heat treating D2?

[MixonKnives]

Just curious if any one here heat treats there own D2? I've been doing some research and decided to get some D2 to try out. If at all possible I want to heat treat my D2, I prefer to heat treat all my own blades.

My current heat treat equipment consists of a 3 burner comercially made, ventri style propane forge. And a 10 gallon trash can full of oil. I know D2 is air hardened, so the quench shouldn't be to difficult. But the temp and soak time I hear is CRITICAL.

The only way I can think to keep the forge at a constant soak temp is those controls that turn on and shut off the flow of propane depending on temp.

If I was to keep the forge in the 1800-1875 range, which is the numbers I've read most often on the hardening temp, should there be any problem with heat treating it myself?

As long as my hardening step works out good I just have to work out the tempering/working hardness step.

Thanx for any info.
Michael

[RJ Martin]

Michael: If you can maintain the temp between 1825 and 1875, you should be OK. 1850 is ideal for D2. I don't know how neutral the atmosphere in your furnace is, but, depending on the thickness of the blade, I'd soak at temp between 15 and 20 minutes.
If your furnace is really neutral, another 10 minutes wouldn't hurt.

[MixonKnives]

I assume the atmospere only makes a difference as far as scale build up goes? If this is the case I'll use HT foil. I've also heard of putting paper inside the foil when heat treating. The paper will flame up and exhaush the oxygen inside the "foil envelope"

My next question is, would it be possible after the quench, and temper, is it possible to do a "soft draw" on the tang/ricasso? If I remember what I read correctly this is harder to do on air hardening steels. But if its possible it would be worth the try, in case it matters my first blades will be full tang, slab handle style knives.

Thanx again for the info.

[RJ Martin]

Foil is an excellent choice, if available. I am not an advocate of paper in the foil pack. Make a nice, tight fitting pack and make the creases sharp-there'll be almost no air inside.

[mete]

How are you measuring temperature , it is critical ??

[RJ Martin]

Yes, temperature is critical. You mentioned using a pyrometer to controlled your burners-that is critical for a steel like D2, unless you want to do LOTS of experimentation with burner settings and soak times, breaking blades, Rockwell testing, etc. to find out what works.
The window for D2 is between 1825 and 1875, although you could probably push it another 25 degrees in both directions.

[MixonKnives]

They do make pyrometers that will automatically shut off burners on set parameters right? I'd REALLY like to know where to get one. If anyone could point me in the right direction I'd GREATLY appriciate it.

Thanks again,
Michael

[Fox Creek]

A lot of these HT furnace controls are available from the Ceramic/Pottery Industry suppliers. The electric kilns can be set up with add-on digital electric controls like commercial industrial HT ovens, or control systems using pyrometric cones to "trip" controls at a maximum temp specified by the cone selection, commonly called "kiln sitters". Lots of studios doing slumped and fused glass work use glass kilns with similar controls. I have seen old natural-gas fired glass enameling ovens that were Victorian monsters with flames licking from each pipe junction like St. Elmo's fire. The same shop had some antique glass beveling equipment too.....My wife is a full time potter, and I know more about refractories and furnaces/Kiln from there than the knife side of things. I keep harping on the cross referencing of the two disciplines for materials and resources.

[MixonKnives]

I'm sure if I were to have one, an electric kiln would make this task so much easier, but for now I'm just set up with a propane forge. I'm assuming with the proper adjustments I can probably make my forge idle at the proper temp, would this be effective enough to do the heat treat?

Also, I've been throwing around the idea of inserting a length of pipe in the forge, and the placing the blade inside that pipe, mostly to help even out the temp. My forge has 3 very hot burners right in the center of the forge, but the distance between the burner and the forge opening is such that its very difficult to get an even temperature across the full length of the blade. Even when doing the push/pull method. I'm hoping the pipe will help even out the heat distribution.

Michael