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Treatment of 416 SS

What is a good method of treating 416SS surface to avoid rusting or ion contamination after selective nickel plating?

Ronald Steven
shop foreman - Roswell, Georgia, USA
2004

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Best is passivation prior to plating. Since 416 is a free-machining SS containing > 0.15% S, the "A-A-A" process is suitable: Alkaline soak - Acid passivate (e.g., Type II per QQ-P-35C [link is to free spec at Defense Logistics Agency, dla.mil]C) - Alkaline soak [rinses not shown]. See numerous letters re passivation of 303 SS. However, nitric acid will strip Ni plating. citric acid is more selective for removal of Fe, so you can probably passivate in a citric acid solution or selectively with a citric acid paste. Contact Lee Kremer of Stellar Solutions [a finishing.com supporting advertiser] for more info.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2004

WHAT WOULD CAUSE THE PASSIVATION OF 416 S.S. TO TURN BLACK. THE PROCESS WE ARE APPLYING IS AS FOLLOWS ASTM A967 NITRIC 1. PLEASE ADVISE AS THIS PROBLEM ONLY SEEMS TO OCCUR EVERY SO OFTEN.

RANDY PERRY
CUSTOM JOB SHOP OWNER - BALTO., MD, U.S.A.
2007