Edge Retention versus Toughness Solved. (A pro-toughness post)

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KnightAspirant

KnightAspirant

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If I could sum it up in two lines it would be:

If you use your knife for anything other than opening a cardboard box and packing tape, buy a steel that prioritizes toughness.

If you only open boxes and process cardboard with your knife and it gets a lot of shelf time, you can get away with a steel that prioritizes edge retention.


Here's why, in my opinion, based on use- If you buy a steel that's low on the toughness scale but high on the edge retention scale and put a nice sharp edge on it, and then you do some cutting that is off-ideal with it (whittling a stick with some knots in it that puts some lateral force on your edge) you can easily get micro chips in your edge and be damned to a life on the sharpening stone wondering why you have to sharpen all the time. Think M390.

Conversely, using a blade with a higher toughness can take being used for whittling on a knotty stick, where you are prying off some strips of stubborn wood as you go. For example, ELMAX. You'll be sharpening less often.

A blade steel like ELMAX dulls more evenly over time along its edge, where a lower toughness and greater edge retention steel like M390 will acquire acute dull spots (tiny tiny chips) while the rest of the blade is still razor sharp. One of these is more annoying than the other!

Owning a high edge retention daily carry is making me an advocate for high toughness steel.

What do you think? People love to say things like "well you just aren't using it right" as if we users are supposed to cut in constant perfected alignment with the edge apex every time and baby our movements. We are dudes guys.

High toughness=more controllable and predictable in use.
High edge retention= surprise micro chips.

What high toughness steels would you recommend that you would put in the "super steel" category?
 
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I'm not concerned with whether something is considered a "super" steel as much as I am that it is a balanced steel.

So the steels I generally gravitate toward are tool steels like 3V, Cru-Wear, 4V, M4 and K390...and on the stainless side, MagnaCut.

(I have tons of other stainless and non-stainless steels in my collection, but those are the steels I have a special affinity toward.)
 
It's really about balance -- finding the right balance of toughness and hardness and edge wear that allows efficient cutting and reduces edge damage.

I've drifted more toward toughness lately. Pretty much anything 60 Rc or higher will prevent rolling for me. The higher you go after that, the more chipping you risk. But the steel alloy matters. Your use of the knife matters. Geometry matters. Heat treat matters. Stain resistance matters. It's a dance.

Toughness can be overdone. You can roll, dent or bend it under hard use.
 
Elmax and m390 have nearly the same toughness. I think two better examples would be something like m390 and magnacut/3v/cruware. Or if you want to jump on recent events in the knife world's why not compare magnacut with magnamax which are exactly what you speak about...a less tough higher edge retention steel and a tougher medium edge retention steel.

So your theory is often why people prioritize geometry over steel type. Thinner geometry cuts longer and tougher steels that are able to get hard enough can potentially be the best of both worlds. I think many people recognize this however, which is why it steels like k390 and now Magnamax are still becoming more and more popular and a favorite among enthusiasts.

Using the classic CATRA definition of edge retention is difficult because like you said there are so many different mediums and techniques in which people cut stuff. Perhaps in the future we will get some studies comparing things like cruwear/magnacut at a thinner edge angle against something like magnemax or k390 at a more obtuse edge angle doing various tasks and then inspecting the edge while also measuring for remaining sharpness. These types of tests are difficult however because the result in one test might be completely different than another based off just a slight change in end user usage.

However great post. I think it's a question many of us are constantly trying to explore and get a better idea of. (Please correct me if I am misspeaking here) DeadboxHero DeadboxHero for instance helped develop the new iteration of 15v which has to me a pretty good balance of just enough toughness to maintain thin edge angles with such high carbide and pretty high (not the highest though) edge retention in CATRA tests (also at high hardness). Where you will get the highest edge retention however is so highly dependent on how you use your knife and what kind of damage it will be taking that my guess is it will be somewhat different for everyone.
 
Blues said:
I'm not concerned with whether something is considered a "super" steel as much as I am that it is a balanced steel.

So the steels I generally gravitate toward are tool steels like 3V, Cru-Wear, 4V, M4 and K390...and on the stainless side, MagnaCut.

(I have tons of other stainless and non-stainless steels in my collection, but those are the steels I have a special affinity toward.)
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I only have a couple in 4v but haven't used them extensively. The other four you listed are the ones I've whittled the collection down to as far as users and they do everything I need them to.
 
I have a pretty good collection of various steels on a lot of knives, all the way to Magnacut, and like most of them for various reasons, But if I was forced to own only one steel on my knives, Believe it or not, I would pick a good 440C from a good manufacturer that has been treated properly. To me, it covers a wide range of tasks, and can be quickly brought back to excellent sharpness with a few licks on a stop or stone. I've even done it on a smooth river rock in the field.
 
DBG40 said:
I have a pretty good collection of various steels on a lot of knives, all the way to Magnacut, and like most of them for various reasons, But if I was forced to own only one steel on my knives, Believe it or not, I would pick a good 440C from a good manufacturer that has been treated properly. To me, it covers a wide range of tasks, and can be quickly brought back to excellent sharpness with a few licks on a stop or stone. I've even done it on a smooth river rock in the field.
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my brother in blades right here ^
 
Danke42 said:
I contend that toughness is edge retention.
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It isn't that simple. Take a low carbon steel that cannot get hard enough to maintain an acute enough to be useful apex without rolling. That is a basic example of toughness not equating to edge retention.
 
I‘m with Blues Blues for fixed blades. And, I’ll add AEB-L to his list. It’s nice to have a harder stainless folder for boxes, food, etc., though (S90V, M390, Elmax, etc.).

So I carry both :)

Of course I have tough folders too, for the „one knife does all“ days.
 
Maybe I'm mistaken, but this sounds more like an argument for edge stability than knife toughness.

A knife can be incredibly tough (i.e. difficult to break) but not hold and edge well. It may not microchip, but it means frequent sharpening, and we're right back to square one.

Also, don't forget edge geometry. If you have an edge that is chipping, making the edge geometry slightly thicker may solve the problem completely. Geometry can solve many, many problems.

And of course what you prioritize should be determined by what task you want the knife to perform... but I'm not going to get into that.

For a general purpose knife, I think it need to be tough enough for normal use, hold an edge long enough to get through a normal day, and be able to hold a good edge angle without issue. If it is lacking in any one of those, you'll likely end the day frustrated.
 
KnightAspirant said:
my brother in blades right here ^
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I got a little bit down the latest and greatest" super steels rabbit hole for a while, and some of them are good, but as a good ol, in the field pocket knife, I found myself reaching for a 440C blade most of the time. There was a time when it was considered a top end steel, and to me, it still is.
 
DBG40 said:
I got a little bit down the latest and greatest" super steels rabbit hole for a while, and some of them are good, but as a good ol, in the field pocket knife, I found myself reaching for a 440C blade most of the time. There was a time when it was considered a top end steel, and to me, it still is.
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My old friend and a wonderful maker, the late Kit Carson was a fan of 440C. Oddly enough, I remember having issues sharpening it back in the late 90's...before I accumulated more suitable sharpening gear.
 
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