If you want iron screws to be more corrosion resistant, the screws will be galvanized. So it's usually carbon steel which is steel. Galvanized screw is the steel that has been removed from the rust in the zinc liquid, the temperature of the zinc liquid needs to be about 500 degrees, which can make the steel surface of the bolt attached with zinc layer, the purpose is to play the role of anti-corrosion.
The galvanized layer is glued firmly, but it should be noted that the amount of galvanized should be in the appropriate range, because if the content is relatively small, it will be easy to fall off in a humid environment.
Galvanized screws can be hot plated or cold plated, hot plating is by soaking in zinc solution, through high temperature can melt the zinc, and then add some other auxiliary materials. Its advantage is that the corrosion resistance is relatively strong, and the hardness of the formed galvanized layer will be better.
Cold plating can also be taken, that is, electroplating, which requires electrolysis and does not require heating. However, the amount of zinc is relatively small, and it is easy to fall off in a humid environment. The former belongs to chemical treatment, the latter belongs to physical treatment.
