can all knives be equally sharpened?

[sogflash]

I'm trying to learn about the different blade steels, and how they perform.

can a chap knife with inexpensive blade steel be sharpened as sharp as a knife with a quality blade steel? if so, I guess the cheaper blade steel will wear it's edge down a lot faster.

 

[Tsujigiri]

No, steels with finer grains can be made sharper. But there are expensive steels that don't get as sharp as cheaper steels and vica versa. Furthermore, finer grains mean more toughness and strength, since grain boundaries serve as barriers for dislocation movement in the steel, and large, coarse carbides make the material brittle.

 

[hardheart]

I don't side what grain size has to do with sharpness, modern abrasives cut through all carbides with no issue, straight martensite is no challenge.

 

[Jason B.]

Most every knife I have ever sharpened will get to a similar level of sharpness, the biggest difference always seems to come from the quality of heat treat and not so much the steel.

 

[THG]

All I know is that I can't get cheap chinese crap sharp. No matter what I do, some of those knives just won't get sharp.

 

[Jason B.]

Cheap steel with a good HT is good steel, crap steel with a good HT is still crap steel.

 

[Noctis3880]

I don't side what grain size has to do with sharpness, modern abrasives cut through all carbides with no issue, straight martensite is no challenge.

If that was truly the case, diamond wouldn't show such a marked improvement in sharpening 9% and higher vanadium steels like S90V.

Again, if you use the analogy of cobblestones in a sidewalk, trying to sharpen something like that will result in the steel matrix itself being worn away with the carbides exposed, leaving a "toothy" edge. The finer the grain size, the finer the teeth, and the sharper the edge will be. Sort of like comparing boulder size cobblestones and sand.

Just because the carbides aren't as hard as the abrasives you use doesn't mean it won't resist the abrasion.

 

[stoffi]

Practically speaking, you can get any ol' piece of metal razor sharp; but, one of the main differences is how long that edge will last.

 

[Razorsharp-Travis]

I can get a victorinox knife hair whittling- if im lucky
I can get my spydercos hair splitting, sharp to sharpest-
8Cr13MoV, (just hair splitting)
VG-10 (hair splitting easily )
H1 (hair splitting with less resistance 'oh my god' sharp).
I made a Kiridashi out of a Power hacksaw blade , I dont know what steel it is, (M2 ?) but it will pop a hanging hair in half- by far my sharpest edge. (omg I sliced at thin-air cutting a void leading to another world of infinite mystery sharp )

I think, in the order I put it, would be the grain size of each steel too- large- sharp_ small-sharper

 

[Jason B.]

I can get a victorinox knife hair whittling- if im lucky
I can get my spydercos hair splitting, sharp to sharpest-
8Cr13MoV, (just hair splitting)
VG-10 (hair splitting easily )
H1 (hair splitting with less resistance 'oh my god' sharp).
I made a Kiridashi out of a Power hacksaw blade , I dont know what steel it is, (M2 ?) but it will pop a hanging hair in half- by far my sharpest edge. (omg I sliced at thin-air cutting a void leading to another world of infinite mystery sharp )

I think, in the order I put it, would be the grain size of each steel too- large- sharp_ small-sharper

Nah, its just your sharpening skill.

 

[db]

Short answer is yes you can get almost all knife steels about the same sharpness. At the extreme end of sharp I do believe there is a small degree that some steels seem to get just a hair sharper. But in real life there are very few people that even come close to getting a knife to that level of sharpness. We can talk about grain size, carbides, and all that jaz but for 99% of people it just doesn't matter. If you cann't get a sharp edge on a knife it is probably because of you and not the steel.

 

[db]

Now here really is how different people get different results. My Vic.SAKs get as sharp as any edge can get. It sure doesn't last as long as a full hard 1095 edge, but that 1095 edge doesn't last as long as a full hard M2 edge does for me either. Some steels are just easier to sharpen but they all do get pretty darn sharp. Heck I don't think I've ever seen a dull burr on any steel including non knife steels.

 

[P1GEONPOO]

My knife is sharper than your knife. ner ner n ner ner.

 

[philwar]

HT being assumed of good quality, different steels get sharp to a different degree. Designing the blade geometry and edge profile should already take the strong and weak sides of steel into consideration, but if you look at the Spyderco Mules (which to my knowledge are identical in design and profile) they don't all get equally sharp. The differences may be small but they are noticeable.

 

[db]

Which Muels don't get as noticeably sharp as the others?

 

[richard j]

sogflash, i sharpen a lot of knives and what i consider cheap steel is most of the stainless steel knives coming from pakistan. you can tell these knives by the color and finish they have. they will not take a good edge and i will not even waste my time to sharpen them. if they do happen to take a good edge, it will not last long like you said in your post. a high quality knife steel will hold an edge a long time if it has the right heat treat and the right edge. here in this post is a good example of how an edge can make a difference in how well a knife can cut and hold an edge http://www.bladeforums.com/forums/showpost.php?p=9207988&postcount=710

 

[hardheart]

If that was truly the case, diamond wouldn't show such a marked improvement in sharpening 9% and higher vanadium steels like S90V.

Again, if you use the analogy of cobblestones in a sidewalk, trying to sharpen something like that will result in the steel matrix itself being worn away with the carbides exposed, leaving a "toothy" edge. The finer the grain size, the finer the teeth, and the sharper the edge will be. Sort of like comparing boulder size cobblestones and sand.

Just because the carbides aren't as hard as the abrasives you use doesn't mean it won't resist the abrasion.

A sharp edge will have a radius about 100 times smaller than the size of the larger carbides in some ingot steels. A 30 micron carbide does not prevent a D2 or 154CM blade from reaching a sub micron edge radius. We also would not be able to achieve polished edges if the carbides could not be abraded. Surface irregularities of this size are about an order of magnitude larger than the scratch pattern needed to give the human eye the appearance of a smooth mirrored surface.

Also, there are steels with sub-micron carbides, or no primary carbides, so the diference in carbide volume and size among steels is massive, much greater than the difference in edge radius off the hone.

Astm Grain size 14 is still 2.8 microns in nominal diameter, which is much, much larger than the radius of a sharp edge. If you finish at greater than 4000 JIS/8000 mesh, then your abrasive is then smaller than the grain. And reducing the grain size too much reduces hardenability, so we don't see knifemakers pushing for super fine grain anyway.

Grain is the steel, the iron and carbon crytalline matrix. It is visible in fractured steel with the naked eye when very large. We do not see grains in a polished surface, because that is the steel, what we abrade and polish. A badly heated piece of steel can have a smooth finished surface but a jagged surface along a fracture with massive grains displayed (00 grain size is over 500 microns). The edge is a smoothed surface we create, it does not follow grain. It is the same for the other edges of a piece of steel, like the spine, tang, and elsewhere.

Diamond sharpens faster, but ceramics, boron nitride, boron carbide, silicon carbide, and aluminum oxide all abrade cutlery steel.

 

[Noctis3880]

A sharp edge will have a radius about 100 times smaller than the size of the larger carbides in some ingot steels. A 30 micron carbide does not prevent a D2 or 154CM blade from reaching a sub micron edge radius. We also would not be able to achieve polished edges if the carbides could not be abraded. Surface irregularities of this size are about an order of magnitude larger than the scratch pattern needed to give the human eye the appearance of a smooth mirrored surface.

Also, there are steels with sub-micron carbides, or no primary carbides, so the diference in carbide volume and size among steels is massive, much greater than the difference in edge radius off the hone.

Astm Grain size 14 is still 2.8 microns in nominal diameter, which is much, much larger than the radius of a sharp edge. If you finish at greater than 4000 JIS/8000 mesh, then your abrasive is then smaller than the grain. And reducing the grain size too much reduces hardenability, so we don't see knifemakers pushing for super fine grain anyway.

Grain is the steel, the iron and carbon crytalline matrix. It is visible in fractured steel with the naked eye when very large. We do not see grains in a polished surface, because that is the steel, what we abrade and polish. A badly heated piece of steel can have a smooth finished surface but a jagged surface along a fracture with massive grains displayed (00 grain size is over 500 microns). The edge is a smoothed surface we create, it does not follow grain. It is the same for the other edges of a piece of steel, like the spine, tang, and elsewhere.

Diamond sharpens faster, but ceramics, boron nitride, boron carbide, silicon carbide, and aluminum oxide all abrade cutlery steel.

You're using some strange terms there. A "radius" to me generally refers to the distance from the center of a circle to the outside. I assume you mean the apex of the edge or the bevel itself?

It's certainly true that D2 and 154CM takes a razor edge much better than S30V, but I have a theory on that. According to Crucible, Chromium carbides are around Rc 66-68 whereas Vanadium carbides are Rc 82-84. I'm thinking because the Chromium carbides are softer, they would be easier to polish to a fine edge compared to vanadium carbides.

That's not to say it can't be done, as I did manage to put an edge on my R.J. Martin Overkill in S110V that can cut free-hanging hair. Though I was not able to get quite as sharp an edge on S90V and CTS-20CP with any consistency. The difference isn't drastic, as they can both whittle hair easily. It's just that I found M390 and Elmax take that stupid sharp edge without as much effort.

Didn't you own a Fantoni folder in S125V in the past? Didn't you observe the same thing with that? Or did you not attempt to take it down to submicron levels? To be honest, I think the difference in sharpness would be subtle, like comparing a 1 micron finished edge to a 0.25 micron edge.

Also, I have to ask how much truth is in the statement that reducing grain size cuts down on hardenability, as CPM-D2 and CPM 154 seems to get as hard as their non-powder counterparts.

 

[Jason B.]

The terms are not strange just correct. It's a reference to apex width compared to the size of the carbide. The apex of a edge is round if you look close enough

Actually S30V will get much sharper because its a cleaner steel. Same reason elmax gets so insanely sharp.

Carbides have little to do with overall sharpness.

 

[Noctis3880]

The terms are not strange just correct. It's a reference to apex width compared to the size of the carbide. The apex of a edge is round if you look close enough

Well, I don't have a loupe or microscope, so the edge just looks like it disappears to my naked eyes. And if I looked any closer, I'd cut my eye.

Actually S30V will get much sharper because its a cleaner steel. Same reason elmax gets so insanely sharp.

Strange, I've gotten a sharper edge easier on my Emerson CQC Super 7 compared to my BM 943. And my Umnumzaan doesn't seem to get much sharper than hair whittling. Could just be the angles though. Still, people have noted that Elmax seems to get sharper and holds that razor edge longer. I think one of them was you:thumbup:.

Carbides have little to do with overall sharpness.

Maybe, maybe not. All I know for sure is that large chunky carbides tend to leave a very toothy edge whereas a 3rd generation PM steel like M390 stays razor sharp for a long while. Sort of like comparing stainless with carbon steels in the kitchen.