GALVANIZED STEEL PLATE AND ALLOYED GALVANIZED STEEL PLATE WITH SUPERIOR APPEARANCE AND PLATING ADHESION, AND METHODS OF MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a galvanized steel plate and an alloyed galvanized steel plate that use a high-Si containing steel plate as a base material, and have beautiful appearances free of a surface defect and superior plating adhesion, and methods of manufacturing the same.SOLUTION: There is provided a galvanized steel plate with superior appearance and plating adhesion that has a component composition of 0.20-0.50 mass% C, 0.1-3.0 mass% Si, 0.5-3.0 mass% Mn, 0.001-0.10 mass% P, 0.01-3.00 mass% Al, less than or equal to 0.200 mass% S, and Fe and inevitable impurities for the rest, and includes an internal oxide layer of 4 m or less in thickness on a ferrite side from the boundary surface between ferrite and a galvanized layer and a decarbonization layer of 16 m or less in thickness on the ferrite side from the boundary surface between the ferrite and galvanized layer, the internal oxide layer including Si oxide, including Fe and/or Mn represented as FeMnSiO, by 50% or more in terms of area rate. Here, X=0-1 and Y=3 or 4.