Subject: Re: One for the Archive 21yn valve steel (armco)

From: [email-masked]
Date: Thu, 16 May 1996 10:58:41 -0400

Mike Linn, and all; re Armco 21yn valve steel for exhaust valves;
Armco Steel at one time made high strength exhaust valve steels at their
Baltimore, Md. bar mill.  The 21yn,  was a 21 chromium (12 Nickel - I think)
Nitrogen strengthened stainless used just for truck and auto exhaust valves.
 This and straight 21-12 (with out the .20/.25 Nitrogen) are used because of
their excellent resistance to corrosion caused  by combustion products.  The
forging range is pretty exact, ie, not over 2200F, and not below 1800F.  They
are non-hardenable (by heat treat), and run about 100,000 tensile, about RC22
(bhn 240) when annealed at 1900F water quench.
Mike Schermerhorn