Full tang O1 heat treat ?

C_Claycomb

C_Claycomb

Joined
Dec 11, 2000
Messages
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This is probably a dumb question, but when treating a full tang, O1 blade with a torch, how should the tang be treated? I know on stub and stick tangs that only the blade is hardened, but it those cases the tang is hidden in the handle. Does having the tang exposed make a difference? If so, how on earth do you manage to keep the whole blade and tang at critical temperature all together?

One other thing, does anyone have their torch fixed and move the blade about, or does everyone move the torch over a stationary blade.

I know, I am being dense! This is the first time I have tried any of this stuff.

Thanks

Chris
 
I always leave the tang soft,because I usually edge quench my high carbon blades.The first heat treat set up I ever made used a stationary mapp flame.It worked fine, but it wasn't pretty.If you are serious about heat treating I highly recommend Evenheat kilns.They are worth the price.
 
A kiln would be great. However I don't even have a workshop of my own, so everything has to fit in a carry bag!! :D Been using a bench at the factory where I work, that is where the torch is. They have a heat treat unit which would have done the blades for free, but they are closing that down and I missed my chance :(

Just curious, how long can one get away with between quenching and tempering? Have heard it to be about 20 minutes. What happens if you excede that?

Thanks
 
Buy 5 or 6 fire brick and bore a hole in one for the torch to fit thru. You'll save alot of gas during heat treat since the brick hold the heat in.
 
It's a good idea to get the quenched blade to the tempering oven as quickly as possible. That said I've diddled around for several hours before I've tempered and I've also put them straight in the oven after quenching. The problem is that stresses in the hardened blade continue to build up the longer the blade is left untempered. Accordingly, the blade can warp, crack or shatter all on it's own. According to Howard Clark, some steels like L6 continue to develop martensite longer than some of the simpler 10xx series steels and this can cause warping so tempering quickly can help forestall problems.

So, tempering as quickly as possible after quenching is certainly a good prcatice to cultivate. I don't think I would wait more than a couple of hours and if I did that enough times I'd probably end up with some problem blades sooner or later.

However, as with all things there are execptions. Some well known makers have developed a heat treat regimen for two steels in particular, 5160 and 52100 that calls for multiple quenching, leaving the blade untempered at room temperature in oil for as long as 24 hours before the next heat and quench. I have done this with 5160 with no ill effects.
 
I got a coffee can, perlite, furnace cement and a corn meal container. Mixed the perlite and furnace cement and packed it in the can around the cornmeal container. Punched a hole in the can and stuck a torch in it. Instant forge. Works good and cheap. Outside of 'forge' does not get hot in the time it takes to heat the blade. Could be smaller.
 
I seriously doubt that I am who he is talking of but as silent said, I normally wait twenty four hours between hardening and tempering and have never had a blade warp or crack in this interim and I have went so far as to emurse an untempered blade into liquid nitrogen after the blade had cooled to room temp I have had them warp and/or crack during hardening though. I think that my success is at least partially due to the multiple annealing steps that I use prior to hardening and also the extra steel that I leave around the actual cutting edge of the knife. The process that I follow is laid out in Ed Fowler's book, Knife Talk. The steel that I use is 5160 and 52100 and also my own mix of damascus.
 
Thanks.

You have pretty much answered my questions. I was worried about the time to temper since the oven I can use is at home and the torch is at work. It would have been a pain in the ass to have to do only one blade at a time.

Now all that is left is to go and give it a try :D

Thanks

Chris
 
I for one am curious about how things come out. Let us know will ya?

Add my own related quesion if I may - does the amount of stress building up in the blade and the consequent warping and cracking depend on wether the blade is edge quenched or not? Does it depend on relative thickness of different parts of the blade?
 
I think that the amount of warping does depend to some extent on how thick the material in question is. I also found out through expermentation that uneven heating will cause warping.

Bill
 
Let me clarify my above post. By uneven heating I mean spendinding more time on one side of the blade than the other. This applies to those of use that use a torch for heating the blade for hardening and to a lesser degree those that heat in a forge. I found in my tests that if you had a slight to moderate bend in the blade after hardening that it could be straitened by heating the concave side of the blade more than the convex side. heat to non magnetic and quench as normal. the blade will mostly straighten on its own. It is vastly better to keep the heateven and avoid the warp to begin with but this may help some if you find that you do have a warp. That is if you don't mind doing a multiple quench:D


Bill
 
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