Sharpening high hardness and wear resistant steels

[Steel_Drake]

Testing edge retention has nothing to do with it, this is about the feel I get from the stone when I am sharpening. Again, you may not be able to sense it but I can. I have also performed CATRA testing so I am no strange to what it takes to get consistent edge retention data.

I used edge retention testing merely as an example of how much rigor is required to distinguish between the performance of similar steels. The claim that someone could distinguish M4 from HAP40 on a double blind basis simply by feeling the edge or the subjective feedback from the sharpening stone is so extraordinary, that I won't even be engaging it unless you can provide some similarly extraordinary evidence that such a thing is possible.

I don't even know where you are getting this metal matrix ploughing theory but it has no relevance here.

My apologies if I misunderstood, but I used that term to try and describe the phenomena where the abrasive is able to cut the metal matrix around the carbides, but not the the carbides themselves, which are either knocked out or the edge or left exposed at the apex and highly prone to carbide tear out, similar to process described for stropping highly wear resistant steels and why diamond or CBN must be used instead of aluminum oxide compounds.

In particular, I assumed you meant the kind of process shown in that thread and in particular shown in this image in that thread:


And I thought "metal matrix ploughing" might be a convenient term to describe the effect. It was my understanding that you were alleging that a similar process occurs sharpening highly wear resistant steels on waterstones, and in particular that the effect occurs on both aluminum oxide and silicon carbide waterstones. If this does not accurately represent the effect that you believe is occurring, could you please let me know.

I probably should have said that most will not notice it until just beyond 1000 grit. It's not that it's not occurring its that the abrasive is still large enough to scoop out the carbides on most steels.

I still am not clear as to whether you mean the consquences will or will not occur at 1000 grit, and whether you are asserting they have on the apex will or will not be noticeable in use of an edge finished at 1000 grit?

I use edge trailing strokes on waterstones, produces a sharper edge and is the recommended method sense forever. I can apply microlevels with waterstones without issue so I'm not sure what you even mean by that.

I don't want to divert the thread from the topic at hand by getting into a discussion of sharpening technique. I will merely note that I use edge-leading and scrubbing strokes on waterstones, and that I was mentioning how I sharpen purely to point out that even if the effect you are claiming did occur and had a noticeable effect, that I wouldn't notice in my regular sharpening because I am never leaving an apex produced directly by a waterstone anyway.

1k to 4k would do.

To clarify, do you mean that I could do the comparison at ~1k between the edges produced by an Atoma 1200, King 1000, DMT EF, and SPS-II 1000 and that the results would be valid in your opinion?

To go above that I'd probably have to use the DMT EEF, SPS-II 3000, and King 4000 to get similar grit ratings across the three types.

 

[HeavyHanded]

I'm losing track of this thread.

Here's a short bit I put together in a recent conversation with a friend on this topic. Am discussing in particular high VC powder steels with carbides in the 1-3 micron range:

Have looked into the tech on VC, as a surface coating it can be in the neighborhood of AlumOx or just under SiC at the extreme low end. Normally it is much harder. The VC in PM steel tend to be 1-3 micron.

In my own experience I was gifted a knife of s110v at approx 64 RC, was one of Bluntcut's trial runs, so F&F was very rough. I took it to 120 SIC wet dry and it ground the surface/primary grind easily. I'm thinking "I'll have this thing beautiful in no time". 320 grit and still cutting fine, maybe a bit slower. At 600 surface finishing "ground" to a near standstill. Possible to sharpen at 600 and raise a burr but surface finishing not happening much. Switched to 16 micron diamond film and it began polishing up the surface again no issues.

Abrasives tend to stand about 10% proud, so 600-800 grit is about 20 micron, 2 micron gouge area. The carbides now able to fight one to one with the abrasives and in my experience it really shows. Have had this hold true on hard stones as well.

At rougher grit levels - 320-600 etc, I speculate the carbides fracture out, or at least to some extent are shaped by the abrasive, as 3 micron would be still too broad for good cutting performance at the peaks. Or maybe the carbides that are aligned with the grind path are the ones that remain and present a sharper side in the direction of the edge. In any event it is 100% possible to craft strong performing edges on these steels at low finish levels with just about any manufactured abrasive.

Whatever the reason, rougher SiC and AlumOx work fine on these steels, finer grades do not. Also, these steels tend to be run high RC, low 60s minimum, which will also make the rougher abrasive create a finer cutting edge/brighter finish compared to steels in the 50s.

If the VC carbides were like D2 and in the 20-30 micron range I'm not thinking they could be sharpened at all with anything but diamond or CbN.

Personally I find SiC to work better than AlumOx on HSS even at higher finishes. With Vanadium only super abrasives will do a quality job. I have gotten these steels to perform well enough or even very well off of SiC but is not as nice an outcome off of diamonds.

Even a relatively small percentage makes a big difference, that's why the latest version of my Washboard compound has 8 carats of diamond added. A small amount by weight but gets the job done in conjunction with the SiC - keeping in mind the entire thing isn't solid VC and the SIC will still work fine on the non-carbide areas.

If you compare even an EF DMT to a 4K king on s30v or higher VC content I believe the function will be pretty clear.

You can likewise use a series of silicon carbide wet/dry on the primary grind on a high VC steel and see if performance falls off at 600-800 as I observed. On s110v it was obvious.

Edit to add:
You have to also keep in mind that the coarser grit is really working with a greatly higher unit pressure. You cannot match it by simply pressing harder on a finer abrasive, the dynamics are quite different, and this also accounts for larger abrasives' ability to work high VC steel, whereas on a solid surface of VC it might not even scratch.

 

[David Martin]

I have to admit I'm not on pace with this topic as well. It seems like it's a he say, she said and what does that mean, discussion... Maybe not.
HH, I see what you're saying about larger coarse grit cutting with vanadium packed steels. And why as you go to finer grits they will have difficulty cutting it. Your noticing this happens at 600 grit others say at 1000. Still, Jim Ankerson, myself and some others don't sharpen higher than 400 grit. Are we getting an inferior edge because the vanadium carbides weren't refined? 2) The vanadium carbides won't be refined until the sharpening grit matches the size of the carbides. Around 3u or 1500 grit. Hence, we'll need an EEF diamond to take us to that level of refinement. DM

 

[HeavyHanded]

I have to admit I'm not on pace with this topic as well. It seems like it's a he say, she said and what does that mean, discussion... Maybe not.
HH, I see what you're saying about larger coarse grit cutting with vanadium packed steels. And why as you go to finer grits they will have difficulty cutting it. Your noticing this happens at 600 grit others say at 1000. Still, Jim Ankerson, myself and some others don't sharpen higher than 400 grit. Are we getting an inferior edge because the vanadium carbides weren't refined? 2) The vanadium carbides won't be refined until the sharpening grit matches the size of the carbides. Around 3u or 1500 grit. Hence, we'll need an EEF diamond to take us to that level of refinement. DM

And that's one of the mysteries going on here.

I personally believe my speculation, at least to some extent.

Hypothetically the carbides fracture as the larger abrasive tears through the structure, leaving them not sharpened, but broke off sharp.

And then some will be aligned more advantageously by default - the ones sideways in direct path get torn out or broken, the ones that offer less resistance stay embedded in the remaining steel at that better angle and act as part of the cutting edge.

Its tough to pin down, if you etch the steel to better see the carbides you're liable to loose the morphology of the very cutting edge - it'll be first thing to go actually.

 

[David Martin]

I can see that as a viable possibility. Still, sharp is sharp and these VC blades will carry usage for a LONG time. DM

 

[Steel_Drake]

I'm losing track of this thread.

The vanadium carbides won't be refined until the sharpening grit matches the size of the carbides. Around 3u or 1500 grit. Hence, we'll need an EEF diamond to take us to that level of refinement.

I apologize if things have gotten a little off course in this discussion. Ultimately, I am trying to establish what parameters would be necessary to test for the presence of this effect and how large a difference it makes (if any) to the performance of the resulting edge.

So far, my plan is to use an SPS-II 3000, King 4000 and DMT EEF as the three closest stones of each type I have to a 3u particle size, sharpen the knife (be it in CPM-M4 or Maxamet or 1095 as a control) on each of those abrasives and then do a small amount of corrugated cardboard cutting to see if any of the edges experience a rapid and dramatic loss of initial sharpness compared to the edges obtained off the other stones.

My reasoning is that the kinds of issues with apex formation you all are describing should, if I understand correctly, lead to problems with carbide tear out and thus the effects should show themselves very quickly as a dramatic loss of initial sharpness when the edge is used to slice corrugated cardboard or shave pine. Thus, the fastest and least messy way to test this is just to slice some cardboard and see if there is a dramatic loss of initial sharpness. I happen to have some carbdoard kicking around and figure it will be less messy to use for this test than buying some lengths of pine and shaving it as Luong suggested earlier in this thread.

My thinking is to use at least three blades for the test, one in 1095 as a control to show what differences the different abrasives produce in the absence of any question of issues cutting VC (honestly because I expect the initial sharpness to be lower off the waterstones regardless of steel as I prefer to use edge leading strokes for burr minimization purposes and thus some measure of apex rounding due to the presence of a slurry is unavoidable), one in M4 as a practical middle ground, and one in Maxamet when I receive my mule. I am not particularly concerned about the geometries of the three blades being similar because this is not an edge retention test, merely a check to see if any rapid losses of initial sharpness are experienced.

Does this sound like a reasonable methodology to test this?

 

[Jason B.]

I used edge retention testing merely as an example of how much rigor is required to distinguish between the performance of similar steels. The claim that someone could distinguish M4 from HAP40 on a double blind basis simply by feeling the edge or the subjective feedback from the sharpening stone is so extraordinary, that I won't even be engaging it unless you can provide some similarly extraordinary evidence that such a thing is possible.

I really don't care how extraordinary it may seem, I've called the steel on unmarked blades before and I could do it again. I've sharpened nearly every steel used in knives 100x over and this experience has given me the ability to feel things others cannot. On the stones M4 and Hap40 are very different thanks to the higher percentage of Vanadium found in M4 which makes it more wear resistant. They perform different, sharpen different, cut different and I'm sorry if you cannot tell the difference but I can.



My apologies if I misunderstood, but I used that term to try and describe the phenomena where the abrasive is able to cut the metal matrix around the carbides, but not the the carbides themselves, which are either knocked out or the edge or left exposed at the apex and highly prone to carbide tear out, similar to process described for stropping highly wear resistant steels and why diamond or CBN must be used instead of aluminum oxide compounds.

In particular, I assumed you meant the kind of process shown in that thread and in particular shown in this image in that thread:


That's a good picture but you forgot the following picture. Pretty much proves the point.


This guy explains some of the base principles of grinding PM steels, pay careful attention to what he says.
[video=youtube;sdxf32F3j3k]https://www.youtube.com/watch?v=sdxf32F3j3k&index=39&list=PLFA60459F187488EF[/video]


And I thought "metal matrix ploughing" might be a convenient term to describe the effect. It was my understanding that you were alleging that a similar process occurs sharpening highly wear resistant steels on waterstones, and in particular that the effect occurs on both aluminum oxide and silicon carbide waterstones. If this does not accurately represent the effect that you believe is occurring, could you please let me know.

Metal Matrix ploughing seems to point to Metal Matrix Composites. One example would be Aluminum infused with carbon fiber or aluminum and Silicon carbide. I don't see that term used anywhere else.

I think this can be more simply defined as the resistance to wear due to a material hardness difference.


I still am not clear as to whether you mean the consquences will or will not occur at 1000 grit, and whether you are asserting they have on the apex will or will not be noticeable in use of an edge finished at 1000 grit?

They occur at ANY GRIT, but abrasive size and carbide size play a big role in deciding at what point the interaction of the two become a serious issue.



To clarify, do you mean that I could do the comparison at ~1k between the edges produced by an Atoma 1200, King 1000, DMT EF, and SPS-II 1000 and that the results would be valid in your opinion?

IMO, 600 mesh diamond is closer to a 1000 grit waterstone. You could do that but I think you need to use a higher grit stone such as the king 4k.

To go above that I'd probably have to use the DMT EEF, SPS-II 3000, and King 4000 to get similar grit ratings across the three types.

In bold again

 

[ice-pic]

I have been following this thread and found it very helpfull.
This 10v 68hrc paring knife on steroids has taken me for a journey.
Scratched out the grind lines to give a smoother line pattern along the blade.
I did this with some old lansky diamond stones.Coarse,medium then fine.
Followded up with SiC sandpaper.
Sharpening was done on a wicked edge at 15deeg per side,from 100grit all the way to 1000 grit diamond.
The first sharpening went great,but the next day it had a wire edge bur on it which occoured overnight on its own.
So I resharpened it from 400 to 1000 grit being supercarefull and gentle.
Same thing happened again.
Resharpened a third time fron 800 to 1000 being ultra carefull and using an optivisor to magnify the blade to stone contact area and guiding every stroke.
It seems stable now and cuts like a banshiee
So i guess my point is this steel does seem to respond to diamond to me.

photos https://goo.gl/photos/htcpmbfQhEsqqsKWA

View attachment 670860
View attachment 670861

 

[Steel_Drake]

That's a good picture but you forgot the following picture. Pretty much proves the point.

Jason, before I attempt to argue or show that a phenomena is or is not happening and does or does not have a noticeable effect on edge performance, I first would like to clarify what the phenomena you are describing is. I posted that picture to try and clarify my understanding of what you are arguing is happening and whether the phenomena is the same one I saw described in that other thread. I was not, at that point, making an argument as to whether it happens or not.

That is why I did not bother posting the other picture: I did not think it was necessary for the purpose of clarifying whether the picture I did post depicted the same phenomena you were talking about.

This guy explains some of the base principles of grinding PM steels, pay careful attention to what he says.

Yes, I understand what he is talking about. His explanation doesn't, however, cover what I believe are the relevant questions here: Specifically, whether this phenomena still occurs when using highly friable aluminum oxide or silicon carbide waterstones, and whether it produces a detectable difference in the performance of the knife in terms of initial sharpness and edge retention.

The whole reason I want to test it is precisely because I have not made up my mind in advance.

I am genuinely curious because I don't know how to reconcile the dire warnings about this phenomena in this thread with the fact that I literally just sharpened a Spyderco PM2 in CPM-M4 on a King 1000 followed by an SPS-II 3000 and had no trouble getting an apex that would do crossgrain pushcuts on newsprint and which didn't experience any catastrophic drop in sharpness after slicing several strips off some cardboard I have through the corrugations.

Ultimately I'm interested in trying to figure out why my experiences with this topic have been so different from what others are describing.

They occur at ANY GRIT, but abrasive size and carbide size play a big role in deciding at what point the interaction of the two become a serious issue.

Again, could you please clarify for me whether you think that the interaction between carbide size and grit becomes a serious issue around JIS 1000 or is a higher grit necessary before it becomes a serious issue? So far the consensus in this thread appears to be that it would be better to test for this phenomena around JIS 4000 rather than 1000, do you agree with this?

 

[BluntCut MetalWorks]

Let's using a hypothetical/theoretical scenario.

ISTP (2um infinite strong tough particle = forever stays as spherical particle - 2um diameter)
UA (ultimate abrader/cutter, like a light saber except can't cut ISTP)
Blade consists of hardened steel matrix(martensite and nothing else) with certain uniformly distributed density(UDD) of ISTP. Started in a bar shape (no edge).

Now use UA cut a Blade at 1-20 dps (cutting raises angle from zero to N). With UDD is 15+%:

1. The 2 bevel planes of UA won't interect because line-of-sight blocked by ISTP
2. The thinnest shaping intersection (apex) would be 2um. Apex will has an attachs burr mirror image of the edge bevel (wedge shape going from N to zero dps)

Therefore even with UA, a 2um apex thick would be the highest attainable dimension. As dps is getting higher, UA intersection points/lines increases but for apex blocked/protected by ISTP - those area will be at least 2um wide.

Clearly when the edge shaped this way, the apex area are weakened because matrix is receded/under-cut ISTP boundaries/interfaces/binding. In other word, edge retention/endurance is low in the first 2-3um of apex area.

***
Reality factors in complexity & gray-areas, so outcome will range from principle/hypothetical_above to various degrees depend on materials & forces & geometry involved. One thing for sure, physics doesn't care for how we feel/like/judge...

 

[BluntCut MetalWorks]

Ice - COOL handle :thumbup:

Concur with diamond! My video tries to convey to use appropriate abrasive (type & size), which is a lot easier to attain quality outcome.

I have been following this thread and found it very helpfull.
This 10v 68hrc paring knife on steroids has taken me for a journey.
Scratched out the grind lines to give a smoother line pattern along the blade.
I did this with some old lansky diamond stones.Coarse,medium then fine.
Followded up with SiC sandpaper.
Sharpening was done on a wicked edge at 15deeg per side,from 100grit all the way to 1000 grit diamond.
The first sharpening went great,but the next day it had a wire edge bur on it which occoured overnight on its own.
So I resharpened it from 400 to 1000 grit being supercarefull and gentle.
Same thing happened again.
Resharpened a third time fron 800 to 1000 being ultra carefull and using an optivisor to magnify the blade to stone contact area and guiding every stroke.
It seems stable now and cuts like a banshiee
So i guess my point is this steel does seem to respond to diamond to me.

photos https://goo.gl/photos/htcpmbfQhEsqqsKWA

View attachment 670860
View attachment 670861

 

[BluntCut MetalWorks]

steel_drake - you've good sharpening skills, thereby yielded higher apex quality than norm when using abrasive near its effective limit. Appropriate test might be whittle bamboo or raw bone with 12um, 6um, 3um abrasive finished edges. This might be impractical in real-life use but we/sharpeningnut like to dork until carbide (and along with chunk of matrix) fall/tear from edges just for fun.

btw - close up pic of spsii edge shows scratch pattern of std 30um abrasive or so, that was why I suspect new/sharp EF plate. I can't get anywhere close to that level of deep/clear scratch with green SiC 1200 grit on wood board (Do this for 10 stroke or so, since grit fracture extremely fast).

 

[Wowbagger]

M4 from HAP40 on a double blind basis simply by feeling the edge or the subjective feedback from the sharpening stone is so extraordinary

James is ignoring my question but as far as the above I can TOTALLY believe someone used to sharpening a good number of alloys on a daily basis could tell them apart by sharpening them . M4 is a pretty big deal and as far as what I have read / seen testing HAP 40 is pretty low on the list.

In other words there is a very SIGNIFICANT difference between them.
In still other words sensing the difference between HAP40 and S35VN might be a touch more challenging. Heck Jason could probably even do that if there was money on the table or he got ahold of some good espresso that day.

I am not any kind of big sharpening expert and I could tell some of the steels apart just by how the bur behaves and the extent of the bur.

annnnnnd . . . don't underestimate the human ability to sense subtly. Two examples (or three) nearly every morning I can "guess" within a minute, (nearly always on the minute) what time it is when I walk into the kitchen and look at the clock before I leave for work even though I don't wear a watch and haven't looked at a clock for half an hour or so.

There is a spinning wheel at work that I spin and stop (the wheel is 26 inches in diameter) and I can stop it in the same relationship nearly every time without trying just because I have done it about every day for thirty years. And lastly have you ever thought how inexplicable that a person can put their hand in exactly the right place to catch a ball without looking at their hand and lining things up some how. I mean . . . with practice it just happens.

With as much practice as Jason has had it is easily conceivable he can sense one steel from another and may not even be able to explain it let alone TEACH IT.

 

[Steel_Drake]

Let's using a hypothetical/theoretical scenario.

Luong, that was a very clear explanation, thank you. My issue is that I cannot detect any difference in the level of sharpness obtained on a blade in M4 between my SPS-II 3000 and my DMT EEF, nor was I able to notice a much more rapid blunting of one compared to the other in slicing some corrugated cardboard and then rechecking sharpness on newsprint.

steel_drake - you've good sharpening skills, thereby yielded higher apex quality than norm when using abrasive near its effective limit. Appropriate test might be whittle bamboo or raw bone with 12um, 6um, 3um abrasive finished edges. This might be impractical in real-life use but we/sharpeningnut like to dork until carbide (and along with chunk of matrix) fall/tear from edges just for fun.

Thank you for the compliment. I am planning to use ~3um abrasive for the sake of keeping the testing from getting too extensive. Would you not expect slicing corrugated cardboard to reveal the effect? Should I whittle some bamboo or pine instead?

[/quote]btw - close up pic of spsii edge shows scratch pattern of std 30um abrasive or so, that was why I suspect new/sharp EF plate. I can't get anywhere close to that level of deep/clear scratch with green SiC 1200 grit on wood board (Do this for 10 stroke or so, since grit fracture extremely fast).[/QUOTE]

I will take some more pictures of the same knife with an edge off my SPS-II 3000 and 10000 for you as well tomorrow.

M4 is a pretty big deal and as far as what I have read / seen testing HAP 40 is pretty low on the list.

In other words there is a very SIGNIFICANT difference between them.

Wowbagger,

There is ~1% more vanadium in M4 and ~8% cobalt in HAP40 that is not present in M4, but it is not expected in a knife application that the cobalt would cause a significant effect (it is included in HAP40 to promote hot hardness), therefore Jason's assertion amounts to asserting that he can subjectively distinguish a ~1% difference in vanadium content between two steels by feel. I'll leave you to figure out for yourself how likely that actually is.

 

[Wowbagger]

Still, sharp is sharp and these VC blades will carry usage for a LONG time

I didn't find that to be true. What I mean is I had two sharp edges but one only seemed sharp because it would, indeed, whittle hair but the quality of the edge long term was flawed and insubstantial . . . even though . . . perhaps . . . the S110V was capable of more if properly sharpened (on diamond).

I was sharpening mostly with Shapton glass up to 4000 (which was a decent mirror looking finish) on the Edge Pro. I "sharpened" S110V to literally hair whittling but the edge broke down EXTREAMLY fast to a sharpness bellow what I would have on VG10 or CTS-XHP cutting the same somewhat abrasive materials. I think that these "softer" abrasives was coining or burnishing the steel; with the V carbides along for the ride but when it came to cutting with the edge IT SEEMED that the carbides "fell out" or some such and the rest of the matrix just flattened microscopically. That was the sense I got from my finger nail test . . . which tells me scads about the quality of an edge. See photo. That angle is a bit shallow but you get the idea.

Where as on the "softer" lower carbide steels that also started out hair whittling . . . once it degraded from cutting to a working edge the working edge had more fingernail bite and useful quality than did the S110V edge.

Hence my obsession with paper wheels now and diamond grit . . . er . . . Jason . . . bro . . . are you there man ?

Jason,

I am fooling around with paper wheels (bought one; will probably buy more) but was wondering how hard felt wheels work in comparison . . . for using diamond paste / diamond grit and wax.

any thoughts ?

Or I should lace my other stones with diamond grit ?

 

[Wowbagger]

There is ~1% more vanadium in M4 and ~8% cobalt in HAP40 that is not present in M4,. . . Jason's assertion amounts to asserting that he can subjectively distinguish a ~1% difference in vanadium content between two steels by feel. I'll leave you to figure out for yourself how likely that actually is.

Yes but look at the dif in the cutting ability on Ankerson's tests. All I heard here for a while was HAP40 and when the testing was done . . .
yawn

and am I not correct in thinking that one of the advantages of HAP40 is it is friendly to sharpen similar to S35VN and that one of the things people note when talking about M4 . . . as a caveat . . . they say "but it isn't fun to sharpen".

Heck I don't know . . . I'm still trying to get a durable edge on S110V and that sounds . . . in retrospect . . . like saying "I'm still trying to get wet by jumping into a swimming pool" . . . should be the easiest thing in the world once it is sharp . . . but there it is.

I'm listening now that you posted the alloy comparison though.
Thank you.

 

[David Martin]

Jim Ankerson also only takes his test blades to about 400 grit on a SiC stone. He gets very good cutting longevity on cardboard, sisal rope and such with vanadium carbide steels. But some would say his edges are inferior because he didn't use a diamond stone to cut the vanadium carbides. Still, his proof is in the pudding. DM

 

[BluntCut MetalWorks]

Earlier I posted this image of a coarse SiC edge topology (and 1200 grit finished - weakened a lot of surface carbides)

This edge in use will loose weakened surface carbides fairly quickly however each tooth still is plenty large (10+um) and plenty of carbides are still embedded and readily sprout up when tooth's matrix leg receding from wear. When cutting has lot of draw and pull motions, these teeth will perform fine for cardboard & rope & etc..

Now, if performance measure by amount of steel loss and max loss thickness is limited to 2-3um, then this edge would fail rather fast.

400 grit SiC edge finished will be mostly coarse teeth (similar as pic), except number of weakened carbides will be mainly from plowed collision with carbides. Thus it would be stronger than edge above. Compare to 400 grit diamond, weakened carbides will be even less because some plow collision result in abrade/fracture certain percent of carbides. Easy to extrapolate to 120 or 8000 grit, corresponding to less and more delta (quality) respectively. Um... Jim abandoned polished edge(SiC in EP) in favor coarse edge because(of course, I am guessing) of this reason (a big factor) + normalize steel attributes + ..

Jim Ankerson also only takes his test blades to about 400 grit on a SiC stone. He gets very good cutting longevity on cardboard, sisal rope and such with vanadium carbide steels. But some would say his edges are inferior because he didn't use a diamond stone to cut the vanadium carbides. Still, his proof is in the pudding. DM

 

[martinsanders]

I really don't want to get in the middle of anything so if you refer to this post please do so in a way that doesn't drag me in. I think within a small margin of error one could determine the differences in steels with enough experience. Think of the difference in VG-10 and 154cm and tell me if you can tell a difference in sharpening those two steels blind. I don't have the experience Jason claims but I know for sure I can tell. They just don't feel the same. People forget that many of these steels have very subtle changes in mass % but that this can create a very different steel entirely. Just a little extra mass % of carbon makes a huge molecular % difference because it's mass is so small. Here is some examples that VG-10 and 154cm are similar and the difference in mass and molecular percentages.

I do believe however Jason could be fooled if a typically high Hrc steel was custom made with a low Hrc value in the mid 50's that is usually run in the mid 60's and another steel had an optimum HT but I believe he is saying that with all things being equal the feel of a steel is enough to tip him off as to which steel is which. Most people who have sharpened enough knives can tell the difference in 10v and s110v because of the chromium content in s110v. What I'd find unbelievable is a 100% accuracy in naming 20 different steels correctly just by sharpening them or telling the difference in M390/20cv/CTS-204p double blind.


Sent from my iPhone using Tapatalk

 

[ToddS]

Can anybody point me to a type of steel (or ideally a very small folder made of that steel) and a sharpening technique that SHOULD cause "carbide tear-out" ?

I've shown these images before: S30V sharpened with an aluminum oxide ceramic (sintered) stone and then stropped on hanging denim loaded with Mother's Mag polish (aluminum oxide). You can see the vanadium carbides sitting a bit proud, simply because they abrade more slowly than the matrix.