| 摘要 |
There are provided hot-dip galvanized steel sheets and galvannealed steel sheets that have no surface defects and have a good appearance and good adhesion to the coating and methods for producing the hot-dip galvanized steel sheets and galvannealed steel sheets. The hot-dip galvanized steel sheets and galvannealed steel sheets are produced from high-Si-content steel sheets. A hot-dip galvanized steel sheet having a good appearance and good adhesion to a coating, the hot-dip galvanized steel sheet having a composition comprising, on a mass basis: C: 0.20% to 0.50%, Si: 0.1% to 3.0%, Mn: 0.5% to 3.0%, P: 0.001% to 0.10%, Al: 0.01% to 3. 00%, and S: 0.200% or less, a remainder being Fe and incidental impurities, wherein the hot-dip galvanized steel sheet includes an internal oxidation layer and a decarburized layer, the internal oxidation layer having a thickness of 4 µm or less on a ferrite side from an interface between ferrite and a galvanized layer, the decarburized layer having a thickness of 16 µm or less on the ferrite side from the interface between the ferrite and the galvanized layer, and 50% or more by area of the internal oxidation layer is composed of a Si oxide containing Fe and/or Mn represented by Fe 2x Mn 2-2x SiO y , wherein X ranges from 0 to 1, and Y is 3 or 4. |
