Toughness testing of AEB-L, Niolox, CPM-154, 19C27, 40CP, and D2

Larrin

Larrin

Knifemaker / Craftsman / Service Provider
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There are a lot of steels out there without any reported toughness values. And comparisons between toughness results from one company usually can't be compared with another company, often because they use different testing methods. So we collected together an eclectic group to compare. AEB-L is known for its high edge stability and toughness but as far as I know there aren't any toughness numbers out there. Niolox is a European steel with V and Nb additions which has been pushed before as an "enhanced wear resistance" AEB-L. Everyone knows CPM-154, of course. 19C27 is made by Sandvik but has 1% carbon so its carbide volume is much higher than the 12C27 and 13C26 steels. 40CP is our representative of Carpenter powder metallurgy stainless steels. And D2 is of course the well known tool steel. All of these steels were heat treated using a cryo treatment directly after the quench followed by a double temper. I also added in the CruForgeV testing that we did as a comparison, but I'm too lazy to link to that thread. The austenitizing and tempering temperatures were as follows:
AEB-L: 1950, 350
Niolox: 1975, 350
19C27: 1950, 450
CPM-154: 1950, 450
D2: 1870, 450
40CP: 1925, 350

Anyway, AEB-L is by far the toughest, and its reputation is well founded. Niolox did not do as well as hoped. 19C27 and CPM-154 have similar toughness, around half that of AEB-L but better than 40CP, Niolox, and D2. There still isn't much out there with toughness between AEB-L and 19C27/CPM-154. There are just so many more options when it comes to non-stainless tool steels. Oh, and D2 is confirmed to be overrated.

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Very interesting. How much toughness does AEB-L lose if you take it to 61-62? So is AEB-L @59Rc in the same neighborhood as low temp austenized 52100 or even A2 at 60Rc?
If we go by what Crucible claims, I would guess that S35VN would be in the same range as CPM154 and S30V would be a bit lower?
 
jdm61 said:
Very interesting. How much toughness does AEB-L lose if you take it to 61-62? So is AEB-L @59Rc in the same neighborhood as low temp austenized 52100 or even A2 at 60Rc?
If we go by what Crucible claims, I would guess that S35VN would be in the same range as CPM154 and S30V would be a bit lower?
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Need more testing for sure.

Hoss
 
Would be interesting to see how everybody compared against each other at same hardness,run at 61,62,63
 
jdm61 said:
Very interesting. How much toughness does AEB-L lose if you take it to 61-62? So is AEB-L @59Rc in the same neighborhood as low temp austenized 52100 or even A2 at 60Rc?
If we go by what Crucible claims, I would guess that S35VN would be in the same range as CPM154 and S30V would be a bit lower?
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If cpm154 is as tough as 154cm (Potentially even tougher due to smaller carbides) then I imagine it would be even tougher than s35vn. Apparently 154cm and even 440c are quite tough for stainless.
 
Great info. Just curious do you all see a higher hardness with aust temp of 1975 vs 1950 on aeb-l or is that just the optimum in that kiln? Thanks
 
What is it about aebl that makes it so well versed and better than most steels? Its g it relatively low carbon content and its not really an alloy rich steel. Is it the chromium?
I do wonder what a steel like aebl would look like with a decent amount of vanadium.
 
Toughness can vary with optimized heat treatments for any alloy.

Toughness is affected more by chemical composition and carbide size, type, and volume. D2 with large carbides and high percentage of carbide volume shows low toughness compared to AEB-L that has small carbides and low carbide volume.

We could test many heat treatments at various hardness and the trends would be the same.

PM steels are tougher than the conventional equivalent, 5160 low alloy steel is tougher than 1060, 15N20 is tougher than 1075 because of additional alloy.

Lower hardness will show higher toughness than the same steel with higher hardness.

I could spend my life making test coupons for Larrin to test.

There will be more tests coming.

Hoss
 
Hoss, don't the production knife companies typically leave steels like Niolox and Becut in the upper 50Rc range? What I have read is that Niolox is quite abrasion resistant. IIRC, Bestar doesn't even have data for Becut for any hardnesses higher than the high 50's.
 
jdm61 said:
Hoss, don't the production knife companies typically leave steels like Niolox and Becut in the upper 50Rc range? What I have read is that Niolox is quite abrasion resistant. IIRC, Bestar doesn't even have data for Becut for any hardnesses higher than the high 50's.
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We haven’t really looked into production knives with these steels, not yet any way.

Seems like becut doesn’t have very high attainable hardness to begin with. I need to look it up.

Hoss
 
valknut said:
What is it about aebl that makes it so well versed and better than most steels? Its g it relatively low carbon content and its not really an alloy rich steel. Is it the chromium?
I do wonder what a steel like aebl would look like with a decent amount of vanadium.
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It's all about the carbide volume and size. AEB-L has less than half the carbide volume of the other stainless steels tested. See these threads again: https://www.bladeforums.com/threads/predicting-toughness-with-steel-composition.1534942/
https://www.bladeforums.com/threads/no-your-pm-stainless-steel-isnt-tough.1535555/
 
DevinT said:
Seems like becut doesn’t have very high attainable hardness to begin with. I need to look it up.

Hoss
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That is my impression too. Kevin Wilkins loves the stuff.
 
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