440c vs AEB-L

[Bill Armstrong]

Looking to expand my knifemaking to utilize a stainless steel. 

What are the advantages to using 440c or AEB-L?

[Alan Longmire]

I was hoping Jerrod would chime in, but the article linked below should help.  

 

https://knifesteelnerds.com/2019/03/04/all-about-aeb-l/

 

That article is what made me choose AEB-L.  440C is great, but I can deal with AEB-L more easily with my heat treat setup.  Plus it's easier to sharpen.  Might not hold an edge as long, but it's easy to get shaving sharp.  

 

The short version is these two pics from that article:

 

1. 440-C carbide size

 

 

2. AEB-L carbide size:

 

 

Small carbides = tougher/more impact resistant, plus easier to sharpen/finer edge.  AEB-L does not get as hard as 440-C, but it's more flexible.  It's what they make disposable razor blades out of.

 

 

[Bill Armstrong]

Thanks for sharing, very interesting article. Kinda made my brain hurt a little but  it was beneficial. Will probably have to read it a few times to digest the info better. but for now, a vodka tonic and a nap seem in order.

[Joël Mercier]

22 hours ago, Alan Longmire said:

AEB-L does not get as hard as 440-C

Are you sure about this? I was under the impression AEB-L actually had higher working hardness. It's still plenty tough in the 62-63hrc range(with cryo though). I don't know much about 440C, but 154cm is on the same chart as AEB-L and the later has the same toughness at 62.5hrc than 154cm at 60hrc. And I believe 154cm to be tougher than 440C. 

 

Anyways, bottom line is you won't find any fan of 440C on this forum 

Edited May 18 by Joël Mercier

[Alan Longmire]

10 hours ago, Joël Mercier said:

Are you sure about this?

 

No, I'm not.   I thought 440C as quenched (with cryo) is usually around Rc65, while AEB-L is around Rc63.  It is indeed true that if you want 440C not to be brittle you have to temper it down into the Rc59 range, while AEB-L can be Rc62 and still be much tougher.  Of course, anything over Rc60 is more than hard enough.  

[Jerrod Miller]

On 5/17/2023 at 8:54 AM, Alan Longmire said:

I was hoping Jerrod would chime in

Sorry, I was on vacation last week, so am just now getting back in the swing of things.  

 

I think it is important to note that 440C can technically fall under the category of a cast iron, not a steel.  And I don't say that just to be pedantic, since under certain definitions it is definitely a steel.  The composition is such that you get "primary carbides", which are carbides that form directly out of the liquid during solidification (hence a cast iron - something other than austenite forming upon solidification).  This is one of the big things that makes the 440C carbides bigger.  Once these large carbides form they are difficult to break up.  Bigger carbides are generally worse for everything except wear resistance.  Total carbide volume fraction is a pretty fun thing to look at, as that will tell you a lot about the wear resistance, whereas carbide size tells you more about toughness (in conjunction with volume fraction).  

 

The most important thing when you start choosing between these types of steels is to ensure you choose one that you can heat treat properly.  If you can't do it right, you will likely get better performance from one that doesn't look as good on paper, but is heat treated optimally.