Sharpening high vanadium steels

[Tucson Tom]

The recent thread on "what steel takes the keenest" edge had some interesting comments on sharpening steels with lots of vanadium carbides. In particular, "Bodog" said:

"If the carbides are harder than the sharpening media then you'll only plow the carbides and cut the matrix of the steel. If there is only a steel matrix, meaning no or almost no carbides or you're sharpening is so unrefined that you don't care about sharpening the carbides, then you only need sharpening media harder than the steel matrix itself."

A lot more was said, including the statement that Vanadium Carbides are so hard that you may not actually cut them with anything but diamond or CBN.

So I am thinking about this and my own sharpening equipment -- which at this point is the sharpmaker. So my question is, given the above, would it be true that I am limited in my ability to sharpen high vanadium steels such as say S110V with just the ceramic rods in the sharpmaker? This is no joking matter since it may push me over the edge towards spending money and purchasing a more sophisticated sharpening system like the Edge Pro or one of its brothers.

Note that I don't take this to mean that the ceramics in the sharpmaker cannot sharpen these high vanadium steels. I just suspect that equipment that uses finer CBN or diamond abrasives may produce an edge on these steels that I have yet to see. Or maybe I am hoping for too much.

[Pelagic]

In theory, you will have carbide tear out, but that doesn't mean you can't get it plenty sharp. Spyderco ceramics are a great finishing stone (or transition stone before strops) even on high vanadium steels... people seem to like using them for refining the scratch pattern left by diamond stones and removing that last bit of burr. I guess it depends on how well it works for you and how long it takes. If you're just sharpening occasionally you could probably get by, but even if only for the sake of saving time, if you're sharpening s110v regularly I'd recommend diamond.

[dj moonbat]

I've recently stopped using the Sharpmaker to maintain my knives with big Vanadium. Too early to say whether it's a placebo effect, but my initial impression is that sticking with diamonds creates a more durable edge at similar grit size. And by going to a diamond stone that's a good bit finer than the extra fine rod (Venev diamond waterstone, 2000), I've definitely improved things.

It was only when I went to diamonds-only for S110V that I started getting the kind of edge durability that tracked with the steel's reputation. But I'm a ham-fisted oaf, so YMMV.

I think if you're using those ceramics with really high carbide content steels, and actually using them enough to get to a new microbevel, you've pretty much got to be either popping out grains of carbide, or undercutting the steel supporting those grains such that they get popped out later while you use the knife.

[Squawk]

I'm no expert by any means, but from my understanding, while diamond stones will be a lot faster on high carbide steels, the Spyderco ceramics should still be harder than the vanadium carbides meaning hard enough to cut them. I'd anyway use them only for refining/finishing with a light touch because i can imagine this tearout could maybe happen from using too much pressure?

[Squawk]

Double post

[Ankerson]

I haven't seen any steel that you actually need diamonds to sharpen.

I use Silicon Carbide to sharpen all steels and NEVER had an issue with ANY steel getting it sharp.

I use the Edge Pro with Congress Mold Master Silicon Carbide stones. They are commercial grade stones and are VERY hard and with very little fillers, very high quality.

For touchups I use Spyderco Ceramics.

[Eli Chaps]

I know the internet is full of buzz about how you just can't sharpen the "super" steels with anything but diamond, CBN, or Superman's gaze but I have been getting very good results with S90V and ZDP-189 on Arkansas soft through hard black stones.

I would guess these steels are sharpened on SiC belts just like everything else at the factory. Maybe not but that's my hunch.

I have a KME with diamonds and that will serve as a reprofile or really dull edge tool but I literally blunted the edge of my ZDP-189 Delica and brought it back up with a soft Ark. A diamond would be faster but I only spent about 20min's on the first stone so no big deal to me. I did not blunt the S90V but it was ready for a touch-up and it did just fine on my natural stones.

[The Meat man]

I know the internet is full of buzz about how you just can't sharpen the "super" steels with anything but diamond, CBN, or Superman's gaze but I have been getting very good results with S90V and ZDP-189 on Arkansas soft through hard black stones.

I would guess these steels are sharpened on SiC belts just like everything else at the factory. Maybe not but that's my hunch.

I have a KME with diamonds and that will serve as a reprofile or really dull edge tool but I literally blunted the edge of my ZDP-189 Delica and brought it back up with a soft Ark. A diamond would be faster but I only spent about 20min's on the first stone so no big deal to me. I did not blunt the S90V but it was ready for a touch-up and it did just fine on my natural stones.

Made me laugh :D

[Ankerson]

I know the internet is full of buzz about how you just can't sharpen the "super" steels with anything but diamond, CBN, or Superman's gaze but I have been getting very good results with S90V and ZDP-189 on Arkansas soft through hard black stones.

I would guess these steels are sharpened on SiC belts just like everything else at the factory. Maybe not but that's my hunch.

I have a KME with diamonds and that will serve as a reprofile or really dull edge tool but I literally blunted the edge of my ZDP-189 Delica and brought it back up with a soft Ark. A diamond would be faster but I only spent about 20min's on the first stone so no big deal to me. I did not blunt the S90V but it was ready for a touch-up and it did just fine on my natural stones.

There tend to be a lot of shills around (for lack of a better word) pushing certain diamond stones for everything. It gets repeated so often that now it seems to be gospel.

Not sure how it all got started, but there are plenty of high quality NON diamond stones on the market that will handle any steel without much problem.


Needing diamonds to sharpen these steels is complete hogwash.

[Chumango]

It is clear that you can get a sharp edge with many types of abrasive media, but what actually happens to the carbides?

Some interesting reading here (with nice photographs). Take it for what it is worth, draw your own conclusions, and balance against your own experience.

https://www.bladeforums.com/threads/can ... t.1519674/

https://www.bladeforums.com/threads/s30 ... s.1535385/

[Ankerson]

It is clear that you can get a sharp edge with many types of abrasive media, but what actually happens to the carbides?

Some interesting reading here (with nice photographs). Take it for what it is worth, draw your own conclusions, and balance against your own experience.

https://www.bladeforums.com/threads/can ... t.1519674/

https://www.bladeforums.com/threads/s30 ... s.1535385/

A lot of it has been way overblown and NONE of it really matters in real life for those who actually use their knives. A lot of it is based on theroy and won't make any difference one way or another.

Sharpening talent is and always will be the most important factor, doesn't matter if the steel is 1080 or MAXAMET.

People tend to overthink it way too much, it's not really all that difficult or even complicated to get a good edge on a blade.

Whenever I need a good laugh I read those types of threads.


There are certain people around that will keep pushing diamonds for their own benefit and it's been going on for awhile.

Same with those who tend to over complicate sharpening for the same reasons.

Most are trying to sell people something...…

Bottom line is that it's NOT really all that hard.

That is one thing that Cliff and I do agree on, one of the only things.

[Chumango]

As I said, draw your own conclusions and balance them against your own experience. The micrographs tell a story, but what is the correct interpretation? How much impact does it have in real life?

[Ankerson]

As I said, draw your own conclusions and balance them against your own experience. The micrographs tell a story, but what is the correct interpretation? How much impact does it have in real life?

Real life, I would say ZERO.

All of those steels can an will take an edge way beyond the point that anyone can do by hand or with a guided system.

Goes to the overthinking aspect of it all.

Sharpness is the actual apex thickness, that isn't theory, that is fact, the smaller the apex is the sharper the edge will be all the way down to atom level. But then that's way beyond what humans can actually do.

[Bodog]

With the current fine carbides with the equal distribution of powder metallurgy, you can absolutely sharpen a knife with any kind of sharpening media that's harder than the steel matrix. Doesn't matter what it is or what kind of steel it is. The carbides are microscopic so they're just going along for the ride with the matrix. Again, if your sharpening media is capable of cutting the matrix you can sharpen the knife to very fine levels depending on the fineness of the abrasives.

If you're trying to go to the absolute highest levels, like more refined than any of us could actually achieve, then your edge would have to be thinner than the carbides in the mix. With some older cast steels that would be something worth considering but with steels using particle metallurgy it would be very hard to get an edge so thin you'd actually need to sharpen the carbides.

The best thing about diamond plates, imo, is that they don't dish and if you're buying from a reputable manufacturer the plates will all be the same thickness which helps tremendously if you're using a guided sharpener.

If i had to speculate, a lot of people will like diamond sharpener more than ceramic because it's a little harder for the diamond plate to glaze over, meaning it will cut cleaner for longer periods without needing to be cleaned off.

Silicon carbide can handle pretty much any steel you throw at it. You won't be sharpening a tungsten carbide drill bit with it.

It always goes back to the steel being like concrete with granite aggregate, PM steels having very, very fine and equally distributed granite chips. IF you can get that concrete to a very fine apex, 1)can the concrete hold that fine of an apex and 2) if it can't then get the apex just thin enough to match the diameter of the granite pieces. If you want it thinner than the granite pieces, then you need to cut the granite as readily as the concrete matrix. The thinner the granite pieces, the easier it will be for normal shaping equipment to get the shape you're looking for.

If there was a non-PM S110V then I'd absolutely recommend diamond or CBN sharpening gear because the carbides would be HUGE and likely thick enough to wear if you DON'T cut the carbides then you'll have a rough, jagged edge.

So, focus on technique and getting quality equipment that gets the job done.

[Ankerson]

Or put another way use what you use to sharpen with and learn how to use it to the best of your ability. :)

That is much more important than the rest.

[Eli Chaps]

...

Sharpness is the actual apex thickness, that isn't theory, that is fact, the smaller the apex is the sharper the edge will be all the way down to atom level. But then that's way beyond what humans can actually do.

This ten fold.

I don't work with steel but I work with metals in insanely high purity ranges as in 6N+ (99.9999%) and I can't imagine these carbides being of sufficient size, let alone be precipitates, to matter at all. These are homogeneous alloys we're talking about here, not free elements within a material. We must be down into the nanometer or even angstrom level. That doesn't even get into the bond strength of these molecules.

I am not a metallurgist but I just talked to three of them about this and all are in agreement that you would never notice this phenomena even if it did happen. Granted, they don't specialize in steel, but they're kinda smart.

[Eli Chaps]

Or put another way use what you use to sharpen with and learn how to use it to the best of your ability. :)

That is much more important than the rest.

Agreed 100%.

[Chumango]

As I said, draw your own conclusions and balance them against your own experience. The micrographs tell a story, but what is the correct interpretation? How much impact does it have in real life?

Real life, I would say ZERO.

All of those steels can an will take an edge way beyond the point that anyone can do by hand or with a guided system.

Goes to the overthinking aspect of it all.

Sharpness is the actual apex thickness, that isn't theory, that is fact, the smaller the apex is the sharper the edge will be all the way down to atom level. But then that's way beyond what humans can actually do.

It wasn't a question of whether different (non-diamond) abrasives can get an edge to a high sharpness. They clearly can. The question was if the potential loss of carbides at the apex (as shown in the micrographs, actual data) makes a difference in the real world. Your experience says no. That may or may not be everyone's experience, which is why I brought it up.

[Bodog]

Or put another way use what you use to sharpen with and learn how to use it to the best of your ability. :)

That is much more important than the rest.

True. But in this day and age i wouldn't recommend an arkansas stone (soft quartz) or really even aluminum oxide stones if you're dealing with vanadium rich alloys. Not so much because of vanadium but because if they're using that steel then the matrix is probably 59 rc + and IF your stone's softish abrasive is harder than the steel then it'd still be kind of slow. Imagine using an abrasive that's 62 RC trying to cut a steel that's 61.5 RC. Sure, it would cut it...but very slowly.

[Bodog]

As I said, draw your own conclusions and balance them against your own experience. The micrographs tell a story, but what is the correct interpretation? How much impact does it have in real life?

Real life, I would say ZERO.

All of those steels can an will take an edge way beyond the point that anyone can do by hand or with a guided system.

Goes to the overthinking aspect of it all.

Sharpness is the actual apex thickness, that isn't theory, that is fact, the smaller the apex is the sharper the edge will be all the way down to atom level. But then that's way beyond what humans can actually do.

It wasn't a question of whether different (non-diamond) abrasives can get an edge to a high sharpness. They clearly can. The question was if the potential loss of carbides at the apex (as shown in the micrographs, actual data) makes a difference in the real world. Your experience says no. That may or may not be everyone's experience, which is why I brought it up.

For whatever it's worth I've gotten CPM-15V at 70+RC to hair whittling using cheap Adaee stones from China. I don't really think most people here think those stones are worth anything but they still work, albeit slower than diamond. And i don't know if most people want to spend time to get a knife sharper than what it takes to whittle hair.

So in real life i could get a refined edge using crap stones with an unknown abrasive. I didn't have an electron microscope to measure whether the edge was refined or not but i had my wife's hair pulled out of a brush that told me it was a refined edge.