How much does toughness matter?

[Deadboxhero]

I don't think it's fair to say toughness doesn't matter in a folder. It depends on your specific use and that varies widely between forum members. It seems that most here are urban folk who primarily cut cardboard and plastic packaging which I guess favours certain steel properties.

My use is mostly farm and field based. The killers of low toughness steels, like my S110V blades, for me are bone, and grit and sand in natural materials like bark. These are what give me chips which are a pain to sharpen out, particularly in the field with limited equipment. I also seem to lose the last tiny bit of the point with less tough steels. It might be so small I need a loupe to see it but it still bugs me.

I don't need anything extreme but steels less tough than S30V often give me grief. For me, K390 is a great balance of toughness and edge stability in a high wear resistant steel. M390 and 20CV not so much, which is a shame because I have real issues with rust with K390 in tropical environments.

After overcoming a bit of steel snobbery, I find the trade offs due to lower hardness and edge holding of H1 and LC200N are worth it in situations remote from bulkier sharpening gear, particularly working long days with very little spare time for damage repair.

I await Magnacut with bated breath if it really is like a rustproof 4V.

Dan

My opinion is that toughness gets passed around too much without context for what is happening.
Geometry geometry geometry.


Difficulty sharpening is a bogeyman.
Spyderco Double stuff 2, with cBN.

There is no sharpening difficulty with good technique, abrasive and good HT.

The problem with high toughness steels is that they don't resist deformation as good, they tend to blunt smooth much easier which means you have to stop and touch them up more frequently. This also means that these knives will be sharpened away much faster over time.

Heres another thought, if the edge has rolled so badly that it looks like a chip what's the difference?




Here is a folder made by another production company in CPM 3V, the focus of the heat treatment
and knife design was to maximize the toughness.
The knife was designed to be used like a mini wreaking bar.

Well, what does that matter at the edge? There is little resistance to deformation so it gets chowdered at the edge very easily.



Here is a blade Elmer sharpened for a customer by hand and shared on his Instagram.

This knife brand is known for focusing on toughness, which people enjoy in this product.

This damage however is a prime example of why trading resilience for the plasticity found in impact toughness is not always best, plastic deformation can be so bad there is no difference between if it chipped or deformed.

I always use diamonds and absolutely agree with your comments but I spend a couple of months a year in the field where I use my knives frequently and the only sharpening opportunities are sitting cross-legged on my swag(bedroll in the US?) at night after a 14 hour day. My technique and situation is less than perfect here and quick, easy sharpening really does count.

Dan

I used to work in the field for extended periods providing medical on the fire line and at base camp.

Being the knife, axe and sharpening geek I was also the guy that sharpened everyone's knives and taught knife and pulaski sharpening when there was downtime on breaks with crews after checking my medical kits, maps and routes for medivacs.

My take away from that experience combined with the materials science and sharpening knowledge I had was that its technique and abrasives over steels being inherently too difficult to sharpen, even geometry and heat treatment played a bigger role than just the steel in sharpenability.

So I feel its a "bogeyman" whenever I hear steel A is too difficult to sharpen compared to steel B in most cases and has become something that is repeated over and over and never tested or ruled out.

In my opinion, extended field excursion doesn't mean that you can't sharpen a harder, higher wear steel unless techniques and tools used need to be reviewed.












I have been a strong proponent of super steels in field knives for a good while.

Prior to making knives I worked with Danjiel Haramina from Malanika to get some of the first true PM tool steel puukkos in CPM M4, Cruwear and 4V.



What was eye opening at the time is that the sharpening difficulty was vastly overblown, yet the increased edge retention in the field was quite exciting.

[Deadboxhero]

Here is an interesting look.

I got a knife in from a friend that works doing HVAC construction work.

Basically a gas station knife.



The steel is some kind of low carbide volume budget stainless at lower hardness.

Low carbide volume and low hardness are factors that improve toughness.

Its interesting looking at the worn edge under magnification.



The edge is worn so badly it looks like its chipped away but it is essentially worn away. The blue line shows where the edge would be if it wasn't worn away.

I feel the term toughness is used generically as "no damage at the edge" by lay people but we have all these different factors eating away at the edge perhaps we should think and discuss more deeply about how these different properties apply at the edge.

[Airlsee]

Every legitimate cutting-edge toughness should have a baseline HRC...don't come with garbage steel under 58 hrc...even that is debatable.

Toughness just like every other blade steel property needs to be considered in context.

[R100]

I don't think it's fair to say toughness doesn't matter in a folder. It depends on your specific use and that varies widely between forum members. It seems that most here are urban folk who primarily cut cardboard and plastic packaging which I guess favours certain steel properties.

My use is mostly farm and field based. The killers of low toughness steels, like my S110V blades, for me are bone, and grit and sand in natural materials like bark. These are what give me chips which are a pain to sharpen out, particularly in the field with limited equipment. I also seem to lose the last tiny bit of the point with less tough steels. It might be so small I need a loupe to see it but it still bugs me.

I don't need anything extreme but steels less tough than S30V often give me grief. For me, K390 is a great balance of toughness and edge stability in a high wear resistant steel. M390 and 20CV not so much, which is a shame because I have real issues with rust with K390 in tropical environments.

After overcoming a bit of steel snobbery, I find the trade offs due to lower hardness and edge holding of H1 and LC200N are worth it in situations remote from bulkier sharpening gear, particularly working long days with very little spare time for damage repair.

I await Magnacut with bated breath if it really is like a rustproof 4V.

Dan

My opinion is that toughness gets passed around too much without context for what is happening.
Geometry geometry geometry.


Difficulty sharpening is a bogeyman.
Spyderco Double stuff 2, with cBN.

There is no sharpening difficulty with good technique, abrasive and good HT.

The problem with high toughness steels is that they don't resist deformation as good, they tend to blunt smooth much easier which means you have to stop and touch them up more frequently. This also means that these knives will be sharpened away much faster over time.

Heres another thought, if the edge has rolled so badly that it looks like a chip what's the difference?




Here is a folder made by another production company in CPM 3V, the focus of the heat treatment
and knife design was to maximize the toughness.
The knife was designed to be used like a mini wreaking bar.

Well, what does that matter at the edge? There is little resistance to deformation so it gets chowdered at the edge very easily.



Here is a blade Elmer sharpened for a customer by hand and shared on his Instagram.

This knife brand is known for focusing on toughness, which people enjoy in this product.

This damage however is a prime example of why trading resilience for the plasticity found in impact toughness is not always best, plastic deformation can be so bad there is no difference between if it chipped or deformed.

I always use diamonds and absolutely agree with your comments but I spend a couple of months a year in the field where I use my knives frequently and the only sharpening opportunities are sitting cross-legged on my swag(bedroll in the US?) at night after a 14 hour day. My technique and situation is less than perfect here and quick, easy sharpening really does count.

Dan

I used to work in the field for extended periods providing medical on the fire line and at base camp.

Being the knife, axe and sharpening geek I was also the guy that sharpened everyone's knives and taught knife and pulaski sharpening when there was downtime on breaks with crews after checking my medical kits, maps and routes for medivacs.

My take away from that experience combined with the materials science and sharpening knowledge I had was that its technique and abrasives over steels being inherently too difficult to sharpen, even geometry and heat treatment played a bigger role than just the steel in sharpenability.

So I feel its a "bogeyman" whenever I hear steel A is too difficult to sharpen compared to steel B in most cases and has become something that is repeated over and over and never tested or ruled out.

In my opinion, extended field excursion doesn't mean that you can't sharpen a harder, higher wear steel unless techniques and tools used need to be reviewed.












I have been a strong proponent of super steels in field knives for a good while.

Prior to making knives I worked with Danjiel Haramina from Malanika to get some of the first true PM tool steel puukkos in CPM M4, Cruwear and 4V.



What was eye opening at the time is that the sharpening difficulty was vastly overblown, yet the increased edge retention in the field was quite exciting.

I reckon you are right about poor techniques and equipment on my part. I don't have trouble keeping any particular steel sharp in the field but I am stymied by repairing edge damage in high wear resistant steels. I loved your field photos. We sure do work in different environments though!





Dan

[Deadboxhero]

Beautiful photos Dan, thank you for sharing.

My opinion is that toughness gets passed around too much without context for what is happening.
Geometry geometry geometry.


Difficulty sharpening is a bogeyman.
Spyderco Double stuff 2, with cBN.

There is no sharpening difficulty with good technique, abrasive and good HT.

The problem with high toughness steels is that they don't resist deformation as good, they tend to blunt smooth much easier which means you have to stop and touch them up more frequently. This also means that these knives will be sharpened away much faster over time.

Heres another thought, if the edge has rolled so badly that it looks like a chip what's the difference?




Here is a folder made by another production company in CPM 3V, the focus of the heat treatment
and knife design was to maximize the toughness.
The knife was designed to be used like a mini wreaking bar.

Well, what does that matter at the edge? There is little resistance to deformation so it gets chowdered at the edge very easily.



Here is a blade Elmer sharpened for a customer by hand and shared on his Instagram.

This knife brand is known for focusing on toughness, which people enjoy in this product.

This damage however is a prime example of why trading resilience for the plasticity found in impact toughness is not always best, plastic deformation can be so bad there is no difference between if it chipped or deformed.

I always use diamonds and absolutely agree with your comments but I spend a couple of months a year in the field where I use my knives frequently and the only sharpening opportunities are sitting cross-legged on my swag(bedroll in the US?) at night after a 14 hour day. My technique and situation is less than perfect here and quick, easy sharpening really does count.

Dan

I used to work in the field for extended periods providing medical on the fire line and at base camp.

Being the knife, axe and sharpening geek I was also the guy that sharpened everyone's knives and taught knife and pulaski sharpening when there was downtime on breaks with crews after checking my medical kits, maps and routes for medivacs.

My take away from that experience combined with the materials science and sharpening knowledge I had was that its technique and abrasives over steels being inherently too difficult to sharpen, even geometry and heat treatment played a bigger role than just the steel in sharpenability.

So I feel its a "bogeyman" whenever I hear steel A is too difficult to sharpen compared to steel B in most cases and has become something that is repeated over and over and never tested or ruled out.

In my opinion, extended field excursion doesn't mean that you can't sharpen a harder, higher wear steel unless techniques and tools used need to be reviewed.












I have been a strong proponent of super steels in field knives for a good while.

Prior to making knives I worked with Danjiel Haramina from Malanika to get some of the first true PM tool steel puukkos in CPM M4, Cruwear and 4V.



What was eye opening at the time is that the sharpening difficulty was vastly overblown, yet the increased edge retention in the field was quite exciting.

I reckon you are right about poor techniques and equipment on my part. I don't have trouble keeping any particular steel sharp in the field but I am stymied by repairing edge damage in high wear resistant steels. I loved your field photos. We sure do work in different environments though!





Dan

[Sharp24/7]

I want to mirror JSumm in that I think *most* people who talk about valuing toughness in a folder are actually valuing edge stability. Edge stability is a factor of toughness, hardness, and geometry, so you can have steels with great edge stability that are not very tough (many of the very hard tool steels fall into this category) and you can have steels with very poor edge stability that are very tough (think LC200N or H1).

One of the reasons why I dislike H1 is that it doesn't have great edge stability in my experience, even in SE blades. I don't particularly care that the knife will bend before it breaks or will roll before it chips, because a bent knife or a knife with a rolled edge is still a tool that will require significant repair before it is fully useable again, and I find that the H1 edge rolls really easily. I'd rather have an edge that doesn't roll *or* chip easily.

Then you have steels like Cru-wear, CPM-M4, Magnacut, etc. that can both be made quite hard *and* are very tough, and you can do ridiculous things like hammer the blade through a mild steel nail with minimal edge damage.

This is my basic understanding. I also agree, I want a magical sweet spot between rolling and chipping where a steel just blunts as it dulls and doesn't roll or chip unless really beat on. Much of this can be fine tuned with edge angle changes but assuming I sharpen everything at the same angle, I want the Goldilocks steel that hits that sweet spot. So far this is exactly what I'm seeing from my MagnaCut Mule.

Evil D my Hogue Deka in Magnacut arrived yesterday and you mentioned the exact results I’m hoping for. Do you happen to know the stock thickness on that Mule?

[Danke]

It sounds like I'm guilty of using the term "toughness" wrong?

I want a knife that resists damage. I don't want rolling or chipping. If I drop it or ding it I don't want that to ruin my day.

So to get that my compromises would be I'd pay more for that steel. And I'd also compromise on corrosion resistance; I don't mind if there are some black marks or patina. I will use a tool steel over ultimate stainless.

[Evil D]

Evil D my Hogue Deka in Magnacut arrived yesterday and you mentioned the exact results I’m hoping for. Do you happen to know the stock thickness on that Mule?

I've got 3.04mm at the spine and 3.05mm at the bottom hook thing of the tang, 2.92mm just above the not-a-thumb hole, 2.56mm half way down the spine and 1.01mm just behind the edge bevel at the very tip.

The edge has been reprofiled down to about 25 degrees inclusive and has a 30 degree inclusive not-so-micro micro bevel that I'm lazily turning into a secondary edge bevel before I get motivated to thin the whole edge back down. The edge measures around 0.030-0.032 or so behind the bevel, so not exactly a thin grind.

[metaphoricalsimile]

It sounds like I'm guilty of using the term "toughness" wrong?

I want a knife that resists damage. I don't want rolling or chipping. If I drop it or ding it I don't want that to ruin my day.

So to get that my compromises would be I'd pay more for that steel. And I'd also compromise on corrosion resistance; I don't mind if there are some black marks or patina. I will use a tool steel over ultimate stainless.

Cruwear or CPM-M4. Magnacut potentially should be good-to-go too, only with really incredibly corrosion resistance.

[blues]

Thanks, Shawn. Always appreciate your helping to put things in perspective.

[Danke]

It sounds like I'm guilty of using the term "toughness" wrong?

I want a knife that resists damage. I don't want rolling or chipping. If I drop it or ding it I don't want that to ruin my day.

So to get that my compromises would be I'd pay more for that steel. And I'd also compromise on corrosion resistance; I don't mind if there are some black marks or patina. I will use a tool steel over ultimate stainless.

Cruwear or CPM-M4. Magnacut potentially should be good-to-go too, only with really incredibly corrosion resistance.

There's like a lot of M4 in here.

[GarageBoy]

887g bess on that edge? I would have expected higher.

I always thought it was funny that all those fancy edc prybars were always made of titanium (flexy) or s30v (looking at you Peter Atwood) - I'm sure if someone made an actual folding pry bar/cold chisel with a reinforced pivot, it'd sell and actually be useful

[Sharp24/7]

Not totally on topic, but I’m trying to decide between an S30V Sage 5 and the Blade HQ Exclusive Sage 5 in M4. I don’t abuse my knives or use them overly hard, but I’m a bit clumsy so I’m looking for that’s not going to chip or break if accidentally drop it on concrete or ding it on a glass cutting board. This would be an easy call except the mint green isn’t a great color and I’m a tad concerned the FRN texturing will tear up my pants. Had a bad experience with a Ritter Hogue doing that. All that said if S30V is durable enough to whether occasional attacks of clumsiness, I’ll go that route. Anyone with more experience than me have thoughts?

[Bill1170]

That Randall knife in Shawn’s photo looks more like it got electrically arced than it looks like a mechanical chip. In my experience, arc divots are narrow and deep while edge chips from lateral force tend to be wider for their depth, like a semicircle.

[Larrin]

887g bess on that edge? I would have expected higher.

I always thought it was funny that all those fancy edc prybars were always made of titanium (flexy) or s30v (looking at you Peter Atwood) - I'm sure if someone made an actual folding pry bar/cold chisel with a reinforced pivot, it'd sell and actually be useful

Once you are above 800g or so it seems like it’s just a random big number sometimes. Like breaking the thread rather than cutting it.

[metaphoricalsimile]

Not totally on topic, but I’m trying to decide between an S30V Sage 5 and the Blade HQ Exclusive Sage 5 in M4. I don’t abuse my knives or use them overly hard, but I’m a bit clumsy so I’m looking for that’s not going to chip or break if accidentally drop it on concrete or ding it on a glass cutting board. This would be an easy call except the mint green isn’t a great color and I’m a tad concerned the FRN texturing will tear up my pants. Had a bad experience with a Ritter Hogue doing that. All that said if S30V is durable enough to whether occasional attacks of clumsiness, I’ll go that route. Anyone with more experience than me have thoughts?

The real answer here is get rid of your glass "cutting" board. They are meant for presentation, not for actual cutting, except maybe with a blade you don't care about keeping sharp like a cheese knife.