[Rhodes22-list] New Toy

[Steve]

Excellent Knife, Roger.
Steve


--- Roger Pihlaja <cen09402 at centurytel.net> wrote:
> 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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