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VoodooMajik
09-02-2012, 09:17 PM
I watched some footage of an old gun HT method I thought was pretty neat. They pack the steel in a container with Charcoal and Bone. After packing they place it in furnace, forge or what have you. and heat it to I believe 1200 degrees. Same tempurature as lava from a volcano, nearly at melting point then quench it. The steel gets so hot that it pulls Carbon from the Charcoal and bone.

There are warpage issues and I'm not certain how it would land on the HRC BUT Could this HT method be applied to knives? appling this to a damascus blade may be interesting!

Some of our more scientific makers/crafstmen/metallurgist may be able to shed some light on this. How it may effect the steels composition and characteristics. If this is something that has not been widely done in regards to knives, maybe DT, BB, Butch, pierre or someone may be willing to give a petty knife a shot.

Would it stengthen ware resistance?

Would it be to Hard, possibly to brittle?

Would the fact that it draws out carbon from it's environment during Tempuring alter the composition in an unworkable or unpredictable manner?

Just something thats been rolling around in my head lately..

SpikeC
09-02-2012, 10:21 PM
Sounds like case hardening to me, the steel gets carbon at the surface butt the core remains lower carbon, and thus resistant to shock.

GlassEye
09-02-2012, 10:23 PM
Sounds like case hardening to me, the steel gets carbon at the surface butt the core remains lower carbon, and thus resistant to shock.

Sounds like the opposite of what one would want in a kitchen knife.

jmforge
09-02-2012, 10:50 PM
It is case hardening. You also get the pretty colors, but they are not terribly durable from what I am told.

PierreRodrigue
09-03-2012, 03:00 AM
Case hardening is still done today in some commercial applications. it is a surface treatment only. I have done it when i was a budding young machinist student. It only affects the outside to a couple thousandths of an inch. We used it when making precision spacers on horizontal milling machines.

SpikeC
09-03-2012, 08:46 PM
When I was 19 I worked in a plating shop and we copper plated the base of ball joints so the ball could be case hardened and the base not so they could be welded on to a base. The end result was a tough component that was very wear resistant on the working surface. The hardening is very thin, so if the ball was honed on a water stone it would then wear out very quickly!

Bill Burke
09-04-2012, 01:37 PM
I saw that addition of american guns and like alot of the **** they do there was some misinformation aired. You could do this to a knife BUT: if you used mild steel then the high carbon edge would go away the first time you sharpened the knife. If you used a high carbon steel it would most likely crack when you dumped it into the water. It might be able to be done on a single bevel knife successfully though but sharpening would have to be done very carefully.

What is the approximate temperature of molten lava?
Approximately 2000 degrees F unless it is in a Lava tube, then it can be over 3000 degrees F because the heat is contained. This also allows the lava to stay in a liquid state and travel farther as seen in Hawaii where it travels undergroun... Read More
Source: http://answers.yahoo.com/question/index?qid=1006050601092

Knife steel melts about 2750 F or so and iron is higher than that and cast iron is lower. And I'll have to check but I think the temp for color case hardening is higher than the stated 1200 degrees F also.

from brownells website, which is the kit they used;

Attempts to color case harden firearm components without proper training
in bracing and blocking procedures will likely result in warped and
ruined parts. Typical oven temperatures range from 1350 F. to 1425 F.

To color case Harden you have to be above the austenitizing tem of carbon steel about 1325 degrees F or there is no hardening.

jmforge
09-06-2012, 01:22 AM
Bill, the other important question would be if the pretty colors on case hardened steel are any more durable than what we get on carbon steel out of the tempering oven or by using a torch? With modern medium carbon steels like they use for firearms parts today, the only reason to case harden IMO is to get the colors.

Bill Burke
09-06-2012, 09:09 AM
Bill, the other important question would be if the pretty colors on case hardened steel are any more durable than what we get on carbon steel out of the tempering oven or by using a torch? With modern medium carbon steels like they use for firearms parts today, the only reason to case harden IMO is to get the colors.

You are right JM. and while the color is a little more durable than tempering colors it is very easy to remove.

joec
09-06-2012, 02:18 PM
I have 3 guns that are case hardened the old way and some with chemical methods (modern way). They don't rust easily however the metal gets pretty hard and is almost impossible to engrave after it is done with standard engraving tools. Now I bought a 12 ga shot shell holder for a reloading press that is case hardened also which surprised me to say the least. As for warping it happens but if perfect temperature control is maintained it rarely happens. You do want to do all machine work etc done before doing it.

Now as for a knife I would have doubts about the hardness of the steel being brittle in some cases as well as how hard it would be to sharpen.

VoodooMajik
09-07-2012, 08:20 PM
Guys have alot of info! Could the method be altered to have that ware resistance penetrate through the rest of the steel?

SpikeC
09-07-2012, 08:45 PM
No.