Since we're on case hardening...

[G_T]

Dumb question here...

I'm thinking of taking a lock plate (Chambers Late Ketland in this case as that's the one I'm fiddling with at the moment but it could be any) and case harden it inside a clay tube packed with bone black, leather scraps, etc, and a pinhole. Possibly even a little potassium ferrocyanide. If I just just let it all air cool inside the clay after being heated for a while, would that eliminate or nearly eliminate warpage issues? Due to the clay and the stuffing the metal would heat and cool much more slowly and I'd expect a lot more uniformly.

Would surface hardness improve enough without quenching and tempering to be worth it? That is, should the plate acquire a bit slicker surface that is more wear resistant and not unattractive?

If you think it would work or know of it working, do you think it would also be suitable for the cock and bridle as well, and possibly other parts?

I know for frizzen, tumbler, sear, proper hardening and tempering is required regardless of case or not. If I did those, I'd give them a secondary heat and oil quench, then temper as needed. I already got surface cracks on one frizzen from water quenching though I've gotten away with it in the past. I didn't get it immediately tempered - my bad!

Gerald

[shortbarrel]

Done many CD locks .Looks like your are on the right path.Before I comment here,I hope some more post come up.

[Anonymous]

If I just just let it all air cool inside the clay after being heated for a while, would that eliminate or nearly eliminate warpage issues? ......... Would surface hardness improve enough without quenching and tempering to be worth it?

Shouldn’t warp, but without quenching you will not harden it. Just letting it air cool as you describe is basically an annealing process.  There is such a thing as air gardening steel, but that’s not what you have here. 

[bob in the woods]

For what it's worth, I tried sugar and just couldn't get it to work . Didn't get any appreciable increase in hardness.

[Metalshaper]

For what it's worth, I tried sugar and just couldn't get it to work . Didn't get any appreciable increase in hardness.

Bob,

 straight sugar or did you carburize it first?? just curious.. Knife guy I knew would fire sugar to carbon.. then mix a paste and pack a blade in it..
said it added the extra carbon and made his edges hold even better?? His mojo, so who knows??

Respect Always
Jonathan

[rich pierce]

My understanding is quite limited about traditional case hardening but I think iron is cooked packed in a semi-sealed container with carbon rich material so that the carbon gases generated in an oxygen depleted atmosphere can carburize the iron. I don’t think a slathering on of a carbon rich substance and brief heating in open air can accomplish anything.

My understanding of quick case hardening materials like Kasenit is that they work quite differently and if a less toxic, carbon-only material worked as well in open air, we’d use it.

[Carl Young]

This is probably more than anyone wants to know on the subject (except JCKelly), but FYI:
https://scholar.google.com/scholar?hl=en&as_sdt=0%2C25&q=carburizing+steels&oq=carburizing+

Carl

[jerrywh]

There is no big mystery when it comes to case hardening. Iron has an infinity for carbon. When heated to a temp of 1500° F iron will absorb carbon at a certain rate pr hour, Aprox. .010 pr inch pr. hour.  It makes little difference what the source of the carbon is. Just plain wood charcoal is about as good as anything. But for doing something like a screw the problem is in keeping the screw in contact with the carbon long enough for the screw to absorb the carbon. Many old blacksmiths used potassium ferrocyanide. But when that was not available they would have made a past out of powdered charcoal and salt. When heated the salt would melt and hold the charcoal in contact with the metal. Even chicken manure will work pretty well in a pinch.  However the best option is to pack harden the whole lock and all the parts in a pack containing carbon. Such things as hoof parings and leather were used just because they were readly available in a blacksmith shop. Not because they did a supirior job. The type of carbon used has little to do with the colors or the appearance of the finished product.  It is the bubbles in the water that produce the colors. You can case harden a screw just by using a
acetylene torch and heating it with a real rich flame for about 5 minutes and quenching it. The carbon rich flame will prevent oxidization just as a gas sieild does in mig welding. Just ask Dave Race, He knows.

[Bob Roller]

I got a pound of Brownell's case hardening compound today just
in time to try it on a double set trigger. It hardened OK but I was
underwhelmed by the color.Another black finish but smooth.
I still have a bit of Kasenit and will use it from time to time
until it's gone.

Bob Roller

[Acer Saccharum]

I don't believe you'll get colors from Kasenit or other such compounds. They seem to leave the metal grey, with a nice skin of hard steel.

It's the quench, coming from a carbon pack, that gives the colors in my experience.

[jerrywh]

I agree with Acer

[bob in the woods]

Metalshaper, I tried the straight sugar, but will give it another go as per your post

[Bob Roller]

I don't believe you'll get colors from Kasenit or other such compounds. They seem to leave the metal grey, with a nice skin of hard steel.

It's the quench, coming from a carbon pack, that gives the colors in my experience.

It would have to be the quench.I use 5 gallons of distilled water and 2 pounds of
potassium nitrate and Kasenit and get some nice colors. The Cherry Red and the Brownell's
harden OK but there is nothing pleasing to our eyes.

Bob Roller

[Dan Fruth]

I have always used Kasenite, and the colors I get are grey and black. I found a 1# can on Ebay a while back, and have plenty for my work.                                                                                                                                                                       


upload pic

[Metalshaper]

Metalshaper, I tried the straight sugar, but will give it another go as per your post

Bob,

 Just know it was the knife builder's mojo, not mine.. He had really nice blades and always bragged on the edge retention..
might of just been he used the right steel and quench??

Respect Always
Metalshaper/Jonathan

[Acer Saccharum]

I don't know what the knife guy was using......

But I've seen recreations of Viking swordsmithing, where the steel is packed with manure, bone, leather, and surrounded in a clay shell. I'm going to guess that this infused the steel with carbon. You'd still have to quench the blade when red hot to get the hardness.

You certainly can add carbon to the steel in one operation, then re-heat and harden in another.

[jerrywh]

 Like Acer says, You can add carbon in one operation and then reheat and quench in another but you will not get colors. In order to get colors the steel must be polished to a degree and then kept from contact with oxygen until it is quenched. Then the oxygen in the bubbles will give the colors to the steel.  The colors are nothing but different degrees of oxidization. Better colors are obtained if the steel is quenched at a temp of about 1350° to 1300°F. Those temps will still give you a hard surface and will not tend to warp as bad. 

[Metalshaper]

I don't know what the knife guy was using......

He was firing the sugar and reducing it to mainly just the carbon.. Burn sugar and you get the idea? I don't know where he got this idea from, like I said it was HIS mojo < not mine >
then he packed the edge and then did whatever his heat treatment was???

Respect Always
Metalshaper/Dagwood

[Bob Roller]

I have always used Kasenite, and the colors I get are grey and black. I found a 1# can on Ebay a while back, and have plenty for my work.                                                                                                                                                                       


upload pic

Try the nitrated water and before heating the part(s) to be hardened,stir the water
with a wooden dowel rod or agitate it with a fish tank aerator and hose.
I know this works and I prove it at least twice a week.

Bob Roller

[JCKelly]

Carl Young were I still employed I'd be drooling over that article by Cao, Enst & Michal!
Back to "reality". If you wanna harden the thing you case-hardened you gotta quench it, preferably in water

Atually the stuff you use for the pack does matter. For the best sliding wear, as on a lockplate, good to have some hoof parings or old leather. They provide nitrogen which is good for DoNotWear hardness, if not for impact toughness.
The beautiful case colors on 19th century guns came from the use of some bone black. It is the tri-calcium phosphate in the bone black which does it. One can get some colors from other mixes but the best will include some bone black.
If you really want to get into COLOR case hardening, read Parts I & II of The Color Case-hardening of Firearms, by Oscar L. Gaddy, in The Double Gun Journal, Winter 1996 and Spring 1997. I might just have these on computer & could email them to one who sent me a real email address.

This goes beyond the original question. Quench the thing into water, directly from the pack & the surface will harden. You may also get some warpage.

As far as sugar goes, some use it in coffee, others on their morning oatmeal. I'd keep it out of the heat treat area, though.

[Clint]

To answer the OP, adding carbon to a piece of steel and cooling it normally will not change the physical characteristics of the metal at all. Rapid cooling will, as we all know, harden the piece and tempering will bring the hardness down to a tolerable degree. A lot of people will tell you to dump all your lock parts into water from a red heat and watch out for the splash. I have hardened thousands of parts and have never "dumped" any of them into a quench. If, for instance, you load a lock plate flat side into the quench, the flat plate and bolster freezes while the pan is still very hot and cools last. That will pull the lock plate towards the pan as it shrinks. If you go into the quench pan side down the pate will pull towards the bolster. SO put the plate into the quench on edge upside down that will freeze the bolster and pan then the plate. Also point the plate north south magnetically and think positively. That will give you a little voodoo and a dash of quantum physics.
Important to note that it is not contact with charcoal that that transforms the metal to carbon steel but rather an envelope of carbon monoxide generated from the charcoal. The carbon monoxide is generated from the heating of charcoal in a oxogen poor atmosphere. All of the other stuff in the horn, bone leather etc add to the mix in the same way that small amounts of thyme turmeric chili etc change the subtle flavors of a cooking recipe. Salt and egg shells are accelerants and reduce the amount of time it takes to carburize parts.
Clint the blacksmith

[jerrywh]

JCKelly. Just for the record, When I case harden I usually us 1/3 bone charcoal. and 2/3 wood charcoal.   I have noticed only a slight difference in the colors though. I buy my supplies from Brownel.  Bob, If you quench at about 1350 you will get a lot better colors and in fresh cool water.  If you heat your parts to 1650 or more you will loose all the color unless you let the pack cool down before you quench.
 1 question , isn't hoof parings the same as raw bone meal unless you char them first???

[rich pierce]

Wood charcoal is low in nitrogen.  It’s mostly carbon.  Proteins are nitrogen-rich because amino acids have nitrogen in them.  Hoof parings are made of keratin protein, like fingernails.  In hide and bone, collagen is the main protein. If protein is protein and the specific amino acid composition doesn't matter (I’m guessing it does not matter) then smiths used what was available, reasonably dry and easy to char, and often throw-away materials. Bones, hoof parings, and hide scraps fit those criteria. I’m sure you could pack with charred beef jerky as a protein source but it’s not a throw away material.  Bone has added phosphate of course and that may be important,or not.