard box placed under the BenchSource, doesn’t even leave scorch marks on it.

 

[Johnboy]

well done I have to say

 

[necchi]

One takes note of the term "furnace cooled" put forth as a part of this process, which is something we do not do when annealing rifle brass, most especially if the cases are immediately dumped in a container of water after heating................which all makes for another argument in favor of air cooling our cases as opposed to "quenching."

PPLLeeaase,,
take a further look at the temps,,^
While the description of the "process" is correct, it's obviously gleaned from data as applied to steel.
Don't further confuse yourself by reading only "some" of the information.

 

[swampshooter]

Quenching has absolutely no effect on brass as it does steel. The brass is quenched to stop the heat migration, nothing else.

 

[tenring]

A long time ago, I read that none of the cartridge manufacturers quench brass. Let it cool slowly.

 

[swampshooter]

Letting it cool slowly can be dangerous. Heat readily migrates in brass. If you get the web hot enough to anneal it , it becomes unsafe as it is too soft to handle the pressures.

 

[Rtheurer]

I wish I had more information about Air cooling vs Quenching. A buddy and I went in on a Bench source anealer. We ( mostly him) have been anealing cases for a little over a year and cooling by air with no ill effect on the lower part of the case. The shortest two cases we deal with are the 6BR and 223. I can say for sure using Templaque as a indicator that the body and base/web area are well above a tempurature that i need to be concerned with. So far its been safe with no indication of failure at all... so with that being said I wondering who here that has annealed alot more than my buddy or myself can point to a specific instance where they had a failure do to air cooling.
Please dont take this as a contradiction Swampshooter or a slight. Read it on a nice calm intrested inyour feedback tone.

being in the plumbing trade i understand the shorter the case the worse the issue could be, as brass is a wonderful conductor of heat.

Like I tell most of my new shooters getting into the sport of shooting that i do " this is A way to do it and how i do it, but that does not mean it will work for you" Its your job to extrapulate the infomation and use what you need to make it work for you.

Looking forward to seeing some examples about this topic. Thanks Boyd, I always enjoy your responses and threads.

Very Respectfuly
RussT

 

[Steve Blair]

If it takes a given amount of thermal energy to heat the upper case to annealing temperature, and the heat source is then removed, the lower case cannot reach the same temperature as the upper case. As the heat migrates through the case, it is attempting to reach equilibrium. Heat cannot appear from nothing, there must be a heat source. [br]
Really simplistically, and ignoring radiation and conduction losses: If the case neck and shoulder are 1/3 of the case mass and the neck and shoulder reach ~850°F, the case will reach equilibrium at ~283°F. This is a crude approximation but should make the point. [br]
That is why Ken Light's machine has a solid wheel in fairly close contact with the case. It provides a heat sink path and prevents the case head from reaching anywhere near the neck and shoulder temperature.

 

[Nomad47]

Totally agree, Steve. Annealing stops as soon as the heat is removed.

 

[Minesweeper3433]

I noticed earlier in another annealing thread that someone mentioned over annealing in a pan of water and thought of a way to make this happen. Tried it and it does in fact over anneal.

I have no experience annealing and used the lock plier trick mentioned in the article to establish over annealed state.

Put rounds in metal baking pan filled with water to cover body of cartridge. It is easier when the water is lower to do this say 1/3-1/2
Use your every day torch and think to yourself hey if I heat from the top down the annealing will be more evenly spread. This is how I got it to over anneal the case head.
Heat straight down and you can in fact over anneal the case head if you heat till the necks start to glow in the dark. What I noticed is if you go back and forth the case head is glowing down in the bottom of the case just as much as the neck.
I have no intention of ever annealing this way myself. As soon as I thought about annealing in a pan I realized I would try to do it straight down to keep it even. I realize now that the bottom of your case is not immersed in water if the case is sitting on the bottom of the pan. I could not replicate this effect if case was filled with water only empty case sitting in water.

 

[jlow]

Slightly confused about your setup…

You said “Put rounds in metal baking pan filled with water to cover body of cartridge. It is easier when the water is lower to do this say 1/3-1/2”. That I understand, but later you said “I realize now that the bottom of your case is not immersed in water if the case is sitting on the bottom of the pan.”

Seems like the two statements are contradictory? Can you please clarify?

 

[BoydAllen]

Decades back, when I tried old cases in a pie pan of water method, in a darkened room, using a propane torch to heat the necks till they barely had the darkest of glows, I moved the torch so as to apply the flame to the SIDES of each case neck, and although the experiment produced necks that were overly soft, the case heads did not show signs of being softened.

I think that the problem that you had came from pointing the flame at the neck from above, directly into the interior, including the base of the case. Understand that I DO NOT recommend the method, but I think that I have identified the reason for the difference in my results and yours, that and the possibility that you were working in a room with a normal level of light, whereas I worked at night, in a room in which I had turned out the light, after the torch had been lit.

If you look up the instructions for Ken Light's annealer, he says that if you head case necks to even the slightest amount of glow, that you have gotten them too hot, and that they will be too soft.

 

[jlow]

BoydAllen – agreed with you on pretty much all your points, especially the one regarding “even the slightest amount of glow” being too hot, that was my learning from David Dorris of BenchSource.

I understand the problem of pointing the flame into the neck from above and how much worse this is, still slightly surprise that one could anneal the head using this method since the outside of the head is still immersed in water and one would think that the heat would be sucked out of the brass by the water on the other side. But I have not done the experiment and so won’t debate this, just surprised.

 

[Killshot]

The smallest rifle case I've done is the 300BLK (a 1" .223 case). With my Bench-Source I've found no problem with heat migrating past where I want it.

And I concur that if you're annealing until the case glows, you're overcooking 'em.
Too many people try to get the cases to "look like new Lapua" when that tells us nothing about the level of annealing we've done.

 

[Minesweeper3433]

I performed my little experiment just to see if, given every chance, I could in fact anneal the case head while it was submerged in water. I could not anneal the body however I believe that because the case head is sitting on the bottom and there is little to no water between the case head and essentially a metal table that I was capable of annealing the case head. I put the cases in the pan by placing my finger over the mouth of the cartridge as I placed it in the pan trapping the air inside preventing it from filling with water.
The entire process of this experiment was to see if I could in fact anneal a submerged object. I could only anneal the surface that was in fact not really submerged but just sitting on a plate surrounded by water. If you place a metal cup in a bowl and then fill the bowl with water there will be no water on the bottom of the cup. If you heat this cup now with the purpose of annealing you can in fact get the bottom of your cup as hot as you want.
This was done with some 7.62x51 brass in a connex in afghanistan so there is very little to no scientific control in this experiment, I just wanted to see if I could do it and have absolutely nothing to do as it is snowing its but off.

 

[BoydAllen]

How was the flame axis oriented to the case?

 

[Minesweeper3433]

BoydAllen: sorry man not understanding what your asking?