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Blackened SST clips are rusting

We use circlip with blackening in automotive seat assembly. We face rust problem very frequently. Please suggest.

SUDHIR PANDEY
Employee - QA - Gurgaon
October 5, 2011

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Hi, Sudhir.

The blackening does not impart significant corrosion resistance, although it might reduce the corrosion resistance if not properly rinsed and post-treated. If the clips are rusting, the grade of stainless steel that is being used is probably not sufficiently corrosion resistant.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
October 5, 2011

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Hi Sudhir

If the material used for circlip is EN 42J then to prevent rusting blackening is not the process. You should go for Phosphating process then if required blackening. This will definitely give you the result still if the problem comes then there is a mistake in the process that is : in the end of process when blackened components come out of the salt and rinsed in water you should put the components in cutting oil solution, now this is the point where the problem would be starting as there would not be enough cutting oil mixed in water or the solution of cutting oil and water could been degraded. Moreover do note that proper drying of the circlips are also necessary.

Lokesh Sharma
- Delhi, India
November 7, 2011