SmallCaliberCentral

Hi,i know this is way of topic but could someone please help. A friend of mine shoots a flint lock and he case hardened the piece of mild steel that acts with the flint to cause the sparks, result... no sparks. Does anybody know if re-heating the part and allowing it to cool will reverse the hardening process. Thanks in anticipation KB.

Kenbro: Yes, you can re-soften it up by annealing the affected part. Instead of creating a way off topic thread, just Google "heat treating" and "annealing", and you'll be set. It's not a big deal, and can be done in less than 1/2 hour.

Did he try re-adjusting the flint or changing the flint out?

Hi Rick,thanks for that ,googled but could'nt find anything specific about reverse case hardening ..the guy has decided to go with reheating and allowing the part to cool in it's own time, should be ok but not end of world if it fails. When i googled heat trreatment my brain started to hurt, there's just so much highly technical stuff involved. Sorry about abusing the forum. regards KB.

Hi Glen, yes he did change the flint, when i asked him about the "flint out" he did'nt know what i was talking about and neither did i, i've never bothered with flintlocks so don't know the terminology. Thanks for the reply, regards KB.

Kenbrofox: you may tell him to pick up a copy of the machinist handbook; inside it outlines a few different methods for heat treating, case hardening, and a bit more metalurgy that may help his cause.

Case hardening is actually the adding of carbon to steel, generally done with a heating the metal to a specific tempature while it is surrounded by a high carbon content material (think charcoal briquets). Work hardening is similar to case hardening in where a repeated action causes the material to dislocate itself (surface level only) reducing the structures ability to give and increasing the surface strenghth. Imagine that the material has a linear grain structure, when it becomes work hardened the grains start to shift into a lattice like structure.


Annealing is a stress-relieving process. To do this one would gradually heat and hold the metal to a specific tempature ( never more than the materials initial tempering tempature or you'll just harden it more ) to stress relieve it. Be warned if you don't wrap the material in a stainless foil you'll get a scaling product out of the oven, not detrimental to the metal, just takes a wire wheel to remove. After you pull it from the oven, set it upright with as much of the surface exposed, and run a fan on it allowing it to air cool, don't quench ( dip ) it in water or oil as this will just reset the temper.

The process should re as followed, though I'm doing this from memory and don't have a book here. This is merely the process that we use to stress relieve dies and molds (moulds lol), I'm not insisting nor encouraging you to do this as I don't know the specific material that is being used. Consult with an actual gunsmith or other saavy person before you try this as it make result in material failure and accidental death or dismemberment.

1. remove all oils, solvents, dirt and grime from material to be stress-relieved.

2. make an envelope out of stainless foil, insert metal, close envelope, wrap envelope in second layer of stainless foil

3. insert stainless foil wrapped metal envelope

4. Heat baking oven to 450'

5. let sit at 450' for 2-4 hours depending on the degree of workhardening you believe has occured

6. remove envelope, remove metal from envelope; use gloves the material is HOT.

7. sit upright in front of a fan until it is cool to the touch.

that should do it, but again consult with someone that knows the material and can give an exact tempature range to stress-relieve at.

BPAIGE

savage rookie, thanks for that exellent info, i will pass it on to my friend ( he's 80 and has never had a 'puter) so he can decide himself which way to go. Regards KB.

Case hardening is actually the adding of carbon to steel, generally done with a heating the metal to a specific tempature while it is surrounded by a high carbon content material (think charcoal briquets). Work hardening is similar to case hardening in where a repeated action causes the material to dislocate itself (surface level only) reducing the structures ability to give and increasing the surface strenghth. Imagine that the material has a linear grain structure, when it becomes work hardened the grains start to shift into a lattice like structure.

Savage, I used to do some hardening and tempering as part of my regular job, but it's been a long time. As I recall you can't harden mild steel, but we did have a metal spray kit and with a torch, shaft or whatever turning in a lathe, that was the only way we could case harden ordinary mild steel, or am I wrong? (The sprayed on material was actually the case hardening) I did make and temper some chisels, etc, that were hard as store bought, but I got the correct type steel from the steel rack, high carbon maybe? Maybe that's what the OP needs for his component.

In my experience, case hardening can be difficult to remove. Annealing the metal might (I stress MIGHT) work. Case hardening usually drives nitrogen and carbon in to the surface of the steel. Annealing might remove enough of the carbon and nitrogen to return the steel to a softer condition but may not take it back to dead soft.

In the olden days (long before I was born and I am 55), soft steels were often case hardened by heating, coating with potassium cyanide, then the cyanide was burned away. This method wasn't too popular, as one good whiff of the fumes would drop the blacksmith or gunsmith dead in their tracks. No kidding. It worked great but was extremely dangerous.

The other method used an iron box and a forge. The part was packed very tightly in the iron (air tight) box with horse hair, hoof trimmings, bits of leather, and sawdust. The sealed box was then placed in the forge and allowed to cook all day, while the forge was used for other tasks. This 'cooking' drove the carbon and nitrogen from the packing in to the surface of the steel.

Whether using the cyanide or cooking method, the hardening was completed by quenching in cold water.

Today, a good job of case hardening can be done with a product called Casenit (I believe I spelled that right). Just follow the directions and it will work quite well. You had better have the part the way you want it though. After the case hardening, a file won't even touch it.

Good luck drawing that part back to dead soft.

Bill.

Hi Bill, thanks for your input. like you said annealing MIGHT work but i have not been able to find anything definate to say it will so i have given my friend all of the information gathered on this forum and now HE can decide how to proceed. Thanks to all. KB.