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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 Brown
lasers - Cranston, Rhode Island, USA

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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.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2005

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Stainless steel 400-series can be passivated by solution without nitric acid.

adv.
We can treat your samples for testing.

Anna Berkovich
Russamer Lab - Pittsburgh, Pennsylvania
(ed. update July, 2025: sorry, Anna has retired)
2005

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