Many metal parts are used in CNC machining, which needs to be welded according to specific needs, but there are corresponding welds when welding metals.In order to prevent the normal use between metals, we need to perform anti-rust treatment between the welds Questions, China Standard Parts Network understands according to the specific situation, tell everyone about the anti-rust treatment of metal welds.
- The acid at the nip is not neutralized or incompletely neutralized during pickling, and the phosphating treatment becomes incomplete and easy to rust. A period of time after painting, rust spreads over the cracks.
- Strong acid pickling, strong alkaline degreasing treatment. The chemicals remaining in the nip are neutralized without washing with water after neutralization. After baking, there are white products at the cracks. After a period of time, these white products will chemically react with the corrosive medium in the air and overflow the cracks.
The solution to the problem:
- Weak degreasing must use weak alkaline degreasing, can not contain caustic soda components, TAL should be controlled at about 15POINT, PH can not exceed 13.
- It is acceptable to use sulfuric acid for pickling, and the pickling time should not be too long. Phosphoric acid is preferred.
- It is best to neutralize with 1-2 sodium carbonate after pickling.
- Surface adjustment is best to use oxalic acid, the concentration is 1 ~ 2.
- The upper limit of acidity of zinc-based phosphating treatment, the concentration of impregnation treatment: TA: 35 or more, FA: 1.2AC: 8 (20CC fermentation tube).
- All washing projects must not be cleaned, and the washing should be kept overflowing.