During forming, machining or other processing operations, iron may be embedded in the surface of stainless steel components. If allowed to remain the iron corrodes and often gives the appearance of large or small rust spots on the stainless steel. In order to prevent this condition on the finished parts, they are given a Passivation Treatment. This treatment, which consists of immersing the stainless steel parts in a a solution of nitric acid without oxidizing salts, will dissolve the embedded iron and restore the original corrosion-resistance surface by forming a thin, transparent oxide film.
We take care in Passivating austenitic or low chromium grades stainless steel. We do not recommend Passivating stainless steel with a carburized/nitrided surface because nitric acid will dissolve the surface and reduce the size of the parts.
Passivating is the cleaning operation for castings, stampings and finished machine parts. By immersing the parts in nitric acid for a specific time to dissolve the iron embedded in the surface by manufacturing.
*Important that the customers identify the type of stainless steel to be Passivated.
Passivation is used to improve the surface condition of stainless steel by dissolving the iron that is embedded in the surface by forming or machining.
1. Stainless steel does not have to be plated to achieve maximum corrosion protection
2. Superior clean surface
3. No rust discoloration of the stainless steel in service
4. Surface preparation for other finishes such as priming or painting
5. Passivated stainless steel will not react with other materials because of iron contamination
1. Where iron contamination is detrimental
2. Sterilization in the medical field
3. Food industry such as mixers, tanks, handling equipment, shelving and fasteners
4. In the architectural field where surface finishes must last for decades
A wide rage of item sizes can be handled from a small micro size to large items as 3′ x 4′ x 6′. We can process large vessels that call for I.D. Passivating as well as components that require special set ups. Our Passivation process meets Federal Specifications QQ-P-35, Types II, and VI.
The Humidity Test shall be used to verify the Passivation process on all martensitic and ferritic stainless steel material (400 & 500 series). After completion of the test, specimens shall show no signs of rust stains or corrosion products.
COPPER SULFATE TEST
The Copper Sulfate Test shall be used to verify the Passivation of austenitic stainless steel material (200 & 300 series). The test shall be conducted in accordance with MIL-STD-753 Method 102. The specimens shall show no signs of a copper deposit.
SALT SPRAY TEST
The Salt Spray Test shall be preformed in accordance with ASTM-B-117 for two (2) hours when specified by engineering drawings. After completion of the test, specimens shall show no signs of rust stains or corrosions.