If the zinc coating is good, but when the light comes out in 3% nitric acid, there is a dark shadow on the coating, and the film is brown when passivation occurs, which may be caused by foreign metal impurities such as copper or lead in the galvanized liquid. When there is a problem in the process of galvanizing, check the temperature and current density first, and then measure and adjust the content of zinc and sodium hydroxide in the bath through the analysis of the bath. Whether DPE levels are low can be determined by Hull cell test.

In strict accordance with the multi-pass small compression rate drawing, the total compression rate is 96.48%, reducing the scraping of zinc layer. The whole wire drawing die is made of tungsten steel die and polycrystalline die. The Angle of the working cone of the wire drawing die is 12° ~ 16°, and the length of the sizing belt is 0.15 of the diameter of the wire, so as to ensure that the deformation of the zinc layer is basically synchronous with the steel wire substrate.