Compared with common zinc plating, mechanical zinc plating, hot dip zinc plating and other surface treatment methods, it is more environmentally friendly. If it only refers to the role of anti-corrosion and oxidation, then hot galvanizing and mechanical galvanizing are preferred. However, these two surface treatments make it more difficult for the bolt to fit the nut. Usually, nuts need reaming, so that the internal thread of the nut will not be galvanized because of the thickening of the bolt surface.