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-----Laser etched SS rusts despite passivation
I work for a medical manufacturer in Memphis, Tennessee. I am having problems with our Citric passivation process on Laser etching. We use anyhting from 17-4, 300 series, 400 series, Nitronic 60, and other medical grade SS. The parts are run thru the passivation process before and after Laser Etch. I noticed the problem after a boil test of some parts. The parts were perfect, no rust, immediately after the boil test but started to show signs of rust after 3 to 5 days. We are using a paste method on some of the laser and putting others thru the passivation tank. We are seeing rust using both methods.
Neal MassengillManufacturing Engineer - Memphis
February 12, 2008
Contact us and send us parts for treatment - we can help
Anna Berkovich
(ed. update July, 2025: sorry, Anna has retired)
February 21, 2008
Hi,
I think citric acid is wrong to use for a passivation.
You should use ASTM A967 for Chemical Passivation Treatments for Stainless Steel Parts. That's is a passivation there you using nitric acid and dichromate.
Best Regards,
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
March 4, 2008
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