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Metal finishing Q&As since 1989
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Types of stainless that cannot be Passivated?
2005
I work in a laser shop making medical devices, I need to know what types of stainless steel cannot be passivated using type 2 or type 6 passivation, or any contact with nitric, were not using the Stellar Solutions [a finishing.com supporting advertiser] Citrisurf as we already use nitric and Turco Nitrad to pickle these parts, a list of types of stainless not to expose to passivation would be helpful.
Thanks
William Brownlasers - Cranston, Rhode Island, USA
Use QQ-P-35C (canceled) [link is to free spec at Defense Logistics Agency, dla.mil] for guidance.
Carburized or nitrided steels should not be passivated (and would corrode during sterilization, anyhow). A relatively new surface hardening process implants carbon atoms into stainless without forming carbides; such stainless can be passivated.
The high-carbon 440C often gives poor results when passivated.
Free-machining stainless steels may require extra care in the Type II passivation. See ASTM A967 or search for the article "HOW TO PASSIVATE STAINLESS STEEL PARTS" by Debold and Martin.
- Goleta, California
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Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2005
Stainless steel 400-series can be passivated by solution without nitric acid.
adv.
We can treat your samples for testing.
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Anna Berkovich
Russamer Lab
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Pittsburgh, Pennsylvania
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2005
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