[Rhodes22-list] New Toy

[Bob Keller]

Roger,
In Georgia you would have been expelled for taking a knife to school...
Bob K


>From: "Roger Pihlaja" <cen09402 at centurytel.net>
>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
>Subject: [Rhodes22-list] New Toy
>Date: Mon, 15 Mar 2004 21:02:10 -0500
>
>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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