Metal finishing Q&As since 1989

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What is the best coating for spring steel clips?

I have some "C" shaped clips manufactured out of .02 tempered spring steel and heat treated to Rc 42-46. These are rusting within weeks. Is there a protective coating I can put on the clips and still allow them to keep their flexibility? I have been looking at a zinc plating but am afraid this may make the clips brittle.

Vicki Fowler
product designer - Sugar Grove, Illinois, USA
June 14, 2011

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Hi, Vicki.

The zinc plating per se is not brittle, but the electroplating process and the acid pretreatments that are usually part of the process release hydrogen which can cause a phenomenon called hydrogen embrittlement. The good news is that the hydrogen can be easily baked out so that are not actually embrittled. But the bad news is that some parts are so sensitive to hydrogen that they can snap right in the plating cycle before the hydrogen relief oven is even reached.

You can send parts to a plating shop for trialing, since this would probably be the least expensive approach. But alternatives include mechanical plating or zinc-rich dip-spin coating. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 14, 2011