Letter 8069

Passivation of 300 series Stainless Steel standoffs 

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Hello,

I am a quality engineer for an electronics company in the Northeast. I am currently investigating passivation issues on 300 series Stainless Steel standoffs clear passivated per QQ-P-35 [link is to spec at TechStreet]. Most standoffs we have received are bright and shiny. We have received a lot that has a dull finish, which the manufacturer indicates was passivated according to requirements.

My question is, would the dull finish be caused by cleanliness issues, or irregularities in the passivation process? Or do different series 300 steels provide different finishes?

Thank you for any help you can provide.

Edward C. Fink
- Andover, MA, USA

The difference in reflectivity that you see may be due to the difference in surface finish prior to passivation. If your bar is cold drawn and bright annealed, you would have a a bright finish. If the other is annealed and pickled, you could have a dull finish. Surface roughness evaluation or microscopic examination should show if this is the case.

Larry Hanke materials testing laboratory Minneapolis, Minnesota

Mr. Fink,

In my opinion, The grade of the stainless steel material has to do alot with the dullness you are seeing. If your manufacturer has stated that the product was passivated to established standard operating procedures, the next step is evaluate the stainless steel to see the content in the material itself. I know by experience that this type of material has variation from lot to lot simply because of the sulfer content.

Regards,

Joel Garcia
- McAllen, TX

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