Chemical conversion agent

A chemical conversion treatment agent that forms a chemical conversion coating on or over a surface of a metallic material, the agent comprising:

• a source of fluorine ions;
• a source A of ions containing zirconium;
• a source B of ions containing aluminum;
• and
• a water-soluble or water-dispersible polymer, or a salt thereof C, containing structural units represented by the following Formula (i):
• at not less than 90% by mole;
• the agent satisfying the following Formula (1):
• (
• A
• ⁢
• c
• +
• Bc
• )
• ×
• (
• pH
• -
• 3
• )
• X
• ≥
• 0.38
• Formula
• ⁢
• (
• 1
• )
• with the proviso that X=7.2×12(−1.6×(Ac+Bc)),
• wherein in the Formula (1),
• Ac is the concentration of zirconium element derived from the Source A in the chemical conversion treatment agent, and is 0.02 g/L to 2 g/L;
• Bc is the concentration of aluminum element derived from the Source B in the chemical conversion treatment agent, and is 0.02 g/L to 2 g/L;
• the ratio of Bc to Ac, Bc/Ac, is 0.03 to 10.0;
• the concentration of the polymer or a salt thereof C, in the chemical conversion treatment agent is 0.0001 g/L to (0.16×Ac+0.23) g/L;
• and
• pH is the pH of the chemical conversion treatment agent, and is 3.8 to 6.0.