CPM-M4 vs CTS-20CP/CPM-S90V

robino said:
i have seen Koster also using 3V in a lot of his knives as an option, and i see in posted graphs that it is quite the tough steel, but seems to 'lack' at the other end of the spectrum...edge retention.

I would like to see a more evenly matched steel, like the M4, which seems to be a good balance of edge retention and toughness as opposed to other steels which seem to stand out at either end but not at both
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NOT for what he wants to use it for it's not.....

The knives have to be able to be maintained out in the field and that could be any place, and by Soldiers....

Anyone who doesn't understand what that means hasn't been in the Military and understands what their knives can go through.

They would be a lot better off with a KA-BAR than an M4 blade.....

The graphs are just general guides, lots of things change when the variables are taken into count like HRC hardness ect...
 
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rustyrazor said:
yeah, I've noticed M4 creeping into a lot of threads as well as A8, then 3v respectively, so it's off to the internet to buy a bit and start the testing process. i'll keep you informed. thanks again
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CPM-M4 is $25 - $30/lb from Crucible. 3V is a couple of dollars/lb less (I just bought some of each from Scott in Dallas). The A8 Modified "Chipper Knife Steel" that a lot of folks claim is Infi is from LaTrobe:
http://www.latrobesteel.com/assets/documents/datasheets/LSS_Chipper.pdf

If you get a quote from them, could you let me know? 3V has radically better toughness than A8 or A8 modified, but it would certainly be an interesting comparison:

A8Modified.jpg
 
:eek:
This is the very first time I see a graph where O1 is tougher than A2 at 60 HRC

sidenote
D2 at 63 HRC should have about 31 joule, S7 at 58 should have about 160 joule, so the bar must be 5 times larger than the one of D2 ?
 
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Ankerson said:
Some steels do better with coarser edges than others, usually the higher the carbide content and the finer grained the steels are the better they do for certian tasks.

The level of edge refinement can make a huge difference in edge retention also, and cutting efficiency.

Most of the time from what I have seen in testing and use something in the middle around 6-10 micron finish tends to work the best overall, it gives a nice balance between edge retention and cutting ability. It's refined enough for push cutting while being aggressive enough to take advantage of the carbides as in lower cutting force needed when slicing.
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Funny thing Is I'd mostly agree with you on the 6-10 micron edge. Heck I'd probably lean more towards the 10 ish micron edge. And then there are times like now that I polish up my edge and think holy crap this thing cuts. So really I seem to be more in the middle trying to decide what type of edge really does work best for me. I've settled on a thin convex edge but the finish really is a work in progress. How does this really relate to the thread? I haven't really found that the steel type makes as much difference as the edge type does. Yes comparing them side by side I can notice a difference but in my every day useage the difference becomes pretty minor. This is based on the better steels at the higher rc levels.
 
regarding the above chart... where would steels like M4, 5160 and say 440c stack up (joule wise that is)?
 
In one test infi shows cobalt, nitrogen and nickel wich are all elements not present in lss chipper or a8 mod wich also show different percentage of elements. Yes they are somewhat similar ,the same absolutely not
 
db said:
Funny thing Is I'd mostly agree with you on the 6-10 micron edge. Heck I'd probably lean more towards the 10 ish micron edge. And then there are times like now that I polish up my edge and think holy crap this thing cuts. So really I seem to be more in the middle trying to decide what type of edge really does work best for me. I've settled on a thin convex edge but the finish really is a work in progress. How does this really relate to the thread? I haven't really found that the steel type makes as much difference as the edge type does. Yes comparing them side by side I can notice a difference but in my every day useage the difference becomes pretty minor. This is based on the better steels at the higher rc levels.
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Edge finish can really make a difference in cutting efficiency AND edge retention, how much of a difference will depend on the steel and the media being cut.

The dullness curve and cutting efficiency does change quite a bit between highly polished, semi polished and coarse edges from what I have seen in my testing on rope and it's a noticeable difference.

I believe Spyderco has done extensive testing in this area.
 
Ankerson said:
Edge finish can really make a difference in cutting efficiency AND edge retention, how much of a difference will depend on the steel and the media being cut.

The dullness curve and cutting efficiency does change quite a bit between highly polished, semi polished and coarse edges from what I have seen in my testing on rope and it's a noticeable difference.

I believe Spyderco has done extensive testing in this area.
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I'm sure they have. Funny thing is results are different for different people as we all handle and use knives differently. And really that is the fun of being a knife/steel nut we will probably never find the perfect match of steel type, edge finish, and thickness, as even for ourselves methods and needs change. I know mine have.
 
k.... so from what I assume from reading the last 3 hours is that if I want toughness, go with 3v, L6 A8 or M4 because they'll take the best beatings of almost any piece of metal given the same geometry and heat treat assuming edge holding comes second in priority (which it does most certainly)
 
If you want toughness, then use 4140, 1055, etc. you are looking for some other balance. 3V and M4 are not "easy" to sharpen when compared to something like 5160, 1095, 13N20, and so forth. There are tons of tough steels to choose from. Not sure what you mean every time you mention strength. That generally references resistance to permanent deformation. With that, the rockwell hardness test is deformation of the steel, and the higher the number the less it deformed.
 
rustyrazor said:
k.... so from what I assume from reading the last 3 hours is that if I want toughness, go with 3v, L6 A8 or M4 because they'll take the best beatings of almost any piece of metal given the same geometry and heat treat assuming edge holding comes second in priority (which it does most certainly)
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get infi if you want toughness. Jerry has a great you break it we replace it policy cause you wont break it. Not to mention I've never had any rust on it meanwhile I rust some ss with ease like aus 8 and zdp
 
the reference to strength is just an overall resistance to permanent damage. I need compression/impact strength so as to be able to hammer the rear of the blade when batonning or so the blade can be used to chop and I need yeild strenth so some jackass can use the knife to pry with. from what I've read from INFI it's BUSSE's own "secret" steel... I'm looking for something available to build my own blades out of. and steels such as 1055 and whatnot are doubtful going to be able to hold a candle to the others in edge retention.
 
Oh , in that case cpm3v is your best route. Its alot tougher then m4 ,m4 is tough but I wouldn't hammer it or pry with it
 
spydusse said:
get infi if you want toughness. Jerry has a great you break it we replace it policy cause you wont break it. Not to mention I've never had any rust on it meanwhile I rust some ss with ease like aus 8 and zdp
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ZDP isn't stainless. Sure it has 20% chromium, but it is all tied up forming carbides.
 
CrimsonTideShooter said:
ZDP isn't stainless. Sure it has 20% chromium, but it is all tied up forming carbides.
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Like spydusse and Ken44 said, it's technically considered a stainless steel since that designation is based purely on the chromium content. There are various numbers floating around for what, exactly, the required chromium percentage is, but since all are in the neighborhood of 12-13%, ZDP's 20% easily exceeds the threshold regardless of which particular standard one uses.

However, I do agree with your underlying point that, even though it meets the technical, chromium-percentage-based standard for "stainlessness", ZDP is very susceptible to rust/patina formation. Even if corrosion resistance were a major concern for me, there are a lot of technically non-stainless steels that I'd take in a heartbeat over ZDP for that purpose (e.g., 3V, M4, INFI, D2, etc.).
 
Steel is very special stuff and has as much depth, personality and behavior as our own minds. That's why it's still a topic of modern materials discussion. These "technical" parameters are further complicated by angles, hardness and how thin the steel/edge might be. Also in working with foundries, I have found that they often add "special ingredients" at 50 parts per million rates that we don't know about or isn't public inbformation.

I have found much knowledge on these forums that is sometimes far beyond the "technical definitions and paramters".

sal
 
spydusse said:
Im almost positive its considered a ss
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Read my reply to Ken.

People are too concerned about what numbers on paper say. Like I said, ZDP is NOT stainless. On paper it is "considered" stainless, but in the real world it is far from it.

There is a big difference between 20% chromium being free to combat rust and 20% chromium being tied up in carbides.
 
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