| 摘要 |
A chemical conversion treatment solution for a steel material is provided. The solution is an acidic aqueous solution of pH 3 to 5 containing 50 to 500 ppm by weight of zirconium fluoride complex in terms of Zr, 5 to 50 ppm by weight of free fluorine, and 5 to 30% by weight in relation to Zr of polyethyleneimine having a weight average molecular weight of 300 to 10,000, a molar ratio of the primary amino group of at least 30%, and a molar ratio of the tertiary amino group of at least 15% in relation to the total amino group content. A method for chemical conversion treatment is also provided. This invention realizes excellent coating adhesion and corrosion resistance after the coating, as well as improved throwing power in the coating, and in particular, in the electrodeposition coating of a steel material.
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