Honda Motor Co., Ltd.

Nihon Parkerizing Co., Ltd.

Yasuhito Murai

Katsutoshi Ando

Yuko Takanashi

Hideki Takakuwa

A solution for treating a surface of an iron material includes (a) zirconium fluoride; (b) ion of a rare earth element and/or a compound containing a rare earth element; (c) a polyallylamine; (d) aluminum ion; and (e) free fluorine ion. Zirconium in the component (a) is at a weight concentration A of 10 to 1000 ppm. The ratio K of the weight concentration B of the rare earth element in the component (b) to the weight concentration A (B/A) is 0.1 to 30. The component (d) is at a weight concentration D of 50 to 250 ppm. The component (e) is at a weight concentration E of 0.5 to 30 ppm. A coating having excellent corrosion resistance before and after the subsequent coating can be deposited on the surface of an iron material by using the surface treating solution which does not contain environmentally harmful ingredients.

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Saitama, Japan

Yasuhito Murai