Old time recipe for hardening a gun part in the wild

[jerrywh]

 I read this in an antique black smithing book about 60 years ago. I know this works for small parts. Take the part and wrap it in a piece of leather. Then wrap the whole thing up in a ball of clay and allow the clay ball to dry thoroughly build good fire and let it burn down to get a bed of coals. Place the clay ball in the coals and build more fire on top of it. After an hour or two dig out the clay ball and while still red hot quench the whole thing in cold water.  The main thing here is to be sure the clay ball is good and dry first.

[davec2]

Jerry,

I wasn't sure I believed this 40 years ago when I read it.  I wrapped three 16 penny nails in a leather thong, covered it with clay, let it dry out, and then threw it in a fire.  After a few hours, I fished it out and quenched it just as you describe.  The nails were soft (i.e. cut easily with a file) when I started but were hard (i.e. file skated off the surface) when I got them out of the quench.  Worked great !!

[smylee grouch]

Would the said part be usable as is or would you have to draw it back some?

[Craig Wilcox]

Smylee, I have done this, and the parts DID come out hard enough that a file wouldn't touch them.  Just polish the parts-pieces, and heat to 500-700 degrees for a bit.  Or treat them in your oven at about 400-425 for an hour or so.  You can also use a butane or propane torch to draw them to a dark blue.  That will make the part useable, and not liable to crack into a zillion pieces if you drop it on something hard.

[ScottH]

What kind of clay works for this?
Thanks

[jerrywh]

Has to be natural clay. The dime store stuff is plastic of some sort.

[yulzari]

Best illustration of the process ever.

[Dennis Daigger]

Thank you, yutzari!  Clickspringprojects.com is an extraordinary source of information.

[shortbarrel]

The nails might have had carbon in them, Use wrought iron iron on your next test. I this system works.

[longcruise]

Is this a case hardening process or harden through and through?

[44-henry]

It is a case hardening process. The carbon material
generates carbon monoxide and dioxide as it is heated and eventually the carbon diffuses into the low carbon steel creating a high carbon case around the part. Time and temp play a crucial role in the process. If left in the pack long enough, assuming a good supply of carbon it can penetrate though the material giving a crude form of steel. In the colonial period this is basically how blister steel was produced. With blister steel the carbon content was inconsistent so the bars would be forged out to work the carbon more uniformly through the material. Once this refinement was done they were called shear steel. The more times this was done, which involved folding the material as it became to thin and subsequent forge welding the grade increased and was referred to as double, or even triple shear.

Is this a case hardening process or harden through and through?

[longcruise]

So, if i formed a trigger out of sheet welding steel that would case harden it?

[Clint]

Most steel objects made today are some variety of low carbon steel. Heating, welding soaking in Pepsi cola etc will have little effect on the metal. Hardenable steel needs to have a measurable percentage of carbon in it. How to put carbon there is the subject of this thread. If you have steel that is very difficult to cut with a hack saw, like allen wrenches or hoe blades, there is probably carbon present. The classic destructive test for carbon steel is to heat it to red and quench it in water. After the quench the metal will either shatter with a hammer blow or bend. If it bends and you still want to harden something made from it you will have to supply your own carbon. The original post is one method for adding carbon to the surface of the steel. I met a man at a shoot in Rhode Island, years ago who made really nice knives out of mild steel and through hardened them with a carbon pack in a camp fire. Steel is the coolest metal in the world.

[rich pierce]

So, if i formed a trigger out of sheet welding steel that would case harden it?

Yes, this and other case hardening methods would work to harden it. Are you talking simple trigger or making set triggers?  I’ve seen original single triggers that were never hardened.

[longcruise]

Talking simple single triggers.  Would a potter's supply outfit have suitable clay?

[jerrywh]

Yes. a potter supply would have tge correct type of clay.

[dogcatcher]

The leather wrap adds a layer of carbon to the steel which helps in the hardening process.  When the heat hots the clay, the leather starts to burn without flame, when making charcoal in a sealed can.  I cannot explain why, just something I remember seeing my grandpa do in his blacksmith shop.  I know it works, but the "why" is not in my pay grade. 

[vtmtnman]

I didn't realize case hardening mild steel was actually this easy to do.Thank you for this thread.I'll have to try this at the forge at some point.

[Joe S]

Case hardening is done by heating the steel in an atmosphere rich in carbon monoxide and carbon dioxide gasses, in the absence of oxygen. The source of the carbon does not matter. Wood charcoal is commonly used for our purposes. In this case, the leather wrap is composed largely of carbon. As it is heated, the leather turns into charcoal. The charcoal goes from the solid phase to a gas, which then diffuses into the surface of the steel. The carbon rich surface of the steel turns mild steel that cannot be hardened into a carbon rich surface that can be hardened, while the interior of the steel is still mild steel.

[flinchrocket]

Thank you Jose, now,the longer you leave it at high temp surrounded with carbon the deeper the carbon will penetrate the steel. Is that correct?

[Joe S]

Yes, although I do not know the details off the top of my head. Time and temperature curves are available on the net, or you could just ask Jim Kibler. He is actually a metallurgist - I'm a biologist.