CPM154CM vs CPMS30V

Get your facts straight. The CPM process produces finer and more evenly distributed CARBIDES. Tougher , takes better edge, easier to sharpen better wear resistance.
It does NOT make a finer grain !!
I have 154CM, CPM154 and S30V. S30V is more wear resistant and I think it's better with micro-serrations. CPM154 is a bit easier to sharpen and can easily be sharpened to a very fine edge.
I'm keeping all three !!!
 
mete said:
Get your facts straight. The CPM process produces finer and more evenly distributed CARBIDES. Tougher , takes better edge, easier to sharpen better wear resistance.
It does NOT make a finer grain !!
I have 154CM, CPM154 and S30V. S30V is more wear resistant and I think it's better with micro-serrations. CPM154 is a bit easier to sharpen and can easily be sharpened to a very fine edge.
I'm keeping all three !!!
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Crucible Website said:
The powder is screened and loaded into steel containers which are then evacuated and sealed. The sealed containers are hot isostatically pressed (HIP) at temperatures approximately the same as those used for forging. The extremely high pressure used in HIP consolidates the powder by bonding the individual particles into a fully dense compact. The resultant microstructure is homogeneous and fine grained and, in the high carbon grades, exhibits a uniform distribution of tiny carbides. Although CPM steels can be used in the as-HIP condition, the compacts normally undergo the same standard mill processing used for conventionally melted ingots, resulting in improved toughness.

CPM Eliminates Segregation

Conventionally produced high alloy steels are prone to alloy segregation during solidification. Regardless of the amount of subsequent mill processing, non-uniform clusters of carbides persist as remnants of the as-cast microstructure. This alloy segregation can detrimentally affect tool fabrication and performance.

CPM steels are HIP consolidated from tiny powder particles, each having uniform composition and a uniform distribution of fine carbides. Because there is no alloy segregation in the powder particles themselves, there is no alloy segregation in the resultant compact. The uniform distribution of fine carbides also prevents grain growth, so that the resultant microstructure is fine grained.
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I'm inclined to side with Crucible on this one. ;)
 
hardheart said:
well, it doesn't say finer, only fine. how fine is the grain in 154CM compared to CPM154? 52100, W2, etc. can have very fine grain, but aren't cpm steels.
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Those are simple carbon/low alloy steels. No/little carbides. You're looking at carbon content and little, if anything, else added. The fine grain structure comes from not having anything else in the mix.

There are a couple good comparison shots of CPM steels vs. conventional smelting in their steel data PDFs (http://www.crucibleservice.com/datasheets/dynamicPull.cfm?gradeName=CPM 3V). I believe it shows a finer grain structure, but I could be wrong. :)
 
"prevents grain growth" No , nothing 'prevents ' grain growth. Retards grain growth perhaps but doesn't prevent. It's like vanadium , added in amounts of about 0.30 % ,will retard grain growth.This it does by going into the grain boundary and slows grain boundary movement [ necessary for grain growth]. You might argue that since S30V has V it should have finer grain size than CPM154. I haven't broken my blades so it's hard to tell !! Custom makers who use CPM154 are very happy with it and will tell you that it takes a very fine edge.But back to the question .The biggest improvement with the CPM steels is the carbide size and distribution.I've been a fan of CPM ever since it first came out many years ago. That's because I had experience with tool steels that had "massive carbides" which caused many problems .These massive carbides could be seen with the naked eye , no microscope needed !! I worked for another steel company at the time.
BTW it's very common on these forums for people to confuse grain size with carbide size.
 
mete said:
"prevents grain growth" No , nothing 'prevents ' grain growth. Retards grain growth perhaps but doesn't prevent. It's like vanadium , added in amounts of about 0.30 % ,will retard grain growth.This it does by going into the grain boundary and slows grain boundary movement [ necessary for grain growth]. You might argue that since S30V has V it should have finer grain size than CPM154. I haven't broken my blades so it's hard to tell !! Custom makers who use CPM154 are very happy with it and will tell you that it takes a very fine edge.But back to the question .The biggest improvement with the CPM steels is the carbide size and distribution.I've been a fan of CPM ever since it first came out many years ago. That's because I had experience with tool steels that had "massive carbides" which caused many problems .These massive carbides could be seen with the naked eye , no microscope needed !! I worked for another steel company at the time.
BTW it's very common on these forums for people to confuse grain size with carbide size.
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Retard: To hold back.
Prevent: To stop.

:confused: on the difference there.

I'm not trying to get into a pissing match, because I will undoubtedly loose, but if the CPM process keeps carbide size small, and by keeping the carbide side small, prevent/retard/stop grain growth, doesn't that lead to a fine grained steel with large amounts of fine carbides?
 
Although I have two Militarys that are CPM S30V, I dont really have experience with how they hold an edge, however, I also have a 154cm combo-edge Benchmade Griptilian and I cant say that I have been impressed with its edge retention.

The knife will dull on me if I cut some cardboard and then I have to carry a useless knife all day until I get home and can take it to the sharpmaker.

One time, I let a co-worker borrow the Grip to use to take some sticky tape off of a floating thing that you hold onto when a boat sinks, when I gave him the knife, he commented on how sharp it was, when I got it back, it was so dull it wouldnt cut anything.
 
Light OT to start...
To make the comparision between S30V and 154cm serious, we should take two IDENTICAL BLADES (same lenght, geometry, edge angle etc).
Of course heat treatement is also important...

After various standartized cutting tests (manila rope / cardboard boxes - whatever) on the both blades we would be able to say - "Yes, CPMS30V is better because it was able to make XX cuts more than 154cm, till the edge was completely dull" :D

BTT
I personally prefer S30V than 154cm.
Both are comparable in sharpening and edge holding, however 154cm is slightly "soapy" in cutting stuff. It just does not have this agrresion found in S30V :)
 
They're my two favorite stainless steels(well,VG10 is right up there with them).If given the choice for the same price,I'd opt for the S30V over 154CM,but not by much.

Now CPM154 is just as good as S30V in my experience.I find it easier to get a sharper edge with CPM154 & it keeps it well enough for my uses.

In my experience Emerson's 154CM is above what anyone else has done with it.Benchmade's 154CM isn't too shabby either.

They're so close,I wouldn't let it be a deciding factor when choosing a knife.
 
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Vanadium carbide is harder than Molybdenum carbide. All else being equal, I would wager CPM S30V would have superior wear resistance versus CPM 154CM.
 
Retard - to cause to move more slowly [F&W 1935 ]
If retarding grain growth is such a factor why don't they give numbers ?
The big difference between CPM154 and S30V is the good amount of vanadium in S30V.Yes it is wear resistant and why you don't see polished blades.
In the Knivesshipfree website - it's the WHITE ,not black, spots that are carbides. While they talk about grain size there too, grain size is not visible in the photo ! So are they talking about grain size or carbide size ??
 
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154CM & S30V are both great imho, i suppose i would prefer the 30v but 154 is plenty good too, imho neither one is hard to sharpen (nothing like M2), both hold an edge well and dont stain easy, the 30v is a wee bit better though, i guess.

imho there isnt a nite and day differnce between the 2 though.
 
I would have to say CPMS30V all the way, especially on my Spyderco's. I also like 154cm on my Emersons, but have not been real fond of my Benchmade's in 154cm.
 
I have a Buck 005RWS, 110, and 192 in Paul Bos heat-treated CPM154. Comparing the 110, actually a Bass Pro special, to an S30V 110, actually a Cabela's special, they appear equivalent, sharpness wise. The as-delivered sharpness was nearly as good as the Buck Custom Shop BG-42 blades - but none seem as sharp, out of the box, as a regular production 420HC. Their Bos heat-treating really makes a difference.

I have S30V in Bucks; 110, 151, 192, 347, 408, & 419. The 151 was the dullest, but still popped a few hairs. After a few minutes on a Spydie 'Sharpmaker', the 151 was fine. A very dull and much used EDC Spydie Native in S30V was a straight-forward sharpening experiment. It had cut down appliance bockets to slicing meat. It's unused Spyderco Native sibling is, like the old one, a hair popper. The sharpness of the 192 and 408/419 are exemplary - and none need touch-up yet. A Gerber Freeman (stag handled) in S30V came as a hair popper - and has stayed that way. I favor S30V, but I really haven't given CPM154 a fair chance - yet. Of course, Buck's 420HC, with a few minutes on a Sharpmaker, can be returned to near scarey-sharp. You'll just do that more often, from my experience, with 420HC than either of the the other two - CPM154 and S30V.

Stainz
 
mete said:
Retard - to cause to move more slowly [F&W 1935 ]
If retarding grain growth is such a factor why don't they give numbers ?
The big difference between CPM154 and S30V is the good amount of vanadium in S30V.Yes it is wear resistant and why you don't see polished blades.
In the Knivesshipfree website - it's the WHITE ,not black, spots that are carbides. While they talk about grain size there too, grain size is not visible in the photo ! So are they talking about grain size or carbide size ??
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I'm with you in the differences in composition, and I'm sure S30V would win out in a edge retention contest.

A lot of 154CM I've seen (Emersons/BM) feel soft. Between 56-57 RC almost. Edges tend to roll, even when cutting mild plastic and wood. Probably easier to steel back into shape though.

Perhaps we should break a couple of knives in half and see some grain size? :D I don't think that grain size is the leading advantage of the CPM process, I think it's the ability to pack the steel full of tiny hard carbides and massive amounts of alloying elements.
 
This was fun!
Thank you for the Valuable information. The only unknown commodity for me was "CPM154". From what I have read it's about what I expected. This will help me decide on future purchases.

I like the fact CPM154 is easier to sharpen than S30V, takes a fine edge, holds an edge decently. It's good enough for me.:)

What I use most of are 3" knives, I like slicers = VG10, 154CM, H1, AUS8 work for me. NOTE - I have some of this size in S30V, It performs well enough, but I would rather have the super sharpness of the "others".

For my larger knives, S30V is what I want.
Thanks Again!
 
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