The salt spray corrosion test is carried out in a salt spray test chamber. It is generally used to test the corrosion resistance of metals or the corrosion resistance of metal surfaces after electroplating. The test is carried out with corrosive gas, and different corrosion methods are adopted according to the specific use environment. The corrosion condition of the salt spray test is mainly judged by four methods, which are rating judgment method, weighing judgment method, corrosive substance appearance judgment method and corrosion data statistical analysis method.

The corrosion data statistical analysis method provides a method for designing corrosion tests, analyzing corrosion data, and determining the confidence level of corrosion data.
The salt spray test standard is divided into ten grades, which is based on the enterprise test standard and conforms to the actual situation. The specific classification and phenomenon of the salt spray test standard are as follows.

Level 1: The defect area accounts for 25%~50%, which is a serious corrosion phenomenon;
Grade 2: The defect area accounts for 10%~25%, the appearance rating is I, and the sample has the phenomenon of matrix metal corrosion;
Level 3: Defect area accounts for 5%~10%, appearance grade H, there is a very thick corrosion product layer or pitting on the surface of the sample, and there is deep pitting;
Grade 4: The defect area accounts for 2.5%~5%, the appearance grade is G, and there is a thick corrosion product layer or pitting corrosion on the surface of the sample;
Level 5: The defect area accounts for 1.0%~2.5%, the appearance grade is F, and there are corrosion products or pitting corrosion on the surface of the sample, and one of them is distributed on the entire surface of the sample;
Grade 6: The defect area accounts for 0.5%~1.0%, the appearance is rated E, the surface of the sample is seriously lost, or there is a thin layer of corrosion products or pitting on the partial surface of the sample;
Grade 7: Defect area accounts for 0.25%~0.5%, appearance grade D, the surface of the sample is severely tarnished or has very slight corrosion products;
Grade 8: The proportion of the defect area is between 0.1% and 0.25%, the appearance rating is C, and the surface of the sample is severely discolored or has very slight corrosion;
Grade 9: The defect area does not account for more than 0.1%, the appearance is rated B, and the surface of the sample has slight to moderate discoloration
Grade 10: No defect area, appearance grade A, no change in appearance of the sample surface.