| 摘要 |
PROBLEM TO BE SOLVED: To provide a phosphation Zn-Al-Mg alloy plated steel plate having improved coating film blister corrosion resistance by modifying a phosphate film. SOLUTION: In a chemical-converted steel plate, a phosphate film with the volume-regulation of metal elements other than Zn is deposited on a surface of the Zn-Al-Mg alloy plated steel plate. A plating layer on the surface of a base material contains, by mass, 3-15% Al and 2-5% Mg. Deposition such as Ni, Co, and Fe to be substitution-deposited on the surface of the base material through phoaphating is set to be≤10 mg/m<SP>2</SP>. Phosphate crystal of the chemical conversion film contains at least Mn or Mg of≥0.04 mol ratio to Zn other than Zn, and the mol ratio of Ni, Co and Fe contained in the phosphate crystal to Zn is controlled to be≤0.05. COPYRIGHT: (C)2006,JPO&NCIPI
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