This technical information has been contributed by
The Electrolizing Corporation of Ohio

Plating/Finishing: Passivating

Metal Finishing - Passivating

Passivation improves the corrosion resistance properties of components made of precipitation-hardened, austenitic, ferritic and martensitic steels. Passivation treatments improve the surface condition of stainless steel by dissolving iron that has been imbedded in the surface during forming or machining. If allowed to remain, the iron can corrode and give the appearance of rust spots on the stainless steel.

Passivation, which consists of immersing stainless steel components in a solution of nitric acid without oxidizing salts, will dissolve the imbedded iron and restore the original corrosion-resistant surface by forming a thin, transparent oxide film.



Water Immersion
Verifies the Passivation process on all grades of stainless steel, with the exception of 440C. After testing, specimens shall show no signs of rust or corrosion.

Copper Sulfate
Verifies the Passivation of austenitic stainless steel in the 200 and 300 Series conducted in accordance with MIL-STD-753 Method 102. The parts show no signs of copper deposit.

Salt Spray
Performed in accordance with ASTM B117 for 2 hours, when specified by engineering drawings. After testing, parts show no signs of rust, stain or corrosion.


The Electrolizing Corporation of OHIO Passivation Process meets ASTM A-967-01 and AMS-QQ-P-35, Types 2, 6, 7 and 8. We process large vessels that call for ID Passivating, components that require special setups, and components from micro to 3 x 4 x 6 in size. We take care in Passivating austenitic or low chromium grades of stainless steel. We do not recommend Passivating stainless steel that has a carbonized/nitrided surface, because nitric acid will dissolve the surface and reduce the size of the component. It is important that you identify the type of stainless steel to be Passivated. In our on-site passivation facility, we can Passivate your 303 stainless steel without etching.

This technical information has been contributed by
The Electrolizing Corporation of Ohio

Home |  About Us |  Back To Technical Library |  Contact Us
Copyright © 1996-2010 All Rights Reserved.
General or Technical Questions? E-mail