1. Let's explore the reasons behind the external corrosion of the acid washing, phosphatizing, and rust water in the entire sheet metal processing process: During the acid pickling and passivation, the acid in the gaps is either not neutralized or neutralized incompletely. The phosphatizing treatment forms a protective film that resists rust. After a period of painting, rust can spread and overflow into the gaps.

2. Strong acid pickling passivation, strong alkaline degreasing treatment; due to chemical reactions among the residual drugs in the gaps, many manufacturers have not thoroughly cleaned them with drinking water, resulting in a milky white reaction product on the gaps after drying. After a period of painting, this milky white reaction product reacts with corrosive chemicals in the air, causing some chemical reactions at the overflow gaps. This presents multiple challenges in rust prevention for sheet metal processing, especially between March and December.

Here are a few suggestions for solving the difficult points of rust prevention in sheet metal processing:

1. Opt for mild alkaline degreasing as much as possible, avoiding any sodium metasilicate content. Keep the TAL around 15 POINT and ensure the pH does not exceed 12.

Step 2: The pickling passivation process can utilize sulfuric acid pickling passivation, and the pickling passivation time does not need to be too long; the use of ammonium sulfate is just right.

After pickling and passivation, please neutralize with 1 to 2 moles of sodium carbonate.

4. Surface adjustments typically use sulfuric acid, an analytical chemical material, at a molarity of 1-2 degrees.

5. Zinc phosphating treatment acid should be used within limitations; try pre-immersion treatment: TA: 45 up and down, FA: 1.3 AC: 8 (20cc fermentation tube).

6. All hand-washed construction projects must be thoroughly cleaned and kept tidy; hand-washing should maintain a flooding style.