different . It has the new K390 steel blade. The flat grind blade is quickly
becoming one of my favorite configurations.
I grew up with saber and convex
grinds but I’m won over by the flat grind. The absence of shoulders makes for
easier cutting. If you’re slicing a wedge of Swiss cheese, you may want the
shoulders as they push the materials apart and away from the knife. But you also
encounter drag. Drag just means you have to put more force on the blade, and for
most applications, forcing a blade is never a good idea. So I’m running some
test because K390 steel sounds like a step backwards.
It’s not stainless. In
fact a product insert warns you to protect the blade.
Bohler-Uddeholm list the
following reasons to use their K390 Microclean steel:
- Good machinability
because of uniform mechanical properties,
- Excellent grindability even with
deep engraving in the tool & die center,
- Uniform low dimensional change during
- Non sensitive against overheating or long soak times.
- Optimal EDM characteristic due to uniform carbide distribution.
Electrical Discharge Machining and it is becoming industries’ favorite machining
and milling tool because it is efficient, economic, fast, controllable and
computer-driven. Many of these steel properties, like dimensional stability are
a big draw for knife makers.
The Chemistry also looks interesting. C 2.4%, Cr
4.2%, Mo 3.8%, V 9%, W 1%, Co 2%.
I should also note, new steels aren’t simply
made by dumping elements together. Tempering, stress relief and hardening cycles
have a major part in any production metal. Still, I find these numbers amazing,
especially the 9% vanadium and 2.4% carbon!
Strictly speaking chromium levels
should be around 11% to be classified as stainless. Chromium forms carbides that
stabilize the microstructure, so in ordinary steels you need an excess of
chromium to react with carbon and still have enough to protect against rust.
Here you have vanadium to form carbides. So is there enough chromium to form the
transparent chromium oxide barrier? I don’t know.
I’ve been cutting cardboard all week, I haven’t noticed any loss of
sharpness. Today I cubed semi-frozen beef for a future chili dinner. I thought
the knife handled better than many of the larger chefs’ knives or the smaller
I sliced up some lemons and limes for summer drinks and the knife worked fine.
Afterwards I noticed the acid fruit left a start of a faint patina. I could
lightly rub it out with a fine metal polish, but I think I’ll keep it. I like a
working knife that looks like a working knife.
I increased the contrast slightly so you could see the patina. I’m wondering if
it will wear away on it’s own.
I think the K390 steel is going to be a winner. I
haven’t had to sharpen it yet, but I have no doubt my Spyderco Sharpmaker is up
to the job. I understand you’re going to see K390 steel in a lot of other
Spyderco products. I also think you’re going to like it.
The Knife Edge: One Man, So Many Knives©: Spyderco K390 steel is written by knife for knifesearch.blogspot.com