S30V 1K SiC and UF abraded surfaces

BluntCut MetalWorks

BluntCut MetalWorks

Knifemaker / Craftsman / Service Provider
Joined
Apr 28, 2012
Messages
3,462
I was testing newly heat-treated s30v blade, decided to investigate an odd edge damage = found it was just a ding... End up with micrograph below - annotation sort of reflects my interpretation. What do you see?

Top circled area is absence of protruding carbides o_O thought-experiment why?

V0nNVIn.png
 
OK Bluntcut, I'll take a stab at it as I find this interesting but not sure how to interpret the pic. o_O ETA: comparing the 2 areas, I'm assuming the UF-ground scratches on the micro are deeper, and there are no/few protruding carbides there because they've been torn out at that point. And there are more protruding carbides in the lower circle because that's the transitional area between your micro and your secondary bevel. Like to hear your theory tho, I'm guessing.

Related: Are you using the Sharp Pebble 1K SiC stone you referenced in another thread recently? Is that 1K ANSI, mesh, JIS, or what rating system? Also, what kind of finish does it put on the S30v blade compared to diamonds?
 
Last edited:
Deeper scratches where there's no carbide and UF plowing deeper, and shallow scratches in carbide area where UF is skating on top of carbides?

Where did the carbides go?
Carbides tearing from apex, maybe taking nearby carbides with them as they ride up the bevel, causing deeper scratches on the way?

Really no clue.
 
Excellent ^ guys!

Micro bevel has higher angle than bevel, so most pressure at apex and gradually less upward. No protruding carbide areas because carbides plough away by burnishing (pushing carbides along surface as plow tips), hence deep scratches at high pressure area. Virtually there is not transitional area from bare to protruding - either carbides there or not, no partially shaped carbides. Protruding carbides top got a good dose of rubbing by ceramic, nice smooth smeared with coat of ferrite (carbide object isn't a perfect sphere - can't be, since mc/it/particle grew by deposition).

OK, so does light pressure with UF produce durable edge?

Well, imagine apex is decorated with protruding carbides.

Scenario 1 - apex matrix width is ~1um. Best case where carbide connected at bottom and along edge = durable. Avg case protruded carbide is 1/2 connected as best case = not durable since easily fall off during burnishing or light use.

Scenario 2 - apex matrix width is 0.5um. There won't be any strongly connected(to matrix) carbides decorate this apex.

Scenario 3 - apex matrix width wider than 5um (at least 2 carbide diameter wide) - feathering/falling-off carbides on cliff could yield keener edge, thus durable however apex width won't be consistent (engineer specs).

Apex decorated carbide fracture boundary is 99%(my wag) followed weakest surface area, which is much larger than carbide interface/boundary. e.g. 2um dia carbide most likely fracture in 3-15um chunk.
 
Chris "Anagarika" said:
Waiting for deeper analysis. :thumbsup:
Click to expand...

:D. Well I'll try, but hoping others jump in. This is admittedly 1 data point in this thread, but frankly this picture--plus other ones I've seen--makes it pretty convincing.

  • I've been using Spydie UF ceramics freehand for a while as a finish-and-refine-apex stone, few super-light passes after apexing on other abrasives. When creating a micro, I use it for that too.
  • Trying this with ALL types of steels, including super steels.
  • It does produce sharp edges as part of the overall sharpening process (which includes stropping with compound after the ceramic).
  • However, when using ceramic with high carbide steels:
  • The above picture, and a few others I've seen, appears to confirm the idea that carbides are torn out.
  • This would then mean the resulting edge is not any more durable than a non-carbide steel.
  • So you're losing all the benefit of the high carbides when you use a ceramic.
That's my takeaway. I'm as convinced as I can be given the evidence I've seen, unless somebody has better evidence to the contrary.
 
It would be cool to see Bluntcut or somebody who has access to the gear needed to take those kinds of photos, do a side-by-side edge retention test. Test 1: take a high carbide super steel knife, apex on diamonds. Then micro-or-refine apex on a UF ceramic. Take a "before" picture of the finished apex. Run an edge retention test cutting some material that quickly wears the edge, and take an "after" picture to show impact on the edge. Test 2: repeat the same test same knife, this time using all diamonds and no ceramic. Would love to see the test results and micrographic pictures to document. Again, a limited data set, but still each example like this that is built up, helps to make the case and support the hypothesis.

Totally open to changing the sharpening process any time that new/better evidence shows up. For now, I'm convinced enough that I'm going to drop ceramics out of the process of sharpening super steels. Although I really like using ceramics in that niche finishing role and will continue to use them for the majority of my knives that are not super steels. It seems like in practical terms, if you're sharpening super steels, it makes sense to stick to 3 widely available abrasives: (1) SiC (and even here, only use at the coarse end of the spectrum), (2) CBN (I'm currently using 1 micron cbn as strop compound, plus it's on the Spydie DS2 pocket stone I'm testing), and (3) diamonds. I just don't see any way to get around that reality right now. If you want to get your super steels sharp and have a durable edge, you need some combo of SiC, cbn, or diamonds.
 
Congrats (golden text), you've good adaptive instinct (hahaha we/knut seem to attained such skills)

Apex has carbides vacated holes, this edge would slice phonebook noisily and some stickiness to skin. Strop would scallop these holes and thin out hole's upper cross-section/wall. Smooth transition between hole/gap to apex translate to quieter slicing (obviously less caught & tear sounds).

Yep, our actions/votes often went ahead of analytics consciousness, i.e. our subconscious is too smarty arrogant to tell us explicitly what the heck it is doing :p

maximus83 said:
:D. Well I'll try, but hoping others jump in. This is admittedly 1 data point in this thread, but frankly this picture--plus other ones I've seen--makes it pretty convincing.

  • I've been using Spydie UF ceramics freehand for a while as a finish-and-refine-apex stone, few super-light passes after apexing on other abrasives. When creating a micro, I use it for that too.
  • Trying this with ALL types of steels, including super steels.
  • It does produce sharp edges as part of the overall sharpening process (which includes stropping with compound after the ceramic).
  • However, when using ceramic with high carbide steels:
  • The above picture, and a few others I've seen, appears to confirm the idea that carbides are torn out.
  • This would then mean the resulting edge is not any more durable than a non-carbide steel.
  • So you're losing all the benefit of the high carbides when you use a ceramic.
That's my takeaway. I'm as convinced as I can be given the evidence I've seen, unless somebody has better evidence to the contrary.
Click to expand...
 
Edge Retention(ER) is open ended in both quali & quanti. In world actual uses, apex width probably 10+um wide, so both diamond & ceramic probably has almost identical ER line. Delineation becomes more pronounce when comparison go toward extreme parameters (apex width, carbide volume, hardness). There isn't much a doubt that diamond is the right abrasive to shape/sharpening Ceramic & WC blades, where M,F,UF would just do damage (DQ in ER race). I wouldn't want a surgeon to use a scalpel in s30v with edge sharpened solely by ceramic - since any hole/dip in apex could tear capillaries... but for rope cutting - diamond & ceramic probably has similar ER performance (diamond probably has advantage only at peak 5% of sharpeness).

maximus83 said:
It would be cool to see Bluntcut or somebody who has access to the gear needed to take those kinds of photos, do a side-by-side edge retention test. Test 1: take a high carbide super steel knife, apex on diamonds. Then micro-or-refine apex on a UF ceramic. Take a "before" picture of the finished apex. Run an edge retention test cutting some material that quickly wears the edge, and take an "after" picture to show impact on the edge. Test 2: repeat the same test same knife, this time using all diamonds and no ceramic. Would love to see the test results and micrographic pictures to document. Again, a limited data set, but still each example like this that is built up, helps to make the case and support the hypothesis.

Totally open to changing the sharpening process any time that new/better evidence shows up. For now, I'm convinced enough that I'm going to drop ceramics out of the process of sharpening super steels. Although I really like using ceramics in that niche finishing role and will continue to use them for the majority of my knives that are not super steels. It seems like in practical terms, if you're sharpening super steels, it makes sense to stick to 3 widely available abrasives: (1) SiC (and even here, only use at the coarse end of the spectrum), (2) CBN (I'm currently using 1 micron cbn as strop compound, plus it's on the Spydie DS2 pocket stone I'm testing), and (3) diamonds. I just don't see any way to get around that reality right now. If you want to get your super steels sharp and have a durable edge, you need some combo of SiC, cbn, or diamonds.
Click to expand...
 
Ultimately you need and abrasive that can shape the carbides with a low enough amount of force they don't get knocked out.

Failing this you will have lateral displacement weaken the carbide anchor. The remaining ones will be wider than they could be across the apex, or missing entirely.

Admittedly there is a lack of actual cut testing to demonstrate a real world effect and is based on mostly anecdotal evidence. There are problems with this - using different abrasives will effect the starting point of the edge - not comparing apples to apples. Contrasting a high carbide and low carbide steel with the same abrasive does not get around this.

You can check (with accuracy) starting and failing cut values for high carbide steels vs lower carbide steels and then do the same with two abrasives on the same steel. This would show not only the change in cut character but also any retention shift.

In some of my previous testing I noted a substantial shift in edge retention on n690, W2 and M2 when the finishing abrasive was changed from AlumOx to SiC. I haven't done similar work with high VC steel but might be a good idea to do so.
 
Wait, what? So now we're saying that despite the test and all the discussion that carbide tear-out with ceramics happens: None of this matters for most real world knife usage, so go ahead and use ceramics anyway with high carbide steels? Most people on this site and in this forum aren't surgeons.

Confused..... :confused:

bluntcut said:
Edge Retention(ER) is open ended in both quali & quanti. In world actual uses, apex width probably 10+um wide, so both diamond & ceramic probably has almost identical ER line. Delineation becomes more pronounce when comparison go toward extreme parameters (apex width, carbide volume, hardness). There isn't much a doubt that diamond is the right abrasive to shape/sharpening Ceramic & WC blades, where M,F,UF would just do damage (DQ in ER race). I wouldn't want a surgeon to use a scalpel in s30v with edge sharpened solely by ceramic - since any hole/dip in apex could tear capillaries... but for rope cutting - diamond & ceramic probably has similar ER performance (diamond probably has advantage only at peak 5% of sharpeness).
Click to expand...
 
Majority of knife users sharpen using grit coarser than 400, so yeah use whatever good enough to plow away steels. otoh, those want durable shaving edge on steels with hard carbide, that when diamond shine at shaping/abrading matrix+hard_carbides. Microbevel often requires 'shape/refine', so diamond is most versatile.

maximus83 said:
Wait, what? So now we're saying that despite the test and all the discussion that carbide tear-out with ceramics happens: None of this matters for most real world knife usage, so go ahead and use ceramics anyway with high carbide steels? Most people on this site and in this forum aren't surgeons.

Confused..... :confused:
Click to expand...
 
bluntcut said:
Oh btw - I was surprised 65rc S30V can burnished a lot more than expected for steel at this hardness. Maybe I check out UF vs 69rc 10V.
Click to expand...

I had a conversation with another sharpening SME here in the forum a week or so ago, and they said they are surprised, using ceramics in a refining role with high carbide steels, it's not supposed to work, but it does. That has been my experience as well.

It seems like what we're saying here is that from the best we can tell, carbide tear-out occurs when you use a ceramic, even lightly at the end of sharpening to refine or micro. But...for ordinary knife uses, that doesn't really impact the durability of your edge. It would only make a difference in specialized applications where you're going for maximum sharpness; in that case, use diamonds.

If that's the point being made, you can see why folks like Cliff, and some of the sharpening pros right here in BF, continue to use ceramics on high carbides. It's conceivable that for normal EDU knife tasks, the average knife owner could do everything they ever needed to do sharpening-wise with a Norton combi Crystolon, a cheap ceramic F or UF hone, and a strop. And this would work perfectly fine even on their high carbide steels. True, they'll be giving up the carbides in that last little bit of edge. But if a carbide falls off a knife edge, and no one ever sees it or feels the difference, did it really happen? :-)
 
maximus83 said:
I had a conversation with another sharpening SME here in the forum a week or so ago, and they said they are surprised, using ceramics in a refining role with high carbide steels, it's not supposed to work, but it does. That has been my experience as well.

It seems like what we're saying here is that from the best we can tell, carbide tear-out occurs when you use a ceramic, even lightly at the end of sharpening to refine or micro. But...for ordinary knife uses, that doesn't really impact the durability of your edge. It would only make a difference in specialized applications where you're going for maximum sharpness; in that case, use diamonds.

If that's the point being made, you can see why folks like Cliff, and some of the sharpening pros right here in BF, continue to use ceramics on high carbides. It's conceivable that for normal EDU knife tasks, the average knife owner could do everything they ever needed to do sharpening-wise with a Norton combi Crystolon, a cheap ceramic F or UF hone, and a strop. And this would work perfectly fine even on their high carbide steels. True, they'll be giving up the carbides in that last little bit of edge. But if a carbide falls off a knife edge, and no one ever sees it or feels the difference, did it really happen? :)
Click to expand...

A lot of it really does come down to the details. Amount of lateral force and the angle of that force make all the difference. I've mentioned before I was able to smooth 'steel' D2 without having any obvious carbide blow out, suggesting that any steel is going to be capable of burnishing. Industrial uses of it run to steels in the upper 60s Rockwell, carbide content notwithstanding. Industrial uses also don't concern themselves with lateral carbide displacement as the force is directly into the steel surface.

In my own experience from a practical standpoint I find a big difference in edge quality on any high carbide steel by switching to diamond. The effect is not so obvious at lower levels but it is still there, and only becomes more apparent as the abrasive gets smaller. Another tack might be to run a survey of folks who sharpen for $ and see what they use on high carbide steels, particularly with Vanadium content of 4% or higher.

There are plenty of experts with their own cutlery and I'm sure they get a knife plenty sharp with whatever means, but what happens when you're getting paid to have your work critiqued?
 
^Yep totally reasonable.

I get why some sharpening pros would evaluate all this and, even if they agree that carbide tear-out occurs, might still come to the conclusion that for ordinary EDU knife sharpening, this doesn't matter enough to change your practice, doing things such as eliminating ceramics or using only diamonds in the higher/finishing grits. The good result that you can get with the ceramics, for some folks, outweighs the modest downsides that accompany ceramic tear-out on an EDU blade.

Still, to your point: it's hard to escape the logic that if you're going for best practice and optimum results, you want to use a material like diamond or cbn that is just factually harder than the vanadium carbides and can abrade them. I'm interested to hear your experience that "from a practical standpoint I find a big difference in edge quality on any high carbide steel by switching to diamond." Those kind of experience-based data points from folks who do a lot of sharpening are super useful to those of us who don't do as much volume of sharpening. I'm going to keep experimenting sharpening my super steels with only diamonds/cbn in the high grits for a while, and see if that makes a noticeable difference in sharpness, cutting performance, edge durability.

At the coarse end of the spectrum: Is it conceivable you'd get the best possible results with high carbide blades, if you just used diamonds end-to-end, not even using a SiC stone for the coarse work? Just speculating here, but interested because I've been using my Crystolon for all my coarse work (regardless of steel type) recently. It certainly works. But if we're going for "optimum results" on high carbides, and only diamonds/cbn will cleanly abrade the carbides, it seems like the quality of the edge finish that you get from your coarse stone sharpening might be better if you used diamonds there, too. Which would lay a better foundational edge for your later sharpening.

Thoughts?
 
bucketstove said:
Hi,
What does that mean exactly? Something to do with carbide volume?
Click to expand...
Extra flat & smooth matrix area inside the ring of protruding carbides - essentially with UF gentle smears/rubs can displace/plastic-flow ~64rc (subtracted 1rc for CV) matrix surface. Also obvious, plastic-flow occurred in other areas but magnitude/scope maybe only 1/4-1/3 trough/scratch depth, hence couldn't filled/smoothed the surface. I am surprised how small percent of plasticity can smear/flow matrix surface without detaching/fracture-away. Wondering about Van_der_Waals_force continuity while moving across interfaces (such as grain boundaries).

maximus83 said:
I had a conversation with another sharpening SME here in the forum a week or so ago, and they said they are surprised, using ceramics in a refining role with high carbide steels, it's not supposed to work, but it does. That has been my experience as well.

It seems like what we're saying here is that from the best we can tell, carbide tear-out occurs when you use a ceramic, even lightly at the end of sharpening to refine or micro. But...for ordinary knife uses, that doesn't really impact the durability of your edge. It would only make a difference in specialized applications where you're going for maximum sharpness; in that case, use diamonds.

If that's the point being made, you can see why folks like Cliff, and some of the sharpening pros right here in BF, continue to use ceramics on high carbides. It's conceivable that for normal EDU knife tasks, the average knife owner could do everything they ever needed to do sharpening-wise with a Norton combi Crystolon, a cheap ceramic F or UF hone, and a strop. And this would work perfectly fine even on their high carbide steels. True, they'll be giving up the carbides in that last little bit of edge. But if a carbide falls off a knife edge, and no one ever sees it or feels the difference, did it really happen? :)
Click to expand...
No, unless users lament how quickly keen edge degraded to working edge. Complainers(aha knut/advanced) probably prefer durable edge at sub 1.5 micron width, thou shall graduate to diamond/cbn refinement :p

As stated (my observation & projection) before, detaching apex carbide will take 3-15um chunk with it. Avg users might even enjoy this toothiness to buzz saw stuff, while users prefer more push/pressure cuttings won't be happy.

HeavyHanded said:
A lot of it really does come down to the details. Amount of lateral force and the angle of that force make all the difference. I've mentioned before I was able to smooth 'steel' D2 without having any obvious carbide blow out, suggesting that any steel is going to be capable of burnishing. Industrial uses of it run to steels in the upper 60s Rockwell, carbide content notwithstanding. Industrial uses also don't concern themselves with lateral carbide displacement as the force is directly into the steel surface.

In my own experience from a practical standpoint I find a big difference in edge quality on any high carbide steel by switching to diamond. The effect is not so obvious at lower levels but it is still there, and only becomes more apparent as the abrasive gets smaller. Another tack might be to run a survey of folks who sharpen for $ and see what they use on high carbide steels, particularly with Vanadium content of 4% or higher.

There are plenty of experts with their own cutlery and I'm sure they get a knife plenty sharp with whatever means, but what happens when you're getting paid to have your work critiqued?
Click to expand...
:thumbsup:

_All__________________________________________________________________
*** abrasive in science/engineer/machinist/etc views on shaping precision for alloyed steels ***

4+ microns apex smoothness: SiC, AlO, SinteredCeramic, Diamond, CBN, BN, etc...

2+ microns apex smoothness:
sub-micron hard particles (carbide, nitride, etc..): ^ above
1+ micron hard particles (carbide, nitride, etc..): Diamond, CBN, BN, etc...

Below 1 micron apex smoothness: Diamond, CBN, BN.

Keep in mind, dulled diamond/cbn will partially behave like sceramic, which burnish by sheer + impact, esp at similar psi. e.g. at same psi, a very dulled DMT XXC will behaves almost/80% like Spyderco F or UF.

If you linearly increase downward psi for sceramic, diamond psi will increase faster because of lower avg density (think contact surface area, where diamond has many smaller tips but evenly spread out, whereas sceramic has less tips but very large contact surface).

When velocity(tangential psi) is high enough, impact from diamond will fracture hard particles, where impact from sceramic to hard particles with result combination of: detach, displaced, cracks footing, burnish/smooth/smear and very tiny% of fracture. Hence diamond is more predictable, which is higher precision than gumbo outcome from sceramic.
 
You must log in or register to reply here.
Back
Top