HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET EXCELLENT IN IMPACT PEELING RESISTANCE AND WORKED PORTION CORROSION RESISTANCE

摘要

A high-strength hot-dip galvanized steel sheet including a hot-dip galvanized plating layer on a steel sheet base material whose tensile strength is 590 MPa or more, wherein the plating layer includes projecting alloy layers being in contact with the steel sheet base material, a number density of the projecting alloy layers is 4 pieces/mm or more per unit length of an interface between the steel sheet base material and the plating layer when seen from a sectional direction, and a maximum diameter of the projecting alloy layers at the interface is 100 µm or less, wherein the steel sheet base material includes: a miniaturized layer being directly in contact with the interface between the steel sheet base material and the plating layer; a decarburized layer being in contact with the miniaturized layer and existing on an inward side of the steel sheet base material; and an inner layer other than the miniaturized layer and the decarburized layer, and one kind or two kinds or more of oxides of Si and Mn are contained in layers of the miniaturized layer, the decarburized layer, and the projecting alloy layers.