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Passivation of 416 SS

Q. We recently have switched over to a cleaning solution called Micro-90 for the cleaning of 416 ss parts prior to passivation. We now have had two lots of parts which have come back from passivation with brown spots (looks like rust) from two different suppliers. Any suggestions which may explain this. Thanks

Steve Dalessio
- Claremont, New Hampshire, USA
2003

A. Sounds like you have a sulfur problem. This is not uncommon with 416ss. You need to preclean with a high pH alkaline cleaner to get rid of the sulfides before passivation. Let us know if you need help.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

2003

A. Steve,

The whole 400 series family is so-so when it comes to corrosion resistance. I like to electropolish it and finish with a citric passivate. With the electropolish we are removing the surface junk and providing a surface that has a chance at being passive, the citric finishes the job.

Jon Quirt
- Minneapolis, Minnesota
2003

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