Posted by Hank P. on December 13, 1999 at 15:25:07:

In Reply to: Re: Topic:Stainless steel corrosion posted by Bill Woolley on November 01, 1999 at 10:44:37:

From my Experience with SS in the marine enviroment. The quality of the surface is everything , there must be no contamination of the surface ie: residue fron steel cutting , forming , or finishing tools. If the surface is uncontaminated , and the alloy is suitable (316 series seems best , Hong Kong & Tiawan stock seems quite inferior) and the problem persists it can almost always be traced to small scratches in the surface (Crevice Corrosion). SS protects itself by forming a covering of chrome oxide. This oxide forms in flakes or scales. When these form in a scratch (crevice) the scales pierce one another allowing O2 to reach the surface where it reacts with iron causing "rust".

Polishing of the surface must progress to a very fine state to prevent this , especially in the area of welds where the alloy may be diluted by heat migration.

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