Letter 3017

Electropolishing T304SS Problem 

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I am experiencing a problem with electroplating T304SS wire shelves. Random wires will come out with a "frosty" appearance. SEM/EDS has not identified any contaminants,and metallography of cross-sectional samples reveals that the "frosty" surface appears to have been corroded (i.e., substantial amount of metal loss). I am now targeting the raw material, but am at a loss for why this is happening? Thank you, Jim Cirilli

Jim Cirilli
testing laboratoriy - New Castle, Delaware

Hello, Jim: Please check our web site via the suppliers' directory on finishing.com. Our company is a supplier of chemicals, equipment, and process know-how for electropolishing, and we believe we can be of assistance to you. We would need additional information regarding your present process in order to be specific. Regards, Ed Bayha

Ed Bayha Metal Coating Process Corporation Charlotte, North Carolina, USA

This frosty pitting sounds like etching, the two most common causes of which are the current density too low and water in the electropolishing solution.

Ted Mooney, P.E.  finishing.com Brick, NJ

We have had 15-5PH stainless steel castings electropolished, and used to have a constant problem with this same random frosting. Our electropolisher tried changing the current densities, and this still did not help. We sent to parts to numerous other electropolishers, and the same frosting still randomly occured. We never found out exactly what was happening, but seemed to reduce the problem by cleaning off every last trace of grease before they were polished. We placed the parts in a 160 deg F bath of sodium hydroxide for 45 minutes. I would be interested in hearing from you if you ever find out the exact mechanics behind this frosting phenomenom as it has been a mystery to me for many years.

Tim Tylaska
- mystic, ct

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