Although stainless steel precision castings have high corrosion and oxidation resistance, once they are not cleaned with oil stains and rust on their surface for a long time, they will also destroy themselves. Therefore, stainless steel castings also need to be cleaned on time, and pickling and passivation treatments are currently relatively common cleaning methods. But how does it actually clean up?
1. Pretreatment before pickling and passivation:
1. For the stainless steel precision casting parts after the manufacturing is completed, according to the standards of the finishing process card, the pretreatment of pickling and passivation can be carried out after the specified items have been checked and reached the standard.
2. Equipment with repair welding will clean the weld, welding slag and spatter on both sides, and the surface of the equipment should be sandblasted or shot blasted (see the accessory equipment process card for details) to remove oil stains and other dirt.
3. When cleaning foreign objects on both sides of the weld, use a stainless steel wire brush, a stainless steel spatula or a grinding wheel to clean it, and rinse with clean water (chloride ion content in the water does not exceed 25mg/l) after cleaning.
2. Pickling and passivation treatment methods:
1. Only parts that have been pre-processed can be pickled and passivated.
2. Pickling liquid pickling is mainly used for the overall cleaning of smaller unprocessed parts, and can be immersed or brushed. When the temperature of the solution is 21-60℃, check it every 10 minutes or so until it shows a balanced white acid etching smoothness.
3. The passivation solution is mainly used for the overall cleaning of small glass containers or parts. It can be immersed or brushed. When the temperature of the solution is 48-60℃, check every 8 minutes. When the solution is 21-47℃ At the same time, check every 20 minutes until a balanced passivation film is formed on the surface.
4. The pickling and passivation parts must be rinsed with clean water on the surface. Use acid litmus paper to test any part of the rinsed surface to make the pH between 6.5-7.5, and then wipe dry or air-dried with compressed air.
5. After pickling and passivation of glass containers and parts, it is strictly forbidden to knock and scratch the passivation film when loading, unloading, hoisting and storage.
The surface of stainless steel precision castings will leave various oil stains, rust, oxide scale, welding spots and other dirt. After pickling and passivation, the surface will become balanced and silvery white, which can also improve the corrosion resistance of stainless steel. However, when starting to clean, you must also be cautious in operating methods. Wear acid-resistant clothing, wear gloves, protective masks, safety goggles and other safety protection methods to prevent injury after contact.