What's Wrong with CPM-9V?

H

Harpoon1

Joined
Apr 3, 2011
Messages
147
Looking at Crucibles comparison chart, 9V look like a great performer, much more wear resistance than A2, D2, 3V and M4. All popular steels and already in widespread use. And it's also tougher, much tougher in some cases, than all of those listed except 3V.

There must be more to this story. Maybe poor grind-ability, expensive, rust or pits too easily, all of the above? What gives?

http://www.crucible.com/eselector/general/generalpart6a.html
 
Not enough consonants.

But on a serious note, good question. I traded for a 10V blade once on here, but it was useless as it was 1/4" thick. Seems like a lot of steels stay out of the spotlight.
 
I think it's because 9v can't be hardened enough to make a good knife blade.

Let's wait for the more knowledgeable guys to chime in.
 
Just took a read through 9v's spec sheet hopefully I can make this post understandable. First off its chemistry does not set it up as a knife steel. It has 9% Vanadium which is alot needless to say. This makes for a very tough steel but not necessarily a steel able to get very hard. The required temperature to achieve HRC 60 is 2050f which is quite high. Furthermore the steel simply is designed to be brought above HRC 56. One has to remember that these are tool steels that are designed for industry and not always ideal for making blades. That much Vanadium and its associated carbides would make a blade very hard to sharpen not to mention the exorbitant cost.
 
Pretty sure it's a hardenability issue, as singularity35 suggested. Tom is right that the difficulty and expense of machining a 9% Vanadium steel, as well as the fact that 9V isn't stainless, makes it an unlikely candidate for production knives. But that doesn't explain why even custom makers who work with 10V and other very high Vanadium, non-stainless steels tend not to use it.

So I think that the main reason for its lack of presence in knife blades, again echoing singularity and Tom, is that it's designed to be run at HRCs in the mid-50s. That may be fine for industrial tooling applications, but it sounds like a recipe for edge rolling in something as thin as a knife edge.
 
Don't pretend that ultra high alloy content has anything to do with whether or not steel is suitable in a knife blade. Most of these steel types prefer temperatures up to 2200 degrees Fahrenheit as well. Both of those issues do limit who is willing/capable of working with the material, but it is still some of the best blade material available (if wear resistance is your priority).

Edit: In regard to CPM 9V, hardenability seems to be the main issue, though CPM S60V still did reasonably well at Rc55-56. People probably just avoid it because CPM 10V behaves more like a normal blade steel and is roughly the same thing.
 
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