Cool! Thanks for the info.
Rob
______________________________ Reply Separator _________________________________
Subject: DML: Re: Stainless Steel 101
Author: <dakota-truck@buffnet.net > at Internet-Link
Date: 10/22/98 7:25 AM
Great info! This is what this site is all about. Thanks, Glen.
----------
> From: Shaun.Hendricks@bergenbrunswig.com
> To: dakota-truck@buffnet.net
> Subject: DML: Stainless Steel 101
> Date: Wednesday, October 21, 1998 5:38 PM
>
> Having worked with and around Stainless Steel for quite some time,
there
> are some myths about the metal that seem to get taken as fact. I'll go
over
> some of the popular ones:
>
> Big Myth #1: Stainless Steel is rustproof.
> Reality: SS is rust resistant because rust is Iron Oxide. If the
molecular
> structure of the metal is such that the oxygen in water can't get to the
> "Iron" (or ferrous) parts of the metal then it doesn't really "rust", but
the
> truth is that it's nearly impossble to stop this reaction from happening,
all
> SS mixtures do is slow the process down some to such a small point that
we
> could almost call it "rust proof".
>
> Myth#2: Stainless Steel is a coating.
> Reality: A coating is something that is applied to an "object" after it
is
> created. SS is created in the firing process of the metal when external
> components such as chromium, nickel, molybdenum and austentite are added
to
> the metal to create SS. Certain types and grades of SS (due to the
process of
> manufacture) push these additives towards the surfaces of cast objects
or, in
> time, they migrate towards those surfaces forming a 'film'. Here's a
clip
> from the Austrailian Stainless Steel Developers Association regarding
Marine
> Grades of Stainless Steel:
>
> "Stainless steel's corrosion resistance depends on the formation of a
> "passive" chromium oxide film on the metal surface which is highly
resistant
> to corrosion. In grades 304 and 316, about 18% of chromium is added to
> generate this film and, in 316, 2% molybdenum is added to further improve
the
> corrosion resistance. Grade 304 is usually only suitable for fittings
which
> are frequently washed with fresh water. Grade 316 is suitable for the
> construction of deck fittings and critical rigging components where salt
can
> concentrate due to evaporation and lie in crevices - conditions which can
> cause pitting of 304."
>
> So even if you strip off this film, the metal can still resist rusting,
but
> not as well. Then again, only some grades are greatly bothered by the
loss of
> the film, duplex SS mixtures don't depend greatly upon that film for
> protection.
>
> Myth#3: Stainless Steel is Stainless Steel
> Reality: As you can tell by reading the above quoted info, there are
many
> grades of Stainless Steel. Each one has it's uses whether its cost
> effectiveness or absolute rust resistance. The problem seems to be, the
more
> additives you put in the steel to make it not rust, the weaker the metal
> either by brittleness or softness.
>
> Now that we've all had our SS lessons for the day (I had to look a lot
of
> this up), I would think that using it in a Throttle Body would be fine,
even
> with a lower grade of SS. I don't think Bruce and Frank need to be
tossing
> Medical Grade Surgical Stainless Steel in there just because the
occasional
> bit of moisture might accumulate on the shaft. I'm sure they both know
that
> and are using a nice piece of machinable SS. Some of the grades of SS
are so
> hard they almost can't be machined except with diamond bits (ran into
some
> like this).
>
> Shaun H.
> "What do ya mean you can barely scratch it? Isn't it just chrome plated
> metal?"
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