| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hot-dip zinc-plated steel sheet for hot press having excellent oxidation resistance. <P>SOLUTION: The hot-dip zinc-plated steel sheet has oxide layers having the thickness of≥10 nm and containing 3Zn(OH)<SB>2</SB>-nSO-nH<SB>2</SB>O (n=0 to 5) are formed on both sides of the plated steel sheet. For example, the steel sheet is hot-dip zinc-plated, and subjected to the temper rolling. Then, the steel sheet is brought into contact with alkaline solution to activate the plating surface. Thereafter, the steel sheet is brought into contact with acid solution containing Zn ions and sulfate ions and having the pH buffering action. After the steel sheet is brought into contact with the acid solution, it is held for 1-90 seconds, and water-rinsed to form the oxide layer. When the steel sheet after coating the oxide layers is heated above the Ac3 transformation point and subjected to the hot press, any defective appearance is suppressed, any peeling of the plating layer is not observed, and excellent oxidation resistance is demonstrated. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
