Anneal or not to

[FroggyOne2]

The way I am doing it, I only have to run the cases in the tumbler once.

 

[timeout]

I have been depriming first per the instructions that came with my bench source. I imagine that is just a CYA safety deal on their part, and would have no actual affect on the cartridge case during annealing. I have not had my annealer for very long and may or may not change my procedure. If you choose to deprime first, a Wilson neck die with the bushing removed can be used.

 

[300 RUM]

The way I am doing it, I only have to run the cases in the tumbler once.

what's your process

 

[amlevin]

I like to anneal clean cases. Easier to see color change and no burned on "gunk". The more 'schmutz" on the case, the uglier it is after annealing. Clean cases give a nice color line on the body, a slightly discolored case neck, just like factory Lapua brass.

For me, it's de-prime with universal depriming die, tumble in Stainless media to clean case inside, outside, and primer pockets too, then anneal. From there I size and trim if necessary. Since I've changed to the Forster Shoulder Bump/Neck Size bushing die, the minute amount of lube left on the outside of the case neck can be wiped off in a flash before I charge the cases.

 

[300 RUM]

I have a FLUKE-62 - INFRARED THERMOMETER, I have been watching the case go to 725F as they spin out of the flame. From what I have read 700-775 is a good temp. Anyone else using a INFRARED THERMOMETER, what are your temp coming out at?

 

[ElJay]

300 RUM,

Can you provide more details regarding your procedure? Dwell time etc. Seems like you have a quantitative approach. Most discussions I've read simply say" You will get the hang of it after a while".

ElJay

 

[spclark]

...people are saying they have to be deprimed before hand. I have never deprimed for the same reasons you described.

People say lots of things but whether what they're trying to tell you works with the way you want to do things is strictly up to you.

I deprime before cleaning cases (SS media convert here) because it gives me a chance to feel for loose primers (I use a Wilson decapping pin & case base and a small ball peen hammer; doing this by hand also keeps primer grit away from my press ram) early on. If I feel a case is too far gone to reload again it gets tossed at the start. With the wet method of cleaning, having the flash hole open on both ends I think gives more thorough flushing of the cleaning solution thru each case and of course the SS media can clean primer pockets too, not a bad thing.

Annealing gets done once cases are thoroughly dry. MUCH easier to judge progress on clean cases.

As for flame dwell time, I count seconds by habit. 7 for 308, 6 for 6mm while watching for a subtle change in the appearance of the cleaned brass. Some cases turn blue / purple if they've sat clean for a few days, all show the blue band below the shoulder when 'done'.

Early on I used the TempLaq to gauge time & flame size on my single-burner propane torch. After 2-300 cases, you do get a feel for what a proper job looks like.

 

[Leaddog]

I anneal after every firing with a Benchsource. Decap, stainless steel clean, dry, then anneal.

 

[markm87]

I agree with spclark and Charlie Watson COMPLETELY.

I won't perform any prep until my brass is decapped and clean. It's not the law... but once you do it this way, you'll never go back to filthy loading.

 

[300 RUM]

300 RUM,

Can you provide more details regarding your procedure? Dwell time etc. Seems like you have a quantitative approach. Most discussions I've read simply say" You will get the hang of it after a while".

ElJay

To start one needs to know what and who your working with. I am more less a physicist, so you can only imagine I over engineer and think every thing.

So to start, the brass used for rifle cases = a 70/30 blend.

The C26000 alloy is also known as C260 (or simply 260), alpha brass, 70/30, and cartridge brass. It has many uses in architectural, electrical, hardware, munitions and plumbing industries. C26000 has a nominal composition of 70% copper and 30 % zinc. It is a single phase alloy (", bcc) up to its solidus at 915°C.

Because C26000 is a single phase alloy it is not considered heat treatable, but it can be strengthened by cold working(also known as sizing, not good) and softened by annealing (good). The high work hardening rate of this alloy means cold working can increase the yield strength dramatically, from 75 MPa in the fully annealed condition to over 450 MPa in the full-hard condition. Along with this increase in strength comes a decrease in ductility, from 68% down to 5%. Recovery annealing will restore a small amount of ductility with little change in strength and hardness. Annealing that results in recrystallization can extend the ductility considerably and can more than halve the hardness and strength. Further annealing will lead to grain growth which can produce further decreases in strength and increases in ductility, but can also lead to a lower fracture toughness.

My take on a proper temperature for annealing cartage brass is 700 F to 800 F. The way we anneal is not truly the correct way how ever it does the job and does it well. Truly annealed brass can take hours at a much higher temp and time. Due to the thickness of material much less time and temp is needed.

My annealing machine, the one I built has a SFPM of 5, I use MAP gas not LP (propane) and my torch tip is a target type (better concentration of heat). The torch tip is much closer to the work piece then what you may be used to and the time is shorter also. I use two torches with their flame front crossing at 18 deg, this gives me a pre and post heat condition. My cases spin 180deg as they are entering the pre heat area, continuing into the flame convergence where a 360 deg rotation takes place under full heat to another 180 turn in to the post heat. This is where I have been able to get the most accurate temp reading of 725 F. Oh maybe I should add when the case is in the flame front the temp on average is 820 F and the time in full flame is 1.5 sec, so (pre heat) .75 sec (full heat) 1.5 sec (post heat) .75 sec total time of 3 sec.

 

[300 RUM]

I agree with spclark and Charlie Watson COMPLETELY.

I won't perform any prep until my brass is decapped and clean. It's not the law... but once you do it this way, you'll never go back to filthy loading.

I can't stand dirty and really like shiny.

 

[Alex Wheeler]

300 RUM,

Can you provide more details regarding your procedure? Dwell time etc. Seems like you have a quantitative approach. Most discussions I've read simply say" You will get the hang of it after a while".

ElJay

To start one needs to know what and who your working with. I am more less a physicist, so you can only imagine I over engineer and think every thing.

So to start, the brass used for rifle cases = a 70/30 blend.

The C26000 alloy is also known as C260 (or simply 260), alpha brass, 70/30, and cartridge brass. It has many uses in architectural, electrical, hardware, munitions and plumbing industries. C26000 has a nominal composition of 70% copper and 30 % zinc. It is a single phase alloy (", bcc) up to its solidus at 915°C.

Because C26000 is a single phase alloy it is not considered heat treatable, but it can be strengthened by cold working(also known as sizing, not good) and softened by annealing (good). The high work hardening rate of this alloy means cold working can increase the yield strength dramatically, from 75 MPa in the fully annealed condition to over 450 MPa in the full-hard condition. Along with this increase in strength comes a decrease in ductility, from 68% down to 5%. Recovery annealing will restore a small amount of ductility with little change in strength and hardness. Annealing that results in recrystallization can extend the ductility considerably and can more than halve the hardness and strength. Further annealing will lead to grain growth which can produce further decreases in strength and increases in ductility, but can also lead to a lower fracture toughness.

My take on a proper temperature for annealing cartage brass is 700 F to 800 F. The way we anneal is not truly the correct way how ever it does the job and does it well. Truly annealed brass can take hours at a much higher temp and time. Due to the thickness of material much less time and temp is needed.

My annealing machine, the one I built has a SFPM of 5, I use MAP gas not LP (propane) and my torch tip is a target type (better concentration of heat). The torch tip is much closer to the work piece then what you may be used to and the time is shorter also. I use two torches with their flame front crossing at 18 deg, this gives me a pre and post heat condition. My cases spin 180deg as they are entering the pre heat area, continuing into the flame convergence where a 360 deg rotation takes place under full heat to another 180 turn in to the post heat. This is where I have been able to get the most accurate temp reading of 725 F. Oh maybe I should add when the case is in the flame front the temp on average is 820 F and the time in full flame is 1.5 sec, so (pre heat) .75 sec (full heat) 1.5 sec (post heat) .75 sec total time of 3 sec.

I love posts like this! Thank you.

 

[spclark]

I love posts like this! Thank you.

A big +1 from me too!

This is the kind of stuff that makes this forum what it is! I learned a TON about annealing cartridge brass in the time it took to read that essay!!

 

[TC260]

The way we anneal is not truly the correct way how ever it does the job and does it well. Truly annealed brass can take hours at a much higher temp and time.

I don't mean to quibble but what isn't correct about what we're doing? A full anneal ruins the properties of the brass for our application. A partial anneal or recovery anneal, is the form of annealing that we should be doing. You mentioned specifically that it improves ductility without changing strength and hardness. Those are the exact properties that we want to change and/or maintain so I don't see how what we're doing is incorrect.

 

[300 RUM]

The way we anneal is not truly the correct way how ever it does the job and does it well. Truly annealed brass can take hours at a much higher temp and time.

I don't mean to quibble but what isn't correct about what we're doing? A full anneal ruins the properties of the brass for our application. A partial anneal or recovery anneal, is the form of annealing that we should be doing. You mentioned specifically that it improves ductility without changing strength and hardness. Those are the exact properties that we want to change and/or maintain so I don't see how what we're doing is incorrect.

I don't think your quibbling, my definition and your Interpretation are both correct, but maybe I should add some clarity about that.

A full anneal temp ranges from 800 F to 1400 F and a partial or recovery anneal temp ranges from 650 F to 825 F, getting a temp reading of 700 F to 750 F would be a good indication your temp is just right. A 750 F reading will/can be +/- 50 F due to heat migration of the very thin material we use. I could write a book about this subject, but I HATE WRITING LOL