ANNEALING

[Webster]

I couldn’t find data for rapid annealing of cartridge brass so I decided to anneal case necks and determine the hardness. Rings were sectioned from Lapua 6mmBR Norma cases that were fired three times. I annealed the brass in a lab quality furnace by hanging the samples on a wire and lowering them into the furnace through a ½” hole. This eliminates recovery time from opening the door. Samples were annealed from 650F to 1600F for 15 seconds and 5 minutes. I did five minutes just to see the affect of time. I should have done 1250F for 5, 15 & 25 seconds to see the hardness differences. 650F will stress relieve and reduce neck splitting but it will not change the hardness to control neck tension. I don’t see how you can have any uniformity with a hand held torch. If you could rotate the case in a drill it might help. The temperature is increasing at about 100F/sec. From this experiment it looks like I am wasting my time annealing at 650F in a lead pot. Also it looks like you want to be slightly higher than 1250F. I looked at the grain size of all the samples they all had the same grain size. Grain growth is time and temperature dependent.

 

[Killshot]

The brass grain structure begins to change around 482º. Most automated annealers bring the mouth/neck/shoulder to between 700º and 800º before the case is doused, flame duration is roughly 6-8 seconds.
The casehead should never reach 475º.

More here: http://www.6mmbr.com/annealing.html

 

[Webster]

Annealing means to make it softer. I don't think you can possibly anneal at 700-800F in 8-15 seconds. Heat treating is time and temperature dependent. You are stress relieving. Published annealing temperatures in metallurgy books give the annealing temperature range as 800-1400F. Published data is normally an hour anneal in a furnace. Rapid annealing data published by metallurgist is almost impossible to find. I think each industry works out the annealing method for their particular product (wire, sheet ect.). My test results show very little softening below 1200F for 15 seconds. Heating with a propane torch till red in a dark room for about 15 seconds gave a hardness that indicated I was above 1300F. If an annealing machine makes the case neck red it has to be well above 800F. The gray that some people mention on annealed case necks is probably zinc oxide.

 

[LHSmith]

What's your point? Only the case necks should get annealed, therefore a furnace is not the proper source for heat.
It's hard to argue with a method that, when done correctly, allows hundreds of reloaders to bring brass back to near it's original state SAFELY and can prove the results on paper (the target).

 

[Webster]

I was only trying to determine what happens to the case neck in 15 seconds at various temperatures (hardness and grain size changes). I used a furnace because it's the only way to accurately heat treat at a given temperature. I am not saying that people should not anneal case necks. I am trying to provide accurate data as to what happens to the neck when you heat treat it.

 

[coyoteklr]

i'll be the first to admit i don't know everything that there is to know about heat treating..... annealing is just one part of heat treating..... and the goals to acheive
what the end result is can be apples and oranges.....
annealing 52100 aircraft bearing quality steel is not like doing brass i'm sure, but that annealing i do know volumes about...but not everything....
there is nothing wrong with experimenting to find out more.... just because someone says this is the best and only way to do it and it is written in stone doesn't necessarily make it so......
our world has the knack of jumping on something or a group that is different mostly out of fear of the unknown..... Hutterites or Amish for example or something that has never been done before.... "if man was meant to fly god would have given us wings instead of arms"..."Nobody will ever set foot on the Moon"....."Nobody wants to reload their own ammo when you can get periectly good ammo at the Gambles store"
I guess what i'm trying to say is don't stomp out someones fire just because they didnn't use the same wood you are used to using.....

 

[Steve Blair]

What we are trying to achieve with cartridge brass is technically not full annealing but tempering. We do not want the brass at dead soft but at a hardness that provides the proper spring tension for bullet grip.

Try sectioning and testing a reasonably sized factory brass sample and compare that to your experimental results. That hardness is the target range, not dead soft. What was your sample population size?

 

[Heavies]

Webster,
Have you seen this thread.
http://www.accurateshooter.com/forum/index.php/topic,3760450.msg35927520.html#msg35927520

This method virtually heats the metal from the inside out, very rapidly and evenly. What would your thoughts be on using induction to anneal rifle brass, its effect on hardness, and the ability to change grain structure?

 

[BoydAllen]

Shooters are looking for a very slight change in the characteristics of their brass, and although the term annealing is commonly used, what is commonly being done to cases, is not a good fit for the metallurgical use of the term. It seems to me that this is the reason for some of the arguments that take place.

For example, a friend ran into problems with two magnum cases. In trying to closely control the amount of shoulder bump he found that the case to case variation in bump, at a particular die setting exceeded the maximum bump that he was shooting for. To solve the problem a two torch annealing machine was purchased, that had a large angle between the torches, and stopped the case while it was heated. Various temperatures of Templaq were used to adjust the dwell time. Due to the torch angles, the outer flames wrapped all the way around the case necks, with the inner cones about 3/4" away from neck. After some experimenting, it was determined that the desired uniformity of shoulder bump (a total variance of about .001) was obtained when the 500 degree Temlaq was melted to a point that was about a half inch below case shoulders. (on 7mm WSM and .338 Lapua cases) The dwell time was 6-7 seconds. I forget the exact time. We were not looking for a radical change in neck tension. Some time later, cases that had been fired a couple of times after their initial "stress relief" had lost some of the uniformity of bump that the heating had provided, indicating that perhaps running them through the machine every couple of firings would be the way to go.

It may be that none of this falls under the classic definition of annealing, but we accomplished our goal.

Previously, I had annealed cases by standing them in a pan of water and using a hand held propane torch to heat them till their necks glowed ever so slightly in a darkened room, at which point I tipped them over into the water. The result, while not dangerous, was unsatisfactory, because the necks were made too soft. In my discussions with others, virtually all had reached the same conclusion. Some time after my glowing and tipping, I happened to read the instructions for one of Ken Light's case annealing machines. I think that he has more background in case annealing than anyone that I know of, and that he has it right. If you get a case neck hot enough to glow, you have over heated it for reloading purposes, because the neck will be excessively softened.

 

[Webster]

I looked at the links. I really like the method. The induction heater in the article is $350-$500 bucks on Amazon. I don't think I will respond to anymore people. I don't need to be nit picked apart by 100 people just because I am trying to provide simple info that people don't have. They can do whatever they want with my info. I agree with everyone that says that annealing or whatever you call it changes neck tension. I don't understand the premise that if you aren't changing the hardness you are changing the neck tension. There should be a direct relationship of hardness to tensile strength, yield strength and % elongation. Does stress relieving heat treatment change the tension without changing the hardness or grain size. I think that only a metallurgist in the copper industry could answer that question.

 

[Heavies]

I don't know about the others, but I think your experiment came out with some interesting data that can be very helpful. Understanding what is going on when you heat up the brass case is invaluable info. I myself am not satisfied with answer like, 'it just works', I like to know what is going on to make it work.
Thank for your work and info Webster.

 

[thefitter]

I have always thought that they annealing processes that are discussed here and on other boards was fledgling experimentation and totally individual at best. Everyone seems to do it differently and until I see hard data like the OP was describing I will continue to search myself for the formula that I believe works for me. Because I have learned that much of this reloading "science" is faith based.

I appreciate the OPs effort.

 

[BoydAllen]

I enjoy learning new information and appreciate the time and effort that it takes to gather it and make it available. I will say that I have seen a tendency, on the part of more than one "engineering type" to substitute calculation for empirical testing. Personally, I think that they both have their place. If one accurately reports that we did it this way, and these were the results, I can see no basis for objection. Similarly, if someone says that he did a test, or has found some information, the same thing applies. For me, neck tension is way too easy to test, to be bothered with figures. Sometimes the difference between what is,and what should be can be significant, probably because of a misunderstanding of what all of the relevant factors are.

 

[thefitter]

I enjoy learning new information and appreciate the time and effort that it takes to gather it and make it available. I will say that I have seen a tendency, on the part of more than one "engineering type" to substitute calculation for empirical testing. Personally, I think that they both have their place. If one accurately reports that we did it this way, and these were the results, I can see no basis for objection. Similarly, if someone says that he did a test, or has found some information, the same thing applies. For me, neck tension is way too easy to test, to be bothered with figures. Sometimes the difference between what is,and what should be can be significant, probably because of a misunderstanding of what all of the relevant factors are.

How do you test neck tension? I have heard the "squeeze it with pliers" technique but that sounds pretty amateurish. Yes I can feel a difference after I anneal but It's hardly quantitative.

When you say you test neck tension are you referring to elasticity, ductility, tensile strength, compressive resistance or what?

Thanks

 

[BoydAllen]

I test by the feel that I get when seating a bullet with a Wilson type die and an arbor press. One can easily feel differences and evaluate consistency. Not being able to put a number on it is no real problem. Play with numbers and units all you want. I have nothing against it, but for the cartridges that I load, I want something that is similar to the average neck tension that is obtained from brass that has been fired a couple of times, with the possible improvement of being more consistent. Making brass last for a great number of loadings is not really a factor, accuracy is. If I get 20 loadings out of a case, I figure that I have gotten my moneys worth. Actually, the only time that I have been recently involved in annealing cases was as described in the earlier post. I do most of my shooting with a 6PPC that I load for at the range, and for which I FL resize every time. No one, that I am aware of, that competes using this caliber, anneals their cases, and this includes some pretty fancy results. On the other hand there are some 1,000 shooters that anneal after every firing. It may be that the higher sectional densities that are typical of the bullets used at 1,000 yards act as a substitute for higher neck tensions that many short range shooters find helpful. Of course, this is just conjecture.

 

[Heavies]

I have always thought that they annealing processes that are discussed here and on other boards was fledgling experimentation and totally individual at best. Everyone seems to do it differently and until I see hard data like the OP was describing I will continue to search myself for the formula that I believe works for me. Because I have learned that much of this reloading "science" is faith based.

I appreciate the OPs effort.

I agree with you Fitter.

That is one of the reasons I am so interested in the inductive process. Differences in the thickness of brass the torch method, even on a timed machine, will be hit or miss at best. Uneven heating will be the ultimate outcome when trying to raise the temperature from the outside of the neck.

With the inductive process the heating is on a molecular level, thus creating an even heat, regardless of the thickness variance. There will be a difference in the tempering due to these variances, however I am thinking that due to the process being even heating, (inside the neck, outside the neck, and in the core or the metal itself) will tend to give better consistency to the process.

I, my self, cannot do this sort of testing, for I have neither the time, budget, or equipment to entertain many of my hypothesis. I am slowly building my tool chest and skill level to try things out, but I really appreciate all the knowledge I have gained from this forum. This is the reason I love this forum. It gives me a place to throw out the ideas and get the experienced comments, from those able to test, and those who have done this before.

 

[TonyR]

Boyd. What neck clearances do the 6PPC shooters typically run? I believe that a very tight chamber mininimizes the hardening that annealing corrects. I typically run 0.003-0.004 in my F-Class rifles. I also anneal to "even" my cases for some matches because it's easier than trying to keep track of how many times 300-400 cases have been fired.

 

[BoydAllen]

I would say that they all run .003 or less, with the majority probably at .0015 +-.0005, although some very good shooters that I know of are closer to .003 than .002. How's that for confusing?

 

[TonyR]

Thanks. I confuse easily and every little bit helps confuse me more. I guess all of this would be easier if things could be proven objectively. A very fine shooter I know told me early on that he is sure a lot of what he does is unnecessary. He just doen't know which things!

 

[pmarauder]

I actually annealed 50 338 Lapua cases last night. Like you Tony, it is easier to "even them up" with annealing, than to keep track of exact number of firings. before annealing, i could notice some cases had more resistance during bullet seating than others, even though they all were sized with the same .365 bushing. I dont have a ken light machine, so i have done the best i can at reading about annealing on this site based on the experts here. My process that i use is i take my "fowler" shot piece of brass and chuck it in a large dewalt drill which acts as a heat sink. I then hold it an inch away from the inner flame of a propane torch in a dark room. I use the same RPM,s and hold it the same distance from the inner flame, all being timed. Once i see the neck show the slightest hint of red, i pull it out of the flame and un-chuck it from the drill and set it on a damp towel. The time was 11 seconds. So for the 49 other pieces of brass, I use the same process, but i reduce the time on flame to 10 seconds. The resuts are the nice blue annealed ring all in the same location about 3/8' down from the neck shoulder junct. Seating resistance were all identical to the feel. Seems to work for me.