| abstract |
(57) [Problem] To provide a method for quickly forming a phosphate film having excellent adhesion and corrosion resistance on an iron-based metal material with a small amount of sludge generated. An iron-based metal material is subjected to anodic electrolysis in an acidic solution having a pH of 1 to 5 and then to cathodic electrolysis in a phosphating solution. For anodic electrolysis, current density: 1 to 100 A / dm 2 , liquid temperature: 90 ° C Hereinafter, the processing time is preferably set to 1 to 60 seconds. In the cathodic electrolysis, current density: 1 to 100 A / dm 2 , liquid temperature: 9 It is preferable that the temperature is 0 ° C. or less and the treatment time is 1 to 60 seconds. The phosphating solution contains phosphate ions as an essential component and contains Mg, It is preferable to contain at least one metal ion selected from Al, Ca, Mn, Fe, Co, Ni, Cu and Zn ions. |