Heat treat question

[killthelights]

Something I haven't seen much in heat treat recipes is when to put the blades in the oven. And what little i have read is conflicting. I would guess it varies with every steel. But if it's not stated do you put the blades in the cold oven and let them heat to austinitize point or do you put them in at the targeted temp? Thanks.

 

[Scaniaman]

I heat the oven to aust temp and let the whole thing soak at it for 30 min or so.
Then pop the blade in. Temp will then drop a little and then over-shoot a little before stable at aust temp again. Once stable at that temp I start the clock for soak time. 10-15 min for my steels RWL 34, AEB-L and 14c28N. Then plate quench.

 

[JTknives]

I would Never put a blade in a cold oven. The oven does not heat evenly on warm up. Our standard is to let the oven reach temp and then we let it soak at that temp for 1hr. Then we put the blades in the oven and add about 5min to the soak time that’s listed for the blade(s). I have a window in my oven so I can watch the blade to see when it hits temp.

 

[killthelights]

I heat the oven to aust temp and let the whole thing soak at it for 30 min or so.
Then pop the blade in. Temp will then drop a little and then over-shoot a little before stable at aust temp again. Once stable at that temp I start the clock for soak time. 10-15 min for my steels RWL 34, AEB-L and 14c28N. Then plate quench.

I've been using a lot of AEB-L lateley so this is good to know. Thanks!

 

[killthelights]

I would Never put a blade in a cold oven. The oven does not heat evenly on warm up. Our standard is to let the oven reach temp and then we let it soak at that temp for 1hr. Then we put the blades in the oven and add about 5min to the soak time that’s listed for the blade(s). I have a window in my oven so I can watch the blade to see when it hits temp.

This is very interesting and I'm glad I asked. I've never heard or read about letting the oven soak at temp before putting the blades in. It makes perfect sense though. Thank you!

 

[JTknives]

I heat the oven to aust temp and let the whole thing soak at it for 30 min or so.
Then pop the blade in. Temp will then drop a little and then over-shoot a little before stable at aust temp again. Once stable at that temp I start the clock for soak time. 10-15 min for my steels RWL 34, AEB-L and 14c28N. Then plate quench.

Not sure about your oven but mine will stabilize before the blade is up to temp.

 

[Scaniaman]

Not sure about your oven but mine will stabilize before the blade is up to temp.

That is interesting. What kind of time have you measured between oven stabilized and blade at temp?

 

[HSC ///]

in at the targeted temp (or very near to)

 

[JTknives]

That is interesting. What kind of time have you measured between oven stabilized and blade at temp?

It all depends on blade size and your oven. But here is a test coupon of our Damascus. Oven stabilized rather quickly which you would expect because it’s a small coupon. But then a quick peak in through the window and it’s far from being at temp. And to make things ever more confusing the TC is about an inch away from it. The TC runs along the floor and enters from the right side of the oven. You can see it right behind the coupon. The coupon is setting on the edge of a chunk of stainless angle iron. I will time the next sample to see how long it takes to actually equalize. For us the window is invaluable and was the best thing I ever did to this oven. I don’t know why other oven manufactures don’t do this. It’s nice having the TC in the same view as the blade because once the TC and blade are the same color you know that’s the temp of the blade.

 

[Scaniaman]

I will time the next sample to see how long it takes to actually equalize

I'll be very interested to hear about that, thanks. What is your Watt and chamber size on that kiln?
Yes, the window is a clever addition!

 

[JTknives]

I’m just under 5000w as I wanted to be able to use a 20amp 240 breaker. When I built it I was only doing a few knives at a time so the chamber is 5.5”x5.5”x32”