Heat treated and tempered my first knife yesterday.

kristoffsky

kristoffsky

Joined
Mar 8, 2011
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Built a little furnace out of bricks and heated it with a torch, with a pyrometer in there to help gauge temperature. Got the A-2 good and hot, and air quenched it. Tempered it at 450 twice. It seems to have come out all right. However, I left the blade pretty thick (thinking there was a good chance that I'd warp it or something) and...wow. Trying to grind in the rest of the bevel sure is taking a while.
 
Welcome to the first hurdle in making your own knives. You discovered the second when grinding the hardened blade. Thick enough for heat treat is usually not thin enough to cut. Most will say that A2 is not a good choice for torch hardening. (FWIW I'm one of them) Is there a reason you used A2 vs. something like 1095 or 1080, or even O1? Sometimes you just have to go with what you got, and A2 can be easier to get than the others. My local Fastenal can get it easy, but I have to look long and wide to find other stuff, especially locally. On line dealers have much more variety.
 
Well, originally I had planned on sending it to someone for heat treating, and the place I was looking at only did air hardening steels. Then I decided to do it myself.
 
There are a lot of negatives when doing air hardening steel with an open chamber and little equipment . Temps, soak time, oxygen exclusion, proper quench, cryo,etc.
It may have got "good and hot" and seem "all right", but there can be all kinds of internal problems with the alloys and carbides.

The plus for air hardening steel is that if you can control these things in a proper HT oven with a foil wrap, you can make the blade almost final thickness and polish before HT. This is why many/most send out their air hardening steels for HT. They have $100,000 of equipment to do it right every time. The blade comes back without decarb and stains, dead straight,and needing only final sanding and sharpening. They also test the results and give you a Rc hardness.
 
Have you had a chance to cut with it yet? Any edge chipping, rolling, or other issues?
 
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