Heat treating AEB L

opaul

opaul

KNIFE MAKER
I read that this steel can be plate quenched and/or oil quenched. This is after it is foil wrapped and heated to 1950 degrees and soaked for 15 minutes.
Seems like it would be easier and less spectacular to plate quench. I suspect 1900 degrees would creat quite the fire ball.
For those that have used it - what HT method did you use?
 
Thanks these are the two references I researched.
AEB-L Heat Treat Information
Preheat: Heat to 1,560° and equalize.

1,940°F Austenitize: Ramp to 1,940°F and hold at temperature for 15 minutes. Oil or plate or air quench as quickly as possible.
1,975°F Austenitize: Ramp to 1,975°F and hold at temperature for 5 minutes. Oil or plate or air quench as quickly as possible.

Temper: Temper immediately after hardening or cryo. Temper at least 2 times for two hours each time. Use the chart below to select the tempering temperature.

Cryogenic Treating: To get the most from AEB-L you must cryo. Cool to -95°F. No soak is required.


  1. Begin with your Damascus product wrapped as tightly as possible in .002 SST foil. Use double folds on all sides to ensure a tight seal.
  2. Preheat your furnace to austenitizing temperature – 1,925 degrees Fahrenheit.
  3. Place your wrapped piece in the furnace.
  4. Allow your furnace to cycle back up to austenitizing temperature.
  5. Soak your piece for 15 minutes.
  6. Quench in oil until it stops smoking.
  7. Temper twice at 350 degrees Fahrenheit for an hour each time.
  8. For advanced cryo hardening, quench in liquid nitrogen for 4 hours, then re-temper once at 350 degrees
 
I use Devin Thomas’ double quench method. 1750 for 10 min, plate quench, then 1975 for 15 min, plate quench. Then, I use LN for 1 hour, triple temper 2 hours each between 350-375 depending on the use of the knife.

Take a look at the AEB-L article on knife steel nerds that Larrin Thomas wrote. It has pretty much all the info you need on this steel.
 
Gene Kimmi said:
I use Devin Thomas’ double quench method. 1750 for 10 min, plate quench, then 1975 for 15 min, plate quench. Then, I use LN for 1 hour, triple temper 2 hours each between 350-375 depending on the use of the knife.

Take a look at the AEB-L article on knife steel nerds that Larrin Thomas wrote. It has pretty much all the info you need on this steel.
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I remember reading that but not in great detail. I believe he said putting the post tempered blade in the freezer would produce a hardness close to cyro.
 
opaul said:
I remember reading that but not in great detail. I believe he said putting the post tempered blade in the freezer would produce a hardness close to cyro.
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Yep, you're right. Larrin has said for AEB-L (and many other) that -95F (dry ice) and LN provide about the same thing. Larrin's stuff shows LN because that's what he's got. From his article on AEB-L: https://knifesteelnerds.com/2019/03/04/all-about-aeb-l/

"Using the freezer or liquid nitrogen also raises the austenitizing temperature that leads to maximum hardness: 1925°F with room temperature, 1950°F with the freezer, and 1975°F with liquid nitrogen. The peak hardness was increased from 62.2 Rc with room temperature to 62.8 Rc with the freezer, to 64 Rc with liquid nitrogen."

So, while a freezer at -5F doesn't provide as much as dry ice or LN, it does a good bit better than room temp.
 
The thing to consider is the amount of retained austenite that would remain at ~62 HRc that could convert to untempered martensite over time.

Doug
 
I messed with AEB-L some, but decided against using it, The reason is the target hardness..... 62-64Rc.... and while I was able to achieve that hardenss level...... that's just too hard IMO. Not necessarily too hard for the steel, but at that Rc level, clients have significant difficulty being able to sharpen a blade... and quickly grow frustrated with a knife/blade they can't resharpen easily.

That's likely not even a concern if you're a hobby level maker, but if you sell knives, it's a big thing to consider (If/how easily a client can resharpen one of your knives). Over the years I've had a ton of people contact me, with a "custom" knife that they couldn't sharpen, and my first question always is..... "Did the maker tell you the Rockwell hardness of the blade?" For those who were told, that Rc number was always in excess of 60. The point being, any knife will need sharpening at some point, and while a blade with a very high hardness MIGHT cut a bit longer, IMO it's not worth it when a client gets frustrated and looks elsewhere for a custom knife.

Maybe I should thank those makers who put out knives with high Rc hardnesses....... they've sent a lot of business my way over the years. :)
 
Ed- what’s your thoughts on the retained austenite? For small knives say under 8” and less than 3/16” thick is there any real issues?
 
AEBL at 61-62 performs great and is surprisingly easy to sharpen. Much easier in my experience than CPM154. That’s one reason I switched to AEBL. (cost was a big factor)

AEBL can develop a positively malevolent burr. In that regard, yes- it can seem impossible to sharpen until you learn how the burr acts and how to account for it because it is different than many other steels.
 
Ed- what’s your thoughts on the retained austenite? For small knives say under 8” and less than 3/16” thick is there any real issues?
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IMO retained austenite can POSSIBLY cause "down the road" issues, and the "richer" the alloy, the more impact is will have as it relates to blades. Do a google search for "retained austenite".... you can find lots of good info on it.

AEBL at 61-62 performs great and is surprisingly easy to sharpen. Much easier in my experience than CPM154. That’s one reason I switched to AEBL. (cost was a big factor)

AEBL can develop a positively malevolent burr. In that regard, yes- it can seem impossible to sharpen until you learn how the burr acts and how to account for it because it is different than many other steels.
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I agree with what you've said John...... and I don't have anything against AEB-L..... in fact at one time I was hoping to use it, for the same reason you mentioned (cost).
But between it's "target hardness" and past experiences with knife buyers, some of whom became clients, fussing about sharpening troubles, I decided against it. It's just a characteristic difference between most stainless steels, and most non-stainless steels..... just another one of those "trade offs" that I always mention.
I've had folks fuss to me about 154, 440, and most of the "designer" steels (CPM SXXV series was/is the absolute worst!) .... so I'm not picking on AEB-L. One could argue that with the higher hardness, a given steel/blade will hold and edge much longer..... but again, any blade that's used, will eventually need sharpening.
I have several kitchen knives that I've made of AEB-L...... and they work great, but they just don't "fit" with what my clients' want/have come to expect from me in the way of ease of sharpening. Personally, I think it's just a lack of education on sharpening in general. Heck, I wish I'd never made a knife of S30V..... EVERY year about August, I get a gob of them in the mail from clients who can't sharpen them....and want me to sharpen them, and get them back before hunting season. :rolleyes:
 
Ed, I totally understand where you’re coming from. I can also relate to people saying AEBL is hard to sharpen because when I was first getting my arms around it (10 - 15 knives into using it) I had several knives that I couldn’t sharpen to save my life. I say that as someone who had always taken pride in my sharpening skills- it was enough to make me pull my hair out. And if those knives had been personal knives I’d have thrown them in the trash and sworn to never touch AEBL again. Being that they were customers’ knives and had to ship, that wasn’t an option, so I was forced to stop, regroup, and rethink my approach.

On the plus side, my customers absolutely love it. Stainless is a giant bonus when you live in the Florida swamp. When I (rarely) do carbon steels I feel like I’m in a race against rust spots and I have heart palpitations every day until they’re shipped out!
 
If AEB-L is hard to sharpen at 62 Rc, try it at 60 Rc. Still works good and darn easy to sharpen (well, except for burr), just touch up on ceramic rod or steel from time to time and sharp lasts a LONG time.
 
Stainless is a giant bonus when you live in the Florida swamp. When I (rarely) do carbon steels I feel like I’m in a race against rust spots and I have heart palpitations every day until they’re shipped out!
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EXACTLY! That's a perfect example of the "trade off" thing. (focusing on/using stainless steels due to rusting issues). Compare that to me, and where I live..... with an average humidity percentage in the teens...... I can leave an unprotected carbon steel blade laying on the bench for literally weeks, and unless I splash water (or maybe coffee from my morning cup) on it...... it'll never tarnish or rust.)

As I've said before..... We all come at things through the lens of our own experience(s). I always enjoy threads like this, because it forces me to look beyond my own little box, and keeps me learning. :)
 
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I don’t consider 3V at 60 to 61 to be hard to sharpen at all, so for me a AE-L at 61 to 62 is dead nuts easy. Part of that may be that I put extremely thin edges on both of those steels.
 
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