Oil Quenching A2?

Troop

Troop

Joined
Oct 26, 2006
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I know that A2 is an "air hardening" steel. But, I've recently heard that if you oil quench it, it comes out harder. I believe it, but, on the quenching data that came with the steel, it says, "TEMPER IMMEDIATELY". (after air quench)
I'm just used to working with 1095, and I temper it with a propane torch after I oil quench it. Can I do the same with A2? I don't want to ruin the steel. Can I "temper immediately" with a propane torch right after quenching it in oil? :confused:
-Thanks for your help.
 
Proper tempering takes 1-2 hours ! Do you hold the torch there for that long ? at a constant temperature ? Much better to use a kitchen oven [clean off oil first] or use a toaster oven...Are you hardening with a torch ? A-2 is a complex steel that requires a proper furnace with precise temperature control. It's easiest to "plate quench" instead of oil.
 
When I temper my 1095 after oil quenching, I polish off the scale, then temper with a torch until it's a tan color. Works great with 1095. I harden with a propane forge, until non-mag, then quench in bucket of 30 weight.
 
Mete,
What do you mean by "plate quench" ? I'm new to forging and heat treating my own knives.
- Thanks
 
You should buy a heat treating furnace so you can control your austenitizing temperature. After that the answer is yes you can oil quench, you can get even harder by using cryo after the quench, and then you shouldn't temper using your torch, you should use a kitchen oven or a toaster oven, using a separate oven thermometer to check your temperature.
 
Larrin said:
You should buy a heat treating furnace so you can control your austenitizing temperature. After that the answer is yes you can oil quench, you can get even harder by using cryo after the quench, and then you shouldn't temper using your torch, you should use a kitchen oven or a toaster oven, using a separate oven thermometer to check your temperature.
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Larrin,
I'm using 1/4" A2. Any recommendations for temp and time with the 'ol kitchen oven? Thanks.
 
Search " plate quench" there's been lots of discussion here. Yes you can cryo.Simple steels can be heat treated simply but the more complex the more difficult. As a beginner stick to the simple ones [5160, 1080 ] till you get some experience and lesarn some more.
 
mete said:
Search " plate quench" there's been lots of discussion here. Yes you can cryo.Simple steels can be heat treated simply but the more complex the more difficult. As a beginner stick to the simple ones [5160, 1080 ] till you get some experience and lesarn some more.
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O.K., Bro'....Thanks, will do. :thumbup:
 
Troop, A2 is a little more complicated to HT then 1095. I oil quenched A2 for a year and a half until I lit my arm up with flame up. I plate quench now and see no difference in hardness after quench. Plate quenching is the way to go with air hardened steels. Plenty of past discussions here about it.
Scott
 
Gossman Knives said:
Troop, A2 is a little more complicated to HT then 1095. I oil quenched A2 for a year and a half until I lit my arm up with flame up. I plate quench now and see no difference in hardness after quench. Plate quenching is the way to go with air hardened steels. Plenty of past discussions here about it.
Scott
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Thanks, Scott. It seems like I'm "biting off more then I can chew" with going from 1095 to A2. I think that I'll work with O-1 for a while first....seems more sane.
 
O1 is a good choice but it does need a small amount of soak time 7 to 10 minutes. 5160 or 1084 is another easy steel to HT. Heat to non magnetic and quench.
Scott
 
Should I soak at cherry red for 7-10 mins (O-1)? I use a propane forge.
- Thanks
 
im more than confused when everyone talks about soaking, i figured while we were on the subject, what does it mean? Does it mean keeping it in the forge for a certain amount of time at a certain temperature?
 
You're exactly right, you're keeping the steel in the Currie Temp range for a long enough period of time to let the carbides form a solution. It kind of like dissolving salt in water, some will dissolve very quickly, it takes time to dissolve into full solution.

A few posts from now, someone will come by and make mince-meat of my poor example, but that's the best way I know to explain it.
 
You're not far off. Soaking dissolves carbides and this takes some time.You want to saturate the matrix with carbon to get the strongest and hardest martensite ! The more complex the steel the higher the temperature needed to do this [~ 1900 F for stainless !] and longer times.
 
Heat treating A2 isn't too terribly difficult if you have a kiln. I think it would be easier than forging any 1095 or yadda yadda as the kiln does the work for you. Make sure if you don't have some sort of inert gas pumped into the kiln that you use stainless steel foil to protect from decarburization.

I find that some people say all you need to soak any thickness is at 20 minutes, but I seem to find that a bit false (no offense to anyone that has told me that). At 20 minutes only, i'm not sure what happens, but the blade does not seem to come out as strong. I would soak at between 1725-1800 degrees for 1/4" stuff for about 35 minutes and all the preheat jargon in between as well before you get it that hot of course. The thicker the steel is, the more time it needs to soak as you wouldn't soak a piece of 1/16" thick A2 the same amount of time as you would say a 1" inch piece of A2.

People also say to temper at 1 hour twice at 400 degrees, but again, didn't seem to give as good results as 2 hours twice or even three times.

I know some guys are gonna smack me for saying all this, but I have the blade to prove it that knicked after hitting a piece of 3/4" thick birch (which has NEVER happened when I stuck to the HT temperatures as I did before).

Tempering immediately doesn't actually mean temper it right out of the oven. It just means temper the blade when it falls to 120' - 150' F as not to shock the hell out of the blade should it fall to room temperature and possibly develop cracks (that you can't see with your eyes).

But never ever ever heat treat A2 with a torch of any kind as you seriously compromise the strength of the cutting edge and everything else by subjecting it oxygen at those temperatures. Not to mention if you're new at heat treating it, it's kinda hard to tell what temperature you're actually at.

Good luck.
 
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