Influences of Surface Status of Cold—rolling Steel Sheet for Automobile on Quality of Phosphating Film

摘要

The influences of chemical compositions,oiling status,roughness of cold-rolling steel sheet surface for automobile on quality of phosphating film were studied by sEM,EDS and XRD. And the relationship was studied between "P ratio" and Zinc content of phosphating film. The result shows that fine and uniform phosphating film is hardly formed on the surface of the cold-rolling steel sheet with increasing of C,Al contents in the sheet or with increasing of amount of oil coating on the sheet surface. It is propitious to improve the quality of phosphating film by increasing Mn content or by roughening the surface of cold-rolling steel sheet. "P ratio" of phosphating film comes down with increase of Zn content in the phosphating film.