Annealing Verification

[Fred Bohl]

Over the last few years I've tried molten lead, molten Cerosafe, molten salt, and my AMP induction annealer. All seem to produce similar results with the AMP being easiest to get apparently repeatable results.

My questions are:
1. How does one tell when the result is as desired or correct?
2. What is required to measure the result?

 

[rardoin]

I'll take a stab Fred-

1. The necks are outlasting the primer pockets....goal of improved brass life accomplished.

2. Consistent/repeatable results on target with the same load parameters......consistent brass resizing and neck tension accomplished.

I could give a rat's arse what the Brinnel number is as long as the above goals are met. IMO a broad range of softening can work as long as all cases can be annealed consitently with to the same degree of 'softness'....regardless of the heat source. For the record I use an AMP because I find it convenient/personal preference.....not that it produces 'a better anneal' per say.

 

[spclark]

I’m with rardoin on this.

Measuring brass hardness to some N-th degree is way beyond my patience, budget or needs.

I started with torch/drill/socket, got predictable results for years. Upped to an MRB device a couple years ago to save time (hey I know I have some left yet but question is how much?) and am entirely pleased over results: less time spent, even more consistent results.

I know what we call ‘annealing’ works & is worth doing. ‘Nuff said. Just don’t overdo it.

 

[918v]

A 650 degree Tempilstik crayon will get you the base minimum temperature to keep the necks from splitting. From there you can increase the temp if needed to achieve optimal neck hardness for optimal seating pressure given your case neck/tooling spec.

 

[riflewoman]

The only way to tell what you are doing to your brass is to take metallographic samples. This means cutting strips from your case neck and shoulder and ruining these case. You’ll need to mount them in a Bakelite mount polish them and etch them to reveal the grain structure. Not hard but not trivial either. Oh I almost forgot, you need experience in reading metallographs in a microscope. That’s the hard part.

Doing non-destructive tests like spring back, hardness, bullet seating force are OK but limited in scope. They don’t tell you what the condition of the grain structure truly is.

 

[Twoboxer]

The only practical way I can think of that makes use of tools you *might* have or could use is to measure the seating force required by a new, presumably annealed, case. And then measure it after one firing or perhaps two.

After your annealing, if the seating force returns to what it was in the new case, your annealing presumably has done its job.

Or you could buy an AMP and send a sample of your batch of brass to them. They will do the required testing and tell you what specific program will achieve it.

 

[Mozella]

The only way to tell what you are doing to your brass is to take metallographic samples. This means cutting strips from your case neck and shoulder and ruining these case. You’ll need to mount them in a Bakelite mount polish them and etch them to reveal the grain structure. Not hard but not trivial either. Oh I almost forgot, you need experience in reading metallographs in a microscope. That’s the hard part.

Doing non-destructive tests like spring back, hardness, bullet seating force are OK but limited in scope. They don’t tell you what the condition of the grain structure truly is.

What you say is mostly true and I can say that because that's exactly what I did when I took a metallurgy class as part of my college education. But we don't care what the grain structure of our brass is. Even if you offered this service for free, not very many shooters would know what to do with the information.

What we care about is eliminating neck splitting and achieving some sort of consistent resizing results along with, we hope, a more consistent neck tension.

I'm convinced that consistency is way more important than the actual hardness and/or grain structure.

It's something like me and my morning coffee. I like it hot, but not too hot. One could say that the only way to tell what I'm doing when I make coffee is to use a thermometer. True enough, but I don't measure the temperature. I follow the same routine when making coffee and I recognize that the temperatures of the components will have an effect on the final product. But I just accept that those temperatures are "normal" and I know if I follow my normal routine, the coffee will be just right. It works for me.

Likewise a setting of 22 (percent duty cycle) on the feed drum motor of my DIY "Skip Design" annealer with the blue torch flame just touching the cartridge neck is my standard. That tests OK with Tempelaq but, more importantly, it provides me with long lasting brass which is also instrumental in me winning my share of F/TR matches.

 

[Fred Bohl]

The only way to tell what you are doing to your brass is to take metallographic samples. This means cutting strips from your case neck and shoulder and ruining these case. You’ll need to mount them in a Bakelite mount polish them and etch them to reveal the grain structure. Not hard but not trivial either. Oh I almost forgot, you need experience in reading metallographs in a microscope. That’s the hard part.

Doing non-destructive tests like spring back, hardness, bullet seating force are OK but limited in scope. They don’t tell you what the condition of the grain structure truly is.

I do know from my engineering education and from my research before starting case annealing experiments that you are correct. That is also why I ordered an AMP when they first became available since they purport to do the testing for the buyer.

I and the several friends I do annealing with the AMP for all like the results because necks are outlasting the primer pockets, cases last longer and the precision target shooters among us think we are shooting better. The first two are easily measurable results but shooting better do to annealing is not an easily detected or demonstrated fact (probably because we are not proficient enough shooters).

I guess I didn't ask the questions as specifically as I should have. What I was looking for was a fairly simple way to determine the minimum and maximum amount of annealing when using molten bath methods.

Thank you all for your inputs so far.

 

[DirtySteve]

You could twist a chamfering tool in the case mouth and check to see if it seems soft.

 

[rardoin]

I guess I didn't ask the questions as specifically as I should have. What I was looking for was a fairly simple way to determine the minimum and maximum amount of annealing when using molten bath methods.

I have tried the 'spring back' test by taking a pair of pliers and grip the mouth of an non annealed case that has been hardened and put enough pressure to elastically deform the mouth and release (make sure that there is no deformation). The take an 'annealed case and exert the same pressure in the same spot and if softened enough it should permanently deform. Not very scientific but was described on this site in the past and maybe better than nothing.

 

[riflewoman]

I have tried the 'spring back' test by taking a pair of pliers and grip the mouth of an non annealed case that has been hardened and put enough pressure to elastically deform the mouth and release (make sure that there is no deformation). The take an 'annealed case and exert the same pressure in the same spot and if softened enough it should permanently deform. Not very scientific but was described on this site in the past and maybe better than nothing.

There was one method described years ago in an old issue of Handliader magazine. The method was to take a case and a drill (to get a steel rod of a known diameter) and squeeze the case neck (top half) in a vise until the case gripped the drill shank. Then measure the permanent deformation. Use a smooth jawed vise. For the love of me I can’t find my old issue that has the information. But the test method was repeatable and could be scaled up or down depending on caliber.

 

[mikecr]

New Lapua cases spring back ~1/2thou, and I believe most find this as useful to load results.
Just measure a seated neck OD, pull the bullet, then measure the spring back OD to see how much you have.
A comparative reference..

We won't know what spring back grip actually is until we come up with a tool to measure it. Far as I know, nobody has. So that's just where we are.

 

[dcali]

There are some pretty thorough tests on the AMP site that verify that "annealed" means just that - fully annealed. At least if you use their machine. The good news is that means it's not that critical. Annealed is annealed.

 

[mikecr]

We don't want 'fully annealed'
What we want is called 'process annealed'

 

[dcali]

What does “process annealed” mean? I think most people are annealing fully, whether they intend to or not. And it makes sense to if you ask me - that’s going to be a lot more consistent.

 

[rardoin]

What does “process annealed” mean? I think most people are annealing fully, whether they intend to or not. And it makes sense to if you ask me - that’s going to be a lot more consistent.

By "fully annealed" do you mean dead soft? I do want some elasticity in the brass. I don't think AMP settings are designed to produce dead soft brass per my observations with a few different brands/chamberings. I did not sleep in a Holiday Inn Express lately so my statement is not qualified.

 

[Webster]

By "fully annealed" do you mean dead soft? I do want some elasticity in the brass. I don't think AMP settings are designed to produce dead soft brass per my observations with a few different brands/chamberings. I did not sleep in a Holiday Inn Express lately so my statement is not qualified.

It's not possible to get a big drop in hardness annealing at 750-900 for a couple seconds. To get dead soft the neck would have to be heated until it was bright red. Please no stupid comments.

 

[Hopkins]

when I have properly annealed a case I can feel the neck give when I collet neck size the case. the case also clings to the sizing mandrel after being neck sized.

 

[riflewoman]

There are some different types of annealing. The definitions are approximately:

Process annealing ( sub-critical annealing) is a thermal treatment to remove residual stress of cold working without a significant reduction in cold worked strength and stiffness. Dislocations are not affected and the fracture resistance is also not affected. If your brass is process annealed only seating stiffness would not be reduced.

Annealing has a critical temperature that must be reached for annealing to occur. This temperature is dependent on the amount of cold work and the nature of the cold work (reversed cold work, multi directional cold work etc). The more cold work applied the lower the critical temperature.

When the critical temperature is reached, all stresses are removed and the metal resorts to its fundamental microstructure, recrystallization starts at dislocations near grain boundaries resulting in a highly refined grain structure. These grains will then start to grow if the temperature is maintained. These processes are time and temperature dependent. I.E. if you heat your brass to 750F for 20 seconds at 900F you might have 5 seconds. Precise parameters are somewhat batch driven. And this is why the old school method of heating with a propane torch to a “start of glow” in a darkened room then tip your cases in to water works so well.

Believe what you want, but that’s the science behind annealing.

 

[rardoin]

It's not possible to get a big drop in hardness annealing at 750-900 for a couple seconds. To get dead soft the neck would have to be heated until it was bright red. Please no stupid comments.

My question was aimed at Damon and to what he considers fully annealed. A legitimate question and in the spirit of the original post and Damon's post in reference to AMP annealers.

Damon, I know AMP shoots for certain Brinnel microhardness numbers and I have used their services to get settings for cases but it certainly does not behave as dead soft brass. In a prior life, working with copper and brass, when I ''fully annealed" the metal I was shooting for a dead soft conditions. I don't think that is what you are considering fully annealed for cartridge necks. My curiosity aimed toward the question of why a certain Brinnel number is aimed for and what experimentation, on targets, determined that that is the ideal level of annealing to shoot for.