Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

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  for Metal Finishing since 1989
  

Passivated parts came back melted

I had a plater process A.I.S.I. 416 threaded rods to AMSQQP35 [canceled] C, Type 1. The parts came back melted. Is This the right specification for Passivate or should I use type 2?

Brian,
Looking at my old copy of Mil QQP35C, it directs 416 SS to be passivated with Type 2. Of course, Type 1 was removed from the C revision of QQP35.

I have another chart here, which I believe is based on a combination of those from QQP35B and QQP35C, which calls for Types 1, 2, 3, or 4 for 416 SS.

Of course, I would be remiss if I didn't point out that citric acid passivation will never etch or "melt" your parts.

The best rule, perhaps, is to use what gives you the results you want and don't use whatever gives you results you don't want.

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