| abstract |
PROBLEM TO BE SOLVED: To provide a protective film having high safety and excellent corrosion resistance and a good appearance by forming a protective film containing no hexavalent chromium or fluorine on a steel material surface from which impurities have been removed. The present invention provides a method for forming a protective film on a steel material surface and a treatment composition thereof, which can obtain a chromate-treated steel material and can be incorporated in a conventional equipment process, thereby reducing the production cost. SOLUTION: This method is a method of forming a protective film on a plating surface applied to zinc or other metal or alloy or the metal, etc., which has been subjected to heat treatment, wherein the surface is subjected to a flash treatment with an alkali metal or the like. And processing by A method for forming a protective film on the surface of a steel material, comprising performing an acid treatment and then applying a protective film agent composition. |