I've been looking into those CPM*V steels myself; specifically S30V, S60V, and S90V. Here's a few excerpts from Joe Talmadge's 2002 paper, at
http://www.nakededgecutlery.com/knifesteels.htm
"ATS-34/154CM, VG-10, and S60V are the next group up. It's difficult
to make generalizations about ATS-34 and 154-CM -- they are in such
widespread use that heat treat varies widely. These steels provide a
high-end performance benchmark for stainless steels, and hold an edge
well, and are tough enough for many uses (though not on par with good
non-stainlesses). They aren't very stain resistant, however. VG-10
can be thought of as being like ATS-34 and 154-CM, but doing just
about everything a hair better. It's a little more stain resistant,
tougher, holds an edge a little better. And VG-10 has vanadium in it,
it's fine-grained and takes the best edge of this group. S60V has by
far the best wear resistance of the group, though consensus is
becoming that it should be left around the same hardness as 440C
(56ish Rc), which means it will be relatively weak compared to ATS-34,
154-CM, and VG-10, and so it will indent and lose its edge quickly
when strength is required. S60V is the winner here when pure
abrasion resistance is much more important than edge strength.
BG-42, S90V, and S30V constitute the next group. BG-42 has better
wear resistance than all the previous steels except for S60V. It is
tougher than ATS-34, and more stain resistant. It is wear resistant
to the point where it can be difficult to sharpen. S90V represents
the ultimate in wear resistance in the steels discussed so far. Also
tougher than ATS-34, and more stain resistant. It can be very
difficult to put an edge on. It is difficult enough to machine than
it is used almost exclusively in custom knives, not production
knives. In your buying decisions, you might want to take into account
the difficulty of sharpening these steels. S30V backs off on the wear
resistance of S90V, but is significantly tougher and easier to
sharpen. It is more wear resistant than BG-42. The jury is still
out, but it may end up this week's ultimate high-end all-around
stainless steel, due to high performance coupled with easier
machineability and sharpenability than the other steels in this class."
"S60V (CPM T440V) - S90V (CPM T420V)
Two steels that hold an edge superbly, world class type edgeholding,
but it can be difficult to get the edge there in the first place.
These steels are made with Crucible's particle metallurgy process, and
that process allows these steels to be packed with more alloying
elements than traditional steel manufacturing methods would allow.
Both steels are very high in vanadium, which accounts for their
incredible wear resistance. Spyderco offers at least one model in CPM
S60V. Spyderco, one major user of S60V, has cut back hardness
down to 55-56Rc, in order to keep toughness acceptable, but that
sacrifices strength so there is a tradeoff. S90V is CPM's
follow-on to 440V, and with less chromium and almost double the
vanadium, is more wear-resistant and tougher than S60V -- and, in
fact, is probably more wear-resistant than any other stainless
steel used in the cutlery industry. As such, S90V
is in the running with steels like BG-42 as among the best
general-purpose stainless steels; however, S90V is even more expensive
and difficult to work than BG-42, so it's strictly in the realm of
custom makers currently..
CPM S30V:
The newest stainless steel from Crucible, purpose-designed as a
cutlery steel. This steel gives A-2-class toughness and almost-S90V
class wear resistance, at reasonable hardness (~59-60 Rc). This mix
of attributes is making S30V one of the hottest stainless steels
going, with makes such as Chris Reeve switching from BG-42 to S30V.
Will this be the new king of general-purpose stainless cutlery steels?
We'll know over the next couple of years."
