Heat Treat Question...

E

Echo4v

Joined
Dec 10, 2008
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I have a knife at home ready for heat treating ( waiting on forge to get here to heat treat it) but I saw something that has me wondering. So I've come to the experts for advice.

When you heat treat a full tang knife, how much of the tang do you heat treat? I saw a guy who has made a lot of knives heat treating and it looked like he only heated about half of the tang. Would that cause potential problems down the road, or is it no big deal since the handle scales will reinforce the steel in that area?

Thanks for the advice
David
 
Lots of makers either leave the tang soft or temper back the tang severely after
quenching the whole knife. The primary idea is that a tang needs to be tough
not hard. Furthermore, it's hard to drill holes in a hard tang.

Despite those reasons, others keep the entire knife, including the tang, hard.
One argument for that is that a properly made hard tang won't fail under any
reasonable stress anyway. Another is that air hardening steels, including all
stainless knife steels, resist selective tempering by their basic design.

For those who oil quench in special quenching oils, partial quenching will cause
the oil to burn which will quickly degrade your somewhat expensive and carefully
obtained quenching oil. If you want a soft tang, you can always temper it back
afterwards.
 
Good question and answer....how is the best way to temper just the tang?
 
Mr. Peirson,

First let me say thank you for the quick response...

Secondly, let me make sure I'm understanding. A tang which is softer than the tempered blade is preferable to a tang that is tempered the same as the blade? How would you accomplish this? Clay coating the tang when tempering? Leaving the oven open with the tang outside the oven while tempering? Or would not heat treating the tang cause it to remain softer even through the tempering process?

Thanks Again
David
 
Some makers consider a soft tang better than a hard one. Others disagree.

Clay coating, not getting the tang as hot as the blade before quenching and partial
quenching can all give you an unhardened tang if that's what you want.

"Leaving the oven open with the tang outside the oven while tempering" is not a
good idea. First, it will mess up the rest of your tempering. Second, if you succeeded
you would succeed in not tempering the already hard tang, thus leaving it harder and
more brittle.

Tempering a hard tang to a higher temperature than the blade ("drawing the tang" more),
will result in a softer tang that is likely to be tougher than an unhardened
tang. There are many threads on this site about doing this (I haven't done it myself
so you'll need an answer from someone else for more detail there).
 
You could clay coat the tang when hardening. Then temper normally, and yes the tang will not have gotten hard (or as hard) in the first place, and will stay that way.

Or you could harden the whole blade (hard and brittle), temper normally (the whole piece will be tougher but still hard enough to keep an edge), and then re-temper only the tang at a higher temp (even softer, wouldn't hold an edge well but very tough).

I believe most makers who do this use an oxy/acetylene torch. You can even use a hardware-store propane torch, but be careful. Since it doesn't get all that hot, it heats up the steel slowly, and of course the heat wants to spread out through the whole blade. So it's a little tricky to get the tang up to the temp you want without getting part of the blade too hot and softening it some, as well. Submerging the blade in a can of water, with the tang stick out so you can heat it up, helps a lot.

If you're making a big chopper, combat knife with a long stout blade, this is a real good idea. But honestly on a smaller knife, it may not be worth the trouble.
 
I make all my full tang knives by heat treating the entire thing the same. My reasoning is that I know that my blades are strong when finished, resilient, tough, hard enough to take and keep an edge but still with enough 'spring' to avoid undue breakage. These are the properties I want in the tang too, so the whole thing gets the same treatment.
I make competition cutrting knives from 01 steel and treat them just the same way. I'm yet to see anyone use (as opposed to abuse) a knife as hard for chopping as we do when cutting a 2x4 in competition, and I know my blades withstand that, so why not treat the tang the same way and get the same performace from that too ?
 
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