Pickling of Austenitic and Duplex Stainless Steel
Pickling is a surface treatment process to remove scaling, thermal oxides, impurities and surface contaminant. The process is carried out by immersion in a pickling solution Willowchem 81) for a calculated time, based on surface area and material specification.
The Pickling process is often used after processes such as welding and annealing. The process incorporates a pickling solution made up from a carefully calculated mix of Nitric acid and Hydroflouric acid. The solution, if correctly formulated, will remove thermal oxides and surface contaminants, as well as leaving the remaining clean surface as passive.
The pickling process will conform to ASTM A380
Benefits of Pickling:
- Dissolves thermal oxides after welding, annealing etc.
- Provides a chemically clean, uniform finish.
- Removes surface contaminants.
- Passivate the surface as well as chemically cleaning.
Below: On-site pickling and passivation - before and after