CPM M4 steel?

Lapedog said:
I get what you’re asking. you were asking a decade ago. Cpm m4 vs m4 right? They’re the same steel the cpmm4 is just carpenter’s version of m4. Despite the cpm it doesn’t seem to be a powder version of m4 unless maybe all m4 is powder, that I’m not sure.

M4 = CPM M4 = CPM Rex M4(hc)
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Fixed that for ya.
 
c5IMeet.jpg

Looks like this after a bit of using it.
Great steel, indeed.
 
Crucible seems to make two different versions of M4. It's not clear to me which one is used in blades: REX M4 High Speed Steel and CPM REX M4 HC(HS). The naming does not make it easy to differentiate.

Quite a few differences. One has silicon, the other has sulfur and no silicon, higher carbon and molybdenum, and lower vanadium.
 
The Gayle Bradley was my first Spyderco, and has been great. I come from the land of the ice and snow (Chicago) and corrosion resistance is not great. The comparison to D2 is ridiculous.

However, proper care has kept it in good condition.

Definitely not a knife I'd carry on my trips home to Galveston. That salt air...
 
David Richardson said:
Crucible seems to make two different versions of M4. It's not clear to me which one is used in blades: REX M4 High Speed Steel and CPM REX M4 HC(HS). The naming does not make it easy to differentiate.

Quite a few differences. One has silicon, the other has sulfur and no silicon, higher carbon and molybdenum, and lower vanadium.
Click to expand...

The steel with sulfur in it is not meant for a knife. They add it there, usually only in thicker sheets, which are intended to be machined. Since sulfur makes grinding it much easier. They say it doesn't make a significant difference, but that does not make sense imho.

There is a reason that hitachi super steels (white and blue) are known for having ultra-low amounts of sulfur - it makes for great blades.
 
Not trying to be argumentative, but Rex 121 and Maxamet have the same amount of sulfur. 15V has more than 2x the amount. I don't know metallurgy, so maybe it's different for those steels. Sulfur alone doesn't seem to exclude metals from making good blades.
 
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