CPM steel !

R.Taylor · Dec 23, 2006

Is it structurally as good as the more common types(ie: VG-10 etc...)
Would it be brittle, easy to snap (twist) off,because of the grain structure?
Like when you are cutting thru a tree branch & you turn your wrist to clear the cut.
Any info appreciated.

yablanowitz · Dec 23, 2006

The CPM S30V steel Spyderco is currently using seems to be quite tough and fairly flexible. As long as you don't get too crazy with it, you shouldn't have a problem. In your example, if you only twist, you should be safe. If you also apply enough lateral force to the handle (essentially prying) you could break the blade. Twisting is more likely to damage the pivot pin than the blade.

nozh2002 · Dec 23, 2006

Here is toughness - wear resistance diagram from Cruccible websit - I just combine two together to see more steel:

As you may see there is CPM 3V which is pretty tough, as well as CPM 9V, as well as all CPM steels are as tough as D2 and M2 and CPM S30V is actually at the bottom.

Thanks, Vassili.

yoda4561 · Dec 23, 2006

Looking at that chart makes me wonder why CPM 9v isn't more popular with the stock removal guys. The charts make it look close to ideal for a knife steel, high wear resistance + toughness that easily bests O1 and approaches 3v.

yablanowitz · Dec 23, 2006

Actually, that answers the question. Stock removal makers don't like working steel that wears out their equipment. Wear resistance that high means industrial pain in the butt to grind.

yoda4561 · Dec 23, 2006

Good point, slipped my mind. Still, I haven't heard of anyone even trying it out, it looks like it could have potential in the super-high performance category.

JD Spydo · Dec 23, 2006

I just wonder how 440V ( S-60V) would have stacked up statistically;. which they obviously omitted from that chart for some reason. I guess because they are not manufacturing it anymore. CPM 440V is truly some of the most difficult steel to sharpen that I've ever come across.

According to one of my Metallurgy Textbooks the definition of "Toughness" relating to metal properties is >> "The ability of a metal to absorb energy ( high strain rates) and deform plastically before fracturing. A tough metal is more ductile and deforms rather than fracturing in a brittle manner" <<

I think that would be a desirable property to have in a fixed blade knife or a big bowie knife but I am not sure what if any advantages that would provide a folder type knife. I think maybe abrasion resistance to me is far more important. But we're all here to learn aren't we

nozh2002 · Dec 23, 2006

CPM S60V is bit less wear resistant and bit less tough then CPM S90V, but still way more wear resistant then CPM S30V.

I guess wear resistance is what make this still goes away in the first place. Manufacturers came up with complain about britellness, so Crusible offer tougher and more wear resistant CPM S90V to substitute CPM S60V, but this is not what everybody was looking for, so CPM S30V wich has I guess acceptable wear resistant for manufacturers take CPM S60V place and was promouted as best super steel. But as I remember Crusible positioned it as enry level PM vanadium steel.

Also CPM S90V require higher temperature for heat treatment - for example Paul Bos do not heat treat it as well as M2 and M4 for same reason - his vacuum owen does not allows this temperature.

As I understand CPM 3V now is also accepted by industry - check it's wear resistance level.

I hope they will find better way to cut blades out blancks - laser, plasma, high pressure water gun... - better then one they use today. I think whoever find this way - win big time.

It is only Microtech who was able to make limited run with CPM S90V so far. Sal about year ago promised Military with CPM S125V, but something went wrong.

Thanks, Vassili.