Zinc-zinc-alloy hot-dip galvanized steel sheet with low unplated defects and excellent coating adhesion and manufacturing method thereof

摘要

Zinc and zinc-alloy hot-dip steel sheets and galvanized zinc and zinc-alloy hot-dip steel sheets for use in automobiles, and methods for producing these steel sheets. Zinc and zinc-alloy hot-dip galvanized steel sheets with an oxide of an element that can be easily oxidized directly under the coating and exhibit a reduced number of vacant spots and good coating adhesion. According to the method, during hot rolling the cooling is performed at a slow-cooling rate so that the temperature for coiling is set at 600 ° C. or higher and the oxide is maintained after the subsequent steps.