PICKLING AND PASSIVATION

Pickling and passivation both are chemical treatment processes used for surface treatment of stainless steel after welding or exposure to high temperature to clean the oxides and any other contamination. This assists in the formation of the new chromium oxide layer and thus helps to regain its corrosion resistance that otherwise would be hampered due to oxides & contamination.

Usually picking is followed by passivation treatment for stainless Steel. Passivation does not remove any oxide or contamination but it helps to increase the thickness of the chromium oxide layer in an acidic environment (usually nitric acid or citric acid).

The passivation process uses nitric acid (HNO3) chemicals/ pastes that have to be applied on the material surface. The chemical reaction by these acids cleans the stainless steel surface from any free iron contamination (if not removed can be an initiation point for the corrosion) left after pickling.

The benefits of Pickling and Passivation are;

• Chemical treatment to prevent corrosion

• Removes surface containment

• Enhance the corrosion resistance of the metal

• Increase product life