Who is using CPM D2

[The Mastiff]

As I struggle to understand this, I think Vassili has a point. Wear resistance and edge retention are often used as synonyms, but reality is more complicated.

Wear resistance is what it is, and it will typically correlate to edge retention, but not always. Hardness and blade geometry and the size of carbides, etc., will affect edge retention.

For example, a steel at a specific wear resistance and hardness may have excellent edge retention on a knife with a 40-degree inclusive edge angle. But if the angle of the edge is made much more acute, the edge will roll or bend or chip, reducing edge retention to average or poor.

Edge retention is affected by more factors than wear resistance.

Twin dog, what you are referring to is actually edge stability. Edges rolling have nothing to do with wear resistance. It means the steel didn't have enough stability to do that edge on that particular job and rolled. Chipping away could be another result. Micro chipping, not obviously a large chip from an impact on something hard like a nail in a log being batoned, for instance.

Wear resistance is either abrasive or adhesive wear resistance. These two types of wear resistance are measured and are what the steel companies list in the specs on a steel.

As I stated in an earlier post edge stability can have an effect on wear resistance but by and large wear resistance comes from the carbides and steel matrix structure. With some steels acidity can even lower wear resistance. Typically, the higher the carbide fraction of a steel, the lower the edge stability. PM technology has helped in this greatly allowing the steels to , as Crucible states" The CPM process results in a finer, more uniform carbide distribution imparting improved toughness and grindability to high alloy steels".

Like recently one "steel guru" revealed what was his theory on PM steel were based - once he change old carpet in his room and use three knives,
CPM S30V one outperforms BM D2 (on my tests BM D2 show worse results) based on this comparison - average CPM S30V vs worse D2 he made big
theory that PM steel with higher carbide volume better. Very interesting reading he came up, which show true power of imagination, but this has
nothing to do with little World of reality..

I suppose you are referring to me as I was the one who was talking about my experiences cutting carpet, and what I learned. I'll say the same thing that I said last time you said this though I have no reason to think it will sink in, or you will understand it. I only stated that I had found that for that particular job, my results were... You couldn't accept that and stated your testing was better and more accurate than my real cutting experience. It was kind of puzzling how you came to that conclusion that your testing was better than real world experience. In fact, I still don't get it.

I've collected, used, bought, sold ( retail on the gun show circut), and even made a few knives up until I lost the space for a shop, and had to have both shoulders srurgically rebuilt.

In that time do you suppose all I ever did was cut an old carpet once and that sums up my experience with knives?

Saying the same things over and over to you really gets old. My mastiff is smarter and learns quicker than you. You should stay in your world of computer programming. You obviously don't understand or get along with real people as you eventually make yourself unwelcome and get ridiculed for your attitude and behavior in every knife forum you participate in. You have terrible coping abilities with and around people and you are the cause of your own problems. We all gave you the benefit of the doubt , and even supported you and your work for a very long time. Some of us more than others. It would be easy to point out what you are doing wrong here but that's been done enough times. You choose to not get along with people for whatever reason.

The difference between you and me is I recognize I have a huge amount to learn about this subject. I admit to being wrong, and not knowing what I don't know. A "Guru" I'm for sure not. I lurk far more than I post here because I'm always looking to learn stuff. I'll take whatever knowledge someone is willing to share with me and try to learn from it. When I make mistakes I try to learn from them and not repeat them over and over. That's another way we differ.

Joe

 

[cziv]

A 4 page thread on CPM-D2? and I though it would be interesting....

I really like the steel and wish it was used more but AFAIK kershaw is the only production knife maker that has it in current production knives. To me its a lot like a carbon class of S30V, it has similar edge retention but all the qualities of a carbon steel.

CPM D2 vs S90V come on... its just not even a comparison. In rope cutting I could see though how one could get the perception that CPM D2 is better. S90V seems to "dull" quickly on rope where the CPM D2 stays sharper, depending on how the edge is judged it could make it seem as though the CPM D2 was out performing the S90V. This is far from what is really happening though and unless other cutting is performed impressions could be skewed.
CPM D2 is a good user steel but its no S90V or M4.

Can you clarify what the bolded section means please? How does something seem like it's better in testing but not really "be" better.

On another note, these threads seem to always degenerate into semantics of retention, stability, wear resistance...etc. Is there a common set of terms that can be used to describe the performance of a steel that everyone can know and use in a post universally? So we're not constantly correcting each other about "what you really mean is ......" type of posts?

What the difference in 154cm, D2 - compared to CPM154cm or CPM D2 - I know that Crucible is the CPM but what do they do that's special to the 154 or th D2?

Last thought, I saw (think it was unit), who had a fistful of the SAME knife and grind - the Endura 4 in different steels. I think that's a way to narrow down testing or impressions. Eliminating variables..ya know?

Anyway carry on gentlemen good thread as always.

 

[nozh2002]

A 4 page thread on CPM-D2? and I though it would be interesting....

I really like the steel and wish it was used more but AFAIK kershaw is the only production knife maker that has it in current production knives. To me its a lot like a carbon class of S30V, it has similar edge retention but all the qualities of a carbon steel.

CPM D2 vs S90V come on... its just not even a comparison. In rope cutting I could see though how one could get the perception that CPM D2 is better. S90V seems to "dull" quickly on rope where the CPM D2 stays sharper, depending on how the edge is judged it could make it seem as though the CPM D2 was out performing the S90V. This is far from what is really happening though and unless other cutting is performed impressions could be skewed.

CPM D2 is a good user steel but its no S90V or M4.

Well CPM S30V steel is no match to CPM D2. CPM S30V pretty average performer and not only by my test (CPM S30V - 30th and CPM D2 14th places) but by CATRA as well.

I though everybody already snapped out of that CPM S30V charm - for 8 years it has enough exposure, already to understand that this is pretty average steel and only good for price $2/lb. and easy to grind + huge hype created 8 years ago. CPM S30V and CPM S35V both on the bottom of Crucible performers and below middle of my list.

If limit choice to steel from Cricible - CPM D2 is best and CPM S30V-S35V would be worse.

Thanks, Vassili.

 

[Artfully Martial]

I've had great experiences with S30V...much better than my D2, although I still like D2.

From anyone, what are the comparative advantages and disadvantages of cpm-d2 versus s30v?

 

[Buster_NW]

A 4 page thread on CPM-D2? and I though it would be interesting....

LOL, thanks to everyone for the input on CPM-D2. Sounds like it's not widely used, which is what I was wondering.

Didn't know this would start a dumpster fire, but that doesn't mean we can't all sit by and warm our hands

Buster

 

[Noctis3880]

I've had great experiences with S30V...much better than my D2, although I still like D2.

From anyone, what are the comparative advantages and disadvantages of cpm-d2 versus s30v?

S30V can outperform CPM-D2 at the same hardness. Only catch is, S30V is typically only found at Rc 57-59 whereas CPM-D2 is around Rc62, giving it an edge. Though at Rc 57-59 S30V will be a lot tougher.

Though corrosion resistance is undeniably several leaps and bounds higher. I think the real question is why anyone would use it over CPM-M4. Regular D2 is no cookie to sharpen, and I have to figure anyone who can handle that wouldn't be bothered much by M4.

 

[Artfully Martial]

corrosion resistance is very low on the scale for me.

how does m390 compare to these?

 

[Jason B.]

cziv, I'm not real good at putting this stuff in words but I'll try. It takes experience with the steel and unfortunately the understanding of all the terms to get a general idea of how they work. Terms like wear resistance are often related to edge holding when in truth they couldn't be further apart. Its why you often hear about someone using a premium steel but being confused when it looses its razor edge after two cuts in cardboard. Nothings wrong with the steel that's just the way it works.

"Softer" low alloy steels rely on the ability of the steel to hold shape in the edge. When dulling happens with these steels they tend to polish at the apex or become flat and bent. High wear steels show less tendency to deform and instead of polishing itself dull from abrasion the abrasive wear makes the edge very rough (think of it like the edge being sand blasted). A theory called carbide tear out seems to be very real in the performance of these steels. The theory says that as the carbides wear they become disloged exposing new and sharp carbides. This is the "looses its sharp edge quick and gets toothy" experience most have with high wear steels. I have no way to prove the theory but it seems right given the performance characteristic.

Its like the VG-10 vs S30V debate, in average use they both perform about the same but if used for cutting meat or carpet the scales would tip drastically one way or the other. VG 10 is designed to take and hold a fine edge so it does not damage the plant material it was designed to cut. It does not encounter high amounts of abrasive wear doing this so having a high volume of carbides in the steel does not benefit its intended use. Now S30V with its large volume of carbides is not a steels designed to keep a fine edge for cutting soft materials. Most every day used consist of cutting harsh materials like cardboard or rope/string, paper, and synthetic materials. These things cause heavy abrasive wear on the metal and thus the designers decided to give it higher levels of wear resistance to cope with the abrasion. They sacrifice sharpness for a long lasting edge.

All to often we try to use steels for the wrong task then complain about the performance. A steel like S90V IMO would be a bad choice for a sushi knife the same way a AUS8 blade would be a bad choice for cutting carpet. That old wrong tool for the job thing.

Another example would be my mule team blades, I have the 52100, CPM-M4, and S90V. Of the three 52100 will leave the other two in the dust when cutting manila rope, M4 might hold close in the long run but that would be a lot of cutting. When I first tested them I fully expected S90V to be top performer but quickly found it to be the worst. It quickly lost its razor edge in favor of a toothy one and this made cutting the rope very difficult. The 52100's higher edge stability and ability to hold sharpness made it a far better steel choice for the cutting test. If I used carpet for the test guess which steel would have come out on top....

Its all about steel selection, edge geometry, and cutting technique, if any of the three are done wrong or selected blindly results will be as random as some testing.

hope this helps.

 

[Leadfoot2]

I'm kind of new to all this testing stuff, and really, I can't see why anyone that would want an accurate test, would be using an actual knife. And on top of that, basing their test results on one or two blades.

I would think that a reasonable person would want to base their testing in a controlled fashion. First off, if I were a reasonable person, I would want to invent a machine to give me precise feedback, and take human intuition (read jumped up and down falsification due to ego) out of the equation...... what's that you say? They already have this machine? And lo, it came to pass, handed down from above. CATRA!!!

Then, being a reasonable person, I would test the steels of choice. Notice I did not say knives, I said steel. Lets say we want to test plain old generic D2. Anyone here know of it?

First I would take 100 identical bars of the steel of choice, and I would bevel a chisel edge on 50 of these at say 10 at 5 degree, 10 at 7.5 degree, 10 at 10 degree, 10 at 12.5 degree and 10 at 15 degree.

Then I would grind the other fifty to a double bevel knife edge, 10 at 10 degree, 10 at 15 degree and so on, and so forth. Giving us 100 edges to test.

And yes these have to be sharpened to uniform edges, each test piece as close as possible to the rest, and from the same manufacturing lot.

Now we come to heat treat, and being a reasonable person, I know that I just added a whole lot of work for myself. Because I have just looked at my steel suppliers instructions, and we have decided that our target range is 57 to 61 HRC and know that to give us a chance at empirical evidence, we will need to test all 100 edges at all 6 steps. I'll do the math for you, 100 x 6 = 600. That's right, we now have 600 edges to test, under very tight climate controlled circumstances.

Oh and just a side note, each test blade will need to be independently tested, twice, for hardness. The cost of diamond tips alone will be astronomical. Eh, what's that? You only test yours by skating a file for hardness? For shame.

You know what, I'm going to fly in the face of reason, buy a truck load of 1/2 inch manila rope, use my finely honed jumped up and down falsification reasoning, type long diatribes in pigeon Engrish and tell the World!!!


Respectfully yours, Leadfoot

 

[Leadfoot2]

On a side note, cutting all that paper, has generated new income as a confetti supplier.


Leadfoot

 

[Ankerson]

cziv, I'm not real good at putting this stuff in words but I'll try. It takes experience with the steel and unfortunately the understanding of all the terms to get a general idea of how they work. Terms like wear resistance are often related to edge holding when in truth they couldn't be further apart. Its why you often hear about someone using a premium steel but being confused when it looses its razor edge after two cuts in cardboard. Nothings wrong with the steel that's just the way it works.

"Softer" low alloy steels rely on the ability of the steel to hold shape in the edge. When dulling happens with these steels they tend to polish at the apex or become flat and bent. High wear steels show less tendency to deform and instead of polishing itself dull from abrasion the abrasive wear makes the edge very rough (think of it like the edge being sand blasted). A theory called carbide tear out seems to be very real in the performance of these steels. The theory says that as the carbides wear they become disloged exposing new and sharp carbides. This is the "looses its sharp edge quick and gets toothy" experience most have with high wear steels. I have no way to prove the theory but it seems right given the performance characteristic.

Its like the VG-10 vs S30V debate, in average use they both perform about the same but if used for cutting meat or carpet the scales would tip drastically one way or the other. VG 10 is designed to take and hold a fine edge so it does not damage the plant material it was designed to cut. It does not encounter high amounts of abrasive wear doing this so having a high volume of carbides in the steel does not benefit its intended use. Now S30V with its large volume of carbides is not a steels designed to keep a fine edge for cutting soft materials. Most every day used consist of cutting harsh materials like cardboard or rope/string, paper, and synthetic materials. These things cause heavy abrasive wear on the metal and thus the designers decided to give it higher levels of wear resistance to cope with the abrasion. They sacrifice sharpness for a long lasting edge.

All to often we try to use steels for the wrong task then complain about the performance. A steel like S90V IMO would be a bad choice for a sushi knife the same way a AUS8 blade would be a bad choice for cutting carpet. That old wrong tool for the job thing.

Another example would be my mule team blades, I have the 52100, CPM-M4, and S90V. Of the three 52100 will leave the other two in the dust when cutting manila rope, M4 might hold close in the long run but that would be a lot of cutting. When I first tested them I fully expected S90V to be top performer but quickly found it to be the worst. It quickly lost its razor edge in favor of a toothy one and this made cutting the rope very difficult. The 52100's higher edge stability and ability to hold sharpness made it a far better steel choice for the cutting test. If I used carpet for the test guess which steel would have come out on top....

Its all about steel selection, edge geometry, and cutting technique, if any of the three are done wrong or selected blindly results will be as random as some testing.

hope this helps.

There is a twist there on this, one just can't say High Alloy because the different carbides react differently and the blades tend to wear differently depending on the type of carbides in the steels.

Vanadium is the hardest, Molybdenum is next and Chromium is last.

It's the Vanadium steels like S90V, S30V, S110V, M4, 10V, 15V that really develop that toothy edge over time.

Throw a curve in there in steels like M390 and ELMAX that have a lot of Vanadium and large amounts of Chromium the edges tend to stay smoother while still cutting aggressively like the steels above.

Then we have the straight Chromium steels like ZDP-189 and XHP that tend to stay smoother even though they are loaded with chromium carbides.

Even with all of that we still have to take into consideration the grain structure of the steels and the refinement of the grain structure and or Generation of PM technology they are.

And we haven't even started talking about Hardness, tempering, blade geometry, edge geometry, blade design, materials being cut and edge finishes.

 

[Noctis3880]

There is a twist there on this, one just can't say High Alloy because the different carbides react differently and the blades tend to wear differently depending on the type of carbides in the steels.

Vanadium is the hardest, Molybdenum is next and Chromium is last.

It's the Vanadium steels like S90V, S30V, S110V, M4, 10V, 15V that really develop that toothy edge over time.

Throw a curve in there in steels like M390 and ELMAX that have a lot of Vanadium and large amounts of Chromium the edges tend to stay smoother while still cutting aggressively like the steels above.

Then we have the straight Chromium steels like ZDP-189 and XHP that tend to stay smoother even though they are loaded with chromium carbides.

Even with all of that we still have to take into consideration the grain structure of the steels and the refinement of the grain structure and or Generation of PM technology they are.

And we haven't even started talking about Hardness, tempering, blade geometry, edge geometry, blade design, materials being cut and edge finishes.

I don't know... While ZDP seems to keep a razor edge longer(and I suspect it's due to the hardness more than anything else), XHP behaved much like D2 in that the fine edge is lost quickly, but it has pretty big teeth better for slicing cuts than push cuts.

 

[Ankerson]

I don't know... While ZDP seems to keep a razor edge longer(and I suspect it's due to the hardness more than anything else), XHP behaved much like D2 in that the fine edge is lost quickly, but it has pretty big teeth better for slicing cuts than push cuts.

I noticed that too when I tested it compared to ZDP, but the dullness curves were the same, interesting how that worked out really.

XHP was more aggressive while ZDP was much smoother.

The ZDP I tested was 65 HRC so I expect that helped it a lot, but as with the Chromium steels they tend to have more of a normal dullness curve.

They go for awhile, dull some then drop off the cliff at the end.

The Vanadium steels tend to dull then level out for a very long time then start to dull again then level out again then finally start to drop off slowly towards the end.

The standard steels have a smooth dullness curve, more like a progressive slant that just continues to get duller.

 

[Noctis3880]

Makes sense. According to crucible, the hardness are as follows:

• HARDENED STEEL • 60/65 HRC
• CHROMIUM CARBIDES • 66/68 HRC
• MOLYBDENUM CARBIDES • 72/77 HRC
• TUNGSTEN CARBIDES • 72/77 HRC
• VANADIUM CARBIDES • 82/84 HRC

What's interesting is that the hardness of chromium carbides barely seem to be much harder than the hardness of the steel itself in ZDP-189, which probably makes it dull at a more linear curve. Though it seems like there isn't really a need for chromium carbides at that hardness.

Would be interesting to see a nitrogen version of ZDP-189, but with a much lower mix of chromium. If you could get the steel at that high hardness range without as much chromium carbides(and without compromising the amount of free chromium), I'd imagine you'd be left with a tougher steel that still holds an edge for a very long time.

 

[Ankerson]

Makes sense. According to crucible, the hardness are as follows:

• HARDENED STEEL • 60/65 HRC
• CHROMIUM CARBIDES • 66/68 HRC
• MOLYBDENUM CARBIDES • 72/77 HRC
• TUNGSTEN CARBIDES • 72/77 HRC
• VANADIUM CARBIDES • 82/84 HRC

What's interesting is that the hardness of chromium carbides barely seem to be much harder than the hardness of the steel itself in ZDP-189, which probably makes it dull at a more linear curve. Though it seems like there isn't really a need for chromium carbides at that hardness.

Would be interesting to see a nitrogen version of ZDP-189, but with a much lower mix of chromium. If you could get the steel at that high hardness range without as much chromium carbides(and without compromising the amount of free chromium), I'd imagine you'd be left with a tougher steel that still holds an edge for a very long time.

There really doesn't seem to be any free lunch with steels, to get one thing we have to give up something else.

The more I test the more I find that nothing is really guess work and things really do tend to be predictable in how they perform, well for me anyway.

I can usually predict were a steel should fit in relation to others by just looking at the alloy content and Hardness, it's gotten to that point for me.

 

[Big Mike]

What a wonderful comment!

Thanks, you deserve it. :yawn:

This is my well known luck of sharpening skills...

Freudian slip no doubt, :foot:

...but depending on luck in sharpening test blades does help explain your results.




Big Mike

 

[nozh2002]

Thanks, you deserve it. :yawn:








Freudian slip no doubt, :foot:

...but depending on luck in sharpening test blades does help explain your results.




Big Mike

Well, answered again! You are just super. You perfectly demonstrates point I made.

Thanks, Vassili.

 

[nozh2002]

cziv, I'm not real good at putting this stuff in words but I'll try. It takes experience with the steel and unfortunately the understanding of all the terms to get a general idea of how they work. Terms like wear resistance are often related to edge holding when in truth they couldn't be further apart. Its why you often hear about someone using a premium steel but being confused when it looses its razor edge after two cuts in cardboard. Nothings wrong with the steel that's just the way it works.

"Softer" low alloy steels rely on the ability of the steel to hold shape in the edge. When dulling happens with these steels they tend to polish at the apex or become flat and bent. High wear steels show less tendency to deform and instead of polishing itself dull from abrasion the abrasive wear makes the edge very rough (think of it like the edge being sand blasted). A theory called carbide tear out seems to be very real in the performance of these steels. The theory says that as the carbides wear they become disloged exposing new and sharp carbides. This is the "looses its sharp edge quick and gets toothy" experience most have with high wear steels. I have no way to prove the theory but it seems right given the performance characteristic.

Its like the VG-10 vs S30V debate, in average use they both perform about the same but if used for cutting meat or carpet the scales would tip drastically one way or the other. VG 10 is designed to take and hold a fine edge so it does not damage the plant material it was designed to cut. It does not encounter high amounts of abrasive wear doing this so having a high volume of carbides in the steel does not benefit its intended use. Now S30V with its large volume of carbides is not a steels designed to keep a fine edge for cutting soft materials. Most every day used consist of cutting harsh materials like cardboard or rope/string, paper, and synthetic materials. These things cause heavy abrasive wear on the metal and thus the designers decided to give it higher levels of wear resistance to cope with the abrasion. They sacrifice sharpness for a long lasting edge.

All to often we try to use steels for the wrong task then complain about the performance. A steel like S90V IMO would be a bad choice for a sushi knife the same way a AUS8 blade would be a bad choice for cutting carpet. That old wrong tool for the job thing.

Another example would be my mule team blades, I have the 52100, CPM-M4, and S90V. Of the three 52100 will leave the other two in the dust when cutting manila rope, M4 might hold close in the long run but that would be a lot of cutting. When I first tested them I fully expected S90V to be top performer but quickly found it to be the worst. It quickly lost its razor edge in favor of a toothy one and this made cutting the rope very difficult. The 52100's higher edge stability and ability to hold sharpness made it a far better steel choice for the cutting test. If I used carpet for the test guess which steel would have come out on top....

Its all about steel selection, edge geometry, and cutting technique, if any of the three are done wrong or selected blindly results will be as random as some testing.

hope this helps.

Very interesting post. If removes all lyrics and "theories", extracting only real use descibed here - bottom line is that cutting manila rope (comonnly accepted media for edge performance testing) plane carbon 52100 left behind both CPM M4 and CPM S90V which is what I had as well with SRS101 (10th place) CPM M4 (12th place) and CPM S90V(16th place).

Now why do you need this silly excuses about CPM S90V is good for something else? Do you really believe this? Common, it is not like hex or strait screwdrivers - this is just cutting and 52100 is just better cutter. Who care how long dull CPM S90V will stay less duller then another dull edge?

You just desperate to be polite to all those "experts" or too brainwashed here to trust your own eyes!

May be CPM S90V is better for cutting press in the paper factory, but it is not better then CPM D2 for knives and would not be better is it manila rope or wood or leather.

Thanks, Vassili.

 

[cziv]

Very interesting post. If removes all lyrics and "theories", extracting only real use descibed here - bottom line is that cutting manila rope (comonnly accepted media for edge performance testing) plane carbon 52100 left behind both CPM M4 and CPM S90V which is what I had as well with SRS101 (10th place) CPM M4 (12th place) and CPM S90V(16th place).

Now why do you need this silly excuses about CPM S90V is good for something else? Do you really believe this? Common, it is not like hex or strait screwdrivers - this is just cutting and 52100 is just better cutter. Who care how long dull CPM S90V will stay less duller then another dull edge?

You just desperate to be polite to all those "experts" or too brainwashed here to trust your own eyes!

May be CPM S90V is better for cutting press in the paper factory, but it is not better then CPM D2 for knives and would not be better is it manila rope or wood or leather.

Thanks, Vassili.

You sound pretty rude today Vassili - you talk about proving steel & edge with manilla rope but yeterday I saw a video of you beating the crap out of a custom Yuna ZDP 189 by diggin in dirt and stones to prove what? That isn't the accepted method, according to you to prove anything. You're lucky you didn't break it or we would have heard about what shitty steel ZDP 189 is right? :thumbdn:

 

[Artfully Martial]

Honestly, I think a lot of people sound rude in this thread. I'm not going to point any fingers, and lord knows I'm not above a heated debate myself, but this is getting pretty personal.