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Passivation of Inconel materials

I have a question about passivating type 625 Inconel. I have a print callout to passivate 625 Inconel. AMS-QQ-P-35 [link is to spec at TechStreet] does not address Inconel materials. It's purpose statement and tables recommending solution type only calls out stainless steels. Are there any detrimental effects that can result from passivating these parts.

Kevin Evers
- New Port Richey, Florida

Kevin:

I do not have any personal experience with using nitric acid with Inconel. We cannot verify that with data on nitric, but we have had success with proprietary formulations of citric acid. Contact us if we can help.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

Kevin, when we have a make-to-print job telling us to passivate any of the Inconel alloys, and it's too much trouble to tell the customer it's a worthless operation, we just do it in type 6 solution. Doesn't hurt, doesn't help, satisfies the print. Good luck!

Lee Gearhart
metallurgist
East Aurora, New York

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