Annealing "ring" ?

[rsbhunter]

I know all brass makes are different mixtures of brass , zinc etc. I'm just curious as to why different makes show such different results from annealing. I use an induction annealer, and the difference in the appearance or annealing mark amazes me. I have some Alpha brass that anneal's and leaves almost no sign , and Lapua that is the poster child for an anneal "ring". It's not a big deal, but I love to know why some things happen the way they do......thanks for any insight....rsbhunter

 

[powderbrake]

I believe they all anneal their cases, but some manufacturers clean them after anneal.

 

[Dusty Stevens]

I think it has to do with the finish and oxidation of the brass more than exact composition

 

[rsbhunter]

I guess, I just figured that if the metal gets that hot, it would show something.. The Alpha shows almost zero!!!... But it's probably as you said, the oxidation... rsbhunter

 

[Webster]

I know all brass makes are different mixtures of brass , zinc etc. I'm just curious as to why different makes show such different results from annealing. I use an induction annealer, and the difference in the appearance or annealing mark amazes me. I have some Alpha brass that anneal's and leaves almost no sign , and Lapua that is the poster child for an anneal "ring". It's not a big deal, but I love to know why some things happen the way they do......thanks for any insight....rsbhunter

I doubt there is more than a few % difference in the zinc content between the different brands of brass. Maybe someone on this website has some composition data. I wouldn't think there would be any difference in how they anneal with slight variations in Cu/Zn. Anything else in the alloy is trace amounts or impurities. Pure copper probably anneals in the same temp range. Tiny chemical films from things like lubes or cleaning agents can change the color after annealing.

 

[rsbhunter]

I was reading on the "AMP" site, they state that just a couple thousandth's of an inch can change the setting/ time on the amp machine. I know that with induction, from dull red glow, to bright red can be only half of a second on the timer.....so I guess it is alot of variables in the process....THAT is why the AMP annealer is as expensive as it is.....rsbhunter

 

[Fast14riot]

Its typically the Cu content that varies in cartridge brass. 68.5-71.5% by weight. Zn is 28.5%. The rest is Fe, Pb, and other trace elements.

 

[backlash]

The best brass annealing video ever made.

 

[rsbhunter]

This site continues to amaze me....the knowledge one can get here is incredible. This just adds to the investigation needed to get all the variables in loading down . I honestly appreciate the people that take the time to share the knowledge that most people don't have......rsbhunter

 

[Clancy]

The accent alone was worth the watch.

 

[Pawnee Bill]

OK, somebody help this old dumb country boy out and post a picture of an "annealing ring". I looked at my annealed cases and I feel like a pig looking at a wristwatch.

 

[JimSC]

I know all brass makes are different mixtures of brass , zinc etc. I'm just curious as to why different makes show such different results from annealing. I use an induction annealer, and the difference in the appearance or annealing mark amazes me. I have some Alpha brass that anneal's and leaves almost no sign , and Lapua that is the poster child for an anneal "ring". It's not a big deal, but I love to know why some things happen the way they do......thanks for any insight....rsbhunter

The color changes are due to oxidation. Each level of heat creates a different depth of oxidation that will reflect a specific wavelength of light and absorb all other wavelengths. The colors you see represent the different colors being reflected based on how deep the oxidation which is based on how hot the metal got at that area.

 

[rsbhunter]

What I was trying to express was the point on the body where you can see the color change of the brass...normally 1/4" to 1/2" down from the body/shoulder junction....probably a totally wrong description.....rsb

 

[jepp2]

Three pics. First is LC factory brass, second is brass all annealed to the same temp (just over 750 F) and the third is brass annealed to over 1000 F (to dull red in a darkened room). The difference you see in the color is due to the patina on the brass when annealed, has nothing to do with the temp the brass was annealed to.
LC Brass

Annealed to just over 750 F


Annealed to just over 1000 F - dull red

 

[JimSC]

Three pics. First is LC factory brass, second is brass all annealed to the same temp (just over 750 F) and the third is brass annealed to over 1000 F (to dull red in a darkened room). The difference you see in the color is due to the patina on the brass when annealed, has nothing to do with the temp the brass was annealed to.
LC Brass

it also has to do with the zinc content, surface contamination and other factors. But show me how you get that oxidation and rainbow ring without heating and I will buy into the "it has nothing to do with the heat" statement


edit - Oxidation forms faster when metal is heated. MG and TIG welders use argon gas in the process to prevent that. If you annealed in a inert atmosphere you would have no ring

 

[JMayo]

That brass is way over annealed in my world .....
But we each play with our toys as we wish !

 

[markm87]

The military spec calls the "ring" an annealing Iris for what it's worth. I think I remember reading an ammo spec that was posted where a visible iris is required for the ammo.

 

[Dave M.]

All annealing, if done right, will leave some discoloration on the brass. If you tumble or clean your brass after annealing, the marks will fade dramatically. Personally, I like the ring and when all of my brass is lined up it shows me even annealing when the “rings” all line up. Peterson brass doesn’t leave the same tell tale sign as Lapua. The first picture is annealed way too deep. Either the coil was too big or the voltage and resultant current was way off from what it should have been. That heat affected zone and resulting “rings” should never transverse that far into the body of the brass. You DO NOT WANT to anneal the body of the brass more than 1/8”, and especially the case head / web area should never be annealed.
Dave M

 

[jepp2]

The first picture is annealed way too deep.

I share that opinion. But I would be willing to bet this - New Factory Brass loaded in the facility near Independence MO meets spec. And I am also willing to bet their analysis is much better than someone "eyeballing" it.

Annealing, new barrel break in, rifle barrel cleaning are all topics where if you ask 10 people you will get at least 12 "Expert" opinions.

 

[RegionRat]

Its typically the Cu content that varies in cartridge brass. 68.5-71.5% by weight. Zn is 28.5%. The rest is Fe, Pb, and other trace elements.

Correct.

In fact, a few Angstroms difference of those oxides is responsible for the different colors. Parts of that color layer are very weak and clean off easily, others may not.

Those tiny trace element fractions are often the ones that create the variety of colors, but even the cleanest raw material will show a patina from being annealed.

When other metals are anodized you can see this same effect. Titanium for example, can have a rainbow of color changes from a tiny difference of thickness in oxide layers and is used for aesthetic purposes.