What is "CPM", and does it make a difference?

When we initially started processing CPM-154 we interchanged the name CPM-154CM with CPM-154 until we decided to drop the CM. I believe they named CPM-154 the way they did so people would know it is the CPM version of 154-CM. They do the same thing with their tools steels like M-4 and CPM M-4.

All manufacturers should be clear on whether they are using CPM-154 or 154-CM.
 
Just to add a bit of further spice and mystery into this discussion, some makers used to mark their CPM 154 blades with 154V. Evidently, they were under the impression that CPM154 contained Vanadium. Alloy charts have confirmed that if CPM154 ever contained any Vanadium, it was so negligible to have not shown up on the alloy tests. Crucible never said it contained Vanadium, either, as far as I know.
 
mystro said:
To answer the original question.....No. I have them all and I cant tell a difference.
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Actually I would find that easier to believe than one might expect. If the heat treat is right(say, on a Hogue), 154CM would be pretty hard to tell apart from CPM154, unless hardness between the two is significantly different. I've also observed less edge damage on my Queen Sodbuster in plain D2 when compared with my Kershaw JYD II blem in CPM-D2.

Still, some steels like S30V or any other high vanadium steel doesn't even seem to be available outside of powdered versions, so I won't complain. Yet it seems good ol' D2 can't be made obsolete so easily. I'm in fact looking for knives in D2 to regrind in order to take advantage of that wonder steel. Not the most stain resistant, but it's nothing a high polish and some Brasso can't fix:thumbup:.
 
Then we have CPM D2 :)


Had a guy swear to me he could tell the steel type just by looking at the blade. I placed 3 blades on the table , he got all three wrong. 1 was D2 , 1 was 1095 and the other was S30v.
 
The difference with CPM D2 is that Crucible isn't the only company that manufactures D2. So it's easy to distinguish normal D2 from CPM D2. But Crucible IS the only company that manufactures 154CM. So the confusion between Crucible 154CM and CPM-154CM is understandable. Perhaps that's why Crucible abandoned the name "CPM-154CM" in favor of "CPM-154" when they made a powder form of 154CM. But by the time they had made the decision to do that, the damage had been done.

I found an interesting post about the history of 154CM and CPM-154 here:

http://edcforums.com/showthread.php...ame-same-steel?p=620465&viewfull=1#post620465

I can't swear for its accuracy, however. FK doesn't identify himself and this is his only post.
 
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my point is we rely on the maker or manufacture of the knife to tell us the steel , if someone said it was CPM D2 vs D2 , who is going to know ?

Heck I have seen a maker advertising his 1095 knives as having Paul Bos HT , which of course those in the know realize is wrong since BOS Company doesnt HT high carbon steels.
 
Precisely. If a knifemaker said they used CPM154CM in the construction of a knife and they used 154CM instead of CPM154, who is going to know? The designation "CPM154CM" isn't supported by the manufacturer of the alloy. So it seems to me the only way to know for sure is to contact the knifemaker and ask them. And I, for one, wouldn't buy a knife constructed of "CPM154CM" without doing just that.

The good news is, most knifemakers and manufacturers seem to realize that there are only two alloys in the 154 series . . . 154CM and CPM154 . . . and they market their knives using the correct alloy designations. So the problem with using "CPM154CM" doesn't appear to be too widespread at this point.
 
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You can't put more than 2% Vanadium into steel by conventional smelting. So all high Vanadium steels are made by the powder process. CPM D-2 exhibits more corrosion resistance than regular D-2 even though the Chrome content is the same in each. 154 mean 15% Chrome and 4% Molybdenum. 154CM is a high purity stainless steel that was developed to resist corrosion at elevated temperatures and the high centrifugal forces as encountered in turbine blades. Bob Loveless pioneered the use of 154CM in knife applications.
 
bld522 said:
The difference with CPM D2 is that Crucible isn't the only company that manufactures D2. So it's easy to distinguish normal D2 from CPM D2. But Crucible IS the only company that manufactures 154CM. So the confusion between Crucible 154CM and CPM-154CM is understandable.
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What does that mean? Duratech T-15 is not produced the same way as T-15. Neither is Micromelt M42 and M42. Or CPM M4 and M4. Or CPM154 and 154CM. If somebody sticks the PM series name on an ingot cast version, Carpenter, Latrobe, and Crucible are not to blame. CPM is not the trademark for any Crucible made steel, it only applies to PM. If the knife is advertised with CPM-whatever, then it better be a CPM version.
 
tiguy7 said:
You can't put more than 2% Vanadium into steel by conventional smelting. So all high Vanadium steels are made by the powder process. CPM D-2 exhibits more corrosion resistance than regular D-2 even though the Chrome content is the same in each. 154 mean 15% Chrome and 4% Molybdenum. 154CM is a high purity stainless steel that was developed to resist corrosion at elevated temperatures and the high centrifugal forces as encountered in turbine blades. Bob Loveless pioneered the use of 154CM in knife applications.
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Are you sure you're not confusing corrosion resistance with the surface finish? If anything I've noted more rust on my CPM-D2 JYD II than my Queen Sodbuster in D2. The JYD II does have a much rougher finish left over from a fresh 40 grit belt while the Sodbuster was finished with a very worn 40 grit belt. Unless both are bead blasted in the same manner and tested with a salt spray, nothing can really be said for certain.
 
hardheart said:
What does that mean? Duratech T-15 is not produced the same way as T-15. Neither is Micromelt M42 and M42. Or CPM M4 and M4. Or CPM154 and 154CM. If somebody sticks the PM series name on an ingot cast version, Carpenter, Latrobe, and Crucible are not to blame. CPM is not the trademark for any Crucible made steel, it only applies to PM. If the knife is advertised with CPM-whatever, then it better be a CPM version.
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Goes back to what I said earlier about some folks confusing the "Crucible" name with the "CPM" trademark. We may understand the difference but that doesn't mean everybody does. Even Crucible appeared to recognize the potential for confusion. That seems to be why they decided to name their new 154 version "CPM154" instead of "CPM154CM".
 
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Noctis3880 said:
Are you sure you're not confusing corrosion resistance with the surface finish? If anything I've noted more rust on my CPM-D2 JYD II than my Queen Sodbuster in D2. The JYD II does have a much rougher finish left over from a fresh 40 grit belt while the Sodbuster was finished with a very worn 40 grit belt. Unless both are bead blasted in the same manner and tested with a salt spray, nothing can really be said for certain.
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I tend to agree, besides easier to sharpen and polish I always thought CPM-D2 was more rust prone.
 
In 12/10/09 posts on CPM D-2; gunmike1, tsdevanna, and yablanowitz all say that CPM D-2 is more rust resistant than D-2. I also read some theory on CPM D-2 corrosion resistance, but I haven't been able to locate it yet.
 
tiguy7 said:
In 12/10/09 posts on CPM D-2; gunmike1, tsdevanna, and yablanowitz all say that CPM D-2 is more rust resistant than D-2. I also read some theory on CPM D-2 corrosion resistance, but I haven't been able to locate it yet.
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We all have our experiences and the knives they happened with, not all the same knife or heat treatment which could influence corrosion resistance among other things.
 
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