Before leaving the factory, high-strength socket head cap bolts generally have to be treated to a certain extent, and the bluing process is one of them. The so-called bluing treatment is to blacken the surface of the bolt.

bluing treatment

The more commonly used methods are: the traditional alkaline blackening and normal temperature blackening, and the normal temperature blackening method is not good for the treatment of low carbon steel. As for bolts produced with A3 steel materials, alkaline blackening is generally used: That is, one blackening, two blackening.

In the process of blackening, the blackening liquid should be prepared first, and its main components are sodium hydroxide and sodium nitrite. In practice, attention should be paid to the degreasing and rust removal of the bolts before blackening, so as to carry out passivation and oil immersion after detonation. These processes have a lot to do with the quality of the blackening treatment.

Metal blue liquid medicine.

The most commonly used method is alkaline oxidation or acid oxidation, which forms an oxide film on the metal surface to prevent the metal surface from being corroded. This treatment method is called "blue".

After the "blue" treatment, an oxide film will be formed on the black metal surface, the inner layer is ferrous oxide, and the outer layer is ferric oxide.

When using the alkaline oxidation method to "blue" the liquid, the surface of the bolt must be cleaned first. During the treatment, it is necessary to analyze whether the composition of the liquid meets the requirements at intervals of one week. "After the bluing treatment, rinse with water.

When using the acid oxidation method to "blue" the liquid, pay attention to the working temperature of "blue" should be 100 degrees, and the processing time should be forty-five minutes to forty-five minutes.

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