Cleaning Before Passivating

Question: I need some advice.

Related Topics:


I need some advice. We have a new customer with 17-2 stainless parts requiring passivation. The parts have a heavy brown oxide on them as received. We need to remove this before the passivation treatment. What do you suggest to do this with?


The 17-2 designation indicates that the stainless steel has 17% chromium and 2% nickel. While the designation you provided is not followed by a “PH,” I will assume it is a precipitation hardening stainless steel since that is how I have typically seen them named (i.e., 17-4 PH, 17-7 PH, etc.). Regardless of the type of stainless steel, I do not believe the product you are using will be very effective since it is caustic-based and intended primarily for mild steel. Aggressive cleaning methods employing mineral acids or abrasive blasting are typically required to remove heavy oxides from stainless steels.

If the 17-2 is in the annealed condition, an acidic treatment can be used to remove oxides. One example would be a mixture of approximately 10% nitric acid and about 3% hydrofluoric acid at room temperature for a few minutes. If the 17-2 is in the hardened condition, it should probably be abrasive blasted to remove the oxide. Following oxide removal, it can be passivated with a standard solution of approximately 40% nitric acid between room temperature and 140F for 30-60 min. This should be followed by a thorough rinsing in clean water.


Related Content

Continuous-Flow Wastewater Treatment System Features Modular Design

Designed for large waste volumes, DMP Corp.’s Module 6000 wastewater treatment system continuously treats rinses and concentrates up to 60 gpm. Its modular, expandable design can handle many different types of wastes from a variety of different industrial applications.