CPM-15V and the Lost CPM-20V – How Much Vanadium Can You Add?

Larrin

Larrin

Knifemaker / Craftsman / Service Provider
Joined
Jan 17, 2004
Messages
4,975
Great info as always. This is probably a stupid question but what exactly is carbide for carbide tooling? It sounds like there are different types for different task.
 
Storm W said:
Is there a way to make it more impact resistant or is that a different mix?
Click to expand...
IIRC, the impact rated grades have finer grain. Not sure if there is a difference in the mix.

Edit: I did not recall correctly, see Larrin's answer below.
 
Last edited:
With carbide you actually make it coarser to make it tougher, and according to Sandrin you need the finer particle size to be able to have a fine edge. So the only way to make it more impact resistant is to have a higher fraction of cobalt. Or you could use steel instead.
 
Larrin said:
With carbide you actually make it coarser to make it tougher, and according to Sandrin you need the finer particle size to be able to have a fine edge. So the only way to make it more impact resistant is to have a higher fraction of cobalt. Or you could use steel instead.
Click to expand...
That is interesting and I was obviously completely wrong. After reading your article and a few others, it is clear that the super fine carbide grains are used for cutting tools to increase hardness and obtain a fine edge, not because the fine grain increases impact resistance. I guess my mind jumped to the wrong conclusion and I never questioned it until today.
 
Big grains, a tad more cobalt interstitially as a consequence. Tire studs are/were a good example. (My first ever gig out of college in '72 was a year working on the "new" notion of ultra fine grain carbide. It was impressive to see the difference between lathe bits made with the regular stuff versus our fine grain material. Rather dramatic. )
 
Larrin said:
With carbide you actually make it coarser to make it tougher, and according to Sandrin you need the finer particle size to be able to have a fine edge. So the only way to make it more impact resistant is to have a higher fraction of cobalt. Or you could use steel instead.
Click to expand...
Just because it kinda goes with your article. Why do they use tungsten carbide instead of Vanadium carbide?
 
Storm W said:
Just because it kinda goes with your article. Why do they use tungsten carbide instead of Vanadium carbide?
Click to expand...
I’m not an expert on cemented carbide so I don’t know the answer to that. It’s been in use since the 1920s. Tungsten carbide is somewhat harder than vanadium carbide. Vanadium is convenient in steel because it forms “naturally” with vanadium additions. Perhaps tungsten carbide is cheaper/easier to produce or more compatible with the cobalt binder. I did find a couple references saying a small addition of vanadium carbide is used to refine the carbide size in tungsten carbide production. There are a few other carbide types used like titanium carbide but tungsten is the most common.
 
I need to crack some books. My last materials class was in the mid 1980s and the last time I looked at a phase diagram was probably 1992-93. I can almost follow these conversations.
 
Larrin said:
I’m not an expert on cemented carbide so I don’t know the answer to that. It’s been in use since the 1920s. Tungsten carbide is somewhat harder than vanadium carbide. Vanadium is convenient in steel because it forms “naturally” with vanadium additions. Perhaps tungsten carbide is cheaper/easier to produce or more compatible with the cobalt binder. I did find a couple references saying a small addition of vanadium carbide is used to refine the carbide size in tungsten carbide production. There are a few other carbide types used like titanium carbide but tungsten is the most common.
Click to expand...
Thanks for taking the time to explain it. If you are ever up here in Syracuse the beer is on me.
 
You must log in or register to reply here.
Back
Top