| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hot dip galvannealed steel sheet manufacturing method of a hot dip galvannealed steel sheet having excellent press-forming property even for a material such as a high-strength hot dip galvannealed steel sheet having high forming load and easy to generate die galling, and the hot dip galvannealed steel sheet. <P>SOLUTION: A steel sheet is subjected to the hot dip galvanizing, and further galvannealing by the heating, and brought into contact with an acid solution after temper rolling. After completing the contact, the steel sheet is naturally left for 1-30 seconds, and rinsed with water. When depositing a Zn-based oxide layer of the thickness of ≥10 nm on the surface of the galvanized steel sheet, Zr ions are contained in the acid solution. Thus, the oxide layer having the mean thickness of ≥10 nm and containing Zn and Zr as essential components is deposited on the surface of the galvanized steel sheet. The acid solution preferably contains at least one kind of sulfate, nitrate, chloride and phosphate of Zr with the Zr ion concentration in a range of 0.1-50 g/l. <P>COPYRIGHT: (C)2007,JPO&INPIT |
