What are the anti-corrosion treatment methods for hexagon head bolts?

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When using hexagon head bolts, anti-corrosion treatment is a very important requirement. Depending on the corrosion conditions, different treatment methods can be used.

1) Oxidation

Since it hardly has the ability to prevent rust due to blackening, it will quickly rust without oil. The torque preload consistency of the blackened square column template is also poor. If improvement is needed, grease can be applied to the internal thread during assembly and then tightened.

2) Sherardizing

Sherardizing is a solid metallurgical thermal diffusion coating of zinc powder. Its uniformity is good, and a uniform layer can be obtained in the threads and blind holes of hexagon head bolts. Its processing process is pollution-free and environmentally friendly.

3) Electro-galvanized

Hydrogen embrittlement is prone to occur in the electrogalvanizing process, and the consistency is poor. Connect and assemble with a square column template with a height of 500. When butting and assembling hexagon head bolts, please pay attention to the consistency of the socket interface. You can take an auxiliary bracket, open the auxiliary bracket, and clamp the auxiliary bracket to the wooden side of the junction of the two square column templates according to the marked position, and tighten it on the other side of the same height to mark the position. First place a single piece of toggle clamp horizontally on the auxiliary support. Place the elbow up so that the end of the second clip passes through the curved space of the clip head, and then place it horizontally on the auxiliary support. In order to improve the torque-pre-tightening force consistency, the method of coating lubricating substances after plating can also be used to improve and increase the torque of the hexagon head bolts.

4) Cadmium plating

The corrosion resistance of cadmium coating is very good, especially in the ocean atmosphere, its corrosion resistance is better than other surface treatments. The waste liquid treatment in the cadmium electroplating process is expensive, and the price is about 15-20 times that of electro-galvanized zinc. Therefore, it is not suitable for hexagonal head bolts in general industries, but suitable for fasteners for oil drilling platforms and HNA aircraft.

5) Chrome plating

The chromium coating is very stable in the atmosphere, is not easy to change color and lose luster, has high hardness and good wear resistance. Chrome plating on hexagon head bolts is usually used for decoration.

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