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

[Larrin]

Can someone explain the resurgence in AEB-L to me? This is such an old steel it seems strange that its apparently amazing qualities for cutlery are only recently being discovered.

You mean it was once being used in knives, then wasn't, and now is again? Or that it was invented a long time ago and is only now being used in knives?

 

[Kevin McGovern]

Can someone explain the resurgence in AEB-L to me? This is such an old steel it seems strange that its apparently amazing qualities for cutlery are only recently being discovered.

I'm not sure of it's development date, but it has been around in razor blades for some time. Only fairly recently however, has it been available in stock thickness of 1/8" and above.

 

[DevinT]

It was developed and used in Europe for a long time. Here in America, 440c was the main cutlery steel for the last hundred years.

John Verhoeven and Roman Landus both did research on AEB-L and published their faverable findings twenty years ago.

Both Uddeholm and Sandvik pushed their cutlery grades here in the eighties but it didn’t catch on. Several makers bought AEB-L but customers didn’t know what it was so it was hard to promote.

I have been using and promoting it’s use since the late eighties. It has a not so flashy chemical composition and it’s very low availability made it hard for makers to get excited about.

A few of us put enough pressure on Uddeholm that they started bringing in more material at better sizes.

It’s a very good cutlery steel, I recommend everyone try it.

Hoss

 

[tim37a]

Hoss - have you done any comparisons between AEB-L and Nitro V for cutlery?
Tim

 

[Kevin McGovern]

It was developed and used in Europe for a long time. Here in America, 440c was the main cutlery steel for the last hundred years.

John Verhoeven and Roman Landus both did research on AEB-L and published their faverable findings twenty years ago.

Both Uddeholm and Sandvik pushed their cutlery grades here in the eighties but it didn’t catch on. Several makers bought AEB-L but customers didn’t know what it was so it was hard to promote.

I have been using and promoting it’s use since the late eighties. It has a not so flashy chemical composition and it’s very low availability made it hard for makers to get excited about.

A few of us put enough pressure on Uddeholm that they started bringing in more material at better sizes.

It’s a very good cutlery steel, I recommend everyone try it.

Hoss

I just realized I'm getting old to call the eighties " fairly recently"

 

[DevinT]

Hoss - have you done any comparisons between AEB-L and Nitro V for cutlery?
Tim

We haven’t. Same class of steel, probably no detectible difference.

Hoss

 

[madcap_magician]

You mean it was once being used in knives, then wasn't, and now is again? Or that it was invented a long time ago and is only now being used in knives?

Oh, just that it has been a known steel for cutting implements for a long time, but only now suddenly are people raving about it for knives. It seems countercultural since it's a pretty simple alloy, and you know, for years the new hotness has been exotic PM alloys.

I guess per Devin and some others, it's always been a thing, it just seems to me like only in the last year have I seen lots of makers on BF posting work in AEB-L.

 

[Willie71]

Oh, just that it has been a known steel for cutting implements for a long time, but only now suddenly are people raving about it for knives. It seems countercultural since it's a pretty simple alloy, and you know, for years the new hotness has been exotic PM alloys.

I guess per Devin and some others, it's always been a thing, it just seems to me like only in the last year have I seen lots of makers on BF posting work in AEB-L.

Aeb-l and 15n20 are both very simple steels without a lot of sex appeal in chemistry. At Rc58-60, they’re nothing to write home about, but pushed to Rc62 or even a bit higher, the toughness lets the fine edge survive, and you get better than expected wear resistance. Both steels make great knives, for outdoorsmen or in the kitchen.

 

[AVigil]

Oh, just that it has been a known steel for cutting implements for a long time, but only now suddenly are people raving about it for knives. It seems countercultural since it's a pretty simple alloy, and you know, for years the new hotness has been exotic PM alloys.

I guess per Devin and some others, it's always been a thing, it just seems to me like only in the last year have I seen lots of makers on BF posting work in AEB-L.

That has a lot to do with it no being available in thicker then 1/8" for years. Only recently has it been available up to .196"

 

[Larrin]

Nothing was really available in small amounts in North America until Admital started selling 13C26 in 2007. AEB-L followed sometime later. This forum has a relatively short memory, it seems. Maybe forums in general.

 

[MBB]

Larrin,

Would you mind clarifying the relationship between toughness and shock resistance? I've been curious about using steels like 9260 and S5 in blades, but have no idea where I could find them available for the knife maker. Also, how do L6/5160/15N20/8670M compare to the specifically shock resistant steels?

Thanks!

 

[samuraistuart]

Larrin, in a sort of duplicate post to MBB, is there a difference between the, forgive my ignorance in correct terminology, "macro toughness" (that is to say the toughness that prevents a tip breaking off in use/torque), and "micro toughness" (that is to say what keeps a hard, fine, thin edge stable under impact). Or are these two the same? If I need clarification on what I mean, let me know, and I will try to expand and/or source some literature to help explain.

 

[DevinT]

Micro toughness has to do with carbide pull out and a steels ability to hold on to carbides.

Hoss

 

[MBB]

So is that a product of breaking covalent carbide bonds or crystalline lattice tears? I assume it's the latter.

(Sorry, I have a background in X-ray crystallography.)

 

[Larrin]

“Edge stability” was coined by Roman Landes to describe a steel’s Ability to hold an acute, polished edge. Therefore it isn’t a single property, but the whole set of properties that allow that to happen. So resistance to rolling or deformation (hardness), chipping (toughness), wear, and even corrosion though I’m not sure Roman included that. When carbides are larger than the edge one is attempting to sharpen, then you can get carbide pullout making sharpening difficult, or even when obtained the edges lose initial sharpness quickly until they reach the radius required by the carbides. But on the topic of toughness, areas of chipping can occur at large carbides or other defects that would be an example of “local toughness.” Retained austenite could also lead to poor local toughness.

 

[madcap_magician]

Great, highly informative discussion. Thanks all!

 

[Justin Schmidt]

“Edge stability” was coined by Roman Landes to describe a steel’s Ability to hold an acute, polished edge. Therefore it isn’t a single property, but the whole set of properties that allow that to happen. So resistance to rolling or deformation (hardness), chipping (toughness), wear, and even corrosion though I’m not sure Roman included that. When carbides are larger than the edge one is attempting to sharpen, then you can get carbide pullout making sharpening difficult, or even when obtained the edges lose initial sharpness quickly until they reach the radius required by the carbides. But on the topic of toughness, areas of chipping can occur at large carbides or other defects that would be an example of “local toughness.” Retained austenite could also lead to poor local toughness.

Hence why AEBL can hold such a fine edge and keep it. Because the carbides are smaller and compact. Also why you say d2 is over rated lol
While reading through the verehoven book he shared a graph.

According to this graph it looks like there is a higher chance of RA when a steel has a carbon content over .9 or below .6 ive also noticed steels with about .6 C are generally known for toughness (AEBL, 15n20, 5160) but toughness is also more relative to RC hardeness. Am i out of the ballpark or on the right track?

 

[Larrin]

Larrin,

Would you mind clarifying the relationship between toughness and shock resistance? I've been curious about using steels like 9260 and S5 in blades, but have no idea where I could find them available for the knife maker. Also, how do L6/5160/15N20/8670M compare to the specifically shock resistant steels?

Thanks!

Toughness and shock resistance are synonymous. Those other steels should also have very high toughness.

 

[Larrin]

So is that a product of breaking covalent carbide bonds or crystalline lattice tears? I assume it's the latter.

(Sorry, I have a background in X-ray crystallography.)

Carbides are intermetallic compound and have multiple types of bonding. However, fracturing the carbides is not required. The brittle carbides act as crack nucleation sites thus reducing the toughness.

 

[Larrin]

While reading through the verehoven book he shared a graph.

According to this graph it looks like there is a higher chance of RA when a steel has a carbon content over .9 or below .6 ive also noticed steels with about .6 C are generally known for toughness (AEBL, 15n20, 5160) but toughness is also more relative to RC hardeness. Am i out of the ballpark or on the right track?

I shared a similar graph in my thread on cryo vs dry ice. I also included a methodology for predicting retained austenite fraction: https://www.bladeforums.com/threads/liquid-nitrogen-vs-dry-ice.1540810/

The lower carbon steels often have better toughness because they also have lower carbide volumes. For a given steel (or carbide volume and size), the next greatest controlling factor is probably hardness. There are other factors, of course.