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What does that mean ed ?

Miller

Yes you are correct… in that annealing does not remove the carbon, but it does disperse the carbon a little more and a little deeper. A hypothetical example; SAE 1010 case hardening steel, case hardened, then annealed may change the carbon content of the steel from .10% to say .12%, which is still within the “safe zone” for case hardening steels (less than .25% carbon).

Steels with greater than .25% carbon are usually considered thru hardening steel, where there is enough carbon present for the steel to harden all the way thru.

For very thin parts this may be a problem, An example of this is if you have a very thin area say .005 thick of low carbon steel (SAE 1010, with .10% carbon) and you case harden to a depth of .002, then anneal the part, you have probably increased the carbon content so that piece may be equal to 1020 or 1030 with .20-.30% carbon, too much resident carbon to be safely case hardened.

Case hardening is certainly not a no risk endeavor. There are way to mitigate the effects such as reducing the soak time at critical temp, reducing the quench temp below the critical temp etc. But the bottom line is that the case hardener needs to have the experience to make that judgment call.

There have been several times that I’ve turned down work, and have refused to case harden a part, the risk just wasn’t worth it.

But on the OTOH, I have seen some folks that would color case just about anything.

Hi Mike, interesting stuff. Actually I think your last two comments there make a lot of sense. For me it was the excitement coupled with just wanting to extend my gun smithing skills. I Admit I've bought a Greener which some say is not worth the risk, but actually, it's a nice little hammer gun that I really wanted to see if I could replicate somewhat it's earlier days...it didn't cost me a lot so it's my risk.

The big thing I've taken from this thread is that it is very true that one shouldn't CCH everything and that some guns should just be twinkled up a bit and left...V true.

Regards,
T

Nothing is without risk.....

In over 25 years of CCH, I have never observed so much as a microscopic crack in any of the parts that I have quote "re-cased".....and I have always magnafluxed (if you know what that is) all my parts through a relatives aircraft crankshaft shop.......

But surely you and Miller know more than the rest of us......and since I do only my own personal guns and parts, I really don't care what you or Miller think or read......both of you need to go out and get some fresh air IMO...........


**Tony: Don't let these people throw water on your great new beginning's......you've done a super job.....

Thanks Doug, I always listen and read peoples views. I'm the type of person that will of course go my own path

Tony, I suspect you won't know if you have warpage until you try to fit the barrels. It would have been nice if you had measurements pre and post. Just cause I'm weird that way. Feeler gage type measurements.

The only place where I can see an embrittlement issue on an action would be when an action had been recased several times. Not common, yet. Most recasing soak parameters are necessarily well within range.
At the met lab sections are routinely cut, polished and reviewed. Case depth takes time. Non-linear time. So, excluding the multi cased action, there is considerable leeway, within the conditions normally used, trained in, and passed along. In cases like these,where destructive testing isn't possible, you just want a procedure that keeps you between "too little, and too much".
Not everyone is comfortable just doing as they are told. Some of us like to know exactly what the range is we can get away with, and what effects our little flourishes leave behind.
Some believe in magic, some in science. It's all good.

Note: I survived being blown up by an annealing furnace. Very surreal event.

Hi Clapper, I've put it to the barrels and it appears fine, I cannot see any difference gappage than prior to my CCH. However, I have to say I've only researched and gathered my data unscientifically. It's very interesing to read what you say about tolerances. I have to say also that I did crap my self the two times so far that I have dropped the parts into the water. Keep it coming!

Great info all round.

T

Very well said CZ.....

Best,

Tell us about that annealing furnace...you scare me now...am I going to blow myself up? /wink

I'm no expert on these things.
My best friend is. Right down to jury rigging a forge and re-caseing a bale spike in our friends barn. In general,I send him the stuff, his people heat treat it. In the last 30 years I have seen carefully controlled science replace the voodoo.
It shows in the consistancy and quality of heat treated parts.

I suspect, that if we start out with a shotgun that weighs enough to be confortable to shoot, it has enough steel in it to be somewhat forgiving of our secondary manufacturing treatments. Which isn't the same set of determinants as effects fuel economy and highway safety. Or, rifle safety for that matter.
Just a viewpoint.