[EMAIL PROTECTED] wrote on 07/19/2006 12:49:28 PM:
> In a message dated 7/19/2006 3:19:10 P.M. Eastern Standard Time,
> [EMAIL PROTECTED] writes:
> DOES rust when there's no oxygen available
> ????? Oxidation without Oxygen ?????
Well its not really rust, its corrosion <breakdown of the surface>. Just like aluminum, the corrosion resistance of a stainless steel is dependent on the presence of a protective oxide layer on the surface of the metal. When water is allowed to stagnate and lose its oxygen(like water in a crack or pit in the metal), the water breaks down the oxide layer and exposes bare metal to what has become a corrosive liquid. There is also a kind of special corrosion called Stress Corrosion Cracking that mostly occurs in 304 and 316 stainless at temperatures above 40 deg C (104F) The part must be under tension <bolting for instance> and temperature above 40C and in a saltwater environment(doesn't have to be stagnate water, although that helps). A bolted connection on a heat exchanger for instance. There are some stainless metals that are more resistant to this than 316 or 304 SS, such as Aquamet, Carpenter and Monel alloys. They are also a lot more expensive.
Jim
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