Study on zinc slag defects on surface of pure hot dip galvanized steel sheet

Hot dip galvanized steel sheet is widely used in the automotive field because of its advantages of low cost, thick hot dip galvanized layer, reducing body defects, improving vehicle performance, and beautifying surface appearance. However, the zinc slag defects on the surface of the steel plate significantly reduce the surface quality of the steel plate. In this paper, the morphology of zinc slag on the surface of a pure hot-dip galvanized steel sheet was analyzed by scanning electron microscope. The results showed that the zinc slag defects on the surface of pure hot-dip galvanized steel strip was round, and the size was large, about 700 um. By adjusting the air knife pressure, the aluminum content in the zinc tank, and the opening of the RCS fan, the number and size of zinc slag defects on the surface of pure hot-dip galvanized steel strip can be significantly reduced. As a result, the steel plate was improved.