Heat Treating A2 in a forge.

[JTknives]

I was doing some 5160 heat treating tonight and as I sat there waiting for the oil to come up to temp my eye caught the roll of SS foil on the shelf. And I got to wondering, which is always a bad thing with me. So I jumped up and grabbed a small strip of A2 and ground out a small mini fillet knife.

Wrapped it in foil and fired up the forge. Foil was single layer and double fold on the edges.

Forge hit 1500 deg and I placed the foil in the forge. The foil pack spans the 2 openings of my forge so I did not have to hold it.

Once things started heating I cranked it to 1750

I adjusted the idle needle gas valve to hold 1750 as best I could so to limit the cycling of the burner. It would kick the burner on high about once a min and just for a fraction of a sec. Normaly I don't go to this much hassle in tweaking the control as no mater what the setting it will hold the temp set. I just wanted to limit the cycling to a minimum.

I let it sit for 30 min just purring away, I would peak at it every so often to make sure the foil was still there. As that's seams to be the big concern with using foil in a forge is that it won't handle the time and will burn away. But after 30min it looks great.

Because I don't have any quench plates I cut open the foil and pull the blade out. And low and behold perfect. No scale to be found and thoes nice blue/purple cloudy wisps showed up.

Next I inspect the foil pouch, looks solid. If it was long enough or I had used quench plates I could reuse it no doubt.

Next was to test hardness, according to my shore tester I'm sitting at 63-64RC from point to tang.

Right now it's in the oven at 400deg for 2hrs then off to the grinder for edge bevels.
I will say I'm very happy with the results. Now I must say A2 is not a steel that should be heat treated in just any forge or backyard fire pit. It requires precise control and if you can hold the heat to that level of precision then try it.

 

[Stacy E. Apelt - Bladesmith]

You can't re-use the pouches. The steel foil is hardened once it is fired and cooled.

 

[i4Marc]

Stacy,

I read a few sources who advocate heating A2 at a rate not to exceed 400˚ per hour ( a couple of well known makers and also manufacturers). Most of the recipies I read through the BF custom search don't mention that. What are the pros or cons of this method?

 

[Stacy E. Apelt - Bladesmith]

In complex shapes and thicker pieces ( like parts and such), the rate matters more. In a thin section like a blade, normal ramp rates are fine. It wouldn't hurt to keep it to a 30 minute ramp ( 1000 degrees per hour) when ramping from pre-heat to austenitization.

 

[JTknives]

I have never reused foil before but I thought I had read here on the forum that people that plate quench can open the foil and put in another blade.

 

[me2]

What is the foil made of?

 

[DevinT]

Most foil is 321 or 309 I believe.

I do a prequench and a full quench using the same foil, I plate quench the blade leaving it in the foil.

Hoss

 

[me2]

I wouldn't think those would harden. I can't imagine all the heat is good for it though.

 

[Greenberg Woods]

I got to ask JT, why do you use 5160 over Aldo's 80CRV2? Arent they very similar, but CRV has about .2% more carbon?

 

[JTknives]

Because I have a crap ton of 5160. Once I use it all up I will be looking into switching. I like the performance I get from 5160, not expensive and tough. Also easy to heat treat and gets razor sharp. All things I need to make a good knife for a good price.

 

[Gossman Knives]

I tried reusing the foil, big mistake.
Scott