Using a forge as a HT oven.

JTknives

JTknives

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Jun 11, 2006
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i have been working on conecting my forge to a pid so i can set a temp and it wil hold it. but my question is this, would i beable to use it to heat treat steals that i normaley would use a oven for. the oven i have at work is so off, by about 300 deg f or so. i am just wanting to do simple steel right now like A2, D2, L6, O1, 5160, S7, W2. this is the steel i have in stock now except the w2 which i will be getting soon. im mostley intersited in L6 as the oven over heated my last blade. thanks
 
JT, I would worry about the uneven heat at forge. I had a couple of good results for D2 in my ex-forge blades HT'd in a black pipe, placed in the middle of the forge. Maybe you can take readings with a TC inside from that pipe. It is doable from my experience as I had no PID and selenoid valve etc. when I tried those D2 HT's in that propane forge, but the pipe thing really did the trick. It was PITA to keep the heat steady, therefore I bought an oven...
 
All of the steels you mention will benefit from an oven, A2, D2 and S7 in particular aren't really simple steels. With multiple thermocouples you might be able to maintain some consistency but it seems like a whole lot of work to achieve and iffy heat treat. If you are using air hardening steels, just send them out or buy an oven, it's not worth cheaping out on.
 
I have not relay messed with A2, D2 or S7. it is just the stock i have. right now I am a 5160, L6, O1 and W2 kinda guy as i am now forging out my blades. I have not forged any W2 yet but i will soon. I heat treat all my 5160 In my forge and have had very good results with very little surface scale. i get my forge up to temp and then put the blade in with the edge up. then turn it down to where it is barley running and let the blade come up to temp. when the blade is up to temp i let it soke for 8 min. the blade is a very even color meaning i can not tell a color difference from the tip to the start of the tang. with my 5160 i have been hitting around 65 rc after quench and after a 400 deg f temper for one hr i hit around 58.5 rc. so i have been very happy with my forge. i now want to heat treat my L6 in the forge as i get hardly any scale in my forge and i hate foil wrapping my knives so they can be used in the oven. I tryed heat treating in the oven with out the foil wrap and the scale was so bad.
 
Yes, a real heat treat oven is better and if you are doing a fair amount of air hardening steels then by all means buy (or make) your own oven in the future. If you are like me and decide to heat treat your own occasional air hardening knives, the following will help you:

PID or pyrometer is a must.
Needle valve after the regulator to fine tune the propane.
Gate valve for the forced air (or other method to control air flow.)
Stainless steel pipe to place inside the forge to even the heat.
Stainless steel tool wrap for the blade.
A fresh 20lb tank or large propane source (you don't want the propane to start dying off halfway through the cycle)

These steps will work on air hardening steels. I have used Indian George's forge (I copied his set up) and I have seen it hold a steady temperature for several hours.

Personally, if I spend alot of time on a quality knife for someone else I will send it out for proper heat and cryo treatment.
 
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