Why s90v and all these other high carbide steels suck for knives

[Wowbagger]

I thought the beauty of high carbide steels like D2, S30V, or S90V were they kept cutting to low sharpness. The carbide tear out produced a jagged (albeit thicker) edge as it micro chipped itself to dull. I thought that was an advantage in some situations?

No one ACTUALLY knows how the high vanadium powdered technology high alloy super steels work.
What I C A N tell you is THE ONLY WAY TO BRING ABOUT A SUCCESSFUL TRANSFORMATION OF THE DULL EDGE will include encircling the knife with an unbroken line of salt and placing candles at the points of a pentacle star, sacrificing at least one three legged chicken and keeping your fingers crossed throughout the procedure are an absolute must.

Any actual observation of the edge during this ritual will, at least, end the transformation and at worst result in the observer being transformed into a newt.

Disregard these warnings at your own peril.

PS: for some reason this simple sharpening, we will call it "edge maintenance", procedure has created the myth in people's minds that high vanadium blades are hard to sharpen or take too much time to maintain. Once you have learned to followed these few simple steps it's a breeze.

 

[newdebate]

^know that.

 

[halden.doerge]

No one ACTUALLY knows how the high vanadium powdered technology high alloy super steels work.
What I C A N tell you is THE ONLY WAY TO BRING ABOUT A SUCCESSFUL TRANSFORMATION OF THE DULL EDGE will include encircling the knife with an unbroken line of salt and placing candles at the points of a pentacle star, sacrificing at least one three legged chicken and keeping your fingers crossed throughout the procedure are an absolute must.

Any actual observation of the edge during this ritual will, at least, end the transformation and at worst result in the observer being transformed into a newt.

Disregard these warnings at your own peril.

PS: for some reason this simple sharpening, we will call it "edge maintenance", procedure has created the myth in people's minds that high vanadium blades are hard to sharpen or take too much time to maintain. Once you have learned to followed these few simple steps it's a breeze.

Finally, someone is making sense in this thread!

 

[Lapedog]

I have what is possibly a dumb question, but I'm hoping someone can answer in a way that I can understand.

For some time now, I've been reading discussions about the effect of carbide size and distribution in steel, and I sort of understand the analogy of very hard particles in a softer matrix. I've read descriptions of carbides "tearing out", etc. But this is all on a microscopic scale, correct? What I can't picture in my I-got-a-C-in-high-school-chemistry-mind is what is the scale relative to the edge. Let's say the edge of my knife is magnified to the size of the prow of an ocean-liner. Are the carbides the size of barnacles, relatively speaking, or much larger than that? Would that really effect the performance of the blade in the real world? Or am I picturing it wrong entirely?

You might enjoy watching this. It is a basic lesson on carbides in powdered vs non powdered steel.

 

[ATJ999]

No a huge fan of S90V or S110V, but M390(20CV/204P) is a high carbide steel and it is without a doubt my favorite steel for smaller knives. It holds a great edge, gets sharp, easy to sharpen, and is surprisingly tough when done right. K390 is another high carbide steel that is very easy to maintain. As well as 3V.
I do love low carbide steels like 1095 and Aeb L, but if I could only choose 2 steels to live the rest of my life with, it would be M390 and CPM 3V. That is really all I would ever need. But, I do like variety, and experiencing new things, so I have lots of other steels.
I do think S90V is one of the least user friendly steels out there, but it is still a decent knife steel. M390 has close to the same edge holding and is much more user/edc friendly, so it usually gets my preference.
I'm sure other peoples experiences vary.

 

[kraftzion]

So if you can get the right mix for strong concrete, why cant you get the right mix for strong "super steels"? And that mix includes proper and very specific heat treatments for the desired characteristics.

You can, the right mixture contains less carbides.

When they talk about tool steels being "notch sensitive" etc. It is when the hardened an tempered steel is being used under very heavy stresses like in a 20,000 ton punch press. If your knife has a notch in it, you want the corners of the notch to have a significant radius so that you don't create a stress riser in that area. If you are not using it as a pry bar you shouldn't have any issues.

The stress placed on a knife edge is greater than the stress placed on metal by a 20,000 ton punch press in my opinion. I tend to agree with Sandvik that a good edge is 1 micron. It is generally accepted that an edge is 30 microns or less.a 20,000 ton punch press is forming flat metal. It all boils down to p.s.i.. When you cut through a piece of paper how much stress are you placing on the edge? Now sometimes you are not contacting the material with the edge directly, it is splitting like a maul splits wood with no contact other than initial. But initial contact is extreme. Maybe somebody wants to do the math as this is just my opinion,
Here is an interesting read on the topic. https://vacaero.com/information-resources/the-heat-treat-doctor/1173-tool-steel-carbides.html

Here is a quote from the article.

Finally, caution should be observed in that although carbides are beneficial in tool steels for a number of reasons (e.g. strength and wear resistance) they are also likely crack initiation sites in instances where high application stress is involved.

the "sharp radii" of a knife edge is an external "radii" (If you want to equate an edge to a radius for the sake of argument).
What they are referring to though is internal radii.

If they were going to be precise enough to use the word "radii" which is not as extreme as "angle" you would think they would have included the word"internal" if that is what the meant. A knife edge is the very definition of an acute angle and is way out of bounds of what these steels were meant for is what that statement means in my opinion.

I will agree though that the super steels may be more prone to edge chipping when being used hard.

Just my 2 cents.

 

[kraftzion]

The biggest variable in knife use is the user. Whether you prefer high or low carbide knives depends on how you use them.

For nearly every thing i carry a knife for, i prefer lower carbide steels, 420hc, bd1, 12c27, etc. My tolerance for dullness is pretty low, so i sharpen pretty regularly. No advantage for high carbide steels there.

I have fairly simple sharpening tools, Norton, King, and Sharpmaker stones. No advantage to high carbide there either.

I have some small DMT stones, and one knife in S110V. Even with the diamond, it doesn't get as sharp as my other knives.

My knife budget had dropped recently. No advantage for high carbide steels there either.

I use rather thin edge angles, 12 degrees and 15 degree microbevel. No advantage there.

I tested S110V and BD1 side by side, and found a slight advantage for BD1.

I can accept that I do things differently than a lot of knife users, but i see no point in dropping more money on knives that need special sharpening gear, and don't offer any advantage in my uses.

If i used 20 to 25 degree bevels, cut a lot of sand paper, and let a knife get dull enough to just barely slice paper, my knife choices would likely be different.

I am op and this is the proper answer. My aggravation with s90v caused me to vent when posting.

 

[kraftzion]

http://www.cliffstamp.com/knives/articles/carpet.html


Kraftzion I don't know what to tell you, your are using a limited test to make broad conclusions.

My conclusions are based on my use of s90v. The video is just a demonstration of high carbide vs low carbide steels that support my conclusions.

 

[kraftzion]

Carbides in cpm steels are microscopic, somewhere in the 0.006 to 0.009 millimeter range. Carbides in conventional D2 can be add much as 0.050 millimeters. Carbides in conventional steels with relatively low carbide volume can be smaller than the width of a sharp edge. See below. Some steels have only tempering carbides, which are 0.000005 millimeters or so.

Sharp edges are somewhere around 0.001 millimeters or less. The smallest I've heard of was 0.0002 millimeters.

Thanks for this info, I have had a hard time finding it. Found the d2 info which is in my opinion the worst knife steel. Although you wouldn't know it considering I have 2 knives with it.

 

[kraftzion]

You dont consider it a knife unless its sharpened 15 degrees per side? Thats narrow minded.

check out Cedric Ada
YT Channel https://www.youtube.com/user/CedricAda/videos
podcast guest http://www.geargeekslive.com/episode-89-favorites-not-best
blogpost part1 https://www.everydaycommentary.com/...17/7/7/cedric-and-adas-steel-test-and-results
blog post part 2 https://www.everydaycommentary.com/...and-adas-thoughts-on-steel-and-edge-retention

I have to ask why sisal or manila rope seems to always be the chosen medium? I have never cut or used either for anything. The things I cut will make you hate most of the steels at the top of that list in my opinion. Try cutting the purple foam board from home depot. Black pipe insulation(rubbetex,armaflex,etc.) Ductboard.Of coarse you would have to take pictures of the edge because you can cut ductboard with a dull knife. You just won't cut it with a sharp knife very long, no matter what steel you use. Guaranteed to chip the steels at the top at 20 degrees.

 

[pinnah]

Pictures of 12C27 and 440C can be found on this page from Sandvik. 440c should probably be considered something of an extreme case as I believe the PM steels have more moderate and evenly distributed carbides.

Still, the pictures help to understand the scale visually.
http://smt.sandvik.com/en/products/strip-steel/strip-products/knife-steel/knife-steel-knowledge/

 

[Mo2]

I have to ask why sisal or manila rope seems to always be the chosen medium? I have never cut or used either for anything. The things I cut will make you hate most of the steels at the top of that list in my opinion. Try cutting the purple foam board from home depot. Black pipe insulation(rubbetex,armaflex,etc.) Ductboard.Of coarse you would have to take pictures of the edge because you can cut ductboard with a dull knife. You just won't cut it with a sharp knife very long, no matter what steel you use. Guaranteed to chip the steels at the top at 20 degrees.

Well for one as he mentions it measures close to catra. But another reason I assume is because it's the same product. When I work with cardboard I have some many different variations of cardboard, I think they want to try and make it uniform across the board.

But yea results will differ between what your cutting but it gives a clear indication of the steel for the most part. Certainly no cut test is going to be perfect or all encompassing and if your taking these tests as absolute, that's not what anyone is saying for the most part.

 

[TheEdge01]

K kraftzion

Might want to fix your title. The video is about s30v instead of the s90v in your title. Don't see many blades made in s30v, for some reason.

Most of Benchmades 2017 lineup has S30V blade steel.

 

[Agith]

I would be inclined to agree with the comments regarding higher carbides in knife steels. However, steels like D2 are effective in maintaining the ability to cut for very long times. Is it going to chip? Depending on your media, possibly. But it will cut through things like animal hide very easily for an extremely long time, and the toothy edge really seems to help with that sort of task, where-as a finer edge may cut well, in my experience it has a more dramatic fall off in cutting ability over time.

Of course we are ultimately talking extreme nuances here. Anything brought to an edge with proper geometry will cut. It's the ability to keep cutting that matters, and the differences between steels tends to be a bit overplayed on this forum.

 

[jbmonkey]

i always liked s60v/440v better than s90v/420v myself. kinda wish it was still around.

i dont dislike these new super steels, but im fine with old steels and i like d2 as well. not my favorite.

point i guess is i like the wide range of choices we have for steels nowadays.

 

[TheEdge01]

Imo every blade steel has it's place in the knife world. In other words, use whatever steel tickles your fancy. If you don't really use your knives hard, chances are you won't be able to tell a difference between a super steel vs a mid range steel. I have owned knives with super steel blades such as Elmax, CPM 20CV, M390, etc. Personally, I don't have anything against super steels, but I just don't see the value unless you really use them, or have plenty of money at your disposal.

 

[lemonslush]

I plan on using my knives and then resharpening them later. I care less about the steel they are made of and more about the design of the blade. Most people dont actually use their knives to their full potential. You put a nice heat treat on a blade and it should serve you decently well. My favorite steel is still h1, holds the best edge out of anything I used.

 

[Gaston444]

I am op and this is the proper answer. My aggravation with s90v caused me to vent when posting.

This is also what observed: If you use low angles and have a low tolerance for dullness before you touch up, some, maybe all, powder steels will not offer any advantages.

What's more, at low angles (15 per side or less) S30V has a strong tendency to micro-fold a tiny wire edges at the slightest provocation (chopping or even push-cutting cardboard): Maybe those micro wire edges will hold on and keep cutting a long time, but it seems to me this fits with a fine carbide grain structure: Bigger carbides may be more brittle and prone to tearing out, but they add more overall rigidity to the edge apex, just like a yardstick folding ruler with 3 links made of wood is more rigid than a bicycle chain with a hundred links made of steel...

Gaston

 

[vwb563]

I thought the beauty of high carbide steels like D2, S30V, or S90V were they kept cutting to low sharpness. The carbide tear out produced a jagged (albeit thicker) edge as it micro chipped itself to dull. I thought that was an advantage in some situations?

Same here. My understanding is the same as yours. I know my S90V Benchmade Amicus / Arcane will loose its hair shaving edge eventually and "feel" dull when doing the arm hair shaving test but still cuts like DAMIT when cutting anything like cardboard or rope. So there has to be something to the theory. I think the micro chipped edge acts like a mini serrated edge but that's just me talking. All I know for sure is there is something going on with the high carbide steels that make them just keep on and keep on cutting.

 

[Shooter4321]

After 3 weeks of daily use I decided not to strop but to sharpen my S90v military. My set up I used is a edge pro and used shapton glass 320.
Raised a bur twice on factory edge and knocked it off....10 min....
I really like S90v..