In order to study the formation mechanism of white spot surface defect structure of phosphating film on the surface of phosphating film, the fine wire rods with the same parent material batch number and the same brand name SCM435 were used in the same zinc phosphating production process: pickling→high-pressure water washing→water washing→phosphating→neutralization →saponification, to prepare the phosphating film with white spot defects and normal phosphating film, and the phosphating slag structure deposited under the same process was taken. Stereomicroscope and scanning electron microscope (SEM) were used to observe the morphology of white spot defects, normal phosphating film and phosphating slag structure, and X-ray photoelectron spectroscopy (XPS) was used to analysis the difference in chemical composition of white spot defects, normal phosphating film and phosphating slag. Result showed that the it could still vaguely be seen that the shape and trend of the phosphating film with white spot defects were similar to the normal phosphating film, but its trunk structure was too coarse, the branch tissue was not obvious and relatively disordered. The white spot defects structure on the surface of the phosphating film was not deposited by phosphating slag. The white spots structure had coarse crystalline structure of normal phosphating film structure morphology and trend, and the structure contained Fe2O3 and more ferrous salt.
