[Rhodes22-list] New Toy

[Michael Meltzer]

sound like a nice knife, have you seen a "reasonable priced" kitchen knife set, I hate the set we have now and my wife has been
buying the latest "ginus" TV specials that also suck.

MJM

----- Original Message ----- 
From: "Roger Pihlaja" <cen09402 at centurytel.net>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Monday, March 15, 2004 9:02 PM
Subject: [Rhodes22-list] New Toy


Hi Everybody,

Well, I'm ready for a new topic.  I just received a new toy today that is totally cool.  The March, 2004, Volume 30, Number 5 & 6
double issue of "Practical Sailor" magazine ran a comparison test on sailor's rigging knives.  They rated the Spyderco SALT 1 as a
best buy.  The thing about this knife that caught my eye was the description of the H1 precipitation hardened stainless steel in the
blade.  In my ME250, Engineering Materials, class last semester, we learned about precipitation hardening of aluminum alloys.
Precipitation hardening is how the really strong, hard, yet ductile aircraft aluminum alloys like Al 7075-T6 are made.  I had never
heard of anything analogous in a stainless steel alloy and I was curious.

So, I went & looked up the properties of H1 stainless steel in the metallurgical literature at the SVSU library.  The H1 alloy is
produced by the Myodo Foundry in Japan and it appears to be a real materials breakthrough.  Normally, with knife blade materials,
there is a tradeoff between the hardness & ability to keep a sharp edge of high carbon tool steels and the corrosion resistance and
nonmagnetic properties of the 300 series stainless steels.  Up until now, it was impossible to have both corrosion resistance and a
really sharp blade in the same alloy.  The H1 alloy works differently.  Precipitation hardening refers to the formation of
precipitates or particles of ceramic intermetallic ferric nitride and chromium nitride compounds.  These intermetallic compounds are
soluble in the base alloy composition above a certain critical temperature, allowing the metal to be hot-worked into the shape of
the blade.  As the metal is cooled according to a proprietary heat treatment schedule, the intermetallic compounds become insoluble,
drop out of solution, & nucleate into tiny particles.  For reasons I won't get into, these particles tend to preferentially nucleate
& grow along grain boundaries in the metal.  The presence of these particles distorts the face centered cubic (FCC) crystal lattice
structure of the base alloy & tends to lock adjacent metallic grains together.  Think of the particles as being sort of like the key
that fits into the keyway that locks a pulley onto a shaft.  Having the grain boundaries of the metal locked together makes the
metal much more resistant to deformation and yielding.  (i.e. it is much harder)  But, it has not been work hardened or tempered
like heat treated high carbon steel blades must be.  The H1 alloy has a low carbon content and the base alloy grains have an overall
austenitic microstructure. (i.e. nonmagnetic and corrosion resistant like 300 series stainless steel)  The H1 alloy has a hardness
and yield strength comparable to a high carbon tool steel while maintaining the overall corrosion resistance, ductility, ultimate
elongation, and nonmagnetic properties of a 300 series stainless steel.  As I said, the H1 alloy appears to be a genuine materials
breakthrough!

Naturally, I had to have one!  I ordered the knife on-line from The Knife Center:

www.knifecenter.com

SP88SBK Spyderco SALT H1 Stainless 3" Serrated Blade Black Zytel Handle: $49.95 + S&H

The Salt 1 is available with either a plain or a serrated edge blade.  I choose the serrated edge because it was recommended by
Practical Sailor for quick 1-pass cutting of tough lines.  Note: By the standards of high end blades, $50 is not a particularly
expensive knife.

Anyway, my new toy arrived via UPS over the weekend & I took it to school today.  In the materials lab, we did some cutting
experiments on tough, exotic materials like Kevlar, Spectra, and Carbon Fiber.  With the factory supplied edge, my new Salt 1 is so
sharp, it's almost scary!  It cut thru several layers of stacked woven prepreg cloth like butter & these were materials that are a
lot of work to cut a single layer with a good pair of scissors.  Under the microscope at 100X magnification, there was no detectable
wear on the edge before vs. after cutting these materials.  The hardness of the blade checks out at >75 on the Rockwell C scale!
The edge is sharpenable on a good Arkansas stone with cutting oil, although with quite a bit more effort than I am used to with even
high carbon tool steel blades.

The Salt 1 rigging knife is a folding, locking design.  It has a belt clip & is deployable with either hand.  Note that the H1 alloy
is also available in fixed blade versions with a sheath.  I'm strongly considering getting a fillet knife and a hunting knife.  If
you have anyone on your gift list that uses & appreciates really good cutting tools, they will absolutely love something like this!
It will instantly become their favorite knife.

Roger Pihlaja
S/V Dynamic Equilibrium
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