[Rhodes22-list] New Toy

[Roger Pihlaja]

Peter,

To sharpen a serrated blade at all, you have to have tapered cylinder-shaped
sharpening stones.  Fortunately, my Boy Scout troop got me a really complete
knife sharpening kit one year for Christmas, so I have the requisite
Arkansas stones.  The edge on the Salt-1 blade has a single taper design,
meaning the serrations are on 1 side and the back side of the blade is flat.
As long as the serrations are not nicked up, routine sharpening can be done
with a flat Arkansas stone from the backside.  In the previous post, I was
refering to how much effort it required to sharpen the flat backside.  The
H1 alloy requires about 10X more passes over the Arkansas stone than a
comparable high carbon tool steel blade.  I would imagine a plain
non-serrated blade would be similar.

Roger Pihlaja
S/V Dynamic Equilibrium

----- Original Message -----
From: "Peter Thorn" <pthorn at nc.rr.com>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Monday, March 15, 2004 9:29 PM
Subject: Re: [Rhodes22-list] New Toy


> Wow, Roger, that's an amazing knife!   Before reading your post, I used to
> think my Smith and Wesson SWAT knife was pretty neat.  It's non-magnetic
> stainless, but certainly not precipitation hardened.
>
> Do you think the non-serrated version would be easier to sharpen?
>
> PT
>
>
>
>
> 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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