48515

Passivated parts came back melted [Connecticut] 

April 15, 2008

I had a plater process A.I.S.I. 416 threaded rods to AMS-QQ-P-35C, Type 1. The parts came back melted. Is This the right specification for Passivate or should I use type 2?

Brian Gamache
Director Of Operations - Bolton, CT, USA

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.

Ray Kremer Stellar Solutions, Inc. Algonquin, IL, USA