AEB-L Edge Stability, please correct me if I'm wrong

[PMQ]

I've been looking at AEB-L for quite a while, and it seems very good on the paper. In Dr Larrin's heat treat datasheet, it shows that AEB-L can get up to 64 HRC while still being much tougher than D2 at 61 HRC. I have never managed to (badly) chip my D2 knives, eventhough D2 isn't very tough.

Does this means that AEB-L has high edge stability?

I watched many Shawn Houston's videos, this is how I understand edge stability, and please correct me if I'm wrong: Edge stability is having a stable edge at high hardness, this is a combination of the chemical composition, carbide size, heat treat quality, geometry,...

The saying is "geometry cuts". High hardness will lead to less deformation, but more prone to chipping. So if you can create a good geometry, and high edge stability , then the knife would cut better?

Thanks.

 

[Seedy Lot]

Yes AEB-L is an awesome steel for many people. I have been running hardness at 61-62 Rc and have had rave reviews from customers who have been blown away by fine edge stability for rough woods use and it is an easy steel to sharpen which is a bonus as many people suck at sharpeing.

 

[Scaniaman]

I take AEB-L to 61/62 Hrc via cryo. It has insane edge stability. A hunting knife I used last year I took to 0.1 mm before sharpening, 250 mm radius bevels. It cut through all the ribs and knee joints on a big moose without any damage.
However, AEB-L's wear resistance is only so so, which got obvious when skinning the same moose.
For it's price/performance ratio it is unbeatable though. I can make 10 AEB-L profiles for the cost of one in say Magnacut.

 

[000Robert]

How can a steel have high edge retention and also be easy to sharpen? The two being synonymous doesn't sound right to me.

 

[SCTorrero]

How can a steel have high edge retention and also be easy to sharpen? The two being synonymous doesn't sound right to me.

I think you're right. I don't know how we are using terms, so we may not all be using common concepts. However, I think of edge retention differently than edge stability. I suspect the answer is "carbides."

 

[A.McPherson]

Edge stability is the ability of the edge to not chip or bend.

Edge retention/ease of sharpening is the ability of the edge to resist abrasion, either during cutting tasks or while sharpening.

At least that's the way I think of it...

 

[000Robert]

Edge stability is the ability of the edge to not chip or bend.

Edge retention/ease of sharpening is the ability of the edge to resist abrasion, either during cutting tasks or while sharpening.

At least that's the way I think of it...

I just don't see how an edge could have great edge retention and also be easy to sharpen. Sounds like a euphemism.

 

[Seedy Lot]

No one says it has great edge retention just great edge stability.

 

[000Robert]

No one says it has great edge retention just great edge stability.

Oh, ok.

 

[Justin W]

AEB-L is great for thin knives. Thin stock is available in many bar sizes. It grinds thin, and cuts like a razor. It should hold up to hard use nearly as well as most carbon steels. It can warp during grinding, and the edge retention is just ok. It's one of the goldilocks steels imo, just right in a lot of ways for a lot of purposes.

 

[Stuart Davenport Knives]

Yeah this is why I kinda have a pet peeve about the use of the word "edge retention" when in most conversations, it's obvious the person actually meant to say "wear resistance". AEBL has relatively low "wear resistance", this makes it easy to sharpen on simple abrasive mediums like AlOx. It has a low volume of very very small chromium carbides that even the simplest of sharpening stones can handle. But, because it has a very low volume of and small carbides, the steel resists chipping, and thus has good "edge stability". I think of "edge stability" as resistance to chipping, especially with those lateral forces.

D2 is about the opposite, sticking with steels with chromium carbides. It's "edge stability" is low, because those chromium carbides are higher in volume and they are much much larger than those of AEBL. But its "wear resistance" is much higher than AEBL, because of that higher volume and size of those chromium carbides. AEBL has like 2-3 micron carbides, whereas D2 can be 50 micron and larger, and a lot more of them. Interestingly, tho, there are two types of chromium carbides, and AEBL has the harder of the two, whereas D2, 154CM, 440C, etc actually have the softer of the two chromium carbides. I learned that from Devin Thomas.

I hear it said quite often, "I don't want the most edge retention out of a given steel, I want more toughness or edge stability". And the way I see it, in ANY given steel, the goal is indeed the most edge retention you can possibly get! But that is not the same as wear resistance. Edge "retention" comes from the sum of all of it....hardness, toughness, wear resistance, edge geometry, edge refinement. But "wear resistance" is pretty much solely dictated by hardness and carbide type/size/volume.

 

[PMQ]

How can a steel have high edge retention and also be easy to sharpen? The two being synonymous doesn't sound right to me.

A steel with high edge retention takes longer to sharpen, not harder to sharpen.

Lets say you have to reprofile a steel like 420HC, you use a 220 grit stone and it takes you 1 minutes. Then you have to reprofile S110V, also 220 grit, and it takes you 5 minutes. The technique does not change, it just takes longer. Provided that your stone can sharpen both 420HC and S110V, if your stone can't sharpen S110V then yes, high wear resistant steel is harder-to-find-a-stone-to-sharpen

The really hard to sharpen knives, IMO, are the ones badly heat treated. I recently made a chopper in 5160, it was badly heat treated (partly my fault) leading to excessive grain growth, and that chopper is literally imposible to sharpen. No matter how careful, how slow, how fast, using 220 grit or 3000 grit,... it cannot get sharp, it just keep microchipping.

 

[000Robert]

It sounds like yall are talking about 'wear resistance' - the ability to withstand abrasion. Strength is the ability to take a load without permanently deforming. But we are lucky to have so many steels to choose from. Not every steel is perfect for every task.

 

[Horsewright]

I run AEB-L at 62-63 and have excellent results with that. The secret with AEB-L at a high hardness is don't let it get dull. It takes very little touch up before it is dull to keep it hair popping. I see this on a daily basis as my own leather knives are all AEB-L. My roundknives and skivers are the one tool that is never put away they are always on the bench. I often cut leather for hours at a time. As soon as the blade starts to drag, couple licks on a strop or a second or two on a buffer and you are right back to cutting. I expect these knives to cut through heavy 8-10 oz saddle leather and sometimes heavier 10-12 oz (seldom use anything heavier in my shop), in one pass and they do. I resharpen my roundknives and skivers maybe every 4-6 months but in reality maybe not that often. But stropped and or buffed often. These are knives that are used daily and often for very long periods of time.

I sell a LOT of knives to working cowboys, ranchers etc. If at a show I can tell if a guy is more of a cowboy type or a hunter type as the cowboy will ask "How easy is it to resharpen." The hunter will ask: "How well does it hold an edge."

If you're at a branding and you've got 150 calves to cut before lunch it DOES NOT matter what your knife is made of you are gonna need to touch it up. The cowboy is looking for something he can touch up quickly by stropping on his chaps, the top of a truck window or the bottom of a coffee mug and back in business. AEB-L brings that to the table.

 

[Blankblank]

Well. If we are going to bring edge retention into this. I would say having decent edge retention, and being easy to sharpen are not mutually exclusive as others have brought up.

Generally speaking, aebl at a higher hardness is likely to hold an edge a bit longer depending on the task, also depending on the task, generally a knife that is thinner behind the edge, and with a lower degree edge bevel will have higher edge retention (provided it's not brought to the point of failure for the given steel). So aebl that's high hardness, with laser thin geometry, is going to have that edge longer in something like a kitchen knife. But because it's laser thin it's much easier to sharpen, than softer, but thicker aebl, because you're removing less material.

Then adding in wear resistance is another thing, but toughness, and even corrosion resistance can effect edge retention as well. It's definitely not a simple thing. And the way the blade will be used effects that as well. Because a chopper make out of 70 hrc rex 121 definitely won't have better edge retention than one made of 3v for that task, but it will certainly hold an edge for quite a long time in other situations.

Then bringing abrasives into the equation of ease of sharpening. Using the proper abrasive for a given steel makes even some of the most wear resistant steels a breeze. Although someone could argue, that having to use harder abrasives to sharpen a steel in itself could constitute it not being as easy to sharpen.


To finish though aebl is definitely a steel with good charecteristics. I will say on larrins site he ties edge stability with hardness. Generally a steel that has higher strength, has higher edge stability, although I think toughness should be tied into that equation for sure.

 

[Horsewright]

I run AEB-L at 62-63 and have excellent results with that. The secret with AEB-L at a high hardness is don't let it get dull. It takes very little touch up before it is dull to keep it hair popping. I see this on a daily basis as my own leather knives are all AEB-L. My roundknives and skivers are the one tool that is never put away they are always on the bench. I often cut leather for hours at a time. As soon as the blade starts to drag, couple licks on a strop or a second or two on a buffer and you are right back to cutting. I expect these knives to cut through heavy 8-10 oz saddle leather and sometimes heavier 10-12 oz (seldom use anything heavier in my shop), in one pass and they do. I resharpen my roundknives and skivers maybe every 4-6 months but in reality maybe not that often. But stropped and or buffed often. These are knives that are used daily and often for very long periods of time.

I sell a LOT of knives to working cowboys, ranchers etc. If at a show I can tell if a guy is more of a cowboy type or a hunter type as the cowboy will ask "How easy is it to resharpen." The hunter will ask: "How well does it hold an edge."

If you're at a branding and you've got 150 calves to cut before lunch it DOES NOT matter what your knife is made of you are gonna need to touch it up. The cowboy is looking for something he can touch up quickly by stropping on his chaps, the top of a truck window or the bottom of a coffee mug and back in business. AEB-L brings that to the table.

Wait! It can't be one of my posts without pics! AEB-L at 62-63 doing the work:

This is my daughter cutting one. I can tell its her cause most of my cowboys eschew red finger nail polish! She was 14 then, she just turned 26.

Still doing the work:

Don't think the AEB-L won't handle an elk too:

Does just fine!

 

[Nathan the Machinist]

AEBL can have very good edge stability. It has decent edge retention. It has mediocre wear resistance.

Wear resistance is the ability to resist material loss from abrasion. Relatively soft high carbide steel or a work piece with a lot of retained austenite can still have fantastic wear resistance despite poor edge retention due to mushy crumbly edge in the narrow section of a knife edge.

Edge stability is the ability to maintain the edge against chipping and roll. Poor edge stability is often a larger culprit in poor edge retention than poor wear resistance. <--- for whatever reason this seems not to be common knoledge around here sometimes.

Wear resistance is not edge retention. Edge retention is the ability to retain an edge. This is largely a combination of both edge stability and wear resistance.

Calling wear resistance edge retention is a common misconception in this industry. Wear resistance is relatively easy to directly measure. There are simple tests that can give a direct number.

CATRA testing is an attempt to measure edge retention, but the test is relatively light controlled cuts in a relatively soft abrasive media and does not include some of the harder materials, lateral loading and impacts in normal knife use that can show a weakness in roll or chipping. It generates a useful measurement but, unless you're pretty easy on your knife edges, I think it tends to be biased more towards wear resistance over edge stability.

AEBL is a fantastic steel.

 

[DeadboxHero]

I've been looking at AEB-L for quite a while, and it seems very good on the paper. In Dr Larrin's heat treat datasheet, it shows that AEB-L can get up to 64 HRC while still being much tougher than D2 at 61 HRC. I have never managed to (badly) chip my D2 knives, eventhough D2 isn't very tough.

Does this means that AEB-L has high edge stability?

I watched many Shawn Houston's videos, this is how I understand edge stability, and please correct me if I'm wrong: Edge stability is having a stable edge at high hardness, this is a combination of the chemical composition, carbide size, heat treat quality, geometry,...

The saying is "geometry cuts". High hardness will lead to less deformation, but more prone to chipping. So if you can create a good geometry, and high edge stability , then the knife would cut better?

Thanks.

AEBL can have very good edge stability. It has decent edge retention. It has mediocre wear resistance.

Wear resistance is the ability to resist material loss from abrasion. Relatively soft high carbide steel or a work piece with a lot of retained austenite can still have fantastic wear resistance despite poor edge retention due to mushy crumbly edge in the narrow section of a knife edge.

Edge stability is the ability to maintain the edge against chipping and roll. Poor edge stability is often a larger culprit in poor edge retention than poor wear resistance. <--- for whatever reason this seems not to be common knoledge around here sometimes.

Wear resistance is not edge retention. Edge retention is the ability to retain an edge. This is largely a combination of both edge stability and wear resistance.

Calling wear resistance edge retention is a common misconception in this industry. Wear resistance is relatively easy to directly measure. There are simple tests that can give a direct number.

CATRA testing is an attempt to measure edge retention, but the test is relatively light controlled cuts in a relatively soft abrasive media and does not include some of the harder materials, lateral loading and impacts in normal knife use that can show a weakness in roll or chipping. It generates a useful measurement but, unless you're pretty easy on your knife edges, I think it tends to be biased more towards wear resistance over edge stability.

AEBL is a fantastic steel.

Wear resistance is a factor though for an edge not blunting completely smooth in use.

It really depends on the user and their preferences.

I like it AEB-L but I'm not going to use it in a situation where I don't have the time to stop and sharpen.

Sometimes it's important to sharpen when you want to not because you have to.

 

[DeadboxHero]

I've been looking at AEB-L for quite a while, and it seems very good on the paper. In Dr Larrin's heat treat datasheet, it shows that AEB-L can get up to 64 HRC while still being much tougher than D2 at 61 HRC. I have never managed to (badly) chip my D2 knives, eventhough D2 isn't very tough.

Does this means that AEB-L has high edge stability?

I watched many Shawn Houston's videos, this is how I understand edge stability, and please correct me if I'm wrong: Edge stability is having a stable edge at high hardness, this is a combination of the chemical composition, carbide size, heat treat quality, geometry,...

The saying is "geometry cuts". High hardness will lead to less deformation, but more prone to chipping. So if you can create a good geometry, and high edge stability , then the knife would cut better?

Thanks.

The origin of the term edge stability comes from Roman Landes.

The book only comes in German, you can get an app for your phone to translate the text to English and there are also pictures.

 

[Nathan the Machinist]

The origin of the term edge stability comes from Roman Landes.

The book only comes in German, you can get an app for your phone to translate the text to English and there are also pictures.

We can also differentiate between fine edge stability, like you would see in a razor, and gross edge stability like you would see in an impact with a chopper. When Roman is using this term, he is discussing how straight razors dull in a non-abrasive failure mode. When I'm using the term, I am also using it in that same way but on a larger scale.

His experience is more involved with commercial production of disposable razor blades. My own experience on this subject is largely my role in producing the knives that are dominating Blade sports which are competition cutters that are also run at narrow geometry but not very narrow like a straight razor. And they're cutting 2x4s, rope, bendy straws etc, not hair. It is a different animal, but they are very related. The knives go "dull" in use and are scrutinized (and have points deducted if there is edge damage) and, just like a straight razor, the thinnest, narrowest, sharpest geometry wins the day. Like Roman, I have spent some time and resources developing optimized heat treats and like Roman, I find the use of the term "edge stability" useful. Generally speaking, the knives in the competitions are not going "dull" through abrasive wear, it boils down to edge stability.

The use of steel as a knife edge is, compared to other areas of the industrial applications of steel, a somewhat niche use. If you're building a bridge, a car, a stamping die or aircraft landing gear, you do not expect catastrophic failure but, it is completely normal to see the apex of the edge of a knife completely destroyed through chipping or yielding where the actual cutting edge is lost through a non-abrasive mechanism. Knives go dull through mechanisms other than abrasive adhesive (etc) wear in a way where the microstructure of the steel is more relevant due to the narrow angles and tiny geometries involved than you would expect on a larger application like a hydraulic cylinder or an extruder screw.

Common sense and experience tells us that knives go dull. And that abrasive wear is often not the primary mechanism. But it is a mechanism that is highly relevant in other commercial realms and there are tools for measuring it so it tends to be overemphasized, in my opinion.