A2 Tool Steel

S

sicilian767

Well-Known Member
Hey guys, sorry it's been months since I posted on here. I used to be a really active user, but then school started back up again and I've been busy writing papers, doing homework and such. In any case, Christmas break is coming, and with it so does the knife making.

I have a few questions, however, regarding A2 tool steel. From what I've read, it's a top of the line steel, although I had one concern. That being the fact that it's supposed to be air hardened. I noticed a few websites sell this for custom knife makers, and my question was, how do you quench this steel? Does anyone know the process on how to treat it? And is it okay to quench it in oil?

Looking forward to hearing what y'all have to say. Y'all have much more experience than me, so I appreciate your help in this.

Thanks and God bless!! :)
 
It's one of my favorite steels. You need an HT oven or other good temp control because it needs to soak at around 1750F for roughly 30 minutes.
This means it needs HT foil or other oxygen protection. I usually plate quench it but air is sufficient. Oil will work but you need to get the somewhat
floppy 1750F blade out of the foil before putting it in the oil. I find this ... challenging ...

All of the above is off the top of my head -- generally accurate but I'm not checking my notes for precise temps, times and protocol.
 
I sent mine out to a local heat treater, but my formula was a fairly standard heat to 1750 F, hold at temperature for 30 min (as recommended above), quench in air (let cool in air), then double temper at 350-375. My target hardness was fairly high at 61 HRc. The shop tested it and was right on. Due to some ham handed finish grinding and power sharpening, the blade did not get made into it's intended kitchen knife, but that has nothing to do with the steel.
 
Thanks for the replies guys. Although, how does it cool fast enough in the air? Isn't air cooling the equivalent of annealing the steal because it's slow? I would think it would need to be quenched in oil to have that rapid temperature transition that allows for the quench. Can anyone clear up the science behind this for me? I'm curious how you can quench it in air.

Thanks again guys!
 
a steel that is rated as "air cooled" can be removed from the heat and placed into a rack or hung in still air at room temperature. If you are cooling more than one blade at a time in a rack, make sure you have sufficient room between the blades to not keep each other from cooling quickly.

If you choose to use a fan for a forced air cool, you should do it longitudinally so it cools evenly on both sides to minimize any chance of warping.

The problem with air cooling is the steel out of the tool wrap quick enough. If you quench in between plates of aluminum, you simply leave the knife in the foil and press between the plates.
 
Ah okay, I was always under the impression that all steels had to quench to a colder temperature within seconds of coming out of the heat. I suppose I learn something new every day. Good info though. Thanks for the help!
 
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